"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:e6472160-3d10-4a1c-8241-759fe215e85e","http://resolver.tudelft.nl/uuid:e6472160-3d10-4a1c-8241-759fe215e85e","Improving plant-level heat pump performance through process modifications","de Raad, B.W. (TU Delft Energie and Industrie); van Lieshout, Marit (Rotterdam University of Applied Sciences); Stougie, L. (TU Delft Energie and Industrie); Ramirez, Andrea (TU Delft ChemE/Chemical Engineering)","","2024","Heat pumps are a promising option to decarbonize the industrial sector. However, their performance at a plant-level can be affected by other process changes. In this work, process changes that improve the heat pump's performance have been identified using Process Change Analysis (PCA), where the background pinch point is used as a reference point for appropriate placement. The effects of the process changes on the heat pump's work requirements are studies by introducing exergy to PCA to form the split exergy grand composite curve. This graph shows the work potential of the streams connected to the heat pump and therefore its work targets. The framework is demonstrated in two case studies. In a biodiesel production plant, it allowed to identify technologies that enhance heat pump performance while reducing overall heating requirements. Here, a heat pump transfers 1.9 MW with a COP of 4.2 but incurs a 40 kW penalty for transferring heat above the background process's pinch temperature. Replacing the wet water washer with a membrane separation unit avoided this penalty, while drastically reducing energy requirements from 0.9 MW to 0.3 MW. in a vinyl chloride monomer-purification process, PCA showed how the extraction of heat by the heat pump impacted the formation of the background pinch, from which an implementation strategy was derived that increased the heat pump's plant-level performance by 6.5% with respect to standard implementation.","Exergy grand composite curve; Heat pumps; Pinch analysis; Process change analysis","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","Energie and Industrie","","",""
"uuid:ee0a3a4f-f638-47ed-8d92-8997a4ca48e3","http://resolver.tudelft.nl/uuid:ee0a3a4f-f638-47ed-8d92-8997a4ca48e3","Photochromic samarium oxyhydride thin films","Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Schreuders, H. (TU Delft ChemE/O&O groep); Dam, B. (TU Delft ChemE/Chemical Engineering)","","2023","Photochromism has been reported for several rare-earth (RE) metal oxyhydride thin films and is characterized by a reversible darkening of the sample when exposed to light with energy greater than its optical bandgap. Here, we extend the range of known photochromic RE-oxyhydrides to include samarium oxyhydrides. These SmH3−2xOx thin films are made by reactive magnetron sputtering of as-deposited SmH1.9+δ and post-oxidation in the air to the oxyhydride phase. The deposition pressure during sputtering is used to control the resultant properties of the Sm-oxyhydride film, such as the optical bandgap, cubic lattice constant, photochromic contrast, and photochromic bleaching speed. Using Sm as the RE-cation results in slower bleaching speeds compared to other lanthanides. We posit that this is due to the stability of the Sm2+ state and the difficulty to oxidizing it back to the original RE3+ state. This points to the key role of the RE-cation charge state for the optical properties of the material.","OA-Fund TU Delft","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:159c241a-4cb2-4bec-839b-2fc653d03fc5","http://resolver.tudelft.nl/uuid:159c241a-4cb2-4bec-839b-2fc653d03fc5","Tuning the Properties of Thin-Film TaRu for Hydrogen-Sensing Applications","Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep); Schreuders, H. (TU Delft ChemE/O&O groep); van Beugen, N. (TU Delft Applied Sciences); Kinane, Christy (External organisation); Hall, Stephen (ISIS Facility); Dam, B. (TU Delft ChemE/Chemical Engineering)","","2023","Accurate, cost-efficient, and safe hydrogen sensors will play a key role in the future hydrogen economy. Optical hydrogen sensors based on metal hydrides are attractive owing to their small size and costs and the fact that they are intrinsically safe. These sensors rely on suitable sensing materials, of which the optical properties change when they absorb hydrogen if they are in contact with a hydrogen-containing environment. Here, we illustrate how we can use alloying to tune the properties of hydrogen-sensing materials by considering thin films consisting of tantalum doped with ruthenium. Using a combination of optical transmission measurements, ex situ and in situ X-ray diffraction, and neutron and X-ray reflectometry, we show that introducing Ru in Ta results in a solid solution of Ta and Ru up to at least 30% Ru. The alloying has two major effects: the compression of the unit cell with increasing Ru doping modifies the enthalpy of hydrogenation and thereby shifts the pressure window in which the material absorbs hydrogen to higher hydrogen concentrations, and it reduces the amount of hydrogen absorbed by the material. This allows one to tune the pressure/concentration window of the sensor and its sensitivity and makes Ta1-yRuy an ideal hysteresis-free tunable hydrogen-sensing material with a sensing range of >7 orders of magnitude in pressure. In a more general perspective, these results demonstrate that one can rationally tune the properties of metal hydride optical hydrogen-sensing layers by appropriate alloying.","metal hydrides; neutron reflectometry; optical hydrogen sensing; ruthenium; tantalum; thin films; X-ray diffraction","en","journal article","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","RID/TS/Instrumenten groep","","",""
"uuid:d9911bd6-3296-4766-9e39-c342188fd4b0","http://resolver.tudelft.nl/uuid:d9911bd6-3296-4766-9e39-c342188fd4b0","Incorporating indirect costs into energy system optimization models: Application to the Dutch national program Regional Energy Strategies","Wang, N. (TU Delft Energie and Industrie; TNO); Verzijlbergh, R.A. (TU Delft Energie and Industrie); Heijnen, P.W. (TU Delft Energie and Industrie); Herder, P.M. (TU Delft ChemE/Chemical Engineering)","","2023","Energy system optimization models are widely used to aid long-term investment decision-making for energy systems. From a socio-technical system viewpoint, existing models focus on the cost modeling of the technical subsystem, while the indirect costs of the social subsystem are not often modeled. This paper incorporates indirect costs into such a model, including those associated with generation capacity, energy production, and bilateral trades, respectively. As a proof-of-concept, the model has been applied to a case study for the Dutch power system, reflecting the Dutch national program Regional Energy Strategies, where regions collectively plan wind and solar energy capacities. We conclude that incorporating indirect costs significantly changed the optimal investment capacities and the associated costs for the regions compared to benchmark results from the conventional models. Furthermore, in this case study, a potential free-rider problem with regard to the national climate target occurs. Our model is used as a negotiation simulator to inform the regions about the hypothetical free-riding behaviors and thus helps to achieve a socially acceptable investment plan. The proposed energy system optimization model with indirect costs goes beyond the prevalent cost-minimization paradigm, and can be used to study transaction costs, trading barriers, and willingness to pay.","Energy markets; Energy system optimization model; Energy system planning; Indirect costs; Transaction costs; Willingness to pay","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","Energie and Industrie","","",""
"uuid:332c2f51-8859-4fc1-be1e-46977ac76626","http://resolver.tudelft.nl/uuid:332c2f51-8859-4fc1-be1e-46977ac76626","Identifying techno-economic improvements for a steam generating heat pump with exergy-based costs minimization","de Raad, B.W. (TU Delft Energie and Industrie; Rotterdam University of Applied Sciences); van Lieshout, Marit (Rotterdam University of Applied Sciences); Stougie, L. (TU Delft Energie and Industrie); Ramirez, Andrea (TU Delft ChemE/Chemical Engineering)","","2023","Steam generating heat pumps show great potential for reducing carbon emissions in the industrial sector. However, predicting their performance is challenging as the exergy destruction of e.g., compressors and expansion valves increases with the temperature lift and condenser temperature. With over seventy design improvements mentioned in the literature, selecting the most effective design improvements is crucial. In this study, energy and exergy-based methods were compared in their ability to identify design improvements for a single stage subcritical heat pump to produce steam from hot condensate. The energy-based method suggested the addition of a sequential compressor with an intermediate cooler; however, this design did not improve the heat pump's techno-economic performance. The suggestion of adding either an internal heat exchanger or a flash vessel by exergy-based methods did lead in both cases to improved techno-economic performance. The internal heat exchanger performed best and increased the coefficient of performance from 2.3 to 2.8 and reduced operational costs by 0.8 M€ after 5 years of operation. Additionally, the initial investment decreased by 135 k€, and the total costs of operation decreased from 10.3 M€ to 8.7 M€. These findings show that exergy-based methods are the way forward in identifying effective design improvements for steam generating heat pumps.","advanced heat pump configuration; Exergy-based costs minimization; High-temperature heat pump; Steam generation; Techno-economic analysis","en","conference paper","International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-06-21","","ChemE/Chemical Engineering","Energie and Industrie","","",""
"uuid:62c34e2b-68f4-40ff-94c0-c0170ec6f1c4","http://resolver.tudelft.nl/uuid:62c34e2b-68f4-40ff-94c0-c0170ec6f1c4","Large Polaron Conduction, Photoconductivity, and Photochromism in GdOxH3−2x Oxyhydride Thin Films","Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Boshuizen, B. (TU Delft ChemE/O&O groep); Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Hsu, Y. (TU Delft QN/Kavli Nanolab Delft); Schreuders, H. (TU Delft ChemE/O&O groep); Savenije, T.J. (TU Delft ChemE/Opto-electronic Materials); Dam, B. (TU Delft ChemE/Chemical Engineering)","","2023","At ambient conditions, rare-earth oxyhydride thin films show reversible photochromism and photoconductivity, while their mechanism and relation are still unclear. In this work, this question is explored with in situ time-resolved measurements of both optical and transport properties of Gd-based oxyhydride thin films. It is found that p-type large polaron conduction is the initial mechanism of charge transport; however, upon photo-darkening, a 104-fold increase of conductivity occurs, and n-type carriers become dominant. Further, photochromism and photoconductivity are shown to originate from a single process, as indicated by the fact that the photoconductivity is exponentially proportional to the increase of optical absorption. This exponential relation, notably, cannot stem from any of the optically absorbing species thought responsible for photochromism and, therefore, suggests that their formation is accompanied by a concerted increase of negative charge carriers in the Gd oxyhydride films.","gadolinium; hydrides; oxyhydrides; photochromism; photoconductivity; polarons","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:54e17433-f8ca-4736-8572-84b626837643","http://resolver.tudelft.nl/uuid:54e17433-f8ca-4736-8572-84b626837643","Evaluation of centralized/decentralized configuration schemes of CO2 electrochemical reduction-based supply chains","Wiltink, T.J. (TU Delft Energie and Industrie); Yska, Stijn (Student TU Delft); Ramirez, Andrea (TU Delft ChemE/Chemical Engineering); Pérez-Fortes, Mar (TU Delft Energie and Industrie)","","2023","Electrochemical reduction of CO2 (CO2ER) is an emerging technology with the potential to limit the use of fossil-based feedstocks in the petrochemical industry by converting CO2 and renewable electricity into useful products such as syngas. Its successful deployment will depend not only on the technology's performance but also on its integration into the supply chain. In this work, a facility location model is used to gain insights regarding the capacity of CO2ER plants that produce syngas and the implications for the central/decentral placement of these CO2-based syngas plants. Different optimal configurations are examined in the model by changing the syngas transport costs. In this exploratory case, the results indicate that centralization is only an option when the syngas and CO2 transport costs are similar. When syngas transport is more expensive, decentralizing CO2-based syngas plants in the supply chain appears more feasible.","CO electrochemical reduction; CO utilization; optimization; supply chain configurations; supply chain modeling","en","book chapter","Elservier","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-01-18","","ChemE/Chemical Engineering","Energie and Industrie","","",""
"uuid:dc227f3c-5e2f-4211-b82b-ed6c8fdd0d20","http://resolver.tudelft.nl/uuid:dc227f3c-5e2f-4211-b82b-ed6c8fdd0d20","Exploring Multi-Anion Chemistry in Yttrium Oxyhydrides: Solid-State NMR Studies and DFT Calculations","Banerjee, Shrestha (Radboud Universiteit Nijmegen); Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Stigter, Marinus (TU Delft RST/Fundamental Aspects of Materials and Energy); Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy); Dam, B. (TU Delft ChemE/Chemical Engineering); de Wijs, Gilles A. (Radboud Universiteit Nijmegen); Kentgens, Arno P.M. (Radboud Universiteit Nijmegen)","","2023","Rare earth oxyhydrides REOxH(3-2x), with RE = Y, Sc, or Gd and a cationic FCC lattice, are reversibly photochromic in nature. It is known that structural details and anion (O2-:H-) composition dictate the efficiency of the photochromic behavior. The mechanism behind the photochromism is, however, not yet understood. In this study, we use 1H, 2H, 17O, and 89Y solid-state NMR spectroscopy and density functional theory (DFT) calculations to study the various yttrium, hydrogen, and oxygen local environments, anion oxidation states, and hydride ion dynamics. DFT models of YOxH(3-2x) with both anion-ordered and anion-disordered sublattices are constructed for a range of compositions and show a good correlation with the experimental NMR parameters. Two-dimensional 17O-1H and 89Y-1H NMR correlation experiments reveal heterogeneities in the samples, which appear to consist of hydride-rich (x ≈ 0.25) and hydride-poor domains (x ≈ 1) rather than a single composition with homogeneous anion mixing. The compositional variation (as indicated by the different x values in YOxH(3-2x)) is determined by comparing static 1H NMR line widths with calculated 1H-1H dipolar couplings of yttrium oxyhydride models. The 1D 17O MAS spectrum demonstrates the presence of a small percentage of hydroxide (OH-) ions. DFT modeling indicates a reaction between the protons of hydroxides and hydrides to form molecular hydrogen (H+ + H- → H2). 1H MAS NMR indicates the presence of a mobile component that, based on this finding, is attributed to trapped molecular H2 in the lattice.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:ec848891-d2ad-482c-a670-59271ad4a112","http://resolver.tudelft.nl/uuid:ec848891-d2ad-482c-a670-59271ad4a112","Formation of vacancies and metallic-like domains in photochromic rare-earth oxyhydride thin films studied by in-situ illumination positron annihilation spectroscopy","Wu, Z. (TU Delft RST/Fundamental Aspects of Materials and Energy); De Krom, Tom (Student TU Delft); Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Van Hattem, Gijs (Student TU Delft); Schut, H. (TU Delft RST/Neutron and Positron Methods in Materials); Dickmann, Marcel (University of the Federal Armed Forces Munich); Brück, E.H. (TU Delft RST/Fundamental Aspects of Materials and Energy); Dam, B. (TU Delft ChemE/Chemical Engineering); Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy)","","2022","Rare-earth (RE) oxyhydride thin films show a color-neutral, reversible photochromic effect at ambient conditions. The origin of the photochromism is the topic of current investigations. Here, we investigated the lattice defects, electronic structure, and crystal structure of photochromic YHxOy and GdHxOy thin films deposited by magnetron sputtering using positron annihilation techniques and X-ray diffraction, in comparison with Y, YH∼1.9, Y2O3, Gd, GdH∼1.8, and Gd2O3 films. Positron annihilation lifetime spectroscopy (PALS) reveals the presence of cation monovacancies in the as-deposited Y and YH∼1.9 films at concentrations of ∼10-5 per cation. In addition, vacancy clusters and nanopores are found in the as-prepared YHxOy and Y2O3 films. Doppler broadening positron annihilation spectroscopy (DB-PAS) of the Y- A nd Gd-based films reflects the transition from a metallic to an insulating nature of the RE metal, metal hydride, semiconducting oxyhydride and insulating oxide films. In-situ illumination DB-PAS shows the irreversible formation predominantly of di-vacancies, as PALS showed that cation mono-vacancies are already abundantly present in the as-prepared films. The formation of di-vacancies supports conjectures that H-(and/or O2-) ions become mobile upon illumination, as these will leave anion vacancies behind, some of which may subsequently cluster with cation vacancies present. In addition, in RE oxyhydride films, partially reversible shifts in the Doppler parameters are observed that correlate with the photochromic effect and point to the formation of metallic domains in the semiconducting films. Two processes are discussed that may explain the formation of these metallic domains and the changes in optical properties associated with the photochromic effect. The first process considers the reversible formation of metallic nanodomains with reduced O: H composition by transport of light-induced mobile hydrogen and local oxygen displacements. The second process considers metallic nanodomains resulting from the trapping of photoexcited electrons in an eg orbital at the yttrium ions surrounding positively charged hydrogen vacancies that are formed by light-induced removal of hydrogen atoms from octahedral sites. When a sufficiently large concentration, on the order of ∼10%, is reached in a certain domain of the film, band formation of the eg electrons may occur, leading to an Anderson-Mott insulator-metal transition like the case of yttrium trihydride in these domains.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","RST/Fundamental Aspects of Materials and Energy","","",""
"uuid:4f46c392-85d8-455e-99ea-9d22742f0136","http://resolver.tudelft.nl/uuid:4f46c392-85d8-455e-99ea-9d22742f0136","Flexible control of pulse intensity and repetition rate for multiphoton photostimulation","Maddalena, L. (TU Delft ImPhys/Microscopy Instrumentation & Techniques); Ouwehand, M. (TU Delft ImPhys/Microscopy Instrumentation & Techniques); Safdar, H. (TU Delft ChemE/Chemical Engineering); Carroll, E.C.M. (TU Delft ImPhys/Microscopy Instrumentation & Techniques)","","2022","In deep tissue imaging, pulsed near-infrared lasers commonly provide high peak powers needed for nonlinear absorption, but average power and linear absorption can be limiting factors for tissue damage through heat. We implemented intra-cavity dumping within a mode-locked Ti:Sapphire laser used for two-photon computer generated holography stimulation. This system enables photostimulation in which pulse energy, average power, and repetition rate can each be varied and harnessed as degrees of freedom. We demonstrate how this system provides a new dimension of temporal control in photostimulation experiments to alter the ratio of nonlinear to linear light-tissue interactions, namely by tuning the laser repetition rate between single-shot and ≈ 3 MHz. Repetition rates below 1 MHz, yielding pulse energies over 60 nJ, facilitated holographic projections with more regions of interest than the highest repetition rate of 3 MHz. Even lower repetition rates ( ≈ 10 kHz) diminished thermal load on the sample, as characterized by quantification of heat shock protein expression in zebrafish tissue.","nonlinear optics; photostimulation; computer generated holography; laser cavity dumping; light-tissue interaction; optogenetics","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ImPhys/Microscopy Instrumentation & Techniques","","",""
"uuid:d2dc40fb-5682-4314-aeda-aeea84d49368","http://resolver.tudelft.nl/uuid:d2dc40fb-5682-4314-aeda-aeea84d49368","Erratum to: Aliovalent Calcium Doping of Yttrium Oxyhydride Thin Films and Implications for Photochromism (The Journal of Physical Chemistry C (2022) 126:34 (14742−14749) DOI:10.1021/acs.jpcc.2c04456)","Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Usman, I.N. (TU Delft QN/Kavli Nanolab Delft); Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Schreuders, H. (TU Delft ChemE/O&O groep); Tyburska-Pueschel, Beata (Dutch Institute for Fundamental Energy Research); Wu, Z. (TU Delft RST/Fundamental Aspects of Materials and Energy); Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy); Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep); De Wijs, Gilles A.; Dam, B. (TU Delft ChemE/Chemical Engineering)","","2022","The energy axes of the RBS and ERD data (contained in Figures 2a,b,d,e, and S4) were originally underestimated, and the corrected figures appear below and in the Supporting Information. The change is in the conversion from raw data to the energy scale, which was initially converted incorrectly. The rescaled x-axis does not change the data conclusions since the assignment of peaks to atoms remains the same and the intensity of the peaks is unaffected. Hence, it has no influence on the calculations and conclusions in the original text. (Figure presented).","","en","journal article","","","","","","Erratum DOI 10.1021/acs.jpcc.2c04456","","","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:833034fe-2d92-4876-87fd-1de58d87b98c","http://resolver.tudelft.nl/uuid:833034fe-2d92-4876-87fd-1de58d87b98c","Electrochemical behavior of cocaine cutting agents at the polarized liquid-liquid interface","Borgul, Paulina (Uniwersytet Lodzki); Sobczak, Karolina (Uniwersytet Lodzki); Rudnicki, Konrad (Uniwersytet Lodzki); Glazer, P.J. (TU Delft Resources & Recycling; TU Delft ChemE/Chemical Engineering); Pawlak, Patrycja (Uniwersytet Lodzki); Trynda, Anna (Central Forensic Laboratory of the Police, Warsaw); Skrzypek, Sławomira (Uniwersytet Lodzki); Poltorak, Lukasz (Uniwersytet Lodzki)","","2022","In this work, we have used cyclic voltammetry to investigate the interfacial behavior of cocaine cutting agents at the electrified liquid-liquid interface formed between a solution of the water and 1,2-dichloroethane phases. Among 27 chemical species used to adulterate cocaine street samples, only 8 were detectable in the available potential window. These include procaine, lidocaine, levamisole, hydroxyzine, caffeine, phenylethylamine, diltiazem, and diphenhydramine. From the calibration curves obtained using voltammetric data, we have extracted the electroanalytical parameters such as detection sensitivities, limits of detection, and limits of quantifications. Also, for each electrochemically active drug, we have calculated diffusion coefficients and plotted the ion partition and concentration fraction diagrams. All this information is discussed in a view of the cocaine sensors development focused on its detection from demanding matrix defined by the street samples composition.","Adulterants; Cocaine sensor; Illicit drugs; Ion partition diagrams; ITIES; Voltammetry","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","Resources & Recycling","","",""
"uuid:c591ede8-e74a-45ff-b997-0f7a2267725b","http://resolver.tudelft.nl/uuid:c591ede8-e74a-45ff-b997-0f7a2267725b","Polymer Modification of Surface Electronic Properties of Electrocatalysts","Venugopal, A. (TU Delft ChemE/Materials for Energy Conversion and Storage); Egberts, Laurentius H.T. (Student TU Delft); Meeprasert, J. (TU Delft ChemE/Inorganic Systems Engineering); Pidko, E.A. (TU Delft ChemE/Inorganic Systems Engineering); Dam, B. (TU Delft ChemE/Chemical Engineering); Burdyny, T.E. (TU Delft ChemE/Materials for Energy Conversion and Storage); Sinha, V. (TU Delft ChemE/Inorganic Systems Engineering); Smith, W.A. (TU Delft ChemE/Materials for Energy Conversion and Storage; University of Colorado)","","2022","Finding alternative ways to tailor the electronic properties of a catalyst to actively and selectively drive reactions of interest has been a growing research topic in the field of electrochemistry. In this Letter, we investigate the tuning of the surface electronic properties of electrocatalysts via polymer modification. We show that when a nickel oxide water oxidation catalyst is coated with polytetrafluoroethylene, stable Ni-CFx bonds are introduced at the nickel oxide/polymer interface, resulting in shifting of the reaction selectivity away from the oxygen evolution reaction and toward hydrogen peroxide formation. It is shown that the electron-withdrawing character of the surface fluorocarbon molecule leaves a slight positive charge on the water oxidation intermediates at the adjacent active nickel sites, making their bonds weaker. The concept of modifying the surface electronic properties of an electrocatalyst via stable polymer modification offers an additional route to tune multipathway reactions in polymer/electrocatalyst environments, like with ionomer-modified catalysts or with membrane electrode assemblies.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:579f2076-23a9-43e5-a546-f9b244350c88","http://resolver.tudelft.nl/uuid:579f2076-23a9-43e5-a546-f9b244350c88","Energy, metastability, and optical properties of anion-disordered R Ox H3-2x (R= Y, La) oxyhydrides: A computational study","Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Stigter, Marinus (TU Delft Fluid Mechanics); Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Banerjee, Shrestha (Radboud Universiteit Nijmegen); Kentgens, Arno P.M. (Radboud Universiteit Nijmegen); Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy); Dam, B. (TU Delft ChemE/Chemical Engineering); De Wijs, Gilles A. (Radboud Universiteit Nijmegen)","","2022","In this paper, we investigate by ab initio DFT how the O:H ratio influences the formation and lattice energy, metastability, and optical properties of Y and La anion-disordered ROxH3-2x oxyhydrides. To achieve this, a set of special quasirandom structures (SQS) is introduced to model anion-disorder along the whole RH3-R2O3 composition line. A comparison with an extensive set of anion-ordered polymorphs of the same composition shows the comparable energy of the anion-disordered phase, which, in particular, in the H-rich composition interval showed the lowest relative energy. In turn, the metastability of the anion-disordered phase depends on the cation size (Y versus La), which determines the maximum H content above which the CaF2-type structure itself becomes unstable. To overcome the accuracy limitations of classical DFT, the modified Becke-Johnson (mBJ) scheme is employed in the study of the electronic properties. We show that major differences occur between H-rich and O-rich R oxyhydrides, as the octahedral H- present for x<1 form electronic states at the top of the valence band, which reduce the energy band gap and dominate the electronic transitions at lower energies, thus increasing the refractive index of the material in the VIS-nIR spectral range. Comparing the DFT results to experimental data on photochromic Y oxyhydride films reinforces the hypothesis of anion-disorder in the H-rich films (x<1), while it hints towards some degree of anion ordering in the O-rich ones (x>1). Our paper exemplifies a strategy to calculate ab initio the electronic/optical properties of a wide range of materials with occupational disorder.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:9bbac4ee-f529-4fd9-8c22-072a849e4b28","http://resolver.tudelft.nl/uuid:9bbac4ee-f529-4fd9-8c22-072a849e4b28","Aliovalent Calcium Doping of Yttrium Oxyhydride Thin Films and Implications for Photochromism","Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Usman, I.N. (TU Delft QN/Kavli Nanolab Delft); Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Schreuders, H. (TU Delft ChemE/O&O groep); Tyburska-Pueschel, Beata (Dutch Institute for Fundamental Energy Research); Wu, Z. (TU Delft RST/Fundamental Aspects of Materials and Energy); Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy); Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep; TU Delft RST/Storage of Electrochemical Energy); De Wijs, Gilles A. (Radboud Universiteit Nijmegen); Dam, B. (TU Delft ChemE/Chemical Engineering)","","2022","To develop an understanding of the photochromic effect in rare-earth metal oxyhydride thin films (REH3-2xOx, here RE = Y), we explore the aliovalent doping of the RE cation. We prepared Ca-doped yttrium oxyhydride thin films ((CazY1-z)HxOy) by reactive magnetron cosputtering with Ca doping concentrations between 0 and 36 at. %. All of the films are semiconductors with a constant optical band gap for Ca content below 15%, while the band gap expands for compositions above 15%. Ca doping affects the photochromic properties, resulting in (1) a lower photochromic contrast, likely due to a lower H- concentration, and (2) a faster bleaching speed, caused by a higher pre-exponential factor. Overall, these results point to the importance of the H- concentration for the formation of a ""darkened""phase and the local rearrangement of these H- for the kinetics of the process.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:c0adbb9b-ddcf-4318-9ece-21a46b8d9689","http://resolver.tudelft.nl/uuid:c0adbb9b-ddcf-4318-9ece-21a46b8d9689","Urinary extracellular vesicles: A position paper by the Urine Task Force of the International Society for Extracellular Vesicles","Erdbrügger, Uta (University of Virginia Health System); Blijdorp, Charles J. (Erasmus MC); Bijnsdorp, Irene V. (Amsterdam UMC); Borràs, Francesc E. (Germans Trias i Pujol Hospital); Bussolati, Benedetta (University of Turin); Byrd, James Brian (University of Michigan Medical School); Jenster, G. (Erasmus MC); van Royen, M.E. (Erasmus MC); van Steijn, V. (TU Delft ChemE/Chemical Engineering; TU Delft ChemE/Product and Process Engineering)","","2021","Urine is commonly used for clinical diagnosis and biomedical research. The discovery of extracellular vesicles (EV) in urine opened a new fast-growing scientific field. In the last decade urinary extracellular vesicles (uEVs) were shown to mirror molecular processes as well as physiological and pathological conditions in kidney, urothelial and prostate tissue. Therefore, several methods to isolate and characterize uEVs have been developed. However, methodological aspects of EV separation and analysis, including normalization of results, need further optimization and standardization to foster scientific advances in uEV research and a subsequent successful translation into clinical practice. This position paper is written by the Urine Task Force of the Rigor and Standardization Subcommittee of ISEV consisting of nephrologists, urologists, cardiologists and biologists with active experience in uEV research. Our aim is to present the state of the art and identify challenges and gaps in current uEV-based analyses for clinical applications. Finally, recommendations for improved rigor, reproducibility and interoperability in uEV research are provided in order to facilitate advances in the field.","biobank; biomarkers; bladder; extracellular vesicles; kidney; liquid biopsy; prostate; rigor and standardization; urine","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:0b125193-94a1-4a19-91fb-a4999acff4f3","http://resolver.tudelft.nl/uuid:0b125193-94a1-4a19-91fb-a4999acff4f3","Influence of Cation (RE = Sc, Y, Gd) and O/H Anion Ratio on the Photochromic Properties of REOxH3-2x Thin Films","Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); De Krom, Tom (Student TU Delft); Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Cornelius, S. (TU Delft ChemE/Materials for Energy Conversion and Storage); Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy); Dam, B. (TU Delft ChemE/Chemical Engineering)","","2021","Rare-earth oxyhydride REOxH3-2x thin films prepared by air-oxidation of reactively sputtered REH2 dihydrides show a color-neutral, reversible photochromic effect at ambient conditions. The present work shows that the O/H anion ratio, as well as the choice of the cation, allow to largely tune the extent of the optical change and its speed. The bleaching time, in particular, can be reduced by an order of magnitude by increasing the O/H ratio, indirectly defined by the deposition pressure of the parent REH2. The influence of the cation (RE = Sc, Y, Gd) under comparable deposition conditions is discussed. Our data suggest that REs of a larger ionic radius form oxyhydrides with a larger optical contrast and faster bleaching speed, hinting to a dependency of the photochromic mechanism on the anion site-hopping.","anions; diffusion; hydride; lanthanides; oxide; oxyhydrides; photochromic; positron annihilation","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:cd96eb2c-76bd-4741-8f34-10efb742145e","http://resolver.tudelft.nl/uuid:cd96eb2c-76bd-4741-8f34-10efb742145e","Iron can be microbially extracted from Lunar and Martian regolith simulants and 3D printed into tough structural materials","Castelein, Sofie M. (Student TU Delft); Aarts, Tom F. (Student TU Delft); Schleppi, Juergen (Heriot-Watt University); Hendrikx, R.W.A. (TU Delft Team Amarante Bottger); Bottger, A.J. (TU Delft Team Amarante Bottger); Benz, D. (TU Delft ChemE/Product and Process Engineering; TU Delft ChemE/Chemical Engineering); Brouns, S.J.J. (TU Delft BN/Stan Brouns Lab); Meyer, A.S. (TU Delft BN/Anne Meyer Lab; University of Rochester); Lehner, B. (TU Delft BN/Stan Brouns Lab)","","2021","In-situ resource utilization (ISRU) is increasingly acknowledged as an essential requirement for the construction of sustainable extra-terrestrial colonies. Even with decreasing launch costs, the ultimate goal of establishing colonies must be the usage of resources found at the destination of interest. Typical approaches towards ISRU are often constrained by the mass and energy requirements of transporting processing machineries, such as rovers and massive reactors, and the vast amount of consumables needed. Application of self-reproducing bacteria for the extraction of resources is a promising approach to reduce these pitfalls. In this work, the bacterium Shewanella oneidensis was used to reduce three different types of Lunar and Martian regolith simulants, allowing for the magnetic extraction of iron-rich materials. The combination of bacterial treatment and magnetic extraction resulted in a 5.8-times higher quantity of iron and 43.6% higher iron concentration compared to solely magnetic extraction. The materials were 3D printed into cylinders and the mechanical properties were tested, resulting in a 400% improvement in compressive strength in the bacterially treated samples. This work demonstrates a proof of concept for the on-demand production of construction and replacement parts in space exploration.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","Team Amarante Bottger","","",""
"uuid:db6841f4-b229-4bd4-ba81-f61edc74a102","http://resolver.tudelft.nl/uuid:db6841f4-b229-4bd4-ba81-f61edc74a102","Simple Accurate Verification of Enthalpy-Entropy Compensation and Isoequilibrium Relationship","Griessen, Ronald (Vrije Universiteit Amsterdam); Dam, B. (TU Delft ChemE/Chemical Engineering)","","2021","In many experimental investigations of thermodynamic equilibrium or kinetic properties of series of similar reactions it is found that the enthalpies and entropies derived from Van ′t Hoff or Arrhenius plots exhibit a strong linear correlation. The origin of this Enthalpy-Entropy compensation, which is strongly related to the coalescence tendency of Van ′t Hoff or Arrhenius plots, is not necessarily due to a physical/chemical/biological process. It can also be a merely statistical artefact. A new method, called Combined K-CQF makes it possible both to quantify the degree of coalescence of experimental Van ‘t Hoff lines and to verify whether or not the Enthalpy-Entropy Compensation is of a statistical origin at a desired confidence level. The method is universal and can handle data sets with any degree of coalescence of Van ‘t Hoff (or Arrhenius) plots. The new method requires only a standard least square fit of the enthalpyΔH versus entropy ΔS plot to determine the two essential dimensionless parameters K and CQF. The parameter K indicates the position (in inverse temperature) of the coalescence region of Van ‘t Hoff plots and CQF is a quantitative measure of the smallest spread of the Van ‘t Hoff plots. The position of the (K, CQF) couple with respect to universal confidence contours determined from a large number of simulations of random Van ‘t Hoff plots indicates straightforwardly whether or not the ΔH-ΔS compensation is a statistical artefact.","artifacts; isokinetic temperature; simulations; statistics; thermodynamics","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","","","",""
"uuid:7a4b98a5-0aaa-4f19-bd26-8703f864e189","http://resolver.tudelft.nl/uuid:7a4b98a5-0aaa-4f19-bd26-8703f864e189","Students' report on an open inquiry","Pols, C.F.J. (TU Delft ImPhys/Practicum support; TU Delft Science Education and Communication); Duynkerke, Lennard (Student TU Delft); Van Arragon, Jels (Student TU Delft); Van Prooijen, Kevin (Student TU Delft); Van Der Goot, Luuk (Student TU Delft); Bera, B. (TU Delft ChemE/Transport Phenomena; TU Delft ChemE/Chemical Engineering)","","2021","As part of the final projects of our introductory lab course, students conceived experiments related to the umbrella topic of 'Physics of toys and sports' and carried out the experiments at their homes. This paper revisits two of these experiments described by student teams and illustrates how self-conceived experiments provide opportunities to truly engage students in doing science.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ImPhys/Practicum support","","",""
"uuid:7ff242bb-31a4-48f1-8e16-5cc7d5bd92e4","http://resolver.tudelft.nl/uuid:7ff242bb-31a4-48f1-8e16-5cc7d5bd92e4","Influence of Crystal Structure, Encapsulation, and Annealing on Photochromism in Nd Oxyhydride Thin Films","Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Nafezarefi, F. (TU Delft ChemE/Materials for Energy Conversion and Storage); Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Cornelius, S. (TU Delft ChemE/Materials for Energy Conversion and Storage); Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep); Schreuders, H. (TU Delft ChemE/O&O groep); Dam, B. (TU Delft ChemE/Chemical Engineering)","","2021","Thin films of rare earth metal oxyhydrides show a photochromic effect, the precise mechanism of which is yet unknown. Here, we made thin films of NdH3-2xOx and show that we can change the band gap, crystal structure, and photochromic contrast by tuning the composition (O2-:H-) via the sputtering deposition pressure. To protect these films from rapid oxidation, we add a thin ALD coating of Al2O3, which increases the lifetime of the films from 1 day to several months. Encapsulation of the films also influences photochromic bleaching, changing the time dependency from first-order kinetics. As well, the partial annealing which occurs during the ALD process results in a dramatically slower bleaching speed, revealing the importance of defects for the reversibility (bleaching speed) of photochromism.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:a6fd61bd-0010-4c8b-a8f3-df016acd59d5","http://resolver.tudelft.nl/uuid:a6fd61bd-0010-4c8b-a8f3-df016acd59d5","Structural properties and anion dynamics of yttrium dihydride and photochromic oxyhydride thin films examined by in situ μ+SR","Chaykina, D. (TU Delft RST/Fundamental Aspects of Materials and Energy; TU Delft ChemE/Materials for Energy Conversion and Storage); De Krom, T. (Student TU Delft); Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Schreuders, H. (TU Delft ChemE/O&O groep); Suter, A. (Paul Scherrer Institut); Prokscha, T. (Paul Scherrer Institut); Dam, B. (TU Delft ChemE/Chemical Engineering); Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy)","","2021","Thin films of rare-earth metal oxyhydrides, such as yttrium oxyhydrides (YH3-2xOx), show a photochromic effect where the transparency of the films decreases reversibly upon exposure to UV light. However, the exact mechanism behind this effect is unknown. In this paper, we describe the behavior of YH3-2xOx thin films, with different O2-:H- ratios, under dark and illuminated conditions using in situ muon spin relaxation (μ+SR), and compare that to an oxygen-free reference compound, yttrium dihydride (YH2-δ). The muon acts as a local magnetic probe in our compounds, giving information related to electronic, structural, and photochromic properties. Although YH2-δ is the parent compound to YH3-2xOx, the muon behavior in these two materials is different - the muon electrostatically interacts primarily with H- (dihydride) or O2- (oxyhydride) - leading to the use of different theoretical models. For YH2-δ, we observed the formation of an entangled H-μ complex and the onset of Mu+ diffusion and H- rearrangement above 150 K (EA,Γ=67±13meV). For the oxyhydrides, we adopted a transition state model, where Mu0 formation and gradual Mu+ recovery take place, accompanied by the formation of a Mu+-O2- complex and a polaron at the Y cation. The activation energy (EA,dia) associated with Mu+ recovery is dependent on lattice relaxation and is lower for thin films of higher H content (EA,dia=29-45meV). In situ illumination further reduces this energy barrier for all measured oxyhydrides, suggesting that the photochromic effect involves a reversible structural rearrangement during photodarkening.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","RST/Fundamental Aspects of Materials and Energy","","",""
"uuid:2894b642-3ac9-4727-93f1-8ba855d2d10b","http://resolver.tudelft.nl/uuid:2894b642-3ac9-4727-93f1-8ba855d2d10b","Biocompatible Graphene Oxide Nanosheets Densely Functionalized with Biologically Active Molecules for Biosensing Applications","Lehner, B. (TU Delft BN/Stan Brouns Lab; Kavli institute of nanoscience Delft); Benz, D. (TU Delft ChemE/Product and Process Engineering; TU Delft ChemE/Chemical Engineering); Moshkalev, Stanislav A. (University of Campinas); Meyer, Anne S. (University of Rochester); Cotta, Monica A. (University of Campinas); Janissen, R. (TU Delft BN/Cees Dekker Lab; Kavli institute of nanoscience Delft)","","2021","Graphene oxide (GO) has immense potential for widespread use in diverse in vitro and in vivo biomedical applications owing to its thermal and chemical resistance, excellent electrical properties and solubility, and high surface-to-volume ratio. However, development of GO-based biological nanocomposites and biosensors has been hampered by its poor intrinsic biocompatibility and difficult covalent biofunctionalization across its lattice. Many studies exploit the strategy of chemically modifying GO by noncovalent and reversible attachment of (bio)molecules or sole covalent biofunctionalization of residual moieties at the lattice edges, resulting in a low coating coverage and a largely bioincompatible composite. Here, we address these problems and present a facile yet powerful method for the covalent biofunctionalization of GO using colamine (CA) and the poly(ethylene glycol) cross-linker that results in a vast improvement in the biomolecular coating density and heterogeneity across the entire GO lattice. We further demonstrate that our biofunctionalized GO with CA as the cross-linker provides superior nonspecific biomolecule adhesion suppression with increased biomarker detection sensitivity in a DNA-biosensing assay compared to the (3-aminopropyl)triethoxysilane cross-linker. Our optimized biofunctionalization method will aid the development of GO-based in situ applications including biosensors, tissue nanocomposites, and drug carriers.","APTES; bioconjugation; colamine; DNA biosensor; graphene oxide; poly(ethylene glycol); surface chemistry","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","BN/Stan Brouns Lab","","",""
"uuid:88746b84-33f8-4156-9b50-5acc9436be98","http://resolver.tudelft.nl/uuid:88746b84-33f8-4156-9b50-5acc9436be98","Suppression of the Phase Coexistence of the fcc-fct Transition in Hafnium-Hydride Thin Films","Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep); Schreuders, H. (TU Delft ChemE/O&O groep); Kim, H.J. (National Institute of Advanced Industrial Science and Technology (AIST)); Sakaki, Kouji (National Institute of Advanced Industrial Science and Technology (AIST)); Hayashi, Shigenobu (National Institute of Advanced Industrial Science and Technology (AIST)); Ikeda, Kazutaka (The High Energy Accelerator Research Organization (KEK)); Otomo, Toshiya (National Institute of Advanced Industrial Science and Technology (AIST)); Dam, B. (TU Delft ChemE/Chemical Engineering); Asano, Kohta (National Institute of Advanced Industrial Science and Technology (AIST))","","2021","Metal hydrides may play a paramount role in a future hydrogen economy. While most applications are based on nanostructured and confined materials, studies considering the structural response of these materials to hydrogen concentrate on bulk material. Here, using in situ in- and out-of-plane X-ray diffraction and reflectometry, we study the fcc ↔fct transition in Hf thin films, an optical hydrogen-sensing material. We show that the confinement of Hf affects this transition: compared to bulk Hf, the transition is pushed to a higher hydrogen-to-metal ratio, the tetragonality of the fct phase is reduced, and phase coexistence is suppressed. These nanoconfinement effects ensure the hysteresis- free response of hafnium to hydrogen, enabling its remarkable performance as a hydrogen-sensing material. In a wider perspective, the results highlight the profound influences of the nanostructuring and nanoconfinement of metal hydrides on their structural response to hydrogen with a significant impact on their applicability in future devices.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","RID/TS/Instrumenten groep","","",""
"uuid:44b6c8b4-3716-4cca-bf4c-9671a86ba266","http://resolver.tudelft.nl/uuid:44b6c8b4-3716-4cca-bf4c-9671a86ba266","Modeling the decentralized energy investment and operation in the prosumer era: a systematic review","Wang, N. (TU Delft Energie and Industrie); Verzijlbergh, R.A. (TU Delft Energie and Industrie); Heijnen, P.W. (TU Delft Energie and Industrie); Herder, P.M. (TU Delft ChemE/Chemical Engineering)","","2020","This paper reviews the literature on the modeling approaches on decentralized energy investment and operation in the prosumer era. The study has several contributions. Firstly, it adds investment models into the review which have not been previously reviewed for decentralized energy modeling. Secondly, a modeling framework consisting of four building blocks is proposed that covers model conceptualization and model operationalization. Thirdly, the relationship between trading mechanisms and model methods is revealed using four evaluation criteria. Furthermore, by reviewing the papers, several trends in the literature are found. Operational models and local markets have been extensively studied, while wholesale market integration and investment models lack scientific attention. Among different trading mechanisms, the usage of bilateral contracts is most commonly seen. Lastly, optimization models significantly outnumber other model methods, and then it follows that their pitfalls such as the scalability of the model and the existence of stable outcomes need to be further addressed in future research.","Investment; Market design; Modeling; Operation; Prosumers; Review","en","conference paper","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2021-04-10","","ChemE/Chemical Engineering","Energie and Industrie","","",""
"uuid:a6af8c3f-0bb8-41d2-9b0f-a8d80900ca4a","http://resolver.tudelft.nl/uuid:a6af8c3f-0bb8-41d2-9b0f-a8d80900ca4a","Resilient Drinking Water Resources","Kloosterman, Ritsche A. (Vitens NV); van der Hoek, J.P. (TU Delft Sanitary Engineering); Herder, P.M. (TU Delft ChemE/Chemical Engineering)","","2020","A significant challenge for managers of drinking water infrastructures is to make effective strategic decisions for assets with a long lifetime in an uncertain and changing environment. Water resources, which are part of the drinking water infrastructures, have a special position in this decision making process as they operate at the interface of the socio-technical and the socio-ecological subsystems: water resources are the input for the technical system, consisting of pipes and pumps that interact with different actors; and water resources can be seen as output from the ecological system which is influenced by environmental and political issues like climate change, drought and competing and changing uses of water and space. This paper discusses how to design the water resources in such a way that they function in the desired way at present, but that the design also fits an uncertain future as good as possible. To this extent, a framework was developed based upon the notion of resilience. Existing general design principles for socio-technical systems from literature were used as building blocks in the development of our water resources design principles (WR-DP) framework. Three key characteristics of water resources were distinguished in this framework: water quantity, water quality and the environmental impact of the water resources. In addition, we distinguished two dimensions that allowed us to explicitly describe all possible design principles: system scale and class. The first dimension, system scale, ranges from one water resource to a network of water resources. The second dimension, class, makes a distinction between social aspects and technical aspects. Application of the WR-DP framework in a case of a drinking water company in the Netherlands showed the usability of the framework.","Drinking water infrastructures; Long term planning; Resilience; Socio-ecological system; Socio-technical system; Strategic decisions; Water resources","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","Sanitary Engineering","","",""
"uuid:945270a4-01a9-4eab-9830-084086b266a0","http://resolver.tudelft.nl/uuid:945270a4-01a9-4eab-9830-084086b266a0","Commoning toward urban resilience: The role of trust, social cohesion, and involvement in a simulated urban commons setting","Feinberg, A. (TU Delft Energie and Industrie); Ghorbani, Amineh (TU Delft Energie and Industrie); Herder, P.M. (TU Delft ChemE/Chemical Engineering)","","2020","In this paper, we investigate the potential of urban commons for building community resilience. We focus on the issue of adaptability to socio-ecological issues, which depends on the social capital built by the local community of practice. We measure this capital through the variables of volunteer involvement, perceived trust, and social cohesion in an agent-based model, which simulates the dynamics of participation in collective activities. We anchor our model with the case of KasKantine in Amsterdam, a cooperative and restaurant run by volunteers. Our model shows that both trust and social cohesion emerge from the interactions in the cooperative, especially when group sizes are kept small. This contributes to the adaptability of such social-ecological systems, helping their communities build social resilience.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","Energie and Industrie","","",""
"uuid:7f99ae5f-88f2-4062-9a5d-2ebbc28fa5ba","http://resolver.tudelft.nl/uuid:7f99ae5f-88f2-4062-9a5d-2ebbc28fa5ba","Photochromic YOxHy thin films examined by in situ positron annihilation spectroscopy","Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy); De Krom, T. W.H. (Student TU Delft); Chaykina, D. (TU Delft ChemE/Materials for Energy Conversion and Storage); Schut, H. (TU Delft RST/Neutron and Positron Methods in Materials); Colombi, G. (TU Delft ChemE/Materials for Energy Conversion and Storage); Cornelius, S. (TU Delft ChemE/Materials for Energy Conversion and Storage); Egger, W. (Universität der Bundeswehr München); Dickmann, M. (Universität der Bundeswehr München); Dam, B. (TU Delft ChemE/Chemical Engineering)","","2020","Doppler broadening positron annihilation spectroscopy depth profiles were collected on photochromic YOxHy thin films. In situ UV illumination of photochromic semiconductor YOxHy films leads to an increase in S-parameter and a large reduction in W-parameter, possibly caused by a change in the charge state of vacancies or the growth of hydrogen-rich metallic Y(Ox)Hy clusters, albeit that vacancy formation or changes in positronium formation during illumination might also play a role. Intriguingly, both the S- and W-parameters increase during thermal bleaching, indicating that another process takes place. The Doppler parameters do not return to their initial values after complete thermal bleaching, suggesting that persistent local rearrangements of vacancies and possibly hydride ions have occurred during the full photodarkening-thermal bleaching cycle. Positron annihilation lifetime spectroscopy shows that a small fraction of positronium is formed in as-deposited YOxHy films, indicating that the films contain some nanopores.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","RST/Fundamental Aspects of Materials and Energy","","",""
"uuid:2f63eea8-a03e-4398-8d12-64f21c0cf743","http://resolver.tudelft.nl/uuid:2f63eea8-a03e-4398-8d12-64f21c0cf743","DNA-membrane complex formation during electroporation is DNA size-dependent","Sachdev, S. (TU Delft ChemE/Product and Process Engineering); Feijoo Moreira, Sara (Student TU Delft); Keehnen, Yasmine (Student TU Delft); Rems, L. (TU Delft ChemE/Product and Process Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Boukany, P. (TU Delft ChemE/Product and Process Engineering)","","2020","Size of DNA molecules governs their interaction with the cell membrane during electroporation and their subsequent transport inside the cell. In order to investigate the effect of DNA size on DNA-membrane interaction during electroporation, cells are electro-pulsed with DNA molecules; 15 bp, 25 bp, 50 bp, 100 bp and 1000 bp (bp = base pairs). Within the experimental parameter space, DNA-membrane complexes or DNA aggregates are observed at the cell membrane for DNA molecules containing 25 or more base pairs. No aggregates are observed for DNA molecules containing 15 bp. For all DNA sizes, direct access to the cytoplasm is observed, however the amount translocated decays with the size. The observed dependency of DNA aggregate formation on the size of the DNA molecules is consistent with the Onsager's theory of condensation of anisotropic rod-like molecules.","DNA aggregation; DNA size; DNA-membrane complex formation; Electropermeabilization; Electroporation; Gene electrotransfer","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:c97f643c-002f-4dc9-a243-2df4f9a784b1","http://resolver.tudelft.nl/uuid:c97f643c-002f-4dc9-a243-2df4f9a784b1","Low Noble Metal Content Catalysts for Hydrogen Fuel Technology","Westsson, E.E. (TU Delft RST/Storage of Electrochemical Energy; TU Delft ChemE/Advanced Soft Matter; TU Delft ChemE/Chemical Engineering)","Koper, G.J.M. (promotor); Picken, S.J. (promotor); Delft University of Technology (degree granting institution)","2019","The increasing energy demand of the world population in combination with tangible climate change effects stemming from rising carbon dioxide emissions is currently characterizing a large portion of the political and societal debate. Despite huge technological advancement in the field of renewable energy resulting in energy prices lower than that of fossil based energy, the rate of greenhouse gas emissions has not even levelled off but rather kept increasing. A part of the problem lies in the very nature of season and weather dependent energy conversion technologies producing electricity peaks that are hard to buffer. The solar and wind powered scenario is not yet able to completely replace the relatively demand flexible fossil fuel based power plants. The gap between energy production and energy use, in essence meaning storage and distribution of sustainable energy, constitutes one of the largest challenges of our times. Hydrogen has been proposed as a molecule with the potential of being an important energy carrier in a renewable energy based economy. In a fuel cell, hydrogen can be electrochemically oxidized to water, releasing its chemical energy without the emission of combustion by-products like carbon dioxide. Commonly platinum is used as a catalyst to speed up the anode and cathode reactions in a fuel cell. Reversibly, an electrolyser uses electricity to electrochemically split water into its constituents; hydrogen and oxygen. Ideally, hydrogen could be produced where and when the electricity is available or cheap and be stored or transported to the location where it is needed, although technical challenges as well as infrastructural hurdles are still to be solved. If electrochemical devices, such as fuel cells, are to play a major role in the future energy landscape a better understanding of catalytic processes along with cheap and scalable non-noble metal catalysts are still needed.","Fuel cell; Catalysis; Core-shell nanoparticles","en","doctoral thesis","","978-94-028-1696-9","","","","","","","","ChemE/Chemical Engineering","ChemE/Advanced Soft Matter","","",""
"uuid:31c6f93c-c838-46b0-8241-bd42cf6198a7","http://resolver.tudelft.nl/uuid:31c6f93c-c838-46b0-8241-bd42cf6198a7","Response of an actin network in vesicles under electric pulses","Perrier, D.L. (TU Delft ChemE/Product and Process Engineering); Vahid Belarghou, A. (TU Delft ChemE/Product and Process Engineering); Kathavi, Vaishnavi (Student TU Delft); Stam, Lotte (Student TU Delft); Rems, L. (TU Delft ChemE/Product and Process Engineering); Mulla, Yuval (AMOLF); Muralidharan, A. (TU Delft ChemE/Product and Process Engineering); Koenderink, Gijsje H. (AMOLF); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Boukany, P. (TU Delft ChemE/Product and Process Engineering)","","2019","We study the role of a biomimetic actin network during the application of electric pulses that induce electroporation or electropermeabilization, using giant unilamellar vesicles (GUVs) as a model system. The actin cortex, a subjacently attached interconnected network of actin filaments, regulates the shape and mechanical properties of the plasma membrane of mammalian cells, and is a major factor influencing the mechanical response of the cell to external physical cues. We demonstrate that the presence of an actin shell inhibits the formation of macropores in the electroporated GUVs. Additionally, experiments on the uptake of dye molecules after electroporation show that the actin network slows down the resealing process of the permeabilized membrane. We further analyze the stability of the actin network inside the GUVs exposed to high electric pulses. We find disruption of the actin layer that is likely due to the electrophoretic forces acting on the actin filaments during the permeabilization of the GUVs. Our findings on the GUVs containing a biomimetic network provide a step towards understanding the discrepancies between the electroporation mechanism of a living cell and its simplified model of the empty GUV.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:8d8b940f-85e8-4ff4-828c-099ecfd6180c","http://resolver.tudelft.nl/uuid:8d8b940f-85e8-4ff4-828c-099ecfd6180c","Thermal fluctuations in capillary thinning of thin liquid films","Shah, M.S. (TU Delft ChemE/Product and Process Engineering); van Steijn, V. (TU Delft ChemE/Product and Process Engineering); Kleijn, C.R. (TU Delft ChemE/Transport Phenomena); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering)","","2019","Thermal fluctuations have been shown to influence the thinning dynamics of planar thin liquid films, bringing predicted rupture times closer to experiments. Most liquid films in nature and industry are, however, non-planar. Thinning of such films not just results from the interplay between stabilizing surface tension forces and destabilizing van der Waals forces, but also from drainage due to curvature differences. This work explores the influence of thermal fluctuations on the dynamics of thin non-planar films subjected to drainage, with their dynamics governed by two parameters: The strength of thermal fluctuations, , and the strength of drainage, . For strong drainage , we find that the film ruptures due to the formation of a local depression called a dimple that appears at the connection between the curved and flat parts of the film. For this dimple-dominated regime, the rupture time, , solely depends on , according to the earlier reported scaling, . By contrast, for weak drainage , the film ruptures at a random location due to the spontaneous growth of fluctuations originating from thermal fluctuations. In this fluctuations-dominated regime, the rupture time solely depends on as , with . This scaling is rationalized using linear stability theory, which yields as the growth rate of the fastest-growing wave and . These insights on if, when and how thermal fluctuations play a role are instrumental in predicting the dynamics and rupture time of non-flat draining thin films.","breakup/coalescence; thin films","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:8ed0c978-6d1d-4867-854e-4e1650794520","http://resolver.tudelft.nl/uuid:8ed0c978-6d1d-4867-854e-4e1650794520","Control over the Formation of Supramolecular Material Objects Using Reaction-Diffusion","Lovrak, M. (TU Delft ChemE/Advanced Soft Matter); Hendriksen, W.E.J. (Student TU Delft); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); van Steijn, V. (TU Delft ChemE/Product and Process Engineering); Eelkema, R. (TU Delft ChemE/Advanced Soft Matter); van Esch, J.H. (TU Delft ChemE/Advanced Soft Matter)","","2019","Controlled diffusion, reaction and assembly of hydrogelator precursors can be used to create soft hydrogel objects of defined shape and size. In this study we show that controlling local reaction kinetics by means of pH, diffusion length and the concentrations of reactants allows control over the dimensions of formed supramolecular structures. By correlating a reaction diffusion model to experimental results, we show that the influence of all these control parameters can be unified using the Damköhler number, thus providing an easy-to-use relation between experimental parameters and structure dimensions. Finally, our study suggests that control over concentration gradients and chemical reactivity in combination with supramolecular chemistry is a promising platform for the design of soft matter objects of defined sizes, a concept that has received little attention up until now.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Advanced Soft Matter","","",""
"uuid:4f72249c-80f6-4136-b7b7-b72c95e382d7","http://resolver.tudelft.nl/uuid:4f72249c-80f6-4136-b7b7-b72c95e382d7","DNA translocation to giant unilamellar vesicles during electroporation is independent of DNA size","Sachdev, S. (TU Delft ChemE/Product and Process Engineering); Muralidharan, A. (TU Delft ChemE/Product and Process Engineering); Choudhary, Dipendra K. (Student TU Delft); Perrier, D.L. (TU Delft ChemE/Product and Process Engineering); Rems, L. (TU Delft ChemE/Product and Process Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Boukany, P. (TU Delft ChemE/Product and Process Engineering)","","2019","Delivery of naked DNA molecules into living cells via physical disruption of the membrane under electric pulses has potential biomedical applications ranging from gene electro-transfer, electro-chemotherapy, to gene therapy, yet the mechanisms involved in DNA transport remain vague. To investigate the mechanism of DNA translocation across the cell membrane, giant unilamellar vesicles (GUVs) were electroporated in the presence of DNA molecules keeping the size of the DNA molecules as a variable parameter. We experimentally determined the translocation efficiency for each size of the DNA molecule, to compare the results with the existing and conflicting theories of the translocation mechanism i.e. stochastic threading and bulk electrophoresis. We observed that the translocation efficiency is independent of DNA size (ranging from 25–20 000 bp, bp = base pairs), implying that DNA molecules translocate freely across the electro-pores in the lipid membrane in their native polymer conformation, as opposed to unravelling and threading through the electro-pore. Bulk electrophoretic mobility determines the relationship between translocation efficiency and the size of the DNA molecule. This research provides experimental evidence of the mechanistic understanding of DNA translocation across lipid membranes which is essential for devising efficient and predictable protocols for electric field mediated naked DNA delivery.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:a0ad4aa1-c54d-4688-b071-c14c56995c36","http://resolver.tudelft.nl/uuid:a0ad4aa1-c54d-4688-b071-c14c56995c36","On the Stability of Permanent Electrochemical Doping of Quantum Dot, Fullerene, and Conductive Polymer Films in Frozen Electrolytes for Use in Semiconductor Devices","Gudjónsdóttir, S. (TU Delft ChemE/Chemical Engineering; TU Delft ChemE/Opto-electronic Materials); van der Stam, W. (TU Delft ChemE/Chemical Engineering; TU Delft ChemE/Opto-electronic Materials); Koopman, Christel (Student TU Delft); Kwakkenbos, Bob (Student TU Delft); Evers, W.H. (TU Delft BN/Technici en Analisten; Kavli institute of nanoscience Delft); Houtepen, A.J. (TU Delft ChemE/Opto-electronic Materials)","","2019","Semiconductor films that allow facile ion transport can be electronically doped via electrochemistry, where the amount of injected charge can be controlled by the potential applied. To apply electrochemical doping to the design of semiconductor devices, the injected charge has to be stabilized to avoid unintentional relaxation back to the intrinsic state. Here, we investigate methods to increase the stability of electrochemically injected charges in thin films of a wide variety of semiconductor materials, namely inorganic semiconductors (ZnO NCs, CdSe NCs, and CdSe/CdS core/shell NCs) and organic semiconductors (P3DT, PCBM, and C60). We show that by charging the semiconductors at elevated temperatures in solvents with melting points above room temperature, the charge stability at room temperature increases greatly, from seconds to days. At reduced temperature (-75 °C when using succinonitrile as electrolyte solvent) the injected charge becomes entirely stable on the time scale of our experiments (up to several days). Other high melting point solvents such as dimethyl sulfone, ethylene carbonate, and poly(ethylene glycol) (PEG) also offer increased charge stability at room temperature. Especially the use of PEG increases the room temperature charge stability by several orders of magnitude compared to using acetonitrile. We discuss how this improvement of the charge stability is related to the immobilization of electrolyte ions and impurities. While the electrolyte ions are immobilized, conductivity measurements show that electrons in the semiconductor films remain mobile. These results highlight the potential of using solidified electrolytes to stabilize injected charges, which is a promising step toward making semiconductor devices based on electrochemically doped semiconductor thin films.","doping stability; electrochemistry; quantum dots; room temperature freezing; semiconductor devices; semiconductor films","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Opto-electronic Materials","","",""
"uuid:d9ca1e2a-6d76-4257-9649-d26d6e10c44b","http://resolver.tudelft.nl/uuid:d9ca1e2a-6d76-4257-9649-d26d6e10c44b","Numerical analysis of natural convection with conjugate heat transfer in coarse-grained porous media","Chakkingal, M. (TU Delft ChemE/Transport Phenomena; TU Delft ChemE/Chemical Engineering); Kenjeres, S. (TU Delft ChemE/Transport Phenomena); Ataei Dadavi, I. (TU Delft ChemE/Transport Phenomena; TU Delft ChemE/Chemical Engineering); Tummers, M.J. (TU Delft Fluid Mechanics); Kleijn, C.R. (TU Delft ChemE/Transport Phenomena)","","2019","We report numerical simulations of fluid natural convection with conjugate heat transfer in a bottom-heated, top-cooled cubical cavity packed with relatively large (d/L=0.2) solid spheres in a Body Centred Tetragonal (BCT) configuration. We study largely varying solid-to-fluid thermal conductivity ratios between 0.3 and 198, for a fluid Prandtl number of 5.4 and fluid Rayleigh numbers between 1.16 × 10 6 and 1.16 × 10 8 and compare global heat transfer results from our present simulations to our previously published experimental results. The interplay between convection suppression due to the solid packing, and conductive heat transfer in the packing leads to three different regimes, each with a distinct impact of the solid packing on the flow and heat transfer. At low Rayleigh numbers ≈ 10 6 , all packings suppress convective flow. Compared to fluid only Rayleigh–Bénard convection, heat transfer is therefore reduced in low conductivity packings, whereas for high conductivity packings it is increased due to significant conductive heat transfer. At intermediate Rayleigh numbers ≈ 10 7 , low conductivity packings no longer suppress convection, whereas flow is still suppressed in high conductivity packings due to the thermal stratification imposed on the fluid by the solid. Consequently, heat transfer is lower compared to fluid only Rayleigh–Bénard convection, even in high conductivity packings. With a further increase of Rayleigh number ≳ 10 8 , convection starts to be the dominant heat transfer mechanism in all packings, and convective heat transfer is close to that for fluid only Rayleigh–Bénard convection. The contribution of solid conduction in high conductivity packings causes the overall heat transfer to be above that for Rayleigh–Bénard convectin.","Laminar-oscillatory flow; Local fluid flow; Local temperature distribution; Natural convection; Porous media; Structured packing","en","journal article","","","","","","Accepted Author Manuscript","","2021-03-27","","ChemE/Chemical Engineering","ChemE/Transport Phenomena","","",""
"uuid:83d51540-e605-485f-91c8-964d1c252b64","http://resolver.tudelft.nl/uuid:83d51540-e605-485f-91c8-964d1c252b64","Breakup of elongated droplets in microfluidic T-junctions","Haringa, C. (TU Delft ChemE/Transport Phenomena); De Jong, Conrad (Student TU Delft); Hoang, D. (Student TU Delft); Portela, L. (TU Delft ChemE/Transport Phenomena); Kleijn, C.R. (TU Delft ChemE/Transport Phenomena); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); van Steijn, V. (TU Delft ChemE/Product and Process Engineering)","","2019","We show experimentally, and explain theoretically, what velocity is needed to break an elongated droplet entering a microfluidic T-junction. Our experiments on short droplets confirm previous experimental and theoretical work that shows that the critical velocity for breakup scales with the inverse of the length of the droplet raised to the fifth power. For long elongated droplets that have a length about thrice the channel width, we reveal a drastically different scaling. Taking into account that a long droplet remains squeezed between the channel walls when it enters a T-junction, such that the gutters in the corners of the channel are the main route for the continuous phase to flow around the droplet, we developed a model that explains that the critical velocity for breakup is inversely proportional to the droplet length. This model for the transition between breaking and nonbreaking droplets is in excellent agreement with our experiments.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Transport Phenomena","","",""
"uuid:48e4d517-97c3-4f5c-8f7e-e45648a9caf3","http://resolver.tudelft.nl/uuid:48e4d517-97c3-4f5c-8f7e-e45648a9caf3","Effect of 1-ethyl-3-methylimidazolium tetrafluoroborate on the phase equilibria for systems containing 5-hydroxymethylfurfural, water, organic solvent in the absence and presence of sodium chloride","Altway, S. (TU Delft ChemE/Transport Phenomena; TU Delft ChemE/Chemical Engineering); Pujar, S.C. (TU Delft ChemE/Transport Phenomena); de Haan, A.B. (TU Delft ChemE/Transport Phenomena)","","2019","HMF (5-hydroxymethylfurfural) is a well-known promising product from hexose dehydration used for production of biofuels and chemicals. Liquid-liquid extraction is an essential process in HMF production to recover HMF from reaction medium. One of the important parameters needed in the extraction process design is liquid-liquid equilibrium (LLE) data. Organic solvent (methyl isobutyl ketone or 2-pentanol) was applied as extraction solvent to induce phase separation and extract HMF from the aqueous solution in the presence of the ionic liquid [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) and NaCl (sodium chloride). The aim of this study is to investigate the effect of [EMIM][BF4] on the phase equilibria of methyl isobutyl ketone (MIBK) or 2-pentanol, HMF, water systems in the absence and presence of NaCl at 313.15 K and atmospheric pressure (0.1 MPa). The separation factor and the distribution coefficient of HMF were obtained for interpreting liquid-liquid extraction performance. The results indicated that the presence of [EMIM][BF4] caused negative effect on the LLE of organic solvent-HMF-water systems. The slope of tie-lines became more negative with increasing [EMIM][BF4] concentration, indicating lower HMF distribution coefficients and separation factors. However, the presence of NaCl in the HMF aqueous ionic liquid solution can enhance both the separation factor and the distribution coefficient making the HMF extraction more favourable with the HMF distribution coefficient values higher than 1 over the whole range of initial HMF concentrations. According to the results in the present study, MIBK was found superior as an extraction solvent for HMF in the presence of [EMIM][BF4] and NaCl exhibited from the better extraction performance with the separation factors 2.0 times higher than those of 2-pentanol. Furthermore, the NRTL activity coefficient model satisfactorily correlated all the experimental phase equilibrium data provided in this study. The RMSD (root mean square deviations) of the NRTL model were 0.97% and 0.63% for the investigated LLE systems with MIBK and 2-pentanol as solvent in the absence of NaCl, respectively. Whereas, the RMSD of the LLE systems containing NaCl were 0.28% for MIBK-HMF-water-[EMIM][BF4]-NaCl and 0.90% for 2-pentanol-HMF-water-[EMIM][BF4]-NaCl.","5-Hydroxymethylfurfural; Extraction performance; NaCl; Phase equilibria; [EMIM][BF]","en","journal article","","","","","","Accepted Author Manuscript","","2021-01-07","","ChemE/Chemical Engineering","ChemE/Transport Phenomena","","",""
"uuid:733e421f-09bb-4bf3-ab6c-ac6d9d8a1deb","http://resolver.tudelft.nl/uuid:733e421f-09bb-4bf3-ab6c-ac6d9d8a1deb","Photocatalytic Reactor Design: Guidelines for Kinetic Investigation","Visan, Aura (University of Twente); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Lammertink, Rob G.H. (University of Twente)","","2019","This review addresses the inconsistencies in interpreting measurements of intrinsic catalyst properties using lab-scale devices. Any experiment must be analyzed in the framework of a model for which the choice and assumptions regarding the necessary parameters must be based on critical reasoning. Physical intuition about the properties of the system is required for both rigorous 3D computational and simplified analytic descriptions. Any divergence between hypothesis and characteristics of the systems affects both the investigation of intrinsic catalytic properties and the later industrial design where parameters are extrapolated outside their obtained operating range. In this work, we make an overview of the underlying physics of photocatalytic reactions, while focusing on pertinent hypothesis, and discuss the consequences for the most basic reactor designs for which guidelines and criteria are provided to meet their premise.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:cb5af2ec-bcc3-48a7-adee-bc1906b3978c","http://resolver.tudelft.nl/uuid:cb5af2ec-bcc3-48a7-adee-bc1906b3978c","Tailoring the multiphase flow pattern of gas and liquid through micro-packed bed of pillars","Márquez, Nathalie (Avans University of Applied Sciences, Breda); Moulijn, J.A. (TU Delft ChemE/Catalysis Engineering); Makkee, M. (TU Delft ChemE/Catalysis Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering; TU Delft ChemE/Product and Process Engineering); Castaño, Pedro (University of the Basque Country)","","2019","We describe the co-current flow pattern of gas and liquid through micro-fabricated beds of solid and pillars under variable (i) capillary number, (ii) contact angle or wettability and (iii) pillar arrangement, i.e. modifying the distance between pillars or their size and comparing regular with more chaotic systems. Laser-induced fluorescent microscopy and image analysis are used to study the hydrodynamic interactions in terms of dynamics, liquid hold-up, and gas-liquid interfacial area per reactor volume. Those parameters provide insights into the multiphase flow patterns in these systems, how to control them, maximize mass transfer rate and unlock the potential of microreactors to reveal further intrinsic information.","","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-09-29","","ChemE/Chemical Engineering","ChemE/Catalysis Engineering","","",""
"uuid:0107fd15-eb6e-4229-9c7b-f23e9c44cb66","http://resolver.tudelft.nl/uuid:0107fd15-eb6e-4229-9c7b-f23e9c44cb66","Tomographic PIV in a model of the left ventricle: 3D flow past biological and mechanical heart valves","Saaid, Hicham (Universiteit Gent); Voorneveld, Jason (Erasmus MC); Schinkel, C.V. (TU Delft ChemE/O&O groep); Westenberg, Jos (Leiden University Medical Center); Gijsen, F.J.H. (Erasmus MC); Segers, Patrick (Universiteit Gent); Verdonck, Pascal (Universiteit Gent); de Jong, N. (Erasmus MC); Kenjeres, S. (TU Delft ChemE/Transport Phenomena; TU Delft ChemE/Chemical Engineering)","","2019","Left ventricular flow is intrinsically complex, three-dimensional and unsteady. Its features are susceptible to cardiovascular pathology and treatment, in particular to surgical interventions involving the valves (mitral valve replacement). To improve our understanding of intraventricular fluid mechanics and the impact of various types of prosthetic valves thereon, we have developed a custom-designed versatile left ventricular phantom with anatomically realistic moving left ventricular membrane. A biological, a tilting disc and a bileaflet valve (in two different orientations) were mounted in the mitral position and tested under the same settings. To investigate 3D flow within the phantom, a four-view tomographic particle image velocimetry setup has been implemented. The results compare side-by-side the evolution of the 3D flow topology, vortical structures and kinetic energy in the left ventricle domain during the cardiac cycle. Except for the tilting disc valve, all tested prosthetic valves induced a crossed flow path, where the outflow crosses the inflow path, passing under the mitral valve. The biological valve shows a strong jet with a peak velocity about twice as high compared to all mechanical heart valves, which makes it easier to penetrate deeply into the cavity. Accordingly, the peak kinetic energy in the left ventricle in case of the biological valve is about four times higher than the mechanical heart valves. We conclude that the tomographic particle imaging velocimetry setup provides a useful ground truth measurement of flow features and allows a comparison of the effects of different valve types on left ventricular flow patterns.","Flow; Left ventricle; Particle image velocimetry; Prosthetic heart valves; Tomographic PIV","en","journal article","","","","","","Accepted Author Manuscript","","2020-04-22","","ChemE/Chemical Engineering","ChemE/O&O groep","","",""
"uuid:35ab5285-9520-4a31-a2d2-7bade67c66f8","http://resolver.tudelft.nl/uuid:35ab5285-9520-4a31-a2d2-7bade67c66f8","The role of gel-phase domains in electroporation of vesicles","Perrier, D.L. (TU Delft ChemE/Product and Process Engineering; TU Delft Reservoir Engineering); Rems, L. (TU Delft ChemE/Product and Process Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Boukany, P. (TU Delft ChemE/Product and Process Engineering)","","2018","Transient permeabilisation of the cell membrane is a critical step to introduce drugs or DNA into living cells, yet challenging for both biological research and therapeutic applications. To achieve this, electroporation (or electropermeabilisation) has become a widely used method due to its simplicity to deliver almost any biomolecule to any cell type. Although this method demonstrates promise in the field of drug/gene delivery, the underlying physical mechanisms of the response of the heterogeneous cell membrane to strong electric pulses is still unknown. In this study, we have investigated the role of gel-phase lipids in the electroporation of binary giant unilamellar vesicles (GUVs), composed from DPPC (gel-phase) and DPhPC (fluid-phase) lipids (molar ratio 8:2 and 2:8). We have observed that the exposure to electric pulses leads to expel of fluid-phase lipids and concomitant decrease in GUV size, whereas the gel-phase domains become buckled. Based on experiments on pure fluid-phase and gel-phase GUVs, we have found that fluid-phase lipids can be expelled by electrical forces and the highly viscous gel-phase lipids cannot. Moreover, our analyses suggest that pore formation occurs primarily in fluid-phase domains and that the pore size is similar in all GUVs containing fluid-phase lipids, irrespective of the gel-phase percentage.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:3dcf2932-5a96-4a6c-8147-c0494c49c3d3","http://resolver.tudelft.nl/uuid:3dcf2932-5a96-4a6c-8147-c0494c49c3d3","Evolution of nonconformal Landau-Levich-Bretherton films of partially wetting liquids","Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Shah, M.S. (TU Delft ChemE/Product and Process Engineering); Parthiban, Pravien (National University of Singapore); Khan, S.A. (National University of Singapore)","","2018","We experimentally and theoretically describe the dynamics of evolution and eventual rupture of Landau-Levich-Bretherton films of partially wetting liquids in microchannels in terms of nonplanar interface curvatures and disjoining pressure. While both the early-stage dynamics of film evolution and near-collapse dynamics of rupture are understood, we match these regimes and find theoretically that the dimensionless rupture time, Tr, scales with κ-10/7. Here, κ is the dimensionless curvature given by the ratio of the Laplace-pressure discontinuity that initiates film thinning to the initial strength of the disjoining pressure that drives the rupture. We experimentally verify the rupture times and highlight the crucial consequences of early film rupture in digital microfluidic contexts: pressure drop in segmented flow and isolation of droplets from the walls.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:ba917eb8-0d71-4c16-ac44-b6da67e47692","http://resolver.tudelft.nl/uuid:ba917eb8-0d71-4c16-ac44-b6da67e47692","Oriented Attachment and Nanorod Formation in Atomic Layer Deposition of TiO2 on Graphene Nanoplatelets","Grillo, F. (TU Delft ChemE/Product and Process Engineering); La Zara, D. (TU Delft ChemE/Product and Process Engineering); Mulder, P.C.M. (TU Delft Applied Sciences); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Ruud Van Ommen, J.","","2018","Understanding the spontaneous organization of atoms on well-defined surfaces promises to enable control over the shape and size of supported nanostructures. Atomic layer deposition (ALD) boasts atomic-scale control in the synthesis of thin films and nanoparticles. Yet, the possibility to control the shape of ALD-grown nanostructures remains mostly unexplored. Here, we report on the bottom-up formation of both linear and V-shaped anatase TiO2 nanorods (NRs) on graphene nanoplatelets during TiCl4/H2O ALD carried out at 300 °C. NRs as large as 200 nm form after only five ALD cycles, indicating that diffusional processes rather than layer-by-layer growth are behind the NR formation. In particular, high-resolution transmission electron microscopy reveals that the TiO2 NRs and graphene nanoplatelets are in rotational alignment as a result of lattice matching. Crucially, we also show that individual nanocrystals can undergo in-plane oriented attachment.","","en","journal article","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:69ac7b36-c2c3-4813-835c-2630f796b38d","http://resolver.tudelft.nl/uuid:69ac7b36-c2c3-4813-835c-2630f796b38d","Correlated, Dual-Beam Optical Gating in Coupled Organic–Inorganic Nanostructures","Wurst, Kai M. (Eberhard Karls Universität Tübingen); Bender, Markus (University of Heidelberg); Lauth, J.D. (University of Oldenburg); Maiti, Sonam (Eberhard Karls Universität Tübingen); Chassé, Thomas (Eberhard Karls Universität Tübingen); Meixner, Alfred (Eberhard Karls Universität Tübingen); Siebbeles, L.D.A. (TU Delft ChemE/Chemical Engineering; TU Delft ChemE/Opto-electronic Materials); Bunz, Uwe H.F. (University of Heidelberg); Braun, Kai (Eberhard Karls Universität Tübingen); Scheele, Marcus (Eberhard Karls Universität Tübingen)","","2018","An optical switch with two distinct resonances is formed by combining PbS nanocrystals and the conductive polymer poly[sodium 2-(2-ethynyl-4-methoxyphenoxy)acetate] (PAE) into a hybrid thin film. Infrared excitation of the nanocrystals invokes charge transfer and consecutive polaron formation in the PAE, which activates the switch for excited-state absorption at visible frequencies. The optical modulation of the photocurrent response of the switch exhibits highly wavelength-selective ON/OFF ratios. Transient absorption spectroscopy shows that the polaron formation is correlated with the excited state of the nanocrystals, opening up new perspectives for photonic data processing. Such correlated activated absorption can be exploited to enhance the sensitivity for one optical signal by a second light source of different frequency as part of an optical amplifier or a device with AND logic.","conductive polymers; coupled organic–inorganic nanostructures; photoswitches; polarons","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-01-01","","ChemE/Chemical Engineering","ChemE/Opto-electronic Materials","","",""
"uuid:92711678-eb6b-45ec-bfc0-74a345f6d659","http://resolver.tudelft.nl/uuid:92711678-eb6b-45ec-bfc0-74a345f6d659","The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films","Gudjónsdóttir, S. (TU Delft ChemE/Opto-electronic Materials; TU Delft ChemE/Chemical Engineering); van der Stam, W. (TU Delft ChemE/Chemical Engineering; TU Delft ChemE/Opto-electronic Materials); Kirkwood, Nicholas; Evers, W.H. (TU Delft BN/Technici en Analisten; TU Delft ChemE/Chemical Engineering; Kavli institute of nanoscience Delft); Houtepen, A.J. (TU Delft ChemE/Chemical Engineering; TU Delft ChemE/Opto-electronic Materials)","","2018","Control over the charge density is very important for implementation of colloidal semiconductor nanocrystals into various optoelectronic applications. A promising approach to dope nanocrystal assemblies is charge injection by electrochemistry, in which the charge compensating electrolyte ions can be regarded as external dopant ions. To gain insight into the doping mechanism and the role of the external dopant ions, we investigate charge injection in ZnO nanocrystal assemblies for a large series of charge compensating electrolyte ions with spectroelectrochemical and electrochemical transistor measurements. We show that charge injection is limited by the diffusion of cations in the nanocrystal films as their diffusion coefficient are found to be ∼7 orders of magnitude lower than those of electrons. We further show that the rate of charge injection depends strongly on the cation size and cation concentration. Strikingly, the onset of electron injection varies up to 0.4 V, depending on the size of the electrolyte cation. For the small ions Li+ and Na+ the onset is at significantly less negative potentials. For larger ions (K+, quaternary ammonium ions) the onset is always at the same, more negative potential, suggesting that intercalation may take place for Li+ and Na+. Finally, we show that the nature of the charge compensating cation does not affect the source-drain electronic conductivity and mobility, indicating that shallow donor levels from intercalating ions fully hybridize with the quantum confined energy levels and that the reorganization energy due to intercalating ions does not strongly affect electron transport in these nanocrystal assemblies.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Opto-electronic Materials","","",""
"uuid:a212e1ad-67cb-4a2c-858e-ca882c5de93a","http://resolver.tudelft.nl/uuid:a212e1ad-67cb-4a2c-858e-ca882c5de93a","Effect of Inventory Change in a Liquid - Solid Circulating Fluidized Bed (LSCFB)","Gnanasundaram, Nirmala (VIT University); Venugopal, Aswin (National University of Singapore); Katragadda, Y. (TU Delft ChemE/Chemical Engineering); Ullas, Gokul (VIT University)","","2017","Circulating fluidized beds (CFB) play a major role in the chemical industry especially as heterogeneous catalytic reactors. Research on hydrodynamic properties of Liquid - Solid CFBs (LSCFB) is significantly under-reported as compared to Gas - Solid CFBs (GSCFB). Steadily, prominent research is being established in fields like food industry (whey protein recovery), waste management (removal of heavy metals from radioactive wastes) and others, which use LSCFBs. In this context, it is important to have significant knowledge about the changes occurring in hydrodynamic properties like solid hold-up, rate of solid circulation etc., on changing certain critical physical properties such as inventory height. An LSCFB of height 2.95m and riser outer diameter 0.1m was chosen and the effect of inventory height on the properties was studied by taking the initial inventory heights as 15cm, 25cm and 35cm. The hydrodynamic studies concentrated on axial solid holdup, average solid holdup, solid circulation rate and slip velocity. On increasing the inventory, uniformity of axial solid holdup was confirmed along with studying holdup patterns. Solid flux was seen to follow an inverse relationship to holdup, as expected. The change in slip velocity with varying inventory was also checked, and was found to decrease with inventory. The distribution parameter, Co of the drift flux model was used to determine the extent of non-uniformity in solid distribution. Co was calculated to be less than unity in the range of 0.983-0.994, suggesting non-uniformity in solid distribution, with higher solid concentration by the walls compared to the core.","axial solid holdup; inventory; LSCFB; slip velocity; solid circulation rate","en","journal article","","","","","","","","2018-07-29","","ChemE/Chemical Engineering","","","",""
"uuid:05d2bd16-ff1c-4e6d-96ef-f42eb1c0ac21","http://resolver.tudelft.nl/uuid:05d2bd16-ff1c-4e6d-96ef-f42eb1c0ac21","Polymer conformation during flow in porous media","Kawale, D. (TU Delft Reservoir Engineering; Dutch Polymer Institute); Bouwman, G.W. (TU Delft ChemE/Chemical Engineering); Sachdev, S. (TU Delft ChemE/Product and Process Engineering); Zitha, P.L.J. (TU Delft Reservoir Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Rossen, W.R. (TU Delft Reservoir Engineering); Boukany, P. (TU Delft ChemE/Product and Process Engineering)","","2017","Molecular conformations of individual polymers during flow through porous media are directly observed by single-DNA imaging in microfluidics. As the Weissenberg number increases during flow (Wi > 1), we observe two types of elastic instabilities: (a) stationary dead-zone and (b) time-dependant dead-zone washing. When stretched polymer chains enter a dead-zone, they first re-coil and, once inside the dead-zone, they rotate and re-stretch again. The probability distribution of DNA chains under the stretched condition inside the dead-zone is found to be heterogeneous with a broad distribution.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","Reservoir Engineering","","",""
"uuid:f399c76b-72b5-408f-b223-897c003a349d","http://resolver.tudelft.nl/uuid:f399c76b-72b5-408f-b223-897c003a349d","Low-temperature atomic layer deposition delivers more active and stable Pt-based catalysts","Bui, H.V. (TU Delft ChemE/Product and Process Engineering); Grillo, F. (TU Delft ChemE/Product and Process Engineering); Kulkarni, S.S. (TU Delft ChemE/Product and Process Engineering); Bevaart, Ronald (Student TU Delft); Nguyên, V.T. (TU Delft RST/Fundamental Aspects of Materials and Energy); van der Linden, B. (TU Delft ChemE/O&O groep); Moulijn, J.A. (TU Delft ChemE/Catalysis Engineering); Makkee, M. (TU Delft ChemE/Catalysis Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2017","We tailored the size distribution of Pt nanoparticles (NPs) on graphene nanoplatelets at a given metal loading by using low-temperature atomic layer deposition carried out in a fluidized bed reactor operated at atmospheric pressure. The Pt NPs deposited at low temperature (100 °C) after 10 cycles were more active and stable towards the propene oxidation reaction than their high-temperature counterparts. Crucially, the gap in the catalytic performance was retained even after prolonged periods of time (>24 hours) at reaction temperatures as high as 450 °C. After exposure to such harsh conditions the Pt NPs deposited at 100 °C still retained a size distribution that is narrower than the one of the as-synthesized NPs obtained at 250 °C. The difference in performance correlated with the difference in the number of facet sites as estimated after the catalytic test. Our approach provides not only a viable route for the scalable synthesis of stable supported Pt NPs with tailored size distributions but also a tool for studying the structure-function relationship.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:77ed6a3b-a5c9-4f0c-83cb-d3f0e3082a36","http://resolver.tudelft.nl/uuid:77ed6a3b-a5c9-4f0c-83cb-d3f0e3082a36","Tuning roughness and gloss of powder coating paint by encapsulating the coating particles with thin Al2O3 films","Valdesueiro, David (Delft IMP B.V.); Hettinga, Hans (DSM); Drijfhout, Jan Pieter (DSM); Lips, Priscilla (DSM); Meesters, G.M.H. (TU Delft ChemE/Product and Process Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2017","In this work, we report a method to change the surface finish of a standard polyester-based powder coating paint, from gloss to matt, by depositing ultrathin films of Al2O3 on the powder coating particles. The coating experiments were performed in a fluidized bed reactor at 1 bar and 27 °C, using a gas-phase coating process of alternating exposure of the particles to the two precursors (trimethylaluminium and water), similar to atomic layer deposition (ALD). We varied the number of coating cycles (1, 2, 3, 5, 7 and 9 cycles) to obtain film thicknesses of the alumina shell ranging from 1 to 30 nm. The average growth per cycle of the process is 3.5 nm, significantly larger than the one for pure self-limiting ALD. When the average alumina shell was thicker than 6 nm, the shell prevented the flow of the core particles, even though the powder particles did soften above the glass transition temperature. With the particles morphology intact, this resulted in a rough and matte surface finish of the coating after curing. The surface roughness, with a value around 9 μm determined by surface profilometry, is associated to the alumina coated particles as observed with SEM and EDX analysis. In addition, the matte finish coating showed mechanical resistance similar to that of uncoated powder particles.","Alumina coating; Ambient conditions; Atomic layer deposition; Core-shell particles; Matte powder coating; Surface appearance","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:bb1ee32c-9daf-4c4d-80f9-6937862c3637","http://resolver.tudelft.nl/uuid:bb1ee32c-9daf-4c4d-80f9-6937862c3637","Modelling and Numerical Simulations of a Membrane Electrode Assembly for Fuel Cell Applications: A hydrogen crossover study based on Non-Equilibrium Thermodynamics","Ripepi, D.","Koper, G.J.M. (mentor)","2017","In this study a one-dimensional, steady-state, non-isothermal numerical model was developed in order to investigate the transport phenomena occurring in a membrane electrode assembly for fuel cell applications and to provide an insight on the effects of the hydrogen crossover. The hydrogen that permeates through the membrane is consumed without generation of useful work. Moreover, the effects caused by the hydrogen crossover are so far unclear. This complex phenomenon is usually neglected in fuel cell modelling and the results of experimental measurements are often not in agreement. The proposed model consists of a set of transport equations, based on non-equilibrium thermodynamic. The latter derives from irreversible thermodynamics and it provides a systematic way to study heterogeneous systems, like fuel cells. The numerical results are thermodynamically consistent with the second law of thermodynamics. Initially the isothermal boundary condition was applied to the system in order to first study the coupled charge and mass transport, including the hydrogen crossover. However, it was found out that the thermal effects are not negligible in the simulated system and thus the constant temperature assumption was removed. The model described with the NET method provides useful information about the driving forces profiles (total pressure, hydrogen partial pressure, electric potential and temperature) and entropy production. This allows a more accurate estimation of non-constant parameters and also a more reliable prediction on the hydrogen crossover flux over a wide range of operating conditions. An optimization procedure was carried out showing that even though the set of optimal parameters produced an increment of almost four times in crossover, the power output increased without being affected by the variations hydrogen permeation. Although the results of the simulations show that hydrogen crossover has no significant effects on fuel cell performance in term of power output, the adopted method of non-equilibrium thermodynamics permitted to identify that part of the reduction in cell voltage in near open circuit conditions is attributable to the hydrogen crossover. The effects of hydrogen permeation are only noticeable at very low current densities, so when the crossover flux is comparable to the hydrogen reacting at the catalyst layer. A final analysis was carried out with increased permeability (ten, fifty and a hundred time). This verified that considerable hydrogen crossover flux lead to effects on net heat flux, entropy production, temperature distribution and power output.","","en","master thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","Sustainable Energy Technology",""
"uuid:11b2fc73-33fd-4be2-ac07-bc159df4ad4d","http://resolver.tudelft.nl/uuid:11b2fc73-33fd-4be2-ac07-bc159df4ad4d","Industrial Integration of Aerosol Route to Nanofinishing of Highly Effective Antibacterial Textiles","Bhamidipati, A.S.M.","Schmidt-Ott, A. (mentor); Valenti, M. (mentor)","2017","In the field of nanotechnology, the need to develop a green process for the production of nanoparticles brought into light the concept of nanoparticle aerosol generation. A novel method to produce an aerosol by synthesizing nanoparticles of conductive material having a potential to be scaled up is by spark ablation. Nanosized particulate antibacterial agents exhibit a high surface-to-volume ratio, which leads to a high antibacterial effiency. In this study, nanoparticles deposited on quartz fiber filter discs using aerosol generation were used to show the possibility of textile nanofinishing which can be applied to produce an advanced class of antimicrobial agents. The influence of various parameters on the particle size has been studied and singlet nanoparticles of silver (less than 10 nm) were successfully produced. Antimicrobial tests were carried out on the synthesized nanoparticles deposited on the filter fibers of various sizes, compositions and agglomerated states. A time-kill curve was determined based on the cell count of the bacteria at each time interval. Antimicrobial activity of the synthesized nanoparticles was very effective (comparable to 6 μM AgNO3), and faster death of bacteria was obtained for non-coalesced (high-surface area) particles when compared to the coalesced ones (low-surface area). Size-selected particles and alloyed particles produced by spark mixing also seemed to have an effect on the bacterial colony. The antimicrobial activity of Silver nanoparticles produced by spark ablation was confirmed and nanoparticle migration from the filter was observed. Using the spark ablation tech- nique, further studies to confirm the antimicrobial activity of various nanoparticles can be performed and can be used in various applications such as textile nanofinishing and water disinfection.","Spark ablation; Antimicrobial activity; Textile nanofinishing","en","master thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:7d53acca-bf24-4e29-b975-6271ecb7b9e8","http://resolver.tudelft.nl/uuid:7d53acca-bf24-4e29-b975-6271ecb7b9e8","Novel Materials for Artificial Photosynthesis: Study of light scattering mechanism of surface plasmon resonance and application in water splitting","Pridhivi, V.","van Ommen, J.R. (mentor); Smith, W.A. (mentor)","2017","To address the energy demand of the growing world population, the transition from polluting exhaustible energy sources to clean inexhaustible energy sources is imminent. Solar energy is one of the energy sources that has been studied extensively. In particular, the application of solar energy in photoelectrochemical water splitting has gained wide interest in generating hydrogen as renewable fuel. The objective of the research is the elucidation of light scattering mechanism of surface plasmon resonance of silver. Surface plasmon resonance is the phenomenon of collective oscillation of free electrons in noble metals on electromagnetic irradiation. This property of noble metals is valorised in influencing the optical and photoelectrochemical efficiency of photoanodes of interest. In this study, n-type photoanodes, BiVO4 and TiO2 are prepared and functionalized with different sized silver nanoparticles. The influence of size of nanoparticles is investigated with respect to the ability of light scattering using UV-Vis absorption measurement and Incident Photon to Current Conversion efficiency. The difference in optical and photoelectrochemical behaviour imparted by nanoparticle on BiVO4 and TiO2 gives insight about the light scattering mechanism and the need for spectral overlap of silver surface plasmon resonance with the bandgap of the semiconductor.","Surface Plasmon Resonance; Light Scattering; Photoelectrochemical Water Splitting","en","master thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","ChemE/Product and Process Engineering","",""
"uuid:d72daf4c-d030-4d7d-97ee-42d9f8a2c2cc","http://resolver.tudelft.nl/uuid:d72daf4c-d030-4d7d-97ee-42d9f8a2c2cc","Efficient electricity storage with a battolyser, an integrated Ni-Fe battery and electrolyser","Mulder, F.M. (TU Delft ChemE/Materials for Energy Conversion and Storage); Weninger, B. (TU Delft ChemE/Materials for Energy Conversion and Storage); Middelkoop, J. (TU Delft ChemE/Chemical Engineering); Ooms, F.G.B. (TU Delft RST/Bedrijfsondersteuning); Schreuders, H. (TU Delft ChemE/Chemical Engineering)","","2017","Grid scale electricity storage on daily and seasonal time scales is required to accommodate increasing amounts of renewable electricity from wind and solar power. We have developed for the first time an integrated battery-electrolyser ('battolyser') that efficiently stores electricity as a nickel-iron battery and can split water into hydrogen and oxygen as an alkaline electrolyser. During charge insertion the Ni(OH)2 and Fe(OH)2 electrodes form nanostructured NiOOH and reduced Fe, which act as efficient oxygen and hydrogen evolution catalysts respectively. The charged electrodes use all excess electricity for efficient electrolysis, while they can be discharged at any time to provide electricity when needed. Our results demonstrate a remarkable constant and a high overall energy efficiency (80-90%), enhanced electrode storage density, fast current switching capabilities, and a general stable performance. The battolyser may enable efficient and robust short-term electricity storage and long-term electricity storage through production of hydrogen as a fuel and feedstock within a single, scalable, abundant element based device.","","en","journal article","","","","","","","","2017-12-14","","ChemE/Chemical Engineering","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:096fe588-11f9-45dc-86fa-dd6f09be2b7c","http://resolver.tudelft.nl/uuid:096fe588-11f9-45dc-86fa-dd6f09be2b7c","Understanding and Controlling the Aggregative Growth of Platinum Nanoparticles in Atomic Layer Deposition: an Avenue to Size Selection","Grillo, F. (TU Delft ChemE/Product and Process Engineering); Bui, H.V. (TU Delft ChemE/Product and Process Engineering); Moulijn, J.A. (TU Delft ChemE/Catalysis Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2017","We present an atomistic understanding of the evolution of the size distribution with temperature and number of cycles in atomic layer deposition (ALD) of Pt nanoparticles (NPs). Atomistic modeling of our experiments teaches us that the NPs grow mostly via NP diffusion and coalescence rather than through single-atom processes such as precursor chemisorption, atom attachment, and Ostwald ripening. In particular, our analysis shows that the NP aggregation takes place during the oxygen half-reaction and that the NP mobility exhibits a size- and temperature-dependent scaling. Finally, we show that contrary to what has been widely reported, in general, one cannot simply control the NP size by the number of cycles alone. Instead, while the amount of Pt deposited can be precisely controlled over a wide range of temperatures, ALD-like precision over the NP size requires low deposition temperatures (e.g., T < 100 °C) when growth is dominated by atom attachment.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:a76fa178-64cb-4281-8dbd-4ad981ef30b1","http://resolver.tudelft.nl/uuid:a76fa178-64cb-4281-8dbd-4ad981ef30b1","Modeling the size distribution in a fluidized bed of nanopowder","Fabre, A. (TU Delft ChemE/Product and Process Engineering); Salameh, S. (TU Delft ChemE/Product and Process Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2017","Fluidization is a technique used to process large quantities of nanopowder with no solvent waste and a large gas–solid contact area. Nonetheless, nanoparticles in the gas phase form clusters, called agglomerates, due to the relatively large adhesion forces. The dynamics within the fluidized bed influence the mechanism of formation, and thus, the morphology of the agglomerates. There are many theoretical models to predict the average size of fluidized agglomerates; however, these estimates of the average lack information on the whole size range. Here, we predict the agglomerate size distribution within the fluidized bed by estimating the mode and width using a force balance model. The model was tested for titania (TiO2), alumina (Al2O3), and silica (SiO2) nanopowders, which were studied experimentally. An in-situ method was used to record the fluidized agglomerates for size analysis and model validation.","Agglomerate; Fluidization; Model; Nanoparticle; Size distribution","en","journal article","","","","","","Accepted Author Manuscript","","2019-03-03","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:dabc1baf-26dc-4c5d-b9ab-44b0fe200856","http://resolver.tudelft.nl/uuid:dabc1baf-26dc-4c5d-b9ab-44b0fe200856","Entrainment of nanosized clusters from a nanopowder fluidized bed","Fabre, A. (TU Delft ChemE/Product and Process Engineering); Clemente, Alberto (Universidad de Zaragoza); Balas, Francisco (Universidad de Zaragoza; Biomaterials and Nanomedicine (CIBER-BBN)); Lobera, M. Pilar (Universidad de Zaragoza; Biomaterials and Nanomedicine (CIBER-BBN)); Santamaría, Jesús (Universidad de Zaragoza; Biomaterials and Nanomedicine (CIBER-BBN)); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2017","The release of nanosized particles from fluidized beds of ceramic oxide nanopowders, namely, TiO2 (P25), Al2O3 (AluC) and SiO2 (A130) has been assessed for the first time. Previous models and experiments for processing engineered nanoparticles (ENP) using fluidized beds reported only the formation of micron-sized cluster agglomerates in the gas phase. In this work, aerosol spectrometry techniques such as scanning mobility particle sizing (SMPS) and optical particle counting (OPC) have been combined with powder technologies, such as the borescope high-speed camera system, to determine the particle size distribution from 5 nm to 1 mm above a fluidized bed. Furthermore, the morphology of nanoparticulate aerosol at different locations in the bed was determined by offline electron microscopy. The results demonstrate that free nano- and micron-sized particles are released from fluidized beds. Since the structures found above the bed are also expected to be present within fluidized beds, a revision of existing nanoparticle fluidization models, and improved safety and control measures in reactors for gas-phase ENP processing are needed to avoid nanoparticle release.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:88ee89b4-3f9d-4489-ba59-f27a840b923b","http://resolver.tudelft.nl/uuid:88ee89b4-3f9d-4489-ba59-f27a840b923b","Microcapsules with a permeable hydrogel shell and an aqueous core continuously produced in a 3D microdevice by all-aqueous microfluidics","Mytnyk, S. (TU Delft ChemE/Advanced Soft Matter); Ziemecka, I. (TU Delft ChemE/Advanced Soft Matter); Olive, A.G.L. (TU Delft ChemE/Advanced Soft Matter); Totlani, K. (TU Delft ChemE/Product and Process Engineering); Oldenhof, S. (TU Delft ChemE/Advanced Soft Matter; Netherlands Forensic Institute - NFI); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); van Steijn, V. (TU Delft ChemE/Product and Process Engineering); van Esch, J.H. (TU Delft ChemE/Advanced Soft Matter); van der Meer, J.W.M.","","2017","We report the continuous production of microcapsules composed of an aqueous core and permeable hydrogel shell, made stable by the controlled photo-cross-linking of the shell of an all-aqueous double emulsion. While most previous work on water-based emulsions focused on active droplet formation, here double emulsion droplets were spontaneously generated at a three-dimensional flow-focusing junction through the break-up of a double jet formed by immiscible aqueous solutions of polyethylene glycol and cross-linkable dextrans. The capsules obtained with this lipid-free, organic-solvent-free, and surfactant-free approach displayed excellent stability under a variety of harsh conditions (3 <pH <13, high salinity). Drying and rehydration experiments demonstrate the permeability of the shell, which may enable molecular-weight-dependent release and uptake of polar solutes.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Advanced Soft Matter","","",""
"uuid:2184c881-bd47-4030-bd06-02e165f1b64a","http://resolver.tudelft.nl/uuid:2184c881-bd47-4030-bd06-02e165f1b64a","Flow Experiments in a Carotid Artery Bifurcation for Magnetic Drug Targeting","Blakborn, I.A.","Kenjeres, S. (mentor)","2016","Magnetic Drug Targeting could be used to cure atherosclerosis in the Carotid Artery. The idea of this method is that magnetized drug particles are added to the blood in the artery while applying a magnetic field at the location where the drugs is desired to enter the tissue. Therefore the concentration increases at the location of the atherosclerosis while minimizing the side effects in the rest of the body. For the prediction of the amount of drugs entering the tissue it is necessary to accurately determine the flow profiles in the Carotid Artery. Since the geometry of the Carotid Artery is unique for each person, a cheap and fast method to accomplish flow profiles is demanded. Simulations using Computational Fluid Dynamics could meet these requirements. To validate Computational Fluid Dynamics simulations, experimental velocity measurements in a model of a Carotid Artery Bifurcation were performed. Particle Image Velocimetry and Magnetic Resonance Imaging were performed in the Carotid Artery Bifurcation and Particle Image Velocimetry and Laser Doppler Anemometry were performed in a cylinder, wherefore an analytical solution is available. The reproducibility of Particle Image Velocimetry results was tested by comparing the measurements with previous work. Three different measuring techniques were used. The Particle Image Velocimetry results in the Carotid Artery Bifurcation showed indeed similar results. In addition, the possibility of constructing a quasi-3D model of data from different planes was investigated. It was concluded that due to interpolations a significant amount of information is ignored when the data from different planes were combined. Phase-ContrastMagnetic Resonance Imaging experimentswere repeated with some recommended improvements implemented. Smoothness of the images has improved. Qualitatively the results show in general good agreement with the PIV results. Finally, Laser Doppler Anemometry was tested as measuring technique to measure the flow in the Carotid Artery Bifurcation model. Therefore the technique was tested in a cylinder. In general the results show good agreement. Moreover, a high resolution could be obtained if the refractive conditions are of sufficient quality.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:0934e266-229e-46f5-ba24-619d8552a178","http://resolver.tudelft.nl/uuid:0934e266-229e-46f5-ba24-619d8552a178","Simulating blood flow and oxygen transport in stenosed large arteries","Visser, D.","Kenjeres, S. (mentor); Khalafvand, S.S. (mentor)","2016","Altered flow and mass transfer patterns are thought to play an important role in the early onset of atherosclerosis. A disturbed wall shear distribution and the prevalence of hypoxic (low oxygen tension) are specifically believed to be atherogenic factors, which can function as a positive feedback on the development of atherosclerosis. In this work, blood flow and oxygen mass transport have been modelled in stenosed arteries and numerically evaluated, to better understand the atherogenic processes that contribute to this development. Three stenosed geometries have been considered: one with light (31% asymmetric area reduction) stenosis and two with moderate stenosis (56% area reductions, one of which asymmetric, another axisymmetric). Two different rheological models have been created for blood. In the first, blood is assumed to be Newtonian; in the latter, the Carreau-Yasuda model is considered to account for the shear thinning effect of blood and to reproduce a more physiologically accurate rheological model, after which the two models have been compared. The simulations mimicked the flow conditions in large arteries, with Re = 300 and using the velocity profile of the internal carotid artery for transient simulation runs. Results show that wall shear stress (WSS) and Sherwood profiles are highly dependent on stenosis geometry, although certain characteristics are found for all stenoses. First, a region of increased wall shear stress can be found proximal to the stenosis throat, usually followed by a low shear region distal to the stenosis throat. Wall shear stress magnitudes can reach 10 to 20 times the Poiseuille value depending on the geometry and the length of the stenosis. Second, the Sherwood profile in stenosed arteries follow the same characteristics, although asymmetric stenoses can lead to more complex patterns at both the diseased and healthy wall of a stenosed artery. One particular asymmetric stenosis geometry caused significant hypoxic regions just distal and distolateral to the stenosis throat, with Sherwood numbers as low as Sh = 1:37. This might indicate that oxygen transport to the wall is fluid phase-limited in these aforementioned regions. The lowered oxygen transport through the artery wall can lead to a change in wall permeability which has been linked to an early onset of atherosclerosis.","","en","bachelor thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","Transport Phenomena","",""
"uuid:b7ccbf27-52cf-4d50-ba64-9282aec248e4","http://resolver.tudelft.nl/uuid:b7ccbf27-52cf-4d50-ba64-9282aec248e4","Simulation Verification and Optimization of a Vertical Axis Wind Turbine using CFD","Kortleven, M.","Kenjeres, S. (mentor); Heemink, A.W. (mentor)","2016","In this research computational fluid dynamics (CFD) is used to model a vertical axis wind turbine. Well known turbulence models | i.e. the k-epsilon and k-omega SST model | are used and compared in their performance against each other and a set of experimental data. The formal research question is ""What models are available for the simulation of vertical axis wind turbines and what considerations should be taken into account to most effectively obtain the power coefficient of those turbines?"" The results show that the 2D k-epsilon simulations approximate the experimental data the closest, but that the difference between the simulations and the experiment in the k-omega model can be explained by the simulations being 2D and the experiment being 3D. To improve the results and verify that a 3D simulation indeed does produce better results, another study should be conducted in 3D when more computation power is readily available. As to what considerations should be taken into account: Meshing determines largely how long a simulation will take and to what accuracy a result can be calculated. The sliding mesh method should be used to decrease calculation time, so that the mesh does not need to be recalculated every time step. The orders of the different variables should be set to second order accuracy for the pressure p, the momentum, the turbulent kinetic energy k and the time derivative. The second order calculation of these variables results in a significant increase in accuracy of the simulations relative to simulations conducted in first order accuracy. For further improvement a research could be set up that involves both the experimental and the CFD part. That way the practical limitations to building a wind turbine could be modelled in the simulations, possibly resulting in even better synergy between the measurements and the simulations.","CFD; Simulation; Vertical Axis Wind Turbine; Optimization","en","bachelor thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","Transport Phenomena","",""
"uuid:12394dce-a714-4282-8930-93e09e932793","http://resolver.tudelft.nl/uuid:12394dce-a714-4282-8930-93e09e932793","Modelling and design of a flat plate fixed film photoreactor for phenol degradation","Galnares de la Garza, F.O.","van Ommen, J.R. (mentor)","2016","This paper presents the mathematical modelling and design of a flat plate photoreactor with a fixed film photocatalyst to degrade phenol. Phenol was used as target pollutant as it is one of the most studied contaminants in photocatalysis and it is present in many of the wastewater streams containing pesticides, drugs, and dyes which cannot be treated with conventional wastewater technologies. To model the photoreactor, first a Zero Reflectance Model assuming no energy absorption or scattering by the fluid phase was used to compute the rate of photon absorption. Interest was also placed on determining the effect of the photocatalytic film thickness on both the internal diffusion and the rate of photon absorption. Afterward, the material balance of the pollutant was computed considering convection, diffusion, and a Langmuir Hinshelwood type of kinetics to describe the degradation of phenol. As the reaction just takes place at the bottom of the reactor, external mass transfer limited the overall phenol degradation. Therefore, several reactor heights were investigated to diminish external mass transfer limitations and determine the optimal photoreactor dimensions. For instance, for a throughput of 50 liters per day and assuming 10 hours of sunlight, to reach 95% phenol conversion the photoreactor height should be below 0.45cm, which corresponds to a photoreactor length of approximately 25 meters. In contrast, when the reactor height was diminished to 0.1cm, the required reactor length to reach 95% conversion decreased to 10 meters.","advanced oxidation technologies; heterogeneous catalysis; photocatalysis; titanium dioxide; mineralization; fixed film; flat plate photoreactor; phenol; photocatalyst thickness; Langmuir-Hinshelwood; diffusion; diffusion limitation; local rate of photon absorption; conversion; residence time","en","student report","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","Sustainable Energy Technology","",""
"uuid:f5430510-9362-44d8-a022-6a663a82fd6b","http://resolver.tudelft.nl/uuid:f5430510-9362-44d8-a022-6a663a82fd6b","Interferometric scattering of light by an ensemble of flowing spherical particles: Extracting a heartbeat from a pulsatile flow","Joosten, T.H.","Bhattacharya, N. (mentor); Kenjeres, S. (mentor); van As, K. (mentor)","2016","Due to the increasing problem of cardiovascular diseases, the demand for diagnosing measurements is also increasing. These measurements should be cheap, nondestructive, accurate and real-time. Measurements like these already exist in the form of photoplethysmography (PPG). However, these measurements make use of a scalar quantity which throws away valuable information which can possibly be utilized to extract more parameters from the given setup. This research investigates the possibility to extract a heartbeat from a scattered incoming plane wave on an ensemble of spherical objects, which represent the red blood cells. We calculate the scattered field due to the presence of the particles and capture it by a numerical camera. Van As has created a code in order to simulate this setup. This research utilizes this code to extract an introduced periodicity in a flow by analysis of the speckle patterns, more specifically, by the speckle contrast. The present research is not able to retrieve the introduced periodicity in the flow. This might be explained by the combination of the use of a small camera, the amount of particles used and the use of a small camera integration time as these are the major differences with the experimental data Loozen has provided.","blood; Mie theory; scattering; light; pulsatile flow; numerical study; Womersley flow; speckle pattern; speckle contrast","en","bachelor thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","Optics/Transport Phenomena/Numerical Analysis","",""
"uuid:414ba247-8b1f-482e-a841-53f9e02b1431","http://resolver.tudelft.nl/uuid:414ba247-8b1f-482e-a841-53f9e02b1431","Modeling and simulation of diffusion-convection-reaction in heterogeneous nanochannels using OpenFOAM","Pimpalgaonkar, H.G. (TU Delft ChemE/Transport Phenomena); van Steijn, V. (TU Delft ChemE/Product and Process Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Kleijn, C.R. (TU Delft ChemE/Transport Phenomena)","Simos, Theodore (editor); Tsitouras, Charalambos (editor)","2016","We present a finite volume implementation of a phase field method in OpenFOAM as a tool to simulate reactive multiphase flows on heterogeneous surfaces. Using this tool, we simulate the formation and growth of a droplet due to a chemical reaction on a hydrophilic catalytic patch surrounded by a hydrophobic wall. We compare the growth dynamics with a quasi-static growth model from literature and show that they qualitatively agree.","","en","conference paper","American Institute of Physics","","","","","","","2017-06-08","","ChemE/Chemical Engineering","ChemE/Transport Phenomena","","",""
"uuid:39d46ecf-c446-445e-ba16-81017b10f53e","http://resolver.tudelft.nl/uuid:39d46ecf-c446-445e-ba16-81017b10f53e","Mechanism and Dynamics of Charge Transfer in Donor-Bridge-Acceptor Systems","Gorczak-Vos, N.","Siebbeles, L.D.A. (promotor); Grozema, F.C. (promotor)","2016","Photoinduced charge transfer in organic materials is a fundamental process in various biological and technological areas. Donor-bridge-acceptor (DBA) molecules are used as model systems in numerous theoretical and experimental work to systematically study and unravel the underlying mechanisms of charge transfer. Despite the respectable successes, especially experimental work tends to suffer to some extent from oversimplification or unverified assumptions. This thesis points out common pitfalls: the general assumption of localised initial and final states for charge transfer, the reduction of the electronic structure of the DBA molecule to the frontier orbitals of the donor, bridge, and acceptor fragments, and the consideration of the electronic structure of these fragments as an inherent property. I would like to stress, that this thesis does not claim substantially new theoretical insight. The aim rather is to make one step towards a more thorough interpretation and prediction of experimental results in a combined computational and experimental effort based on existing theoretical models. The level of theory is sufficiently high to capture the underlying principles of the experimental observations. This in turn leads to the rational design of functional organic materials. Photoinduced charge transfer is experimentally investigated by means of broadband femtosecond transient absorption spectroscopy. The photophysical processes upon light absorption are disentangled and marked with rate constants by careful analysisof the two-dimensional data. (Time-dependent) density functional theory is employed to interpret the results, particularly to assess the initial and final states, and the effective electronic coupling that dictates charge transfer. Chapter 2 emphasises the role of the initial state for charge transfer. In a series of linearly conjugated DBA systems containing n = 1-3 phenyl bridges, the distance dependence of electron and hole transfer are compared. Although both processes seemingly exhibit equally high energy barriers that were estimated on basis of isolated fragment, electron transfer features an almost distance independent charge transfer rate constant whereas a relatively strong distance dependence is observed for hole transfer. This discrepancy is traced back to modified energy barriers caused by connecting the donor, bridge, and acceptor fragments. The changed electronic structure of the fragments leads to a delocalisation of the initial excitation over the donor and bridge in case of electron transfer. The delocalisation was not expected based on the experimental steady-state and transient absorption spectra. This chapter demonstrates the issue of estimating charge transfer properties of a DBA molecule in terms of properties of the isolated fragments, and the necessity of computational chemistry to examine the initial excitation. Chapter 3 investigates the effect of cross-conjugation on photoinduced charge transfer that is usually treated in the context of quantum interference. Hole transfer in the DBA molecule from Chapter 2 containing the linearly conjugated biphenyl bridge is compared to DBA systems with a singly and a doubly cross-conjugated biphenyl bridge. Moreover, charge transfer in these DBA molecules is compared to charge transport in single molecule junctions containing the same biphenyl bridges in between electrodes. The experimental results on hole transfer are counter-intuitive since the linearly conjugated DBA system exhibits an equally small hole transfer rate constant as the singly cross-conjugated DBA system. Additionally, the rate constant is even lower than for the doubly cross-conjugated DBA molecule. By contrast, charge transport follows the general expectation of similarly low conductance for the two cross-conjugated bridges and significantly higher conductance for the linearly conjugated one. The peculiar behaviour of the DBA molecules is found to stem from the specific symmetry of the initial and final state with respect to the fragment orbitals of the bridge. This symmetry relation inhibits the direct electronic coupling of the initial state to a number of bridge orbitals in the linearly and the singly cross-conjugated DBA systems and leads to unusual quantum interference effects. This pathway exclusion for charge transfer by symmetry is further experimentally confirmed in Chapter 4. This chapter compares hole transfer in a linearly and cross-conjugated DBA molecule containing the same donor and acceptor as in Chapter 3 but different bridge moieties. Opposite to the previous bridges, the conjugation is varied by using chemically different bridges instead of the positions at which donor and acceptor are connected. While the pathway selection on grounds of symmetry is responsible for the difference between the investigated DBA systems and single molecule junctions, it might be exploited in a functional way. The results of Chapters 2 to 4 pointed out two rules for designing DBA systems exhibiting pronounced effects of quantum interference: initial and final states have to be localised on the donor and acceptor while still coupling to all fragment orbitals of the bridge. On basis of these conditions the computational design of appropriate DBA molecules is presented in Chapter 5. Using the symmetric linearly and singly cross-conjugated biphenyl bridges from Chapter 3 required the search for asymmetric donor and acceptor moieties. This chapter demonstrates the challenge to find the right balance between a too weak and a too strong electronic coupling and the importance of computational methods for the rational design of functional DBA systems. Chapters 2 to 5 deal with photoinduced charge transfer in DBA molecules where the bridge moiety acts as a tunnelling medium. Chapter 6 takes a step away from this tunnelling regime and investigates experimentally electron injection from an electron donor into base pairs in DNA hairpins. The dynamics of electron injection and recombination in various sequences of natural and halogenated bases, which constitute different energetic landscapes for charge transfer, are examined in view of efficient long range electron transfer. Expectedly, the rate constant of electron injection is enhanced with a stronger driving force originating from the reduction potential of the first base. Yet while the identity of the second base only slightly affects the rate constant of electron injection, the recombination dynamics are strongly altered in the presence of halogenated bases. This observation indicates that electrons are injected into localised states on the first base with subsequent electron migration. Equal efficiency of electron migration in base pair sequences with a down-hill and a up-hill energetic landscape leads to speculations that this migration occurs via delocalisation rather than hopping between consecutive bases.","charge transfer; donor-bridge-acceptor; cross-conjugation; DNA hairpins; transient absorption; DFT","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:1a90478e-8270-4cfa-8603-f9c4a62ebbb5","http://resolver.tudelft.nl/uuid:1a90478e-8270-4cfa-8603-f9c4a62ebbb5","Singlet Exciton Fission and Photochemical Upconversion","Aulin, Y.V.","Siebbeles, L.D.A. (promotor); Grozema, F.C. (promotor)","2016","The Sun is the main source of renewable energy on Earth. Our planet receives about 174 PW of solar power. At the same time, global energy consumption from all energy sources is orders of magnitude lower and is equal to approximately 16 TW. Clearly, solar energy has a tremendous potential, as well as numerous advantages over conventional sources of energy. In recent years the photovoltaic industry exhibited significant growth, however the main obstacles that are preventing widespread introduction of solar cells are their still low efficiency and high cost. The major factors contributing to the low efficiency are non-efficient conversion and lack of absorption of sunlight by the active layer material. Sunlight has a broad spectrum spanning over the UV, visible, and NIR optical ranges. Commonly, solar cells are constructed using a single junction, which leads to two fundamental loss mechanisms: i) for photons with a higher energy than the band gap the energy surplus is lost as heat and only the band gap energy harvested, ii) photons with an energy lower than the band gap are not harvested at all. Together, these losses constitute a limitation of the efficiency of a silicon solar cell by half. In the work described in this thesis we have explored ways to decrease these losses by using advanced materials that allow to efficiently down-convert high energy photons, and up-convert low energy photons to the energies close to the band gap energy. Both of these approaches can be achieved in certain classes of organic materials and are known as singlet exciton fission and photochemical upconversion. This thesis combines the results of experimental research of both singlet exciton fission and photochemical upconversion in organic materials by means of laser spectroscopy tools: transient absorption and time resolved luminescence. Singlet exciton fission is a process by which a singlet excited state is converted into a combination two triplet excited states with half the energy. The two triplet together constitute an overall singlet state and hence it is a spin-allowed process that can in principle be very efficient. In this thesis, singlet fission has been studied in a range of perylenediimide (PDI) derivatives in the crystalline state. Substitution at imide nitrogen position allows to obtain different crystal structures in the solid state. In this way the electronic coupling between neighboring molecules in a crystal can be varied without significantly changing the energetics of their singlet and triplet levels. Singlet exciton fission was experimentally detected for a variety of different crystal structures of PDI. The formation of triplet excited states was found to occur on a sub-picosecond time scale. The experimentally detected fission rates and triplet yields were significantly higher than predicted by earlier theoretical calculations and were found to depend only very weakly on the crystal structure. The latter can be explained by intermolecular vibrational modes that could significantly speed up fission in perylenediimides. Photochemical upconversion can be seen as the reverse process of singlet fission. In this case, two triplet excited states, formed through a triplet sensitizer, are combined into a single higher lying singet excited state by triplet-triplet annihilation. Using this approach it is possible to convert low-energy photons that are normally not absorbed in a solar cell into higher energy photons that can be converted efficiently. In this thesis, photochemical upconversion was studied in bi-component mixtures of triplet sensitizer and triplet acceptor in solutions. Metal based porphyrins were used as triplet sensizers, and diphenylanthracene was used as triplet acceptor. The triplet sensitizer produces triplets by fast intersystem crossing due to spin-orbit coupling. The triplets are subsequently transferred to the triplet acceptor by Dexter energy transfer. When two acceptor molecules in the triplet state encounter each other, triplet-triplet annihilation occurs which results in emission from a singlet state. The overall process can be described as conversion of two low energy photons into one high energy photon. In this way, photons that are normally not absorbed by an active material in a solar cell can be converted into photons that can be absorbed, leading to a significant potential enhancement of the overall efficiency. In this work the dependence of the photochemical upconversion process on the metal in triplet sensitizer (porphyrin) was studied. Efficient upconversion was observed for platinum and palladium based porphyrins ( 25-30%) while for the zinc porphyrin the efficiency was considerably less ( 12%). For free base porphyrin, no upconversion was detected. The upconversion process is the result of a series of individual steps outlined above where most steps are the same for all the combinations. The differences in efficiency are traced back to the dependence of energy transfer efficiency on core metal of the porphyrin. Finally, we have made an attempt to achieve upconversion from the near infrared region. For this purpose, we have used porphyrin oligomers consisting of two or four porphyrin rings that have a red-shifted absorption beyond 700 nm. It is shown that using the two-ring oligomer as a sensitizer for a perylene bisimid, it is possible to convert 700 nm light to the 500-600 nm range. For the four-ring oligomer, no noticeable upconversion was observed, possibly because the triplet of the porphyrin oligomer is just below that of the perylene bisimid in this case.","","en","doctoral thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:14f1f322-7013-46d5-b6a1-c5a02fa01a8c","http://resolver.tudelft.nl/uuid:14f1f322-7013-46d5-b6a1-c5a02fa01a8c","Metal-Organic Frameworks for solar energy utilization","Nasalevich, M.A.","Kapteijn, F. (promotor); Gascon, J. (promotor)","2016","The research strategy followed in this work was inspired by natural photosynthesis that, for simplicity, can be divided into three principal steps: (i) efficient light absorption at wavelengths abundant in the solar light; (ii) long-lived charge separation achieved by funnelling of the photogenerated electrons away from the light-absorbing antenna; (iii) chemical reaction taking place at the specific catalytic sites. The idea of the present research was to mimic the key-principles of photosynthesis and implement them in Metal-Organic Frameworks. The first principle is covered in Chapter 4 where the light absorption properties of a Ti-based framework were synthetically tuned as to allow for lowering the excitation energy and sensitizing the MOF to a larger fraction of the solar spectrum. Chapters 2 and 3 investigate the photoexcitation processes in MOFs with the aim of prolonging the lifetime of photoexcited states similarly to (ii). Finally, in Chapter 5 additional catalytic sites (iii) were introduced in NH2-MIL-125(Ti) improving the catalytic activity by one order of magnitude. Chapter 1 introduces Metal-Organic Frameworks (MOFs) as potential photocatalysts and their characteristics. At first, general synthetic strategies of improving photocatalytic activity are discussed and a brief historical overview of the TiO2-based catalysts development is given followed by recent advances in the field. Further, the pioneering examples of using MOFs as photocatalysts are reviewed. The development of MOF-based photocatalysts is compared against more common photocatalysts such as TiO2. Some of the strategies such as sensitization towards a desired wavelength and introduction of additional catalytic sites are similar in both cases. At the same time MOFs are characterized by the microporous and well-defined structure, excellent tuneability and the lack of photoconductivity. All these aspects have strong implications for the synthetic strategies of the catalyst development. In this chapter three different roles of MOFs are discussed: a) MOFs as mere containers for photocatalytically active species; b) MOFs as photocatalysts both absorbing light and carrying out catalytic reactions; c) MOF-based composites where the frameworks are multifunctional, they absorb light and carry additional catalytic sites. Chapter 2. Here fundamentals of photoexcitation in NH2-MIL-125(Ti) are investigated with the help of ultrafast spectroscopy. MIL-125(Ti)-type frameworks are known to undergo ligand-to-metal charge transfer (LMCT) yielding Ti3+ and the positively charged organic-defined counterparts. UV-pump Visible-probe spectroscopy has shown that the excited states of NH2-MIL-125(Ti) possess a substantially longer lifetime as compared to the amine-free analogous MOF, MIL-125(Ti). Moreover, the difference in spectral signatures of the excited MIL-125(Ti) and NH2-MIL-125(Ti) was documented and associated to the difference in the organic-defined positively charged holes. The assignment of the transient spectral features of NH2-MIL-125(Ti) was carried out with the help of spectroelectrochemistry. Vis-pump IR-probe spectroscopy demonstrated that the photogenerated holes within NH2-MIL-125(Ti) are likely localized on the NH2-group of aminoterephthalates as the N-H stretch vibrations are heavily involved in the photoexcitation process. Kinetics of the photogenerated charge carriers in different solvents is described: in contrast to what was expected we found that the lifetimes of the excited states do not change depending on the solvent polarity. Chapter 3. In this chapter the role of d0 metal ion constituting frameworks of NH2-MIL-125 and NH2-UiO-66 is unravelled. In their works Walsh et al. have shown for the case of the MIL-125(Ti) series MOFs that the highest occupied crystal orbital (HOCO) is localized at the organic linker whereas the lowest unoccupied crystal orbital (LUCO) localizes at the inorganic secondary building unit (SBU), titanium oxocluster. Thus the HOCO-LUCO optical gap can be tuned by introducing various substituents into the aromatic system of the linker for the cost of modifying the oxidative power of the resulting photocatalyst. In this chapter the target reaction was hydrogen evolution. In this case, the reductive power of a photocatalyst is of crucial importance. The main hypothesis was that by changing the metal in the same group from Ti to Zr or Hf one should be able to tune this reductive power for the frameworks bearing the same organic linker and a similar topology. However, this is only true if LMCT operates in all MOFs considered. With the help of DFT it was found that the LUCO of NH2-MIL-125(Ti) is localized at the titanium oxocluster whereas the ones of NH2-UiO-66(Zr/Hf) are localized at the organic linker. The same conclusion was confirmed by EPR. This LMCT of NH2-MIL-125(Ti) possesses a substantially longer lifetime compared to the purely organic-based transitions found in the UiOs as revealed by transient absorption spectroscopy. This in turn results in a superior performance in photocatalytic H2 evolution in the case of Ti-based MOF. The positive role of structural defects in H2 evolution catalysed by the UiOs, although modest, was also documented. Chapter 4 introduces a framework with an extended conjugated aromatic system of the linker derived from NH2-MIL-125(Ti). The NH2-containing parent MOF was post-functionalized with dye-like molecular fragments resembling a well-known organic dye, methyl red. This was done by following a traditional synthetic pathway of obtaining organic dyes through the diazotization reaction. At the first stage the NH2-groups of NH2-MIL-125(Ti) react with nitrosonium ions, NO+, generated in situ by the HCl/NaNO2 pair while the second step is the reaction of the obtained N?N+-MIL-125(Ti) with diethylaniline. The resulting MOF absorbs a larger fraction of visible light extending to ca. 620 nm and thus has a superior performance in photocatalytic oxidation of benzyl alcohol. Furthermore, the photoconductance of MIL-125(Ti) was assessed by time-resolved microwave conductivity (TRMC). The experiments revealed that the material demonstrates very low levels of photoconductance that are temperature dependent. This type of behaviour is characteristic of the temperature-activated hopping as a type of charge carrier transport and is in contrast to the conductance of semiconductors that hardly changes with temperature. Based on these results it was recovered that MIL-125(Ti) and possibly many other MOFs should not be seen as true semiconductors but rather as arrays of coordination complexes arranged in a crystalline lattice. Chapter 5 illustrates an example of Active Site Engineering in Metal-Organic Frameworks. A well-known electrocatalyst, cobaloxime was encapsulated within the cavities of NH2-MIL-125(Ti). The direct sorption of the molecular complex into the pores of MOF did not proceed likely due to the size-selectivity of the pore windows. Therefore, a two-step synthetic strategy was developed where at the first stage the pores of the MOF were loaded with a flexible organic ligand while at the second CoBr2 was added under oxidative conditions. The organic ligand complexates with cobalt ions in the pores of NH2-MIL-125(Ti) forming a cobaloxime bearing Co(III) encapsulated the pores. The chapter contains an extensive characterization of the obtained composite and a discussion of possible differences between the molecular cobaloxime in solution vs. the one encapsulated in the MOF. The obtained Co@MOF catalyst evolves hydrogen at a rate 20 times greater than the one of the bare MOF. The external quantum efficiency for the composite was found to be 0.5%. This is a rather modest number if compared against the state of the art semiconductor-based systems. However, it should be emphasized that this catalyst outperforms the majority of reported MOF-based photocatalysts as explained in Chapter 5. Moreover, the composite purely consists of abundant elements (Ti, Co, C, O, N, Br, H) and, from that perspective, fulfils the global scale up requirements. Cobaloximes typically act as excellent catalytic sites yet they are not able to undergo charge separation upon illumination and require an external source of electrons. The electrons can be supplied by electrodes as well as by excited organic dye molecules. In this work with the help of EPR it was found that the MOF acts as a photosensitizer absorbing photons and injecting electrons in the cobalt complex. At the same time no Ti3+ was detected in irradiated Co@MOF composite in contrast to what was found in the bare NH2-MIL-125(Ti). Instead, cobalt reduction from Co3+ to Co2+ was detected. This suggests that the electron injection from the photoexcited MOF is fast while the resting state of the Co@MOF composite is Co(II). However, the turn-over frequency of the composite is still rather moderate and a more detailed investigation of the mechanism is needed to rationalize this performance. This is an elegant example of a multifunctional catalytic system for photocatalytic generation of hydrogen by water splitting, based on the abundant element Co.","Metal-Organic Frameworks; Photocatalysis; NH2-MIL-125(Ti); Hydrogen evolution","en","doctoral thesis","","","","","","","","2016-05-01","Applied Sciences","Chemical Engineering","","","",""
"uuid:74dfe07e-24eb-40ee-bbe3-aafc417e8065","http://resolver.tudelft.nl/uuid:74dfe07e-24eb-40ee-bbe3-aafc417e8065","Tunable and highly efficient light-harvesting antenna systems based on 1,7-perylene-3,4,9,10-tetracarboxylic acid derivatives","Dubey, R.K.; Inan, D.; Sengupta, S.; Sudhölter, E.J.R.; Grozema, F.C.; Jager, W.F.","","2016","We report the synthesis and excited-state dynamics of a series of five bichromophoric light-harvesting antenna systems, which are capable of efficient harvesting of solar energy in the spectral range of 350–580 nm. These antenna systems have been synthesized in a modular fashion by the covalent attachment of blue light absorbing naphthalene monoimide energy donors (D1, D2, and D3) to green light absorbing perylene-3,4,9,10-tetracarboxylic acid derived energy acceptors, 1,7-perylene-3,4,9,10-tetracarboxylic tetrabutylester (A1), 1,7-perylene-3,4,9,10-tetracarboxylic monoimide dibutylester (A2), and 1,7-perylene-3,4,9,10-tetracarboxylic bisimide (A3). The energy donors have been linked at the 1,7-bay-positions of the perylene derivatives, thus leaving the peri positions free for further functionalization and device construction. A highly stable and rigid structure, with no electronic communication between the donor and acceptor components, has been realized via an all-aromatic non-conjugated phenoxy spacer between the constituent chromophores. The selection of donor naphthalene derivatives for attachment with perylene derivatives was based on the effective matching of their respective optical properties to achieve efficient excitation energy transfer (EET) by the Förster mechanism. A comprehensive study of the excited-state dynamics, in toluene, revealed quantitative and ultrafast (ca. 1 ps) intramolecular EET from donor naphthalene chromophores to the acceptor perylenes in all the studied systems. Electron transfer from the donor naphthalene chromophores to the acceptor perylenes has not been observed, not even for antenna systems in which this process is thermodynamically allowed. Due to the combination of an efficient and fast energy transfer along with broad absorption in the visible region, these antenna systems are promising materials for solar-to-electric and solar-to-fuel devices.","","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:faf82475-bd68-45c2-85f2-65f01d47071d","http://resolver.tudelft.nl/uuid:faf82475-bd68-45c2-85f2-65f01d47071d","Microfluidic microneedle or micropipet comprising a nanogap sensor for analytical applications","Rassaei, L.","","2016","The invention provides asensor device comprising a substrate, especially a needle with a needle tip, wherein the substrate, especially the needle, even more especially the needle tip, comprises a sensor unit, wherein the sensor unit includes a stacked layer structure including an electrode layer, wherein the stacked layer structure further includes a nanogap dividing the electrode layer in a first electrode and a second electrode with the nanogap in between, wherein the nanogap has a width (w) selected from the range of 10-500 nm, such as from the range of 20-200 nm, and wherein in a specific embodiment the needle further comprises a microfluidic channel structure with an orifice, wherein the orifice is especially arranged at the needle tip, for delivery or extraction of a fluid.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:96a05294-960e-412e-beb7-5f57ed77ef92","http://resolver.tudelft.nl/uuid:96a05294-960e-412e-beb7-5f57ed77ef92","Deposition Mechanism of Aluminum Oxide on Quantum Dot Films at Atmospheric Pressure and Room Temperature","Valdesueiro Gonzalez, D. (TU Delft ChemE/Product and Process Engineering); Prabhu, M.K. (TU Delft ChemE/Product and Process Engineering); Guerra Nunez, C.R. (TU Delft ChemE/Product and Process Engineering; Swiss Federal Laboratories for Materials Science and Technology (Empa)); Sandeep, C. S Suchand (University of Potsdam); Kinge, S.S. (TU Delft ChemE/Opto-electronic Materials); Siebbeles, L.D.A. (TU Delft ChemE/Opto-electronic Materials); de Smet, L.C.P.M. (TU Delft OLD ChemE/Organic Materials and Interfaces); Meesters, G.M.H. (TU Delft ChemE/Product and Process Engineering); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); Houtepen, A.J. (TU Delft ChemE/Opto-electronic Materials); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2016","Stability of quantum dot (QD) films is an issue of concern for applications in devices such as solar cells, LEDs, and transistors. This paper analyzes and optimizes the passivation of such QD films using gas-phase deposition, resulting in enhanced stability. Crucially, we deposited alumina at economically attractive conditions, room temperature and atmospheric pressure, on (1,2-ethanediamine) capped PbSe QD films using an approach based on atomic layer deposition (ALD), with trimethylaluminum (TMA) and water as precursors. We performed coating experiments from 1 to 25 cycles on the QD films, finding that alumina formed from the first exposure of TMA. X-ray photoelectron spectroscopy points to the presence of oxygen-rich compounds on the bare QD films, most likely from entrapped solvent molecules during the assembly of the QD films. These oxygenated compounds and the amine groups of the organic ligands react with TMA in the first cycle, resulting in a fast growth of alumina. Using 10 cycles resulted in a QD film that was optically stable for at least 27 days. Depositing alumina at ambient conditions is preferred, since the production of the QD films is also carried out at room temperature and atmospheric pressure, allowing combination of both processes in a single go.","","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:09426c59-2bbc-4b5a-b078-582029dfc76f","http://resolver.tudelft.nl/uuid:09426c59-2bbc-4b5a-b078-582029dfc76f","Unraveling a two-step oxidation mechanism in electrochemical Cu-MOF synthesis","Schäfer, P.; Van der Veen, M.A.; Domke, K.F.","","2016","To employ the full potential of electrochemical (ec) synthesis to grow metal–organic frameworks (MOFs) in more complex organizations at the mesoscale, it is vital to understand the underlying crystallization reaction pathway. For the MOF most typically grown electrochemically, CuBTC, we systematically investigated the role of oxygen species in the synthesis.","","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:afd78689-d332-4761-b651-47de4c440757","http://resolver.tudelft.nl/uuid:afd78689-d332-4761-b651-47de4c440757","Decentralized water purification using solar thermal energy","Bhardwaj, R.","Mudde, R.F. (promotor)","2016","Provision of clean drinking water to poor can prevent a large number of deaths and illnesses amongst children around the world. In 2010, about 0.75 million child deaths were caused due to diarrhea, and a further 22.5 million years of life were lost due to ill-health, disability or early death caused by unimproved water and inadequate sanitation around the world. Most of these people live in regions with limited or no electricity, and abundance of sunshine and salt water or unclean water. Solar thermal distillation using solar stills is the most potent way of cleaning the salt water in the absence of electricity. Several products, such as the inflatable stills for life rafts, water-cone and water pyramid have been demonstrated for the purification of salt water. None of these is specifically targeting a single family. We found that simple ways of natural cooling improve the production considerably. Moreover, dripping from cleaned water from the condensing area reduced the production. A simple rule could be formulated that provides an estimate of the maximum length before dripping starts. With this a more clever design of the collection of clean water allows stills of larger scale that still produce efficiently. The work of this thesis we aim at a plastic based solar stills capable of providing at least 2.5 liters/day of drinking water, an amount put forward by the UNICEF. The results are being used by Dr Ten B.V. for the development of a simple and replicable mass manufacturing process for plastic based stills. Future projects for the use of solar stills are under consideration with several governments and organizations like UNHCR","","en","doctoral thesis","","","","","","","","2016-09-30","Applied Sciences","Chemical Engineering","","","",""
"uuid:11caef74-1ce4-450f-b5ab-a7d7537937a7","http://resolver.tudelft.nl/uuid:11caef74-1ce4-450f-b5ab-a7d7537937a7","Deposition of conductive TiN shells on SiO2 nanoparticles with a fluidized bed ALD reactor","Didden, A.; Hillebrand, P.; Wollgarten, M.; Dam, B.; Van de Krol, R.","","2016","Conductive TiN shells have been deposited on SiO2 nanoparticles (10–20 nm primary particle size) with fluidized bed atomic layer deposition using TDMAT and NH3 as precursors. Analysis of the powders confirms that shell growth saturates at approximately 0.4 nm/cycle at TDMAT doses of >1.2 mmol/g of powder. TEM and XPS analysis showed that all particles were coated with homogeneous shells containing titanium. Due to the large specific surface area of the nanoparticles, the TiN shells rapidly oxidize upon exposure to air. Electrical measurements show that the partially oxidized shells are conducting, with apparent resistivity of approximately ~11 k? cm. The resistivity of the powders is strongly influenced by the NH3 dose, with a smaller dose giving an order-of-magnitude higher resistivity.","fluidized bed; atomic layer deposition; coreshell particles; titanium nitride; conductive shells; microelectronic contacts","en","journal article","Springer","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:013e4dff-22f9-4a8a-bbce-c8d7e496347c","http://resolver.tudelft.nl/uuid:013e4dff-22f9-4a8a-bbce-c8d7e496347c","Computational design of donor-bridge-acceptor systems exhibiting pronounced quantum interference effects","Gorczak, N.; Renaud, N.; Galan, E.; Eelkema, R.; Siebbeles, L.D.A.; Grozema, F.C.","","2016","Quantum interference is a well-known phenomenon that dictates charge transport properties of single molecule junctions. However, reports on quantum interference in donor-bridge-acceptor molecules are scarce. This might be due to the difficulties in meeting the conditions for the presence of quantum interference in a donor-bridge-acceptor system. The electronic coupling between the donor, bridge, and acceptor moieties must be weak in order to ensure localised initial and final states for charge transfer. Yet, it must be strong enough to allow all bridge orbitals to mediate charge transfer. We present the computational route to the design of a donor-bridge-acceptor molecule that features the right balance between these contradicting requirements and exhibits pronounced interference effects.","Gold for Gold; Open Access","en","journal article","Gold for Gold Open Access","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:d65aeaa3-882f-49a6-bbad-5eb1a166bebd","http://resolver.tudelft.nl/uuid:d65aeaa3-882f-49a6-bbad-5eb1a166bebd","Modeling of wind turbine wake with a sliding mesh","Van der Auweraert, J.F.","Hennen, J. (mentor)","2016","","","en","bachelor thesis","","","","","","","","2016-02-01","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:be103e3b-6975-4862-b87c-d897cbfbb3d2","http://resolver.tudelft.nl/uuid:be103e3b-6975-4862-b87c-d897cbfbb3d2","Synthesis and Characterization of Porous Carbon-MoS2 Nanohybrid Materials for Charge-Enhanced Electrocatalysis","Dolinska, J.; Chidambaram, A.; Adamkiewicz, W.; Estili, M.; Lisowski, W.; Iwan, M.; Palys, B.; Sudholter, E.J.R.; Marken, F.; Opallo, M.; Rassaei, L.","","2016","Porous carbon nanohybrids are promising materials as high-performance electrodes for both sensing and energy conversion applications. This is mainly due to their high specific surface area and specific physicochemical properties. Here, new porous nanohybrid materials are developed based on exfoliated MoS2 nanopetals and either negatively charged phenylsulfonated carbon nanoparticles or positively charged sulfonamide functionalized carbon nanoparticles. MoS2 nanopetals not only act as a scaffold for carbon nanoparticles to form 3D porous hierarchical architectures but also result in well-separated electrochemical signals for different compounds. The characteristics of the new carbon nanohybrid materials are studied by dynamic light scattering, zeta potential analysis, high resolution X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, infrared spectroscopy and electrochemistry. The new hybrid materials show superior charge transport capability and electrocatalytic activity toward selected biologically relevant compounds compared to earlier reports on porous carbon electrodes.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:997b52c5-6b70-4e03-91b7-e0e2b0530465","http://resolver.tudelft.nl/uuid:997b52c5-6b70-4e03-91b7-e0e2b0530465","Methanol-to-olefins process over zeolite catalysts with DDR topology: Effect of composition and structural defects on catalytic performance","Yarulina, I.; Goetze, J.; Gücüyener, C.; Van Thiel, L.; Dikhtiarenko, A.; Ruiz-Martinez, J.; Weckhuysen, B.M.; Gascon, J.; Kapteijn, F.","","2016","A systematic study of the effect of physicochemical properties affecting catalyst deactivation, overall olefin selectivity and ethylene/propylene ratio during the methanol-to-olefins (MTO) reaction is presented for two zeolites with the DDR topology, namely Sigma-1 and ZSM-58. Both catalysts show high selectivity towards light olefins and completely suppress the formation of hydrocarbons bigger than C4, with selectivity to ethane not exceeding 1% and some traces of propane. By applying seeded growth approach, a series of Sigma-1 zeolites with tunable crystal size and acidity was synthesized. For this series the highest methanol throughput at 450 °C before deactivation was found for crystals 0.5 ?m in size with an acidity corresponding to 0.5 Al atoms per zeolite cage, and a selectivity to ethylene and propylene reaching 90%. Comparison between ZSM-58 and Sigma-1 catalysts with similar morphologies and acidity under the same reaction conditions revealed a three times higher throughput of methanol in case of ZSM-58. The analysis of functional surface groups, assessed through FT-IR, revealed the presence of silanol defects in Sigma-1 responsible for faster catalyst deactivation. These silanol defects can be selectively removed (confirmed by FT-IR) from the zeolite framework by applying a mild treatment in presence of NaOH/CTAB, leading to an improved catalyst lifetime. Co-feeding experiments with short olefins and water show low reactivity of primary MTO products, which only react at the surface of the catalyst particles. These results demonstrate that migration of the reaction zone in case of DDR catalysts hardly affects catalyst stability, product composition and nature of deactivating species. The nature of these species depends mostly on reaction temperature: at low temperatures deactivation occurs mainly due to the formation of inert adamantane species, while at high temperatures poly-condensed aromatic hydrocarbons play the major role in deactivation.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:07290684-352e-4d20-94ce-ab258df392af","http://resolver.tudelft.nl/uuid:07290684-352e-4d20-94ce-ab258df392af","Second harmonic generation microscopy reveals hidden polar organization in fluoride doped MIL-53(Fe)","Markey, K.; Putzeys, T.; Horcajada, P.; Devic, T.; Guillou, N.; Wübbenhorst, M.; Van Cleuvenbergen, S.; Verbiest, T.; De Vos, D.E.; Van der Veen, M.A.","","2016","Polar metal–organic frameworks have potential applications as functional non-linear optical, piezoelectric, pyroelectric and ferroelectric materials. Using second harmonic generation microscopy we found that fluoride doping of the microporous iron(III) terephthalate MOF MIL-53(Fe) induces a polar organization in its structure, which was not previously detected with XRD. The polar order is only observed when both fluoride and guest molecules are present, and may be related to a complex interplay between the adsorbates and the framework, leading to a modification of the positioning of fluoride in the inorganic Fe-chains. Combined polarized second harmonic generation microscopy and scanning pyroelectric microscopy show that the polar axis is unidirectional and of the same sense over the whole crystal, extending up to 100 micrometers. This finding shows how MOF materials can be endowed with useful properties by doping MOFs with fluoride.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:d4725b17-f337-4f04-96ca-3c8f594b8ebb","http://resolver.tudelft.nl/uuid:d4725b17-f337-4f04-96ca-3c8f594b8ebb","Synthesis of 1,2-biphenylethane based single-molecule diodes","Galán, E.; Perrin, M.L.; Lutz, M.; Van der Zant, H.S.J.; Grozema, F.C.; Eelkema, R.","","2016","We have described the synthesis of novel biphenylethane-based wires for molecular electronics. Exceptional single-molecule diode behavior was predicted for unsymmetrically substituted biphenylethane derivatives, synthesized here using the so far unexplored unsymmetrically substituted 1,2-bis(4-bromophenyl)ethanes as key intermediates, which were obtained from the corresponding tolane precursor by selective hydrogenation.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:276944aa-369a-4a4e-bf0b-27b9aba7e6ee","http://resolver.tudelft.nl/uuid:276944aa-369a-4a4e-bf0b-27b9aba7e6ee","Control of interpenetration of copper-based MOFs on supported surfaces by electrochemical synthesis","Sachdeva, S.; Pustovarenko, A.; Sudhölter, E.J.R.; Kapteijn, F.; De Smet, L.C.P.M.; Gascon, J.","","2016","A study of a copper-based metal–organic framework (MOF) synthesized by an electrochemical route is presented. Morphological and adsorption properties of the MOF synthesized as bulk powder and on supported copper surfaces were investigated. Differences in these properties and structural refinement studies indicate that when 4,4?,4??-s-triazine-2,4,6-triyl-tribenzoic acid (H3TATB) is used as linker interpenetration can be prevented when the structure is grown on a surface.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:21fb1ef0-0113-4e48-bd24-836cffd8ad1a","http://resolver.tudelft.nl/uuid:21fb1ef0-0113-4e48-bd24-836cffd8ad1a","Analysis of the continuum surface force method","Wang, S.J.","Van der Heul, D.R. (mentor); Kenjeres, S. (mentor)","2016","In the two-phase ?ow models developed in the Scienti?c Computing group of the Delft Institute for Applied Mathematics (DIAM) the strict application of the continuum surface force method was identi?ed as one of the causes for an observed discrepancy between the experimentally observed and theoretically predicted rise speed of a single gas bubble. In this report the mathematical correctness of the derivation of the CSF model and some of its assumptions are veri?ed.","CSF; surface force","en","bachelor thesis","","","","","","","","","Applied Sciences","Chemical engineering and mathematics","","Applied physics and applied mathematics","",""
"uuid:185999ce-41f2-4cac-9c4d-27782df18fbf","http://resolver.tudelft.nl/uuid:185999ce-41f2-4cac-9c4d-27782df18fbf","Carbon/H-ZSM-5 composites as supports for bi-functional Fischer-Tropsch synthesis catalysts","Valero-Romero, M.J.; Sartipi, S.; Sun, X.; Rodríguez-Mirasol, J.; Cordero, T.; Kapteijn, F.; Gascon, J.","","2016","Mesoporous H-ZSM-5–carbon composites, prepared via tetrapropylammonium hydroxide (TPAOH) post treatment of H-ZSM-5 followed by deposition of pyrolytic carbon, have been used as the support for the preparation of Co-based Fischer–Tropsch catalysts. The resulting catalysts display an improved performance during Fischer–Tropsch synthesis (FTS), with higher activity, higher selectivity towards C5–C9 (gasoline range) hydrocarbons and lower selectivity towards C1 (and C2) than Co/mesoH-ZSM5 (without pyrolytic carbon). This is due to the weaker metal–support interaction caused by the deposited carbon (as revealed by XPS) leading to a higher reducibility of the Co species. Further, the partial deactivation of the Brønsted acid sites by pyrolytic carbon deposition, as was observed by NH3-TPD, allows the modification of the zeolite acidity. Both the olefin to paraffin (O/P) and the isoparaffin to normal paraffin (I/N) ratios decrease with the increase in the carbon content, opening the door to further tune the catalytic performance in multifunctional FTS operations.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:8174e3e8-8ca0-4d0d-a5fa-413d872a09fb","http://resolver.tudelft.nl/uuid:8174e3e8-8ca0-4d0d-a5fa-413d872a09fb","Contact mechanics of highly porous oxide nanoparticle agglomerates","Fabre, A. (TU Delft ChemE/Product and Process Engineering); Salameh, S. (TU Delft ChemE/Product and Process Engineering); Colombi Ciacchi, Lucio (University of Bremen); Kreutzer, M.T. (TU Delft ChemE/Chemical Engineering); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2016","Efficient nanopowder processing requires knowledge of the powder’s mechanical properties. Due to the large surface area to volume ratio, nanoparticles experience relatively strong attractive interactions, leading to the formation of micron-size porous structures called agglomerates. Significant effort has been directed towards the development of models and experimental procedures to estimate the elasticity of porous objects such as nanoparticle agglomerates; however, none of the existing models has been validated for solid fractions below 0.1. Here, we measure the elasticity of titania (TiO2, 22 nm), alumina (Al2O3, 8 nm), and silica (SiO2, 16 nm) nanopowder agglomerates by Atomic Force Microscopy, using a 3.75 μm glass colloid for the stress–strain experiments. Three sample preparations with varying degree of powder manipulation are assessed. The measured Young’s moduli are in the same order of magnitude as those predicted by the model of Kendall et al., thus validating it for the estimation of the Young’s modulus of structures with porosity above 90 %.","Young’s modulus; Porous agglomerates; Atomic force microscopy; Oxide particles; Nanoparticles; Particle characterization; Instrumentation","en","journal article","","","","","","","","","","ChemE/Chemical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:5c5f7f48-ca17-4df7-a372-aba47ac7ac2b","http://resolver.tudelft.nl/uuid:5c5f7f48-ca17-4df7-a372-aba47ac7ac2b","Out-of-equilibrium self-assembly approaches for new soft materials","Hendriksen, W.E.","Van Esch, J.H. (promotor); Eelkema, R. (promotor)","2015","Living creatures exists for an important part out of soft material, such as skin, organs and cells, that are out-of-equilibrium formed by the self-assembly of molecular building blocks. Natural materials are continuously active with dynamic processes occurring, such as growth, shrinkage and transport mechanisms under the consumption of energy. Extending the knowledge on out-of- equilibrium self-assembly will open new opportunities for programmable and self-healing materials. In this thesis a new design approach for out-of-equilibrium formed self-assembled materials is described and tested experimentally. A key development is the chemical fuel driven self-assembly of molecular gelators and colloidal particles. Using thermodynamic insights for the out-of-equilibrium self-assembly an understanding of the different processes is obtained. Then the development of an organic reaction-diffusion based system results in the spatial organization of self-assembled materials. Finally, a step towards controlled enzyme interactions by materials is made through the immobilization of proteins to self-assembled materials.","self-assembly; soft matter; out-of-equilibrium; complexity; gelator; gel; proteins; reaction-diffusion; fuel driven; dissipative; chemistry; supramolecular; thermodynamics; colloids","en","doctoral thesis","TU Delft Library","","","","","","","2015-12-03","Applied Sciences","Chemical Engineering, Advanced Soft Matter","","","",""
"uuid:bddc6abb-dfc3-4036-8a11-ff889821864c","http://resolver.tudelft.nl/uuid:bddc6abb-dfc3-4036-8a11-ff889821864c","Optimised high voltage spinels for Li-ion batteries","Fredon, R.","Bruck, E. (promotor)","2015","Mankind has started taking the global warming problem into consideration, and has been doing so for decades. The relevance of the problem is slowly reaching everyone’s mind, which has resulted in fast growth in important related research topics, among which energy materials. One of the most important challenges has to do both with transportation and the production of polluting gases. In the last 3 decades, lithium ion batteries have grown to be a key technology, and are without doubt one of the most promising energy carriers for transportation and grid energy storage. Despite the technology being well established, the performance of lithium ion batteries still could (and should) be improved on a number of points, such as energy density, lifespan, efficiency and safety. These are mainly materials challenges. This thesis looks at the positive electrode material as a way of obtaining a higher energy density in lithium ion batteries. This thesis was written within the EuroLiion project, which has the goal to develop a new Li- ion cell for traction purposes, such as a car pulling up, with the following characteristics: High energy density of at least 200 Wh/kg Low cost, i.e. a maximum of 150 Euro/kWh. Chapter 1 provides a history of batteries, introduces some generalities and basic knowledge about batteries. In the end, it presents an overview of the EuroLiion project. Chapter 2 gives an overview of the known technologies in terms of lithium nickel manganese oxide (LNMO), as well as an extensive list of the coatings and dopings that can be applied to this material in order to improve it. From this research and its results, in terms of particle size and its effect on performance, the effects of the different coatings, etc..., the positive electrode material for the whole project is chosen. Chapter 3 describes the production of different variations of the material, and an evaluation of their behaviour. The results of an in-situ X-Ray absorption Spectroscopy study are presented. The effect of the oxidation state of the chromium doping on the LNMO, while the battery is cycled, is studied. SEM and EDX pictures of the material and its doping are also shown. In chapter 4, in order to measure the enhancement due to the chromium doping, while having a topographic picture of the interface between the positive electrode and the electrolyte, an AFM analysis is presented. A new way is introduced to monitor ‘in vivo’ the ion and electronic transport between the positive electrode and the electrolyte. Chapter 5 is a direct continuation of chapter 4. Indeed, due to lack of results to explain the enhancement of the material by the chromium doping, more structural measurements and surface characterizations, such as SEM, EDX, XAS, and XPS, are presented and explained. The correlation between the lithium content and the nickel content at different states of charge is also explained. Finally, at this stage of the project, the material has been improved and the reasons and scientific explanations of why this material is better are known. Development is now finalized and the material is in production by a Dutch company and sold to the contributors of the EuroLiion project for testing in prototypes. Chapter 6 explains the whereabouts of the whole project, including external work on the other parts of the project, such as electrolyte, anode, packaging and economic details. In conclusion, during these 4 years of research, I synthetized, developed and tested a material that gathers all the desired performances. When my material has been chosen to be implemented and used by the EuroLiion partners, I also had a technical and scientific support for the industrial scale production of the material, which was well very rewarding and allowed me to gain some knowledge and be in close cooperation with the industry. To create a more powerful and efficient battery, the other elements need to be improved, in order for all parts of the cell to work in harmony and deliver the best performances possible.","Li-ion batteries; LNMO; cathode material","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:80834569-3918-4444-9ad7-c1041e41bed5","http://resolver.tudelft.nl/uuid:80834569-3918-4444-9ad7-c1041e41bed5","Optical and Electrical Biosensors: A Chemist's View","Ullien, D.","Sudholter, E.J.R. (promotor)","2015","This thesis covers work done on silicon nanowire field effect transistors and optical microring resonators. An effort was put to develop point-of-care devices based on this platforms to facilitate rapid and reliable diagnosis of influenza A.","biosensor","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:4c7ea584-7168-4661-9e30-d20d07dc2ac3","http://resolver.tudelft.nl/uuid:4c7ea584-7168-4661-9e30-d20d07dc2ac3","Gas-phase Deposition of Thin Aluminium Oxide Films at Ambient Conditions","Valdesueiro, D.","Kreutzer, M.T. (promotor); Van Ommen, J.R. (promotor); Meesters, G.M.H. (promotor)","2015","Particles are widely used in the chemical industry as raw material and end product. In many applications of particles, it is advantageous to give them a coating that can either protect the particle from outside influences or give it an additional function. Technologies to provide micron-sized particles with relatively thick coatings (in the order of ?m) are readily available. However, for many applications it would be attractive to apply coatings to fine particles (of the order of 50 ?m or smaller) and to make these coatings thinner (<< 1 ?m). This opens possibilities for new properties. In addition, a lower amount of the compound would be needed to coat the material of interest. This thesis focuses on a technique for depositing ultrathin and conformal films, with control down to nanometre scale, with high a utilisation of the precursors: atomic layer deposition (ALD) applied to fine particles. ALD is a gas-phase coating technique that relies on two self terminating reactions, that form a coating cycle, after which a fraction of a monolayer of compound is deposited on the substrate. This cycle can be repeated a desired number of times to deposit thicker layers. Amongst the wide variety of compounds that have been deposited with ALD, alumina (Al2O3) has been the favourite one to study, due to the ideal layer-by-layer growth mode that is observed when used trimethyl aluminium (TMA) and water as precursors, and its broad applicability in different fields. Thin Al2O3 ALD films have been used, for example, in the fabrication of semiconductor devices, in the production of catalysts and the passivation of the cathode of the Li-ion batteries. Besides these applications, other materials such as polymers or biological products could benefit from the deposition of ultrathin alumina films. However, alumina has been typically deposited at relatively high temperatures, i.e., ~170 °C and < 1 mbar, inhibiting its application to heat-sensitive materials. This is our main motivation to investigate the deposition of alumina films at room temperature and atmospheric pressure. Working at ambient conditions would, in first place, permit the coating of heat sensitive materials, and, in second place, facilitate the coating process and improve the scaling-up prospects, since less complex equipment would be required. Atomic layer deposition provides accurate control over the film thickness based on the selfterminating nature of the ALD reactions. That means that deposition only takes place as long as there are surface species available for reaction. The combination of the operating temperature and pressure, and the purging of the reactor with nitrogen after each reaction, ensure the removal of unreacted precursor molecules from the surface of the substrate. However, the physisorption of these unreacted molecules is the main challenge that we face when depositing alumina at 25 °C and 1 bar, since the normal boiling temperature of TMA and water is 125 and 100 °C, respectively. In Al2O3 ALD processes at 170 °C and < 1 mbar, where no physisorption occurs, the thickness of the deposited films depends solely on the number of coating cycles, since once the active sites on the surface are depleted, no more reaction takes place, regardless of the amount of precursors fed to the reactor in excess. In contrast, at ambient conditions, the thickness of the alumina film will depend on the number of cycles and on the dosing time of the precursors due to the accumulation of the unreacted precursor molecules that are fed in excess. In this work, we aimed at controlling the physisorption of the precursors at ambient conditions by adjusting the dosing time of the precursors to the reactor. By feeding the amount of precursor molecules needed to saturate the active sites present on the surface of the substrate (TiO2 nanoparticles in our case), we obtained similar growths as in pure ALD, i.e., 0.1-0.2 nm per cycle, even if the reactions are not self-limiting. Complementarily, having a faster growth of the alumina film could be done by dosing both precursors in excess due to the physisorption of unreacted molecules. These findings were applied in the remainder of the thesis to deposit alumina, at ambient conditions, on three different substrates: polymeric powder coating paint, lead-selenide quatum dot (PbSe QD) films, and silicon carbide (SiC) particles. Two of these materials, the powder coating and the QD films, are heat sensitive, thus working at room temperature was essential. Al2O3 films were used to tune the surface appearance of a powder coating (i.e., dry paint without any solvent). The polymeric core particles were coated with alumina films of different thicknesses. The alumina layers partially confined the core material when it softened above the glass transition temperature. As the softened core did not flow during the curing of the paint, it created roughness of the surface, and therefore, a matte surface appearance. The mechanical properties of the matte powder coating were similar to the ones of the originally glossy one. Thin alumina films were used to tune the final appearance of the powder coating paint without the use of foreign particles that would produce the same effect. Additionally, films of PbSe QD crystals, which are nanosized crystals with very interesting properties for semiconductor applications, were passivated using alumina. QDs films have very promising applications, e.g., as high-efficiency photovoltaic material. However, they are air and heat sensitive and irreversibly oxidize after a short exposure to air, losing their good properties. Previous work showed the passivation of the QDs with alumina at temperatures between 25 and 90 °C, and pressures smaller than 1 mbar. In this work, alumina was deposited at 25 °C and 1 bar to efficiently passivate the QDs. At ambient conditions, a fast deposition of alumina took place as a consequence of different groups that can react with TMA, such as hydroxyl and amine groups. Coating with alumina at ambient conditions can be easily coupled with the fabrication of the QD films, which also is done at room temperature and atmospheric pressure. The final application we considered is the production of radioactive tracer particles. For fluidized bed studies, we would like to label SiC particles with a minimum change to their other physical properties. SiC particles have a rather inert surface towards radioactive ions. We used the Al2O3 coating to enhance the labelling efficiency of this material and produce a tracer. Typically, a completely different material is used for the tracer particles, such as ?-Al2O3. However, this would produce a mismatch in properties such as size, shape and density between the tracer and the material of study. In this work, alumina films were deposited on SiC particles to mimic the affinity of the ?-Al2O3 particles towards the radioactive ions, and produce a SiC-based tracer. Since the labelling efficiency depends on the alumina film thickness, TMA and water were fed in large excess, achieving a growth per cycle of alumina of about 10 nm. The resulting core-shell particles, with an alumina coating of about 400 nm, had only a slightly lower relative activity as the ?-Al2O3 particle. Nevertheless, this SiC based tracer was used in a particle tracking experiment, having enough activity to be detected by the sensors and reconstruct its trajectory during fluidization. One might argue whether the studied deposition process at atmospheric pressure and room temperature is still true ALD, since the reactions are not self-terminating and we deposit several layers of alumina in each cycle. Nevertheless, it gives the possibility of depositing alumina on heat sensitive materials, with good tunability and control over the films thickness, at operating conditions that would simplify the scaled-up of this technology. The findings in this thesis could be expanded to other applications, such as the coating of biological compounds, that would require low-temperature processing, or the deposition of other compounds at ambient conditions, i.e., zinc oxide (ZnO). This is further discussed in the outlook of this thesis.","aluminium oxide; atomic layer deposition; thin films; ambient conditions; room temperature; atmospheric pressure; nanoparticles","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:57caeb7c-1dc5-4211-8e46-5308725f4a2d","http://resolver.tudelft.nl/uuid:57caeb7c-1dc5-4211-8e46-5308725f4a2d","On Recent Progress in Modelling and Simulations of Multi-scale Transfer of Mass, Momentum and Particles in Bio-medical Applications","Kenjeres, S.","","2015","We present a short overview of some of our most recent work that combines the mathematical modeling, advanced computer simulations and state-of-the-art experimental techniques of physical transport phenomena in various bio-medical applications. In the first example, we tackle predictions of complex blood flow patterns in the patient-specific vascular system (carotid artery bifurcation) and transfer of the so-called “bad” cholesterol (low-density lipoprotein, LDL) within the multi-layered artery wall. This two-way coupling between the blood flow and corresponding mass transfer of LDL within the artery wall is essential for predictions of regions where atherosclerosis can develop. It is demonstrated that a recently developed mathematical model, which takes into account the complex multi-layer arterial-wall structure, produced LDL profiles within the artery wall in good agreement with in-vivo experiments in rabbits, and it can be used for predictions of locations where the initial stage of development of atherosclerosis may take place. The second example includes a combination of pulsating blood flow and medical drug delivery and deposition controlled by external magnetic field gradients in the patient specific carotid artery bifurcation. The results of numerical simulations are compared with own PIV (Particle Image Velocimetry) and MRI (Magnetic Resonance Imaging) in the PDMS (silicon-based organic polymer) phantom. A very good agreement between simulations and experiments is obtained for different stages of the pulsating cycle. Application of the magnetic drug targeting resulted in an increase of up to ten fold in the efficiency of local deposition of the medical drug at desired locations. Finally, the LES (Large Eddy Simulation) of the aerosol distribution within the human respiratory system that includes up to eight bronchial generations is performed. A very good agreement between simulations and MRV (Magnetic Resonance Velocimetry) measurements is obtained. Magnetic steering of aerosols towards the left or right part of lungs proved to be possible, which can open new strategies for medical treatment of respiratory diseases.","blood flow; LDL transfer; aerosol distribution; magnetization force","en","journal article","Springer","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:8df625df-b133-429a-b507-00babfb4d5a0","http://resolver.tudelft.nl/uuid:8df625df-b133-429a-b507-00babfb4d5a0","Formation of polyelectrolyte multilayers: Ionic strengths and growth regimes","Tang, K.; Besseling, N.A.M.","","2015","This article presents a study of layer-by-layer (LbL) formation of poly-electrolyte multilayers (PEMs). Upon increasing ionic strength LbL growth patterns vary from linear for the lowest salt concentrations ([NaCl] = 0, 0.001, and 0.01 M) to exponential (for [NaCl] = 0.5 and 1 M). The slope of the linear growth at the lowest ionic strengths increases with increasing [NaCl]. During the LbL process at 0.5 M NaCl we observe a cross over from exponential to linear growth for which the slope is orders of magnitude larger than those observed at low salt concentrations. We provide a comprehensive interpretation of these growth behaviors, which are also reported for many other LbL PEM systems, based on the generic features of the phase diagram of aqueous solutions of mixtures of oppositely charged poly-electrolytes. Processes occurring in LbL formation of PEMs can be understood as moving in the direction of equilibrium, while never achieving it. The experimental model system in this study was: polydiallyldimethylammonium chloride/polystyrene sulfonate (PDADMAC/PSS). PEM formation was followed in situ by optical reflectometry in combination with well-controlled transport conditions (impinging jet stagnation point flow).","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:a330e264-344b-4153-8827-ccd95784f2aa","http://resolver.tudelft.nl/uuid:a330e264-344b-4153-8827-ccd95784f2aa","Single element hydrogen sensing material","Dam, B.; Boelsma, C.","","2015","The present invention relates to a single element thin-film device, to a method for producing a thin-film device, to a single element for detecting hydrogen absorption, to a hydrogen sensor, to an apparatus for detecting hydrogen and to an electro-magnetic transformer comprising said sensor. A thin-film device comprises a substrate, an active sensing layer whose optical properties change depending on hydrogen content, and a protective layer on the active sensing layer.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:8687dc2e-fff3-45cf-9a7d-536b35e9a28d","http://resolver.tudelft.nl/uuid:8687dc2e-fff3-45cf-9a7d-536b35e9a28d","Small azomethine molecules and their use in photovoltaic devices","Dingemans, T.J.; Petrus, M.L.","","2015","The present invention is in the field of a small azomethine molecule having photovoltaic characteristics, a method of synthesizing said molecule, use of said molecule in a photovoltaic device, a solar cell comprising said molecule, and a film comprising said molecule. The present molecules may find application in the field of organic solar cells.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:969326c9-c563-42bc-b292-c7bac2564804","http://resolver.tudelft.nl/uuid:969326c9-c563-42bc-b292-c7bac2564804","Electrocatalytic Activity and Durability of Pt-Decorated Non-Covalently Functionalized Graphitic Structures","Negro, E.; Stassi, A.; Baglio, V.; Arico, A.S.; Koper, G.J.M.","","2015","Carbon graphitic structures that differ in morphology, graphiticity and specific surface area were used as support for platinum for Oxygen Reduction Reaction (ORR) in low temperature fuel cells. Graphitic supports were first non-covalently functionalized with pyrene carboxylic acid (PCA) and, subsequently, platinum nanoparticles were nucleated on the surface following procedures found in previous studies. Non-covalent functionalization has been proven to be advantageous because it allows for a better control of particle size and monodispersity, it prevents particle agglomeration since particles are bonded to the surface, and it does not affect the chemical and physical resistance of the support. Synthesized electrocatalysts were characterized by electrochemical half-cell studies, in order to evaluate the Electrochemically Active Surface Area (ECSA), ORR activity, and durability to potential cycling and corrosion resistance.","carbon nanofibers; carbon corrosion; fuel cell; oxygen reduction reaction; durability; Pt catalyst","en","journal article","MDPI","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:04bd403c-c32c-41dc-bfa4-7ece9721ec88","http://resolver.tudelft.nl/uuid:04bd403c-c32c-41dc-bfa4-7ece9721ec88","Dynamics of an oscillating turbulent jet in a confined cavity","Righolt, B.W.; Kenjeres, S.; Kalter, R.; Tummers, M.J.; Kleijn, C.R.","","2015","We demonstrate how the self-sustained oscillation of a confined jet in a thin cavity can be quantitatively described by a zero-dimensional model of the delay differential equation type with two a priori predicted model constants. This model describes the three phases in self-sustained oscillations: (i) pressure driven growth of the oscillation, (ii) amplitude limitation by geometry, and (iii) delayed destruction of the recirculation zone. The two parameters of the model are the growth rate of the jet angle by a pressure imbalance and the delay time for the destruction of this pressure imbalance. We present closed relations for both model constants as a function of the jet Reynolds number Re, the inlet velocity vin , the cavity width W, and the cavity width over inlet diameter W/d and we demonstrate that these model constants do not depend on other geometric ratios. The model and the obtained model constants have been successfully validated against three dimensional large eddy simulations, and planar particle image velocimetry measurements, for 1600 < Re ? 7100 and 20 ? W/d < 50. The presented model inherently contains the transition to a non-oscillating mode for decreasing Reynolds numbers or increasing W/d-ratios and allows for the quantitative prediction of the corresponding critical Reynolds number and critical W/d.","large eddy simulations; Reynolds stress modeling; numerical modeling; viscosity; El Nino Southern Oscillation","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:2d331b08-4ec0-4d76-add3-957dc1af244f","http://resolver.tudelft.nl/uuid:2d331b08-4ec0-4d76-add3-957dc1af244f","Exciton and charge carrier dynamics in semiconductor nanorods and nanoplatelets","Kunneman, L.T.","Siebbeles, L.D.A. (promotor); Schins, J.M. (promotor)","2015","","","en","doctoral thesis","Delft University of Technology","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:f6b11789-2f99-4a9f-969e-d738df001943","http://resolver.tudelft.nl/uuid:f6b11789-2f99-4a9f-969e-d738df001943","Shear banding in entangled polymers in the micron scale gap: A confocal-rheoscopic study","Boukany, P.E.; Wang, S.Q.; Ravindranath, S.; James Lee, L.J.","","2015","Recent shear experiments in well-entangled polymer solutions demonstrated that interfacial wall slip is the only source of shear rate loss and there is no evidence of shear banding in the micron scale gap. In this work, we experimentally elucidate how molecular parameters such as slip length, b, influence shear inhomogeneity of entangled polybutadiene (PBD) solutions during shear in a small gap H ? 50 ?m. Simultaneous rheometric and velocimetric measurements are performed on two PBD solutions with the same level of entanglements (Z = 54) in two PBD solvents with molecular weights of 1.5 kg mol?1 and 10 kg mol?1 that possess different levels of shear inhomogeneity (2bmax/H = 17 and 240). For the PBD solution made with a low molecular weight PBD solvent of 1.5 kg mol?1, wall slip is the dominant response within the accessible range of the shear rate, i.e., up to the nominal Weissenberg number (Wi) as high as 290. On the other hand, wall slip is minimized using a high molecular-weight PBD solvent of 10 kg mol?1 so that bulk shear banding is observed to take place in the steady state for Wi > 100. Finally, these findings and previous results are in good agreement with our recently proposed phase diagram in the parameter space of apparent Wi versus 2bmax/H suggesting that shear banding develops across the micron scale gap when the imposed Wi exceeds 2bmax/H [Wang et al., Macromolecules, 2011, 44, 183].","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:641cc5a0-8f19-491f-b607-60c267349473","http://resolver.tudelft.nl/uuid:641cc5a0-8f19-491f-b607-60c267349473","Flow instabilities and reversals in non-uniformly thermocapillary driven melt pool","Kidess, A.; Kenjeres, S.; Kleijn, C.R.","","2015","With transient LES and DNS simulations, we investigate flow in melt pools driven by thermocapillary forces. The developing pool is at first axisymmetric as are the boundary conditions, but flow instabilities arise that lead to 3D oscillatory flow patterns. At higher laser powers a sign-change in the surface tension temperature coefficient occurs, resulting in a flow reversal in the pool and thus two counter-rotating vortices, which exhibit similar though more complex flow instabilities.","","en","conference paper","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:7244dca5-e0f1-4f5f-a893-f8548de5495f","http://resolver.tudelft.nl/uuid:7244dca5-e0f1-4f5f-a893-f8548de5495f","Influence of Seed Surface Pre-Processing on Crystal Growth Behavior in Cooling Batch Crystallization","Westerlaken, T.P.","Kramer, H.J.M. (mentor); Stankiewicz, A.I. (mentor)","2015","Product quality and yield of pharmaceuticals produced by traditional industrial seeded batch cooling crystallization-operations is subject to large fluctuations as a consequence of seed surface quality. In this research, effects of seed pre-treatment by dry- and wet-milling were investigated on subsequent performance in crystallization behavior by measuring crystal growth rate, with comparative reference, in both stagnant and suspended, turbulent media. It has been shown that pre-processed paracetamol-seeds grew at a lower rate compared to non-processed seeds in stagnant conditions, whereas examination of the effect of seed surface healing increased growth rates. Separate experiments with suspended seeds of paracetamol and lactose in turbulent media, analyzed by in situ crystal size-measurements on growth rate, were found subject to attrition and agglomeration respectively. Consequently, processing of image-analysis, relating to crystal growth, was found inadequately performed.","crystallization; seeding; surface quality; milling; crystal growth; paracetamol; lactose; image-analysis","en","master thesis","","","","","","","","2019-08-26","Applied Sciences","Chemical Engineering","","Process Engineering","",""
"uuid:f9a5af37-2fe2-4be6-9e4b-37c273e2d435","http://resolver.tudelft.nl/uuid:f9a5af37-2fe2-4be6-9e4b-37c273e2d435","Modulation of the wall-heat transfer in turbulent thermomagnetic convection by magnetic field gradients","Kenjeres, S.; Zinsmeester, R.; Pyrda, L.; Fornalik-Wajs, E.; Szmyd, J.","","2015","We present combined experimental and numerical studies of the heat transfer of paramagnetic or diamagnetic fluid inside a differentially heated cubical enclosure subjected to the magnetic field gradients of different strength and orientation. In contrast to the previously reported studies in literature, which observed solely laminar flow regimes, here we focused on the fully developed turbulent flow regimes. That was possible by using a combination of the state-of-art superconducting magnets (with a strength up to 10 T and magnetic field gradients up to 900 T2/m) and by selecting various paramagnetic or diamagnetic working fluids (in a range of 10 Pr 1000). Detailed comparison between experiments (integral wall-heat transfer, temperature time-series at different locations within the enclosure) and direct numerical simulations (DNS) are performed and generally very good agreements are obtained in predicting the integral heat transfer. In addition, analysis of the long-term averaged first- and second-moments of velocity and thermal fields is performed. Finally, budgets of the turbulent kinetic energy and of the temperature variance are analyzed and the mean mechanism of the thermal plume reorganization in terms of the proper-orthogonal decomposition (POD) modes is presented.","","en","conference paper","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:bd1711b2-b085-4dd9-9a8d-f5ae2b2967f8","http://resolver.tudelft.nl/uuid:bd1711b2-b085-4dd9-9a8d-f5ae2b2967f8","Polymers of Intrinsic Microporosity as High Temperature Templates for the Formation of Nanofibrous Oxides","Al-Kutubi, H.; Rassaei, L.; Olthuis, W.; Nelson, G.W.; Foord, J.S.; Holdway, P.; Carta, M.; Malpass-Evans, R.; McKeown, N.B.; Tsang, S.C.; Castaing, R.; Forder, T.R.; Jones, M.D.; He, D.; Marken, F.","","2015","The highly rigid molecular structure of Polymers of Intrinsic Microporosity (PIM) – associated with a high thermolysis threshold – combined with the possibility to fill intrinsic micropores allows the direct “one-step” templated conversion of metal nitrates into nano-structured metal oxides. This is demonstrated here with PIM-EA-TB and with PIM-1 for the conversion of Pr(NO3)3 to Pr6O11.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:3f40571a-ded8-4f3e-b794-e36f6f07731e","http://resolver.tudelft.nl/uuid:3f40571a-ded8-4f3e-b794-e36f6f07731e","Ru/TiO2-catalysed hydrogenation of xylose: The role of the crystal structure of the support","Hernandez-Mejia, C.; Gnanakumar, E.S.; Olivos-Suarez, A.; Gascon, J.; Greer, H.F.; Zhou, W.; Rothenberg, G.; Shiju, N.R.","","2015","Effective dispersion of the active species over the support almost always guarantees high catalytic efficiency. To achieve this high dispersion, a favourable interaction of the active species with the support is crucial. We show here that the crystal structure of the titania support determines the interaction and consequently the nature of ruthenium particles deposited on the support. Similar crystal structures of RuO2 and rutile titania result in a good lattice matching and ensure a better interaction during the heating steps of catalyst synthesis. This helps maintain the initial good dispersion of the active species on the support also in the subsequent reduction step, leading to better activity and selectivity. This highlights the importance of understanding the physico-chemical processes during various catalyst preparation steps, because the final catalyst performance often depends on the type of intermediate structures formed during the preparation.","","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:0b268d51-550f-4009-924d-c155f5165853","http://resolver.tudelft.nl/uuid:0b268d51-550f-4009-924d-c155f5165853","Photo-assisted water splitting with bipolar membrane induced pH gradients for practical solar fuel devices","Vermaas, D.A.; Sassenburg, M.; Smith, W.A.","","2015","Different pH requirements for a cathode and an anode result in a non-optimal performance for practical solar fuel systems. We present for the first time a photo-assisted water splitting device using a bipolar membrane, which allows a cathode to operate in an acidic electrolyte while the photoanode is in alkaline conditions. The bipolar membrane dissociates water into H+ and OH?, which is consumed for hydrogen evolution at the cathode and oxygen evolution at the anode, respectively. The introduction of such a bipolar membrane for solar fuel systems provides ultimate freedom for combining different (photo)cathodes and -anodes. This paper shows that photo-assisted water splitting at both extreme pH gradients (0–14) as well as mild pH gradients (0–7) yields current densities of 2–2.5 mA cm?2 using a BiVO4 photoanode and a bipolar membrane. The membrane potentials are within 30 mV of the theoretical electrochemical potential for low current densities. The pH gradient is maintained for 4 days of continuous operation and electrolyte analysis shows that salt cross-over is minimal. The stable operation of the bipolar membrane in extreme and mild pH gradients, at negligible loss, contributes to a sustainable and practically feasible solar fuel device with existing photoactive electrodes operating at different pH.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:c8e0c3c7-fc52-45ca-8a79-ee3b550ab5e4","http://resolver.tudelft.nl/uuid:c8e0c3c7-fc52-45ca-8a79-ee3b550ab5e4","Improved extreme ultraviolet light source","Mulder, F.M.","","2015","The present invention relates to an Extreme Ultra Violet light source, to a trap for use in such a light source, to a multilayer mirror for use in such a light source, to a grazing incident mirror for use in such a light source, and to a multi- layer for use in the multilayer mirror. Such a light source may for instance be used in lithography, such as used in semiconductor integrated circuit production.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:2a093d71-1fc3-4356-a56d-b99c6717b62f","http://resolver.tudelft.nl/uuid:2a093d71-1fc3-4356-a56d-b99c6717b62f","Crystal engineering with metal-organic frameworks","Goesten, M.G.","Kapteijn, F. (promotor); Gascon, J. (promotor)","2015","","","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:28b71d28-da98-4390-867c-616f6e335a37","http://resolver.tudelft.nl/uuid:28b71d28-da98-4390-867c-616f6e335a37","Understanding Titanium Dioxide Passivation on Silicon Photoanodes in Photoelectrochemical Cells","Bras, J.A.","Smith, W.A. (mentor); Dam, B. (mentor); Savenij, T.J. (mentor)","2015","Photoelectrochemical (PEC) water splitting is an elegant method to generate renewable hydrogen fuel from water by utilizing the abundant solar energy. Silicon (Si) as a semiconducting photoanode for PEC water splitting has received a growing interest due to the natural abundance of Si, its light absorbing ability, its excellent electronic properties and its low-cost processing. Although Si is a promising photoanode, its sensitivity towards corrosion in aqueous electrolytes hinders its use in PEC applications. To protect Si photoanodes against corrosion, thin layers (1-10 nm) of TiO2 were deposited onto FTO and Si by atomic layer deposition (ALD). Unannealed TiO2 was tested as well as TiO2 that was post-annealed in either air or vacuum environment. The properties that determine the photoelectrochemical activity as well as the stability were studied. The thickness and bandgap were determined by spectroscopic ellipsometry. X-ray diffraction crystallography (XRD) was used to analyse the crystal structure. Other physical, electronic and optical properties were characterized by ultraviolet-visible spectroscopy (UV-Vis), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The electrochemical properties were tested by electrochemical measurements, i.e. cyclic voltammetry and chronopotentiometry. It was found that the addition of very thin layers (<2 nm) of TiO2 on Si photoanodes that were post-annealed at 400°C in vacuum showed a high performance in PEC activity as well as stability. Moreover, the use of a Ni catalyst on the Si/TiO2 photoanodes showed an increase in reaction kinetics with photocurrent density reaching up to 25 mA/cm2. It was found that the stability of Si photoanodes is improved by a thin layer of TiO2 for 8 hours compared to 2 hours without TiO2 protection layer. To understand the charge transfer mechanism through the TiO2 layer, TiO2 layers were fabricated with different thicknesses of TiO2 and annealed in different annealing environments. These different TiO2 were evaluated regarding their PEC activity by cyclic voltammetry. As smaller thicknesses (<2 nm) of TiO2 enhance the PEC activity of Si photoanodes, compared to thicker layers of TiO2, it is implied that the mechanism of charge transport through TiO2 is tunneling. It was also shown that vacuum annealed TiO2 demonstrated a higher PEC activity compared to unannealed TiO2 in Si/TiO2/Ni photoanodes. The fact that annealing increases the PEC activity and removes defects, demonstrates that transport is not by defect states.","PEC; silicon; photoanodes; titanium dioxide; TiO2; passivation","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Materials for Energy Conversion and Storage","",""
"uuid:6c37d4a2-112d-42bb-80e9-643dea16ed17","http://resolver.tudelft.nl/uuid:6c37d4a2-112d-42bb-80e9-643dea16ed17","Photocharged BiVO4 photoanodes for improved solar water splitting","Trze?niewski, B.J.; Smith, W.A.","","2015","Bismuth vanadate (BiVO4) is a promising semiconductor material for the production of solar fuels via photoelectrochemical water splitting, however, it suffers from substantial recombination losses that limit its performance to well below its theoretical maximum. Here we demonstrate for the first time that the photoelectrochemical (PEC) performance of BiVO4 photoanodes can be dramatically improved by prolonged exposure to AM 1.5 illumination in the open circuit (OC) configuration. Photoanodes subjected to such light treatment achieve a record photocurrent for undoped and uncatalysed BiVO4 of 3.3 mA cm?2 at 1.23 VRHE. Moreover, photoelectrochemical tests with a sacrificial agent yield significantly enhanced catalytic efficiency over the whole operating potential range, suggesting elimination of major losses at the semiconductor–electrolyte interface. Finally, we demonstrate that this so-called ‘photocharging’ technique induces a considerable cathodic shift in the photocurrent onset potential and increases the photovoltage extracted from BiVO4 photoanodes.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:5728dde5-e722-46e8-a92f-b62937ecf538","http://resolver.tudelft.nl/uuid:5728dde5-e722-46e8-a92f-b62937ecf538","The Effect of Surfactants on Gas-Liquid Pipe Flows","Van Nimwegen, A.T.","Henkes, R.A.W.M. (promotor)","2015","Liquid loading is a major problem in the natural gas industry, in which gas production is limited by the accumulation of liquids in the well tubing. Liquid loading can be prevented by the injection of surfactants at the bottom of the well. The surfactants cause the liquid in the well to foam, thereby changing the gas-liquid flow in the well. The flow is characterized by the TPC (Tubing Performance Curve), which relates the average pressure gradient in the tubing to the gas flow rate. This work has two main goals: (i) To improve the understanding of the effect of surfactants on gas-liquid flow in pipes, which we characterize by a change in the generalised TPC. The generalised TPC relates the average pressure gradient to the gas and liquid flow rates in the pipe. (ii) To provide subsidies for the development of simple physically-based models for the effect of surfactants on gas-liquid flow. We performed experiments in intermediate-scale pipes (lengths of 12 m to 18 m and diameters of 34 mm, 50 mm, and 80 mm) with air and water at atmospheric conditions, without and with surfactants. Multiple parameters, that also vary between different gas wells in the field, were varied: the gas and liquid flow rates, the pipe diameter, the pipe inclination, the surfactant type and the surfactant concentration. We performed a visualisation of the flow without and with surfactants to obtain qualitative results on the effect of surfactants on the flow morphology, and we related these results to quantitative measurements of the generalised TPC and the liquid holdup. The behaviour of the generalised TPC is to a large extent determined by the transition between annular flow and churn flow. In annular flow without surfactants, at large gas flow rates, the water is present in a film along the pipe wall and in entrained droplets in the gas core; the water always moves upwards, which leads to a relatively regular flow morphology. In the churn flow regime, which occurs at low gas flow rates, the liquid film reverses, as the interfacial friction between the gas and the liquid, which drags the liquid upwards, no longer exceeds the gravitational force on the film. This leads to a complex flow morphology, a large liquid holdup and a large pressure gradient. Surfactants cause the formation of foam through the hydrodynamics of the flow. The foam decreases the density and increases the volume of the film at the wall. This changes the balance between the interfacial friction and the gravitational force, which shifts the transition between churn flow and annular flow to lower gas flow rates. As a result, the generalised TPC is changed by the surfactants, leading to a decrease in the pressure gradient at low gas flow rates. An optimum surfactant concentration exists that results in the largest reduction of the pressure gradient. This concentration increases with increasing film thickness; therefore, it increases with decreasing gas flow rate, increasing liquid flow rate, increasing pipe diameter, and decreasing inclination from horizontal. Qualitatively, these results are unaffected by the type of surfactant that is used. From the results obtained in this work, we qualitatively understand the effect of surfactants on the gas-liquid flow, and we understand why surfactants are able to deliquify gas wells. However, a physically-based model is required to translate the results obtained in this work in a quantitative way to the large-scale gas wells. Such a model requires a characterization of the foaming behaviour of the surfactant-liquid mixture using a small-scale setup. We determined that a small-scale sparging setup, often used in the gas industry, is not suitable, because the hydrodynamics in the sparging setup differ too much from the hydrodynamics of annular flow and churn flow. A small-scale shaking test, in which the hydrodynamics more closely resemble churn flow, shows more potential to characterize the foaming behaviour of the surfactants in the context of gas-liquid flows.","Pipe flow; Multiphase flow; Surfactants; Annular Flow; Churn Flow; Liquid Loading; Gas Well Deliquification","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:d1170db9-524d-4d80-a428-32dbebb5fa26","http://resolver.tudelft.nl/uuid:d1170db9-524d-4d80-a428-32dbebb5fa26","Synthesis of highly dispersed Pd nanoparticles supported on multi-walled carbon nanotubes and their excellent catalytic performance for oxidation of benzyl alcohol","Shinde, V.M.; Skupien, E.; Makkee, M.","","2015","Narrow sized and highly homogeneous dispersed Pd nanoparticles have been synthesized on nitric acid-functionalized multi-walled carbon nanotubes (CNTs) without a capping agent. The TEM images show that the extremely small Pd nanoparticles with an average size of about 1.5 nm were homogeneously dispersed on the surface of the CNTs. The characterization results indicate that the pretreatment with nitric acid not only improved the dispersion of Pd, but also enhanced the strong interaction between the Pd nanoparticles and the CNTs, thereby preventing their agglomeration and leaching in the liquid phase. On pretreatment with HNO3, it is possible to generate more acidic groups on the surface of CNTs without a significant change in textural properties. The catalytic performance of the aforementioned material was investigated for selective oxidation of benzyl alcohol. Pd/CNTs exhibits high activity (~98% conversion) and selectivity (~90%) to benzaldehyde with excellent reusability. The high activity of the catalyst was attributed to the small size, high dispersion of Pd nanoparticles and higher accessibility of reactants. A careful analysis of the kinetic data suggests that there are different sites for the disproportionation and oxidation reactions. The excellent reusability of Pd/CNT catalysts makes this material a promising candidate for selective benzyl oxidation. Further, the results of the present study show that it is possible to synthesize uniformly dispersed Pd nanoparticles on various carbon supports without a capping agent.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:65793186-98ef-40b0-9d7f-dce8a88d133f","http://resolver.tudelft.nl/uuid:65793186-98ef-40b0-9d7f-dce8a88d133f","Large pressure range hydrogen sensor","Boelsma, C.; Dam, B.","","2015","The present invention relates to a thin-film sensor, to a method for producing a thin-film device, to an alloy for use in an optical sensing layer, to use of an alloy for sensing a chemical species such as hydrogen, to a sensor, to an apparatus for detecting hydrogen, to an electro-magnetic transformer comprising said sensor and to a switching device.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:2e24e7e8-575e-4d1a-b5e4-0cdca49d9ab6","http://resolver.tudelft.nl/uuid:2e24e7e8-575e-4d1a-b5e4-0cdca49d9ab6","Metal-Organic Frameworks For Adsorption Driven Energy Transformation: From Fundamentals To Applications","De Lange, M.F.","Kapteijn, F. (promotor); Gascon, J. (promotor); Vlugt, T.J.H. (promotor)","2015","A novel class of materials, i.e. Metal-Organic Frameworks (MOFs), has successfully been developed that is extremely suited for application in heat pumps and chillers. They have a superior performance over commercial sorbents and may potentially contribute to considerable energy savings worldwide. Globally about 33 % of the energy consumption is used for heating and cooling of e.g. houses and buildings. Adsorption driven heat pumps and chillers are very well suited to reduce this energy consumption and can even use low-grade waste heat or sustainable solar energy in combination with environmentally benign working fluids (e.g. water). MOFs are porous crystalline materials built up from inorganic clusters connected by organic ligands in 1, 2 or 3 dimensions, and display a rich variety of topologies and can be functionalized in many different ways. They offer the materials scientist an outstanding platform to design new materials with superior properties. The described research has identified MOFs with sufficient stability against water, that show the desired adsorption behavior of water. These MOF-water pairs possess higher energy efficiency and working capacity than benchmark materials and may operate with a lower driving temperature. The selected MOFs can be coated (without binder) directly on heat-exchanger surfaces for a fast response. In short, there is a bright future for the application of MOFs in adsorption heat pumps and chillers with a large energy savings potential.","adsorption; MOFs; heat pumps; coatings; energy efficiency","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:4fba60ed-0c2d-49de-99fd-fbf6198ea71a","http://resolver.tudelft.nl/uuid:4fba60ed-0c2d-49de-99fd-fbf6198ea71a","Charge transfer versus molecular conductance: Molecular orbital symmetry turns quantum interference rules upside down","Gorczak, N.; Renaud, N.; Tarkuç, S.; Houtepen, A.J.; Eelkema, R.; Siebbeles, L.D.A.; Grozema, F.A.","","2015","Destructive quantum interference has been shown to strongly reduce charge tunneling rates across molecular bridges. The current consensus is that destructive quantum interference occurs in cross-conjugated molecules, while linearly conjugated molecules exhibit constructive interference. Our experimental results on photoinduced charge transfer in donor-bridge-acceptor systems, however, show that hole transfer is ten times faster through a cross-conjugated biphenyl bridge than through a linearly conjugated biphenyl bridge. Electronic structure calculations reveal that the surprisingly low hole transfer rate across the linearly conjugated biphenyl bridge is caused by the presence of destructive instead of constructive interference. We find that the specific molecular orbital symmetry of the involved donor and acceptor states leads to interference conditions that are different from those valid in single molecule conduction experiments. Furthermore, the results indicate that by utilizing molecular orbital symmetry in a smart way new opportunities of engineering charge transfer emerge.","Open Access","en","journal article","RSC publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:3cceee5e-7a9e-4ebc-8a5a-86dc1adf4cce","http://resolver.tudelft.nl/uuid:3cceee5e-7a9e-4ebc-8a5a-86dc1adf4cce","A Clean and Flexible Catalyst Synthesis Method: Metal nanoparticles on a fractal-like nanostructured metal oxide support","Braams, F.P.","Schmidt-Ott, A. (mentor); Smith, W.A. (mentor); Van Ommen, J.R. (mentor)","2015","A highly porous fractal-like nanostructured metal oxide catalyst support with characteristic dimensions of a few nanometers is formed by producing metal nanoparticles in the gas phase, oxidizing them and depositing/sintering them on a nanofiber network. By admixing nanoparticles in the aerosol phase, these can evenly be distributed in the fractal-like metal oxide structure. The nanofiber network is a polymer and is produced by electrospinning [77]. It serves as an initial support, while the structure supports itself after forming a certain thickness. Spark discharge is used to produce the active nanoparticles as well as the support [11]. Rapid diffusion limited aggregation governs the deposition process, guaranteeing formation of the fractal-like structure [38]. Due to the flexible nature of the spark discharge process, a virtually unlimited number of combinations of oxide supports, metals, alloys and bi-catalysts can be made. The method proved to work for titanium dioxide, aluminium oxide and magnesium oxide catalystsupports. Combinations of these metal oxides with gold and platinum proved the broad applicability of the method. The process can be called environmentally friendly, since it does not use any solvents or produce any hazardous waste. Initial photocatalytic experiments on titanium dioxide nanostructures were carried out to test the catalytic activity of the material. It was observed that the titanium dioxide nanostructures were amorphous, but still exhibited catalytic properties. Adding gold nanoparticles to the nanostructures lowered the catalytic effect. In-situ annealing of amorphous titanium dioxide nanoparticles, before admixing gold nanoparticles, yielded highly porous fractal-like crystalline titanium dioxide nanostructures with gold nanoparticles on the surface.","nanoparticles; catalysis; fractals; nanotechnology","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Materials for Energy Conversion & Storage (MECS)","",""
"uuid:67a6e63c-e71e-48a5-95ba-993ce7897a0b","http://resolver.tudelft.nl/uuid:67a6e63c-e71e-48a5-95ba-993ce7897a0b","Gas-Phase Deposition of Ultrathin Aluminium Oxide Films on Nanoparticles at Ambient Conditions","Valdesueiro Gonzalez, D.; Meesters, G.M.H.; Kreutzer, M.T.; Van Ommen, J.R.","","2015","We have deposited aluminium oxide films by atomic layer deposition on titanium oxide nanoparticles in a fluidized bed reactor at 27 ± 3 °C and atmospheric pressure. Working at room temperature allows coating heat-sensitive materials, while working at atmospheric pressure would simplify the scale-up of this process. We performed 4, 7 and 15 cycles by dosing a predefined amount of precursors, i.e., trimethyl aluminium and water. We obtained a growth per cycle of 0.14–0.15 nm determined by transmission electron microscopy (TEM), similar to atomic layer deposition (ALD) experiments at a few millibars and ~180 °C. We also increased the amount of precursors dosed by a factor of 2, 4 and 6 compared to the base case, maintaining the same purging time. The growth per cycle (GPC) increased, although not linearly, with the dosing time. In addition, we performed an experiment at 170 °C and 1 bar using the dosing times increased by factor 6, and obtained a growth per cycle of 0.16 nm. These results were verified with elemental analysis, which showed a good agreement with the results from TEM pictures. Thermal gravimetric analysis (TGA) showed a negligible amount of unreacted molecules inside the alumina films. Overall, the dosage of the precursors is crucial to control precisely the growth of the alumina films at atmospheric pressure and room temperature. Dosing excess of precursor provokes a chemical vapour deposition type of growth due to the physisorption of molecules on the particles, but this can be avoided by working at high temperatures.","atomic layer deposition (ALD); coating; nanoparticles; aluminium oxide; thin films; fluidized bed reactor; ambient conditions; room temperature; atmospheric pressure; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:f5687ca3-6bc3-4421-a129-18fddac73622","http://resolver.tudelft.nl/uuid:f5687ca3-6bc3-4421-a129-18fddac73622","Gas Jets in Granular Matter: Observed by a High Speed X-ray Tomography System","Yang, X.","Mudde, R.F. (promotor); Van Ommen, J.R. (promotor)","2015","High speed X-ray tomography is a promising tool to visualize the time-resolved gas distribution for fluidized beds. The tomography unit at Delft University of Technology is composed of three X-ray tubes and three double-layer detector arrays. The X-ray tubes are places at 120? around the fluidized bed. The detector arrays are placed opposite to the X-ray tubes. The full angle scanning can be done simultaneously, without mechanically rotating the X-ray tube as in traditional medical CT. The temporal resolution can be up to 2500 fps. By using this high speed X-ray tomographic system in my dissertation, we study tomographic reconstruction algorithms and measure different gas jets in the fluidized beds. To evaluate the performance of the novel reconstruction algorithms for high speed X-ray tomography, Simultaneous Algebraic Reconstruction Technique (SART) and Adaptive Genetic Algorithm (AGA) are compared in Chapter 3. The reconstruction quality of AGA is better than SART at low resolutions, but SART performs better at high resolution in finding the right shape. The system noise influences AGA less than SART. SART is much faster and does not have reproducibility problems; poor reproducibility influences the reliability of AGA. The features of the reconstruction quality for SART and AGA are further discussed in Chapter 4. AGA is better than SART in distinguishing small phantoms and small distance between phantoms. SART, on the other hand, is better at reconstructing the shapes than AGA. We developed a hybrid approach to combine the advantages of AGA and SART. The result of AGA is used as initial guess for SART in this hybrid algorithm, by which the reconstruction accuracy is indeed improved. A flat-base spouted bed is studied with the high speed X-ray tomography system in Chapter 5. We focus on the spout diameter and position. The hybrid algorithm is used to visualize the spout in the cross sectional area of the spouted bed. For a more accurate quantitative study, we developed a method to process the raw data directly. The time-averaged results of the spout diameters are validated with the literature. A simple model for the particle circulation is developed based on the time-averaged spout diameter. The model is also validated by measurement of the fountain height. The time-resolved results of the spout diameter are analyzed by the Power Spectral Density (PSD). The stability of the spout diameter is discussed for different measurement heights and gas flowrates by comparing the average PSD. We find that the most stable spout diameter happens at U/Ums ? 1.3 in the middle part of the spout. The time-resolved spout position is plotted by polar coordinates. We found that the spout position is more stable when the diameter is less stable, and vice versa. Another gas jet, i.e. the gas distribution below a downward facing micro-nozzle in a fluidized bed, is also measured using the high speed X-ray tomography in Chapter 6. The improved SART method is used for the reconstruction because we need to consider the transition area between the gas voids and bulk phase. Time-averaged 3-D images of the gas distribution below the nozzle are obtained. The results are compared with direct analysis of the raw data. A bubbling area, a diluted area, and a compacted area are found. We analyzed the dynamics of the gas voids by employing a cross-correlation technique and inspecting the reconstructed pseudo 3-D image. The cross-correlation estimates the direction of bubble motion, and also helps to calculate the bubble velocity and bubble size. The pseudo 3-D image shows the pattern of the gas voids. We found that single bubbles are regularly formed by the nozzle, and move upwards. The expansion, splitting and coalescence of the bubbles were also observed. The gas injected from the nozzle mainly ends up in bubbles. We compared the fluidized bed results with those obtained for a similar nozzle in a gas-water system, and found a similar flow pattern and penetration depth. In summary, we improved the accuracy of high speed X-ray tomography by developing novel data processing approaches, such as the hybrid algorithm and raw data processing. We evaluated the dynamics of the spout in a flat-base spouted bed from the tomographic measurements, and developed a model for particle circulation based on these measurements. We also measured the time-resolved gas distribution below the downward facing micro-nozzle using the high speed X-ray tomography. The obtained results illustrate that X-ray tomography is a valuable tool to study gas-solids distribution – both time-averaged and time-resolved in fluidized beds.","fluidized bed; gas jets; high speed X-ray tomography; image reconstruction algorithms","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:e8972031-94a7-4fd2-bdd0-5defcce3010b","http://resolver.tudelft.nl/uuid:e8972031-94a7-4fd2-bdd0-5defcce3010b","Precursor-Less Coating of Nanoparticles in the Gas Phase","Pfeiffer, T.V.; Kedia, P.; Messing, M.E.; Valvo, M.; Schmidt-Ott, A.","","2015","This article introduces a continuous, gas-phase method for depositing thin metallic coatings onto (nano)particles using a type of physical vapor deposition (PVD) at ambient pressure and temperature. An aerosol of core particles is mixed with a metal vapor cloud formed by spark ablation by passing the aerosol through the spark zone using a hollow electrode configuration. The mixing process rapidly quenches the vapor, which condenses onto the core particles at a timescale of several tens of milliseconds in a manner that can be modeled as bimodal coagulation. Gold was deposited onto core nanoparticles consisting of silver or polystyrene latex, and silver was deposited onto gold nanoparticles. The coating morphology depends on the relative surface energies of the core and coating materials, similar to the growth mechanisms known for thin films: a coating made of a substance having a high surface energy typically results in a patchy coverage, while a coating material with a low surface energy will normally “wet” the surface of a core particle. The coated particles remain gas-borne, allowing further processing.","spark ablation; nanoparticles; coating; gas phase; continuous process; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:aeb8a717-be8f-4f52-b2bf-b5c7d72c55c9","http://resolver.tudelft.nl/uuid:aeb8a717-be8f-4f52-b2bf-b5c7d72c55c9","Increasing the lifetime of fuel cell catalysts","Latsuzbaia, R.","Van Esch, J.H. (promotor); Picken, S.J. (promotor)","2015","In this thesis, I discuss a novel idea of fuel cell catalyst regeneration to increase lifetime of the PEM fuel cell electrode/catalyst operation and, therefore, reduce the catalyst costs. As many of the catalyst degradation mechanisms are difficult to avoid, the regeneration is alternative option to prolong catalyst lifetime. In the thesis, I investigate fundamental aspects of Pt catalyst regeneration ex situ, which can be potentially applied in situ later on. The regeneration strategy consists of two steps: (i) Full or partial dissolution of coarsened Pt catalyst nanoparticles and (ii) Chemical or electrochemical redeposition of the dissolved Pt. I discuss dissolution aspects of Pt nanoparticles in mild and carbon-preserving conditions, which are essential for the subsequent redeposition of the nanoparticles on the same support and potential redeposition strategies. For the redeposition of Pt nanoparticles, we investigate electrodeposition technique and chemical reduction in a templated medium, such as microemulsions.","fuel cells","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:387ff649-1aa3-44a5-a22b-0e33fe39446b","http://resolver.tudelft.nl/uuid:387ff649-1aa3-44a5-a22b-0e33fe39446b","Charge Injection, Charge Trapping and Charge Transfer in Quantum-Dot Solids","Boehme, S.C.","Siebbeles, L.D.A. (promotor); Vanmaekelbergh, D. (promotor)","2015","This study reports on fundamental processes in Quantum-Dot Solids, after light absorption. Transient Absorption and Time-resolved Photoluminescence spectrocopy reveal the dynamics of charge transfer and charge trapping processes. Typically, both occur on a picosecond time scale and compete with each other. We find that the efficiency of these processes depends on the Fermi level in the Quantum-Dot Solid. The latter can be controlled electrochemically, via charge injection into the Quantum-Dot Solid, using a potentiostat. The presented findings aid the rational design of opto-electronic devices based on Quantum Dots, such as solar cells or LEDs.","Quantum Dot; Defect; Charge Transfer; Charge Trapping; Fermi Level; Electrochemistry; Ligands; Energy Level; Transient Absorption; Time-resolved Photoluminescence","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:2ee2b93d-d3e9-41e7-888a-a52f231070c8","http://resolver.tudelft.nl/uuid:2ee2b93d-d3e9-41e7-888a-a52f231070c8","Self-healing supramolecular nanocomposites","Liu, Z.","Picken, S.J. (promotor); Besseling, N.A.M. (promotor)","2015","The aim of this thesis is to execute a bottom-up design of the intrinsically self-healing nanocomposites. We briefly introduced the self-healing materials in chapter 1, covering classification and basic self-healing mechanism. In chapter 2, we have synthesized polyborosiloxane (PBS) according to the last century recipe as the self-healing supramolecular matrix. Additionally, we provided the long existing recipe with exclusive supplementary details, such as reaction kinetics, structural refinement and characterization, mechanical performance, glass transition temperature, etc. We have denoted the refined PBS, in which the end groups of PBS primarily exhibit in the well-defined borono structure (B(OH)2), rPBS. In chapter 3, the molecular interaction of PBS molecules that leads to the self-healing behavior was investigated with modern techniques. Besides the well-known physically cross-linked H-bonds, PBS molecules also cross-link via forming reversible covalent boroxane structures (B-O-B). Chapter 4 and 5 focus on the reinforcing effects of rigid nanoclay particles (Cloisite 20A) and flexible graphene oxide (GO), respectively. As PBS molecules bear the hydrophilic borono end groups, the incorporation of natural clay and graphene oxide leads to softened nanocomposites due to their hydrophilic surfaces. GO platelets efficiently drive the GO/rPBS nanocomposite into thixotropic material readily at a mass fraction of 0.001. However, natural clay surface is not as hydrophilic as GO. The softening effect is not only less pronounced, but also quickly compensated due to the formation of the particle network. Nevertheless, it results in a paste-like thixotrope when the mass fraction of natural clay reaches 0.6. Cloisite 20A and OMGO are surface modified natural clay and GO, with almost the same alkyl modifier. They behave as ordinary reinforcement additives and may efficiently enhance the rheological properties of the nanocomposites.","self-healing; mechanism; nanocomposites; particle network; graphene oxide; thixotropic","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:cc97d502-3ff1-450c-83b1-4c08b4733a5e","http://resolver.tudelft.nl/uuid:cc97d502-3ff1-450c-83b1-4c08b4733a5e","Numerical investigation of dynamic effects for sliding drops on wetting defects","Cavalli, A.; Musterd, M.; Mugele, F.","","2015","The ability to trap or deflect sliding drops is of great interest in microfluidics, as it has several technological applications, ranging from self-cleaning and fog harvesting surfaces to laboratory-on-a-chip devices. We present a three-dimensional numerical model that describes sliding droplets interacting with wetting defects of variable strength and size. This approach provides relevant insight if compared to simplified analytic models, as it allows us to assess the relevance of the internal degrees of freedom of the droplet. We observe that the deformation of the drop enhances the effective strength and range of the defect, and we quantify this effect by comparison to a point-mass model. We also analyze the role of the steepness and strength of the defect on the drop motion, observing that small, strong defects are more effective at trapping than large, shallow traps of same excess surface energy. Finally, our results show quantitative agreement with previously reported electrowetting experiments, suggesting a universal behavior in droplet trapping that does not depend strongly on the nature of the defect.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:04732ecc-5e5b-4334-8f46-5cc4df93c0df","http://resolver.tudelft.nl/uuid:04732ecc-5e5b-4334-8f46-5cc4df93c0df","Numerical methods for the implementation of the Cahn-Hilliard equation in one dimension and dynamic boundary condition in two dimensions","Sibbing, Z.R.","Kleijn, C.R. (mentor); Vermolen, F.J. (mentor); Pimpalgaonkar, H.G. (mentor)","2015","This project can be divided into two parts. The goal of the first part is to numerically implement the Cahn-Hilliard equation in one dimension both explicitly and implicitly. This will be done using Matlab. The goal of the second part is to validate the coupled Cahn-Hilliard-Navier-Stokes equation and the dynamic boundary condition for moving contact lines of (Carlson et al, 2011, p.9) by considering a two-dimensional spreading droplet case. This will be done using the CFD software OpenFOAM. In Chapter 1, the theory of positive and negative diffusion, including the normal diffusion equation and the Cahn-Hilliard equation, are discussed. Some background is given regarding the thermodynamics of the Cahn-Hilliard equation and its steady-state solution. After that, the theory of the coupled Cahn-Hilliard-Navier-Stokes equation, the dynamic boundary condition for moving contact lines and the case which is implemented in OpenFOAM, are discussed. In Chapters 2 and 3, the diffusion equation and the Cahn-Hilliard equation are implemented in one dimension, using the Euler Forward scheme. In implementing the Cahn-Hilliard equation, two different discretizations are used, of which only one gives the desired results. Next, an extensive stability analysis is done, using a linearization of the Cahn-Hilliard equation as well as numerical experiments. The stability condition is increasingly severe with increasing interface width. Regarding the results of the evolving interface, a qualitative analysis is done which discusses three subjects: the deviation of the solutions with the steady-state solution, the interface width for different parameters and grid sizes and the interface overshoot, which is an unphysical appearence. In Chapter 4, two semi-implicit methods and one implicit iterative method, are discussed. The implementations of the two semi-implicit methods, Implicit-Explicit (ImEx) and Modified Furihata, are succesful and their stability conditions are better than the stability condition of the Euler Forward scheme, for most interface widths. The results regarding the evolving interface are nearly identical to the results of the Euler Forward scheme, therefore the qualitative analysis is also similar. The implicit iterative method, which involves the use of the G\^ateaux derivative, has not been succesfully implemented, eventhough two different discretizations are used. The results regarding the evolving interface are behaving in a positive diffusive way, which results in a flattening interface with time. In Chapter 5, the coupled Cahn-Hilliard-Navier-Stokes equation and a dynamic boundary condition for moving contact lines are used to model a spreading droplet on a flat surface. The implemented model is validated using different cases in which the steady-state contact angle and the friction factor of the surface varies. Next, parametric studies are done regarding the interface width, the surface tension and the ratio of the surface tension and the friction factor. The conclusions are that the modeled system differs too much from the system in literature to make an absolute comparison but, qualitatively, the model behaves as expected.","Cahn-Hilliard; Numerical Methods; non-linear partial differential equation","en","bachelor thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:dafd73d6-b402-4150-b6ba-8d542b233baf","http://resolver.tudelft.nl/uuid:dafd73d6-b402-4150-b6ba-8d542b233baf","On the Interaction of Capillary Shapes with Solid Surfaces","Musterd, M.","Kleijn, C.R. (promotor); Kreutzer, M.T. (promotor)","2015","Control over the interaction of droplets with solid surfaces is commonplace in nature. Famous examples are the water-shedding capabilities of the lotus leaf and the water-harvesting skin of certain types of beetles. To date, this type of control remains a challenge in engineering applications. Consider, for example, droplets on the windscreen of a car that need to be wiped off because they unwantedly stick to the glass, or the dripping of droplets from fog harvesting devices, where one actually wants the droplets to stick. In this thesis, we address the interaction of droplets with solid surfaces that underlies the sticking behavior. In particular, we investigate how droplets stick to chemically and physically heterogeneous surfaces, and what shape droplets take when squeezed by various confining geometries. The results of these investigations can be used to predict the force needed to set a droplet on a given surface into motion, and to calculate the volume of droplets in confining geometries. An important tool in our studies is the principle of energy minimization, by which we determine the (local) equilibrium shape of a droplet under the influence of surface tension, gravity and solid boundaries. It turns out that the interaction of droplets with solid surfaces can largely be captured in terms of two aspects of the system. The first is the contact line of the droplet, the line where the fluid-fluid interface meets the solid surface. The second is the contact angle distribution around this line, where the contact angle is defined as the angle at which the fluid-fluid interface meets the solid surface. A core question in our work is how to predict the shape and sticking force of a droplet on a realistic, thus physically or chemically heterogeneous, inclined surface. The answer to this question constitutes an important step towards a model for the sticking force. We resolve this question by studying the model system of a droplet on an incline, using 2D analytical and 3D numerical energy minimization. An important conclusion from our work is that the maximum sticking force of the droplet is determined by local constraints on repositioning of the contact line, originating from a range of possible contact angles within which the droplet can deform while the contact line remains static. The possible, i.e. accessible, shapes of the droplet during the inclination process are then also determined by constraints on repositioning, which causes the initial shape and deformation history of the droplet to influence the shape of the droplet at roll off and thereby the maximum sticking force. Accounting for inaccessible shapes and droplet shape history hence results in accurate predictions of the sticking force, in contrast to currently available models that allow all shapes and are thus bound to yield incorrect predictions. Based on the insight that local constraints control the global shape of the droplet we developed an approach to analytically predict the deformation of 3D droplets upon inclination and the maximum sticking force of these droplets. This prediction can be used for a number of engineering applications where the sticking force of droplets is an important factor. Examples include the design and positioning of solar panels and windscreens, as well as more industrial applications such as condensors and chemical reactors with small flow channels. The analytical model for 3D droplets builds on the findings on the role of local constraints by explicitly modelling the deformation process of the contact line, in contrast to the current state-of-the-art where contact line shapes are either assumed or predicted without regard for the constraints. To keep the model analytically tractable, we parameterize the deformation of the droplet in terms of the contact line shape and the contact angle distribution around the contact line. In combination with a few physically sound assumptions, based on our earlier findings, this model accurately predicts the deformation and maximum sticking force of a droplet, as compared with experiments and numerical simulations. Unlike currently available models, this model also accounts for the history of the droplet in the prediction of the maximum sticking force. Apart from droplets sticking to surfaces we also use energy minimization to determine the shape of bubbles and droplets in straight microchannels of various cross-sectional geometries. With this, we develop a model to calculate the volume of a droplet on the basis of only the channel geometry and the droplet length as observed from a top view. This determination of volume is for example important to accurately determine the concentration of gaseous species or nutrients in studies of mass transfer rates or growth of cells. The model is based on a physical description of the central part of the droplet, where we calculate the shape of a cross-sectional slice of the droplet based on energy minimization. The volume calculation is completed with two caps on the droplet that smoothly fit onto the central part and mimick the physically realistic shape. We compare our analytical model with 3D numerical energy minimization calculations and find excellent agreement for a large range of droplet lengths and channel geometries, thus validating the model for use in quantitative research. The findings of this research can, with small adaptations, be applied in related systems, such as pinned gas bubbles or droplets in a shear flow. We discuss the necessary adaptations and what open questions remain in the field of droplet pinning, specifically related to cases where assumptions made in our work do not apply. This results in a series of recommendations for future research on the role of viscous and inertial effects and heterogeneities with sizes on the order of the droplet.","droplet; pinning; contact angle hysteresis; tilting plate; energy minimization","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:bedd787a-c5c7-4579-b80c-7f780d597179","http://resolver.tudelft.nl/uuid:bedd787a-c5c7-4579-b80c-7f780d597179","Electrolytic cell for the production of ammonia","Mulder, F.M.","","2015","The invention provides an electrolytic cell 10 for the production of ammonia (NH3), comprising an electrolytic cell unit 100 comprising a first electrode 110, a second electrode 120, and an electrolyte 133, further a voltage generator 210, a supply 220 of a dinitrogen comprising fluid 221, and a supply 230 of a water comprising fluid 231. The electrolyte is configured to allow transport of protons. The first electrode is permeable for protons, wherein the first electrode is at first side in contact with the electrolyte and at second side is in fluid contact with the supply of the dinitrogen comprising fluid. The second electrode is permeable for protons but impermeable to 02and H2O. The second electrode is at first side also in contact with the electrolyte, and at second side in fluid contact with the supply of the water comprising fluid. The ammonia can be produced and stored in liquid form.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:60e55457-3bcc-4da8-b1a4-64243c764bd6","http://resolver.tudelft.nl/uuid:60e55457-3bcc-4da8-b1a4-64243c764bd6","Electromagnetic control of oscillating flows in a cavity","Kalter, R.","Kleijn, C.R. (promotor); Tummers, M.J. (promotor)","2015","In continuous steel casting, liquid steel flows turbulently through a submerged nozzle into a thin, vertical mould. In the mould the liquid steel is cooled, such that it solidifies and plate steel is formed. On top of the liquid steel in the mould, a slag layer is present and due to the turbulent behavior of the flow, particles and droplets from the slag layer can get entrained into the bulk flow. This leads to inclusions in the final product, which is unwanted. The flow in the mould needs to be stabilized, such that entrainment effects no longer play a role. For this, electromagnets are generally installed next to the mould. The flow of the electrically conductive liquid steel through the magnetic field induces an electrical current, from which an induced Lorentz force emerges, which acts as a so-called electromagnetic brake. This dissertation presents an experimental study on flow dynamics, heat transfer, and electromagnetic interaction in a thin slab continuous casting mould. To mimic the continuous casting process, a glass model of the mould was fabricated and (salt) water was used as modeling fluid, such that particle image velocimetry measurements could be performed. The flow of both single and bifurcated jets is studied. The jets issuing into the thin cavity and the induced flow in the cavity exhibit a self-sustained oscillating behavior with a frequency that grows linearly with the jet velocity. It was found that the self-sustained oscillations exist due to an imbalance between the inertial forces in the recirculation zones alongside the jets and the pressure force due to a low pressure zone in these recirculation zones. The low pressure zone in the center of the recirculation zones can exist due to the (semi) two dimensionality of the flow. When a thicker cavity is employed, the self-sustained jet oscillations vanish due to a less structured, and more three dimensional, flow pattern. Next, the influence of the self sustained jet oscillations on heat transfer at the wall is studied for flow from a bifurcated nozzle. A constant high inlet flow temperature is applied, in combination with cooling of one of the broad walls. Measurements of the temperature at the cooled wall are performed using thermochromic liquid crystals (TLC’s) attached to the cooled wall. The self-sustained jet oscillations show an imprint on the TLC’s. At the point where the shear layers of the jet reach the wall a hot spot is formed, and in the center of the recirculation zone alongside the jet a cold spot is found. The cold spot moves with the jet oscillation, leading to a non-uniform and time-dependent temperature distribution at the cooled wall. Measurements of the temperature drop of the liquid over the cavity have been performed and the average heat transfer coefficient h was found to scale with Re^0.8. Subsequently, the self-sustained jet oscillations are influenced by means of an applied electromagnetic force. This is done by applying an electrical current through a saline solution across the width of the cavity, in conjunction with a permanent magnetic field perpendicular to the electrical current. The combination of the electrical and magnetic field with a liquid with high electrical conductivity (as compared to tap water) leads to a permanent and local Lorentz force. This Lorentz force can be applied such that the jet oscillations are either suppressed or enhanced. In the oscillation suppressing configuration, the flow due to the Lorentz force prohibits the recirculation zones from forming, and so no low pressure zones emerge alongside the jet. Above a critical forcing strength, this suppresses the self-sustained jet oscillations completely. In the opposite, oscillation enhancing, configuration, the flow due to the Lorentz force increases the formation of the recirculation zones and hence the oscillation frequency increases. We finalize this thesis by discussing how the experimental results from this work can be used in the design and optimization of actual steel casters, and in the validation of numerical models to be used for that same purpose. Shortcomings of the experimental methods are discussed, as well as the appropriate scaling of physical parameters.","continuous casting; electromagnetic brake; electrohydrodynamics","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:15cb6d8f-07fe-4212-bb6c-3a1112b4ca76","http://resolver.tudelft.nl/uuid:15cb6d8f-07fe-4212-bb6c-3a1112b4ca76","Continuous production of nanostructured particles using spatial atomic","Van Ommen, J.R.; Kooijman, D.; De Niet, M.; Talebi, M.; Goulas, A.","","2015","In this paper, the authors demonstrate a novel spatial atomic layer deposition (ALD) process based on pneumatic transport of nanoparticle agglomerates. Nanoclusters of platinum (Pt) of ?1?nm diameter are deposited onto titania (TiO2) P25 nanoparticles resulting to a continuous production of an active photocatalyst (0.12–0.31?wt. % of Pt) at a rate of about 1?g min?1. Tuning the precursor injection velocity (10–40?m s?1) enhances the contact between the precursor and the pneumatically transported support flows. Decreasing the chemisorption temperature (from 250 to 100?°C) results in more uniform distribution of the Pt nanoclusters as it decreases the reaction rate as compared to the rate of diffusion into the nanoparticle agglomerates. Utilizing this photocatalyst in the oxidation reaction of Acid Blue 9 showed a factor of five increase of the photocatalytic activity compared to the native P25 nanoparticles. The use of spatial particle ALD can be further expanded to deposition of nanoclusters on porous, micron-sized particles and to the production of core–shell nanoparticles enabling the robust and scalable manufacturing of nanostructured powders for catalysis and other applications.","atomic layer deposition; nanoparticles; catalysis; chemically reactive flows; transmission electron microscopy","en","journal article","American Vacuum Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:3ed4c199-e244-459f-bd42-9f130a89da7c","http://resolver.tudelft.nl/uuid:3ed4c199-e244-459f-bd42-9f130a89da7c","Plasmonic nanoparticle films for solar cell applications fabricated by size-selective aerosol deposition","Pfeiffer, T.V.; Ortiz Gonzalez, J.; Santbergen, R.; Tan, H.; Schmidt-Ott, A.; Zeman, M.; Smets, A.H.M.","","2014","A soft deposition method for incorporating surface plasmon resonant metal nanoparticles within photovoltaic devices was studied. This self-assembly method provides excellent control over both nanoparticle size and surface coverage. Films of spherical Ag nanoparticles with diameter of ?100 nm were fabricated by depositing size-selected aerosols on various substrates using electrophoresis. This novel deposition method opens the route to embed plasmonic nanoparticles in the intermediate reflector of a micromorph silicon tandem PV cell. We have for the first time fabricated working tandem cells of this type. Compared to a flat reference device the Ag particles enhanced the short-circuit current density due to improved light trapping. The enhancement is, however, limited by the sulfidation on the surface of Ag nanoparticles and a further optimization of the cell fabrication method is required to prevent a reduction of open-circuit voltage and fill factor.","light trapping; plasmonics; silver nanoparticles; aerosol; thin-film solar cells","en","conference paper","Elsevier","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:050c1e0e-89f3-4ee3-a1d0-907bb3a31a3a","http://resolver.tudelft.nl/uuid:050c1e0e-89f3-4ee3-a1d0-907bb3a31a3a","Water-gas shift (WGS) Operation of Pre-combustion CO2 Capture Pilot Plant at the Buggenum IGCC","Van Dijk, H.A.J.; Damen, K.; Makkee, M.; Trapp, C.","","2014","In the Nuon/Vattenfall CO2 Catch-up project, a pre-combustion CO2 capture pilot plant was built and operated at the Buggenum IGCC power plant, the Netherlands. The pilot consist of sweet water-gas shift, physical CO2 absorption and CO2 compression. The technology performance was verified and validated models were obtained. This paper describes the validation of a WGS reactor model and the excellent catalyst resistance to carbiding at steam/CO = 1.5 mol·mol-1 testing. Model-based optimization shows that compared to conventional operation at steam/CO = 2.65, applying steam/CO = 1.5 leads to a 10% lower CO2 capture of penalty of 1155 MJelectric·tCO2?1, albeit at a decreased optimum CO2 capture efficiency of 78.5% versus 87.5%.","pre-combustion CO2 capture; pilot plant; WGS section; reactor model; lowered steam/CO ratio; optimization","en","journal article","Elsevier","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:c2e4855c-e393-49f8-888f-c82e595dcadf","http://resolver.tudelft.nl/uuid:c2e4855c-e393-49f8-888f-c82e595dcadf","Magneto-thermal convection of low concentration nanofluids","Roszko, A.; Fornalik-Wajs, E.; Donizak, J.; Wajs, J.; Kraszewska, A.; Pleskacz, L.; Kenjeres, S.","","2014","The main aim of this paper was to analyze possible utilization of the low concentration nanofluids and the magnetic field to enhance heat transfer. The studied fluids were based on water with an addition of copper particles (40-60 nm diameter). They belonged to the diamagnetic group of materials. As a first attempt to stated target the analysis of enclosure placed in the maximal value of square magnetic induction gradient was carried out. The maximum was in the centre of investigated cavity and it caused the most complex system of gravitational and magnetic buoyancy forces. In the lower part of cavity both forces acted in the same direction, while in the upper part they counteracted. Therefore an enhancement and attenuation of heat transfer could be observed. Due to the particle concentration and magnetic field action the character of flow was changed. In the case of 50 ppm nanofluid the flow was steady end the strong magnetic field didn’t change much in its structure except for the suppression of some vortices. In the case of 500 ppm nanofluid the flow was not steady even without magnetic field, but increasing magnetic induction caused change of its structure towards the inertial-convective regime of turbulent flow.","","en","conference paper","EDP Sciences","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:df31145f-d145-4299-8577-c377851d078b","http://resolver.tudelft.nl/uuid:df31145f-d145-4299-8577-c377851d078b","Simultaneous capture of the color and topography of paintings using fringe encoded stereo vision","Zaman, T.; Jonker, P.P.; Lenseigne, B.A.J.; Dik, J.","","2014","Introduction: Paintings are versatile near-planar objects with material characteristics that vary widely. The fact that paint has a material presence is often overlooked, mostly due to the fact that we encounter many of these artworks through two dimensional reproductions. The capture of paintings in the third dimension is not only interesting for study, restoration and conservation, but it also facilitates making three dimensional reproductions through novel 3-D printing methods. No single imaging method is ideally suited to capture the painting’s color and topography and each of them have specific drawbacks. We have therefore designed an efficient hybrid imaging system dedicated to capturing paintings in both color and topography with a high resolution. Results: A hybrid solution between fringe projection and stereo imaging is proposed involving two cameras and a projector. Fringe projection is aided by sparse stereo matching to serve as an image encoder. These encoded images processed by the stereo cameras then help solve the correspondence problem in stereo matching, leading to a dense and accurate topographical map, while simultaneously capturing its color. Through high-end cameras, special lenses and filters we capture a surface area of 170 square centimeter with an in-plane effective resolution of 50 micron and a depth precision of 9 micron. Semi-automated positioning of the system and data stitching consequently allows for the capture of larger surfaces. The capture of the 2 square meter big Jewish Bride by Rembrandt yielded 1 billion 3-D points. Conclusion: The reproductive properties of the imaging system are conform the digitization guidelines for cultural heritage. The data has enabled us to make high resolution 3-D prints of the works by Rembrandt and Van Gogh we have captured, and confirms that the system performs well in capturing both the color and depth information.","3-D; painting; topography; fringe encoding; stereo vision; OA-Fund TU Delft","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Chemical Engineering","","","",""
"uuid:b8147e67-359c-4072-8ce3-91beddb9b57f","http://resolver.tudelft.nl/uuid:b8147e67-359c-4072-8ce3-91beddb9b57f","Water–gas shift catalyst development for energy efficient applications","Hakeem, A.A.","Kapteijn, F. (promotor); Makkee, M. (promotor)","2014","The water–gas shift (WGS) is a reversible, moderately exothermic reaction (1) and is used for the production of hydrogen from CO rich gas streams (synthesis gas). CO + H2O ? CO2 + H2 ?H°= –41 kJ mol?1 (1) This research has focused on the catalyst development of water–gas shift (WGS) reaction and understanding the catalytic activity contributions by different elements present in the catalyst formulation. The motivation for the catalyst development was to improve the energy efficiency in the process of hydrogen production by WGS for an integrated gasification combined cycle (IGCC) power generation for which a CO2 capture unit is foreseen. The WGS process requirements for a more efficient process are that the newly developed catalysts have to operate at low H¬2O/CO ratio (< 3), medium temperature range (523–673 K), to be resistant or reversible to H2S, and should have similar activity, selectivity, and lifetime to that of the current commercial catalysts. A highly active catalyst Rh/Fe2O3/ZrO2 was developed which outperformed currently available commercial high temperature shift catalyst. The rhodium was investigated to mostly promote the redox mechanism dominant in iron oxide and the presence of rhodium in Rh/Fe2O3/ZrO2 however also led to small amounts of methane produced as a side product.","water-gas shift; catalyst; rhodium; iron oxide","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:52a8b2ab-b8f3-41ea-bf06-cc3592ce04d1","http://resolver.tudelft.nl/uuid:52a8b2ab-b8f3-41ea-bf06-cc3592ce04d1","How to Determine the Core-Shell Nature in Bimetallic Catalyst Particles?","Westsson, E.E.; Koper, G.J.M.","","2014","Nanometer-sized materials have significantly different chemical and physical properties compared to bulk material. However, these properties do not only depend on the elemental composition but also on the structure, shape, size and arrangement. Hence, it is not only of great importance to develop synthesis routes that enable control over the final structure but also characterization strategies that verify the exact nature of the nanoparticles obtained. Here, we consider the verification of contemporary synthesis strategies for the preparation of bimetallic core-shell particles in particular in relation to potential particle structures, such as partial absence of core, alloying and raspberry-like surface. It is discussed what properties must be investigated in order to fully confirm a covering, pin-hole free shell and which characterization techniques can provide such information. Not uncommonly, characterization strategies of core-shell particles rely heavily on visual imaging like transmission electron microscopy. The strengths and weaknesses of various techniques based on scattering, diffraction, transmission and absorption for investigating core-shell particles are discussed and, in particular, cases where structural ambiguities still remain will be highlighted. Our main conclusion is that for particles with extremely thin or mono-layered shells—i.e., structures outside the limitation of most imaging techniques—other strategies, not involving spectroscopy or imaging, are to be employed. We will provide a specific example of Fe-Pt core-shell particles prepared in bicontinuous microemulsion and point out the difficulties that arise in the characterization process of such particles.","core-shell; characterization; bimetallic catalysts; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:6adc60af-f5ac-41dc-8d5e-0de0566a2c6a","http://resolver.tudelft.nl/uuid:6adc60af-f5ac-41dc-8d5e-0de0566a2c6a","Conductive Graphitic Networks: From Atoms to Fuel Cells","Negro, E.","van Esch, J.H. (promotor); Picken, S.J. (promotor); Koper, G.J.M. (promotor)","2014","Graphitic materials have attracted a great interest in the field of sustainable energy production and storage because of their excellent electrical, mechanical and chemical properties. This thesis modestly contributes to this global research by investigating new interconnected carbon nanostructures, here called Carbon Nano-Networks (CNNs). The work is divided into two parts. The first part deals with the synthesis of CNNs consisting of Chemical Vapor Deposition (CVD) of ethene over metal catalyst nanoparticles (NPs) synthesized in bicontinuous microemulsions (BMEs). Chapter 1 focuses on the characterization of dense microemulsions, both experimentally and computationally, using a coarse-grained molecular dynamics simulation tool. Bicontinuity of microemulsions is visualized. Chapter 2 describes the synthesis of NPs in BMEs. The effect of the precursors and of the microemulsion composition on the size, polidispersity and stability of the NPs is analyzed. Finally a mechanism of formation of NPs in BMEs is proposed. Chapter 3 investigates the synthesis of CNNs via CVD of ethene over metallic particles synthesized in BMEs. The effect of synthesis parameters on the final structure is studied. Properties of CNNs, such as porosity and conductivity are investigated. The second part deals with the use of CNNs as catalyst support in Polymer electrolyte membranes (PEM) Fuel Cells. Chapter 4 gives a brief overview of PEM Fuel Cells basics, materials and challenges. In Chapter 5, activity and durability of Pt deposited over CNNs is compared to Pt over carbon nano-tubes and to commercial catalyst. In Chapter 6, CNNs are used as support for non-noble metal catalyst. Performances are evaluated in-situ and ex-situ. Chapter 7 deals with an innovative manufacturing technique for an electrode: CNNs are grown directly over carbon paper. Resistance to corrosion as a function of synthesis parameters is evaluated. Pt is electrodeposited over the synthesized electrode support, and its activity and durability is evaluated and compared to commercial catalyst. The results presented in terms of cost, activity or durability are either superior to commercial catalyst or of the same order of magnitude of state-of-the-art catalyst. Nevertheless, the simplicity of CNNs synthesis procedure, the low price of catalyst precursor and the reduction of manufacturing steps make this novel electrode promising as material for fuel cells. In conclusion, the work described in this thesis certainly does not lead to immediate improvements in efficiency of fuel cells but it does provide for new and potentially more sustainable material solutions with which it may well be possible to attain these improvements in the near future.","pem fuel cell; durability; carbon corrosion; graphitic carbon; Chemical Vapor Deposition; nanoparticle; microemulsion; molecular dynamics; non noble metal catalyst; platinum","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:3f09f1d8-1d4c-4f77-9f02-153b6a5424d4","http://resolver.tudelft.nl/uuid:3f09f1d8-1d4c-4f77-9f02-153b6a5424d4","Molecular composites based on high-performance polymers and an interpenetrating liquid crystal thermoset","Dingemans, T.J.","","2014","The invention is directed to a polymeric composition comprising a first polymer (in particular HPP) and a liquid crystal thermoset (LCT) network that interpenetrates said first polymer, which LCT network comprises LCT oligomers that are at least partly polymerized, as well as to a method for preparing such. The polymeric composition of the invention does not separate into two distinct polymer phases (first polymer and LCT) over time and has improved thermo-mechanical properties. In particular, the invention may be used to improve the properties of HPP. The polymeric composition can be used as a high-resistant material, in particular having improved heat resistance.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:f17b34c8-2686-4cef-addd-1dcfd6b11a83","http://resolver.tudelft.nl/uuid:f17b34c8-2686-4cef-addd-1dcfd6b11a83","Cooperative biexciton generation and destructive interference in coupled quantum dots using adiabatic rapid passage","Renaud, N.; Grozema, F.C.","","2014","We report numerical simulations of biexciton generation in coupled quantum dots (CQDs) placed in a static electric field and excited by a chirped laser pulse. Our simulations explicitly account for exciton-phonon interactions at finite temperature using a non-Markovian quantum jump approach to solve the excitonic dynamics. In the case of noninteracting quantum dots, the biexciton generation is severely limited by the biexciton binding energy. We demonstrate that the application of an axial electric field along the CQDs can yield a favorable excitonic level alignment that compensates for the biexciton binding energy and yields an optimum biexciton generation. On the contrary, well-defined values of the electric field lead to destructive quantum interference that completely inhibits the biexciton generation. We therefore demonstrate here the potential of chirped pulse excitations of CQDs for high-efficiency biexciton generation but also for the control of unique optoelectronic properties of complex quantum systems.","","en","journal article","Optical Society of America","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:e05ff998-d5a6-4150-83ba-85fb37990fd2","http://resolver.tudelft.nl/uuid:e05ff998-d5a6-4150-83ba-85fb37990fd2","Exciton and Charge Carrier Dynamics in Materials for Photovoltaics","Fravventura, M.C.","Siebbeles, L.D.A. (promotor)","2014","This research focuses on the investigation of the opto-electronic properties of a variety of organic and inorganic materials of interest for photovoltaics. Fundamental knowledge on the parameters that play an important role in the process of charge photogeneration is achieved by application of a number of experimental methods, the most relevant of which is the frequency- and time-resolved microwave photoconductance technique.","organic semiconductor; time-resolved microwave photoconductance; TiO2; mobility; triplet-triplet annihilation up-conversion; exciton diffusion length; C60; ZnPc; perylene","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:401c17f3-bc67-433a-ace0-7e24bfe6df89","http://resolver.tudelft.nl/uuid:401c17f3-bc67-433a-ace0-7e24bfe6df89","Experimental and molecular dynamics characterization of dense microemulsion systems: Morphology, conductivity and SAXS","Negro, E.; Latsuzbaia, R.; De Vries, A.H.; Koper, G.J.M.","","2014","Microemulsions are exciting systems that are promising as tuneable self-assembling templating reaction vessels at the nanoscale. Determination of the nano-structure of microemulsions is, however, not trivial, and there are fundamental questions regarding their design. We were able to reproduce experimental data for an important microemulsion system, sodium-AOT–n-heptane–water, using coarse-grained simulations involving relatively limited computational costs. The simulation allows visualization and deeper investigation of controversial phenomena such as bicontinuity and ion mobility. Simulations were performed using the Martini coarse-grained force field. AOT bonded parameters were fine-tuned by matching the geometry obtained from atomistic simulations. We investigated several compositions with a constant ratio of surfactant to oil while the water content was varied from 10 to 60% in weight. From mean square displacement calculation of all species, it was possible to quantify caging effects and ion mobility. Average diffusion coefficients were calculated for all charged species and trends in the diffusion coefficients were used to rationalize experimental conductivity data. Especially, the diffusion coefficient of charged species qualitatively matched the variation in conductivity as a function of water content. The scattering function was calculated for the hydrophilic species and up to 40% water content quantitatively matched the experimental data obtained from small angle X-ray scattering measurements. For higher water contents, discrepancies were observed and attributed to a nearby phase separation. In particular, bicontinuity of water and oil was computationally visualized by plotting the coordinates of hydrophilic beads. Equilibrated coarse-grained simulations were reversed to atomistic models in order both to compare ion mobility and to catch finer simulation details. Especially, it was possible to capture the intimate ion pair interaction between the sodium ion and the surfactant head group.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:d161c1cb-5ba6-4ae9-a2c6-9c27b50b8a24","http://resolver.tudelft.nl/uuid:d161c1cb-5ba6-4ae9-a2c6-9c27b50b8a24","High yield, controlled synthesis of graphitic networks from dense micro emulsions","Negro, E.; Dieci, M.; Sordi, D.; Kowlgi, K.; Makkee, M.; Koper, G.J.M.","","2014","We report on the production of Carbon Nano Networks (CNNs) from dense microemulsions in which catalyst nanoparticles have been synthesized. CNNs are 3D carbon networks, consisting of branches and junctions, and are mesoporous, graphitic, and conductive being suitable as electrode materials.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:d568fce2-1efa-4f2e-9c01-a4ac98e52d49","http://resolver.tudelft.nl/uuid:d568fce2-1efa-4f2e-9c01-a4ac98e52d49","Controlled amino-functionalization by electrochemical reduction of bromo and nitro azobenzene layers bound to Si(111) surfaces","Ullien, D.; Thüne, P.C.; Jager, W.F.; Sudhölter, E.J.R.; De Smet, L.C.P.M.","","2014","4-Nitrobenzenediazonium (4-NBD) and 4-bromobenzenediazonium (4-BBD) salts were grafted electrochemically onto H-terminated, p-doped silicon (Si) surfaces. Atomic force microscopy (AFM) and ellipsometry experiments clearly showed layer thicknesses of 2–7 nm, which indicate multilayer formation. Decreasing the diazonium salt concentration and the reaction time resulted in a smaller layer thickness, but did not prevent the formation of multilayers. It was demonstrated, mainly by X-ray photoelectron spectroscopy (XPS), that the diazonium salts not only react with the H-terminated Si surface, but also with electrografted phenyl groups via azo-bond formation. These azo bonds can be electrochemically reduced at Ered = ?1.5 V, leading to the corresponding amino groups. This reduction resulted in a modest decrease in layer thickness, and did not yield monolayers. This indicates that other coupling reactions, notably a biphenyl coupling, induced by electrochemically produced phenyl radicals, take place as well. In addition to the azo functionalities, the nitro functionalities in electrografted layers of 4-NBD were independently reduced to amino functionalities at a lower potential (Ered = ?2.1 V). The presence of amino functionalities on fully reduced layers, both from 4-NBD- and 4-BBD-modified Si, was shown by the presence of fluorine after reaction with trifluoroacetic anhydride (TFAA). This study shows that the electrochemical reduction of azo bonds generates amino functionalities on layers produced by electrografting of aryldiazonium derivatives. In this way multifunctional layers can be formed by employing functional aryldiazonium salts, which is believed to be very practical in the fabrication of sensor platforms, including those made of multi-array silicon nanowires.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:08d23295-220b-4f0a-a84c-3513c5248122","http://resolver.tudelft.nl/uuid:08d23295-220b-4f0a-a84c-3513c5248122","Droplets on Inclined Plates: Local and Global Hysteresis of Pinned Capillary Surfaces","Musterd, M.; Van Steijn, V.; Kleijn, C.R.; Kreutzer, M.T.","","2014","Local contact line pinning prevents droplets from rearranging to minimal global energy, and models for droplets without pinning cannot predict their shape. We show that experiments are much better described by a theory, developed herein, that does account for the constrained contact line motion, using as an example droplets on tilted plates. We map out their shapes in suitable phase spaces. For 2D droplets, the critical point of maximum tilt depends on the hysteresis range and Bond number. In 3D, it also depends on the initial width, highlighting the importance of the deposition history.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:59fc0b64-31d7-4f08-a793-a0fc016d5e7c","http://resolver.tudelft.nl/uuid:59fc0b64-31d7-4f08-a793-a0fc016d5e7c","Magnetic force microscopy: Quantitative issues in biomaterials","Passeri, D.; Dong, C.; Reggente, M.; Angeloni, L.; Barteri, M.; Scaramuzzo, F.A.; De Angelis, F.; Marinelli, F.; Antonelli, F.; Rinaldi, F.; Marianecci, C.; Carafa, M.; Sorbo, A.; Sordi, D.; Arends, I.W.C.E.; Rossi, M.","","2014","Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool for the characterization of magnetic recording media, superconductors and magnetic nanomaterials, MFM is finding constantly increasing application in the study of magnetic properties of materials and systems of biological and biomedical interest. After reviewing these latter applications, three case studies are presented in which MFM is used to characterize: (i) magnetoferritin synthesized using apoferritin as molecular reactor; (ii) magnetic nanoparticles loaded niosomes to be used as nanocarriers for drug delivery; (iii) leukemic cells labeled using folic acid-coated core-shell superparamagnetic nanoparticles in order to exploit the presence of folate receptors on the cell membrane surface. In these examples, MFM data are quantitatively analyzed evidencing the limits of the simple analytical models currently used. Provided that suitable models are used to simulate the MFM response, MFM can be used to evaluate the magnetic momentum of the core of magnetoferritin, the iron entrapment efficiency in single vesicles, or the uptake of magnetic nanoparticles into cells.","magnetic force microscopy; magnetic nanoparticle; ferritin; magnetoferritin; vesicle; niosome; drug delivery; cell labelling; leukemia cell; folic acid receptor","en","journal article","Landes Bioscience","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:dee42a0a-208a-467f-a967-449517825540","http://resolver.tudelft.nl/uuid:dee42a0a-208a-467f-a967-449517825540","Crystals for sustainability – structuring Al-based MOFs for the allocation of heat and cold","De Lange, M.F.; Ottevanger, C.P.; Wiegman, M.; Vlugt, T.J.H.; Gascon, J.; Kapteijn, F.","","2014","Several Al-based MOFs of the CAU family have been investigated for application in the adsorption driven allocation of heat and cold. The special water adsorption behaviour of CAU-10-H makes it ideal for application in adsorption driven heat pumps and chillers. For increased performance, CAU-10-H crystals have been grown directly on both ?-alumina and metallic aluminium. Crystal growth on these surfaces can be controlled by the addition of acids.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:527a8700-001c-4a12-b7ea-d7abf09d7c6b","http://resolver.tudelft.nl/uuid:527a8700-001c-4a12-b7ea-d7abf09d7c6b","Development of a small scale shaking test to evaluate foamability","Bechan, M.I.S.R.","Portela, L. (mentor); Nimwegen, A.T. (mentor); Kleijn, C.R. (mentor)","2014","The lifetime of a gas well is significantly influenced by the liquids present in the well. These liquids can be found along the walls in an annular flow and is carried up along with the gas as a result of the relatively high gas pressure in the early stages of the well. As time goes on the gas pressure decreases, thus the well’s ability to drag up the liquids with the gas also decreases. As a result the liquids start to accumulate in the tubing and bottom of the well. This severely limits or even halts the gas production. This phenomena is known as liquid loading.","","en","bachelor thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:e13926f0-3616-4aa1-bb0c-212ff47fc929","http://resolver.tudelft.nl/uuid:e13926f0-3616-4aa1-bb0c-212ff47fc929","Catalytic control over the formation of supramolecular materials","Eelkema, R.; Esch, J.H. van","","2014","In this Perspective, we will discuss how the rate of formation of supramolecular materials can be drastically enhanced by catalytically controlling the rate of formation of their molecular building blocks, resulting in the formation of out-of-equilibrium soft materials with enhanced mechanical properties. Also, the use of surface confined, patterned catalysts allows spatial control over self-assembly, which can be applied to the formation of regular, micrometer sized hydrogel patterns. Catalysis has been applied for decades as an indispensable tool in the synthesis of both simple and highly complex molecules and polymers, ranging from milligram lab-scale to multi-ton industrial processes. However, despite being widespread in nature, until recently the use of catalysis to control the formation of supramolecular materials has remained limited. We will demonstrate the large potential of using catalysis as a tool in the construction of soft materials, illustrated by recent developments.","Gold for Gold · Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:f7e5f594-9e51-41fb-ad1f-9df1c0640cd1","http://resolver.tudelft.nl/uuid:f7e5f594-9e51-41fb-ad1f-9df1c0640cd1","Experimental determination of the bubble size in foam created in gas-liquid flow with surfactants","Grasmeijer, J.","Portela, L. (mentor); Nimwegen, A.T. (mentor); Tummers, M.J. (mentor)","2014","In the gas industry there is a common problem during the production of gas, which is called liquid loading. This is the accumulation of water and condensed gas at the bottom of the pipe, through which gas is produced. This occurs when the gas velocity becomes insufficient to drag the liquid to the surface. From experience they know in the gas industry that by adding surfactants to the water at the bottom of the well, liquid loading can be postponed to a lower reservoir pressure. The water will start to form foam, which changes the flow in the well as foam is easier to drag upwards. But the precise effect of the surfactant on the flow is still unclear. By gaining more knowledge, it may be possible to make a model of the flow with surfactant , to predict e.g. the optimal production conditions, like the amount of surfactant that should be used.","","en","bachelor thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:34a245d2-f699-47fe-9f28-bed873feb0da","http://resolver.tudelft.nl/uuid:34a245d2-f699-47fe-9f28-bed873feb0da","Experimental study of fluid flow in the bifurcation of a patient specific carotid artery, with severe stenosis: Comparing PIV, PC-MRI and CFD","Van de Belt, G.","Kenjeres, S. (mentor); Kleijn, C.R. (mentor); Van Osch, M.J.P. (mentor); Tummers, M.J. (mentor); Kalter, R. (mentor)","2014","Magnetic Drug Targeting is a relatively new technique whereby chemotherapeutic agents are attached to magnetic particles that will be injected in an artery upstream of an affected area. By exerting an external magnetic field an internal magnetic field gradient will be induced that will entrap the particles that contain the drugs in the affected region. By doing so only the affected region will be treated, leaving the rest of the body free from drugs and therefore the side effects are reduced as the total dose of the drugs is much lower than when more conventional procedures are used. Clinical trials have been performed using this technique on various types of cancer with promising results.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:a601bc26-c5b4-4edb-8a3f-efb4853c2bbc","http://resolver.tudelft.nl/uuid:a601bc26-c5b4-4edb-8a3f-efb4853c2bbc","Protein detection on biotin-derivatized polyallylamine by optical microring resonators","Ullien, D.; Harmsma, P.J.; Abdulla, S.M.C.; De Boer, B.M.; Bosma, D.; Sudhölter, E.J.R.; De Smet, L.C.P.M.; Jager, W.F.","","2014","Silicon optical microring resonators (MRRs) are sensitive devices that can be used for biosensing. We present a novel biosensing platform based on the application of polyelectrolyte (PE) layers on such MRRs. The top PE layer was covalently labeled with biotin to ensure binding sites for antibodies via a streptavidin-biotin binding scheme. Monitoring the shift in the microring resonance wavelength allows real-time, highly sensitive detection of the biomolecular interaction.","sensors; biological sensing and sensors; optical sensing and sensors","en","journal article","Optical Society of America","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:64f111d9-0663-4b23-81bf-77d288415e33","http://resolver.tudelft.nl/uuid:64f111d9-0663-4b23-81bf-77d288415e33","A thin-film device for detecting hydrogen","Westerwaal, R.J.; Szilagyi, P.A.; Dam, B.","","2014","The present invention relates to a thin-film device, to a method for producing a thin-film device, to a protective layer for shielding an oxygen, moisture and/or carbon monoxide sensitive surface, to a method for shielding such a surface, to a method for forming a metal framework material, to a hydrogen sensor and to an electro-magnetic transformer comprising said sensor.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:06a39564-f39e-4b56-b109-94fb3c1bc74c","http://resolver.tudelft.nl/uuid:06a39564-f39e-4b56-b109-94fb3c1bc74c","Coke formation in the oxidative dehydrogenation of ethylbenzene to styrene by TEOM","Nederlof, C.; Vijfhuizen, P.; Zarubina, V.; Melián-Cabrera, I.; Kapteijn, F.; Makkee, M.","","2014","A packed bed microbalance reactor setup (TEOM-GC) is used to investigate the formation of coke as a function of time-on-stream on ?-Al2O3 and 3P/SiO2 catalyst samples under different conditions for the ODH reaction of ethylbenzene to styrene. All samples show a linear correlation of the styrene selectivity and yield with the initial coverage of coke. The COX production increases with the coverage of coke. On the 3 wt% P/SiO2 sample, the initial coke build-up is slow and the coke deposition rate increases with time. On alumina-based catalyst samples, a fast initial coke build-up takes place, decreasing with time-on-stream, but the amount of coke does not stabilize. A higher O2 : EB feed ratio results in more coke, and a higher temperature results in less coke. This coking behaviour of Al2O3 can be described by existing “monolayer–multilayer” models. Further, the coverage of coke on the catalyst varies with the position in the bed. For maximal styrene selectivity, the optimal coverage of coke should be sufficient to convert all O2, but as low as possible to prevent selectivity loss by COX production. This is in favour of high temperature and low O2 : EB feed ratios. The optimal coke coverage depends in a complex way on all the parameters: temperature, the O2 : EB feed ratio, reactant concentrations, and the type of starting material.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:f72ea06f-3bd7-4b8a-8f8d-6f3724dba093","http://resolver.tudelft.nl/uuid:f72ea06f-3bd7-4b8a-8f8d-6f3724dba093","Voltage control in MV distribution networks with a large share of distributed renewable generation","Papazacharopoulos, N.","Gibescu, M. (mentor)","2014","Traditionally, voltage control in MV distribution networks has been focused on dealing with voltage drop along radially operated feeders. The actual implemented controllers use local voltage measurements and have been designed and calibrated for a passive and radial use of the MV system. The presence of distributed renewable generation (DRG) makes these assumptions no longer valid. The power generated by DRG units will increase the voltage at adjacent nodes and even cause it to be higher than the voltage at the primary substation. Consequently, the presence of DRG will affect voltage control in distribution systems and it needs to be reconsidered whether methods like local voltage control and reactive power injection can still enable the network operator to cope with the newly introduced voltage rise issues. The aim of this study is to create a new voltage control strategy, which will not only successfully limit voltage variations, but also allow for an increased penetration of DRG. The proposed coordinated voltage control strategy deploys control of HV/MV transformers On-Load Tap Changers in combination with active power control provided by Intelligent Nodes, that allows network reconfiguration. The Cigré MV distribution network benchmark is used as a basis for the test system, while appropriate models for the PV Power Plants, the Wind Power Plants and the Intelligent Nodes were developed. In order to draw realistic simulation results, a summer / winter seasonal variation is featured. The proposed voltage control algorithm is incrementally developed, allowing for the identification of factors hindering the controller performance and the development of a control algorithm which is more targeted towards dealing with specific issues. The commercial power system simulation software DIgSILENT PowerFactory 15.0 is used for carrying out these simulations. The analysis of simulation results shows that the proposed voltage control strategy is capable of facilitating the transition towards active MV distribution networks, by offering considerably higher DRG penetration levels and strictly bound network voltages. The modelled controller is particularly applicable to MV distribution networks across North Europe. Among others, the limiting factors for an increased DRG penetration are identified, along with the effects that the reactive power control and the choice of voltage limits have. Finally, recommendations for future research are provided.","voltage control; MV distribution network; distributed renewable generation; On-Load Tap Changer; Intelligent Node","en","master thesis","","","","","","","","2014-06-23","Applied Sciences","Chemical Engineering","","Sustainable Energy Technology","",""
"uuid:c6fca7cd-f214-4ae5-a241-41cc76b97a34","http://resolver.tudelft.nl/uuid:c6fca7cd-f214-4ae5-a241-41cc76b97a34","Diamond Films and Devices: Chemistry, Electronics and Mechanics","Seshan, V.","Sudhölter, E.J.R. (promotor); Van der Zant, H.S.J. (promotor)","2014","Natural diamond is one of the most rare and precious gemstones known to mankind. In addition, it is also known for its exceptional material properties including extreme heat conducting capacity at room temperature, chemical inertness to aqueous environments and excellent electrical insulation that are interesting to both fundamental as well as applied sciences. These attractive properties of natural diamond and the difficulty of its mining led to the production of synthetic diamond via high pressure and high temperature (HPHT) and chemical vapour deposition (CVD) techniques. Gradually, with the utilization and improvements of these techniques, there has been a growing interest in the research community to exploit the superior material properties of diamonds. In this thesis, the chemical, electronic and mechanical properties of CVD diamonds were investigated to mainly elucidate their fundamental properties and also to evaluate their commercial applicability in terms of processing. The thesis is divided into three sections: the surface chemistry (Chapter 2), the bulk (opto)electronic properties (Chapters 3, 4 and 5) and the mechanical properties of thin films (Chapter 6). All chapters deal with CVD diamond, typically nanocrystalline diamond.","CVD diamond; nanocrystalline diamond; chemistry; electronics; mechanics","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Quantum Nanoscience","","","",""
"uuid:f1a8ff30-1a61-49cd-ae57-261525563d26","http://resolver.tudelft.nl/uuid:f1a8ff30-1a61-49cd-ae57-261525563d26","Boundary conditions for surface reactions in lattice Boltzmann simulations","Gillissen, J.J.J.; Looije, N.","","2014","A surface reaction boundary condition in multicomponent lattice Boltzmann simulations is developed. The method is applied to a test case with nonlinear reaction rates and nonlinear density profiles. The results are compared to the corresponding analytical solution, which shows that the error of the method scales with the square of the lattice spacing.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:4b061a61-02e0-4f40-8097-1dafdb95d850","http://resolver.tudelft.nl/uuid:4b061a61-02e0-4f40-8097-1dafdb95d850","Effects of electromagnetic forcing on self-sustained jet oscillations","Kalter, R.; Tummers, M.J.; Kenjeres, S.; Righolt, B.W.; Kleijn, C.R.","","2014","The influence of electromagnetic forcing on self-sustained oscillations of a jet issuing from a submerged nozzle into a thin vertical cavity (width W much larger than thickness T) has been studied using particle image velocimetry. A permanent Lorentz force is produced by applying an electrical current across the width of the cavity in conjunction with a magnetic field from three permanent magnets across its thickness. As a working fluid a saline solution is used. The magnetic field is in the north-south-north configuration, such that the Lorentz force can be applied in an up-down-up configuration or in a down-up-down configuration by switching the direction of the electrical current. A critical Stuart number N c was found. For N < N c , the jet oscillates with a constant Strouhal number St, independent of the Reynolds number Re. For N > N c and an oscillation enhancing up-down-up configuration of the Lorentz force, St grows with N as St ?N??? . In contrast, for N > N c and an oscillation suppressing down-up-down configuration of the Lorentz force, all jet oscillations are suppressed.","Lorentz group; magnets; magnetic fields; velocimetry; velocity measurement","en","journal article","American Insitute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:afa489e0-aa38-423b-b70e-8c4956ddbd6b","http://resolver.tudelft.nl/uuid:afa489e0-aa38-423b-b70e-8c4956ddbd6b","Numerical Studies on Phase Field Diffusion and Flow Solvers","Man, E.","Kleijn, C.R. (mentor); Pimpalgaonkar, H.G. (mentor)","2014","The goal of this project is to validate and evaluate developed numerical solvers that solve both the Cahn-Hilliard diffusion equation and the Cahn-Hilliard-Navier-Stokes coupled equations. The solvers are written for the implementation in the open source CFD software platform, OpenFOAM.","","en","bachelor thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:e04b167d-6dce-4795-8098-901d98a0c680","http://resolver.tudelft.nl/uuid:e04b167d-6dce-4795-8098-901d98a0c680","Harvesting Charges resulting from Carrier Multiplication in Quantum Dots","Ten Cate, S.","Siebbeles, L.D.A. (promotor)","2014","","","en","doctoral thesis","","","","","","","","2014-05-02","Applied Sciences","Chemical Engineering","","","",""
"uuid:01819980-f63c-42b0-8522-ac29ae4c4144","http://resolver.tudelft.nl/uuid:01819980-f63c-42b0-8522-ac29ae4c4144","Experimental study of the structure of a passive scalar in turbulent flows using a wire-mesh sensor: Pipe flowand rod-bundle axial flow","Buskermolen, M.","Portela, L. (mentor); Rohde, M. (mentor); Kruit, P. (mentor); Mudde, R.F. (mentor)","2014","One of the vital safety mechanisms in the reactor core of most nuclear power plants is the negative feedback from the core temperature on the power output. An increased temperature will reduce the power output of the reactor, 'automatically' cooling the it and preventing the nuclear reaction to spin out of control. For this reason, it is important to have a good understanding of the temperature distribution within the reactor core. The water that flows through the core is the main reason for the transport of heat, hence it is of interest to have a good understanding of the behavior of the flow. On of the aspects that defines the flow properties is the geometry of the reactor, a so called 'rod-bundle geometry'. It is the presumption that a large shear in the fluid, induced by the geometry, causes the formation of largescale coherent structures. These structures affect the mixing of heat in the reactor and are, therefore, of interest.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering / Radiation Science and Technology","","Transport Phenomena / Nuclear Energy and Radiation Applications","",""
"uuid:2f646b76-f0b5-4d28-a25b-56222edbcb5d","http://resolver.tudelft.nl/uuid:2f646b76-f0b5-4d28-a25b-56222edbcb5d","Highly efficient carrier multiplication in PbS nanosheets","Aerts, M.; Bielewicz, T.; Klinke, C.; Grozema, F.C.; Houtepen, A.J.; Schins, J.M.; Siebbeles, L.D.A.","","2014","Semiconductor nanocrystals are promising for use in cheap and highly efficient solar cells. A high efficiency can be achieved by carrier multiplication (CM), which yields multiple electron-hole pairs for a single absorbed photon. Lead chalcogenide nanocrystals are of specific interest, since their band gap can be tuned to be optimal to exploit CM in solar cells. Interestingly, for a given photon energy CM is more efficient in bulk PbS and PbSe, which has been attributed to the higher density of states. Unfortunately, these bulk materials are not useful for solar cells due to their low band gap. Here we demonstrate that two-dimensional PbS nanosheets combine the band gap of a confined system with the high CM efficiency of bulk. Interestingly, in thin PbS nanosheets virtually the entire excess photon energy above the CM threshold is used for CM, in contrast to quantum dots, nanorods and bulk lead chalcogenide materials.","physical sciences; nanotechnology; optical physics","en","journal article","Nature Publishing Group","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:590fdf6b-9b73-4bf9-adb4-1003f4f0704b","http://resolver.tudelft.nl/uuid:590fdf6b-9b73-4bf9-adb4-1003f4f0704b","Numerical modeling of heat transfer and fluid flow in welding with a moving heat source","Beekers, J.P.A.","Kleijn, C.R. (mentor); Kidess, A. (mentor)","2014","Worldwide, welding is a multi billion-dollar fabrication technology used extensively in construction and industry. The final quality of a weld is known to be dependent on the hydrodynamics in the liquid region and the energy transfer in the surrounding heat affected zone. Understanding of these processes is therefore vital in improving weld quality.","","en","bachelor thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:4897f625-8b4d-467a-ac53-34a08df1bccd","http://resolver.tudelft.nl/uuid:4897f625-8b4d-467a-ac53-34a08df1bccd","Magnetic Drug Targeting in Human Airway Geometry","Tjin, J.L.","Kenjeres, S. (mentor); Kleijn, C.R. (mentor); Van Ommen, J.R. (mentor); Righolt, B.W. (mentor)","2014","Patient specific drug delivery may improve the efficiency of the medicine and reduce the side-effects. In addition to different medicines and dosages, the target site of the medicine can differ from patient to patient. By using drug particles with a magnetic core, and under the influence of a magnetic field, the particles may be steered towards the point of interest. In the present study, computational fluid dynamics is used to study air flow and particle deposition in human airway geometry. In the first case study, passive particle deposition was carried out in a 90? bend to represent a simplified throat. Random-uniform and deterministic-uniform particle inlet distributions were used. Both the total and cumulative deposition efficiencies showed good agreement with literature. The second case study is again a 90? bend simulation but this time represents a simplified artery. Although the curvature ratio was the same the dimensions of the geometry were much smaller. In addition to passive particle deposition, magnetically enhanced particle deposition was studied and good agreement was obtained with both reference cases. The third case study features a simplification of the conducting airways: a triple bifurcation geometry.","","en","master thesis","","","","","","","","2015-04-25","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:0c687bda-f53a-474d-9cab-dbf141c08716","http://resolver.tudelft.nl/uuid:0c687bda-f53a-474d-9cab-dbf141c08716","Experimental studies on heat transfer in thermo-magnetic onvection for para- and diamagnetic fluids","Mulder, M.","Kenjeres, S. (mentor)","2014","In industrial heat transfer processes, natural convection enters in various forms. One form of natural convection is thermo-magnetic convection. Besides gravitational force, magnetic force causes warmer fluid to rise or fall dependent on the fluids magnetic susceptibility and direction of magnetic field gradient. Magnetic susceptibility is a material property which indicates a degree of magnetization in a material. For paramagnetic fluids magnetic susceptibility depends on temperature, is positive and therefore attracted by magnetic field. Magnetic susceptibility of diamagnetic materials is independent on temperature, is negative and hence repelled by magnetic field. Magnetic force can be used to enhance or suppress gravity. This phenomena is widely investigated for many materials, magnetic field strengths and set-up geometries. In this research thermo-magnetic convection and the effect it has on internal heat transfer is experimentally investigated for para- diamagnetic fluids. Making use of a 10 Tesla superconducting magnet, which can generate field gradients up to 870 T2/m, steady, oscillating and turbulent flow regimes can be observed. I performed the experiments at the AGH University of Science and Technology in Krakow, Poland. A small cubical enclosure filled with para- or diamagnetic fluid is placed at different positions in the magnet to get enhancement or suppression of internal heat transfer. Enclosure is heated from below and top is kept at constant temperature. Temperature of the fluid is measured with thermocouples at six different positions inside the enclosure. From these temperature-time measurements a power spectrumis obtained to determine the characteristic flow regime. Internal heat transfer is investigated by measuring different variables and calculate thermo-magnetic Rayleigh and Nusselt numbers. As paramagnetic fluid a 40% water-glycerol solution is used and gadoliniumnitrate is added to create a higher magnetic susceptibility. Enclosure was placed above the magnet centre which should give a magnetic force that enhances gravitational buoyancy. Temperature difference between the hot and cold plate of the enclosure is 5 and 11±C, respectively case G5A and G11A. Case G5A shows transition in the flow regime from steady to oscillating to turbulent with increasing of magnetic field. Case G11A shows turbulent regime for each measurement. Nusselt number calculations for glycerol solution measurements show an increase, up to 2.5 times, in internal heat transfer. Turbulence causes better mixing and hence better heat transfer. Relation between RaTM and Nu are compared with previous (experimental) relations and show good agreement. Pure water is used as diamagnetic fluid. First enclosure is placed below magnet centre and temperature difference is 5 and 1 ±C, respectively case W5B and W1B. Here magnetic force should enhance internal heat transfer. Case W5A and W3A are measured above the magnet centre and have respectively a temperature difference of 5 and 3 ±C. Case W5B and W5A both show turbulent flow regime for all measurements. Internal heat transfer is about the same for both cases but show a slight increase for W5B and decrease for W5A. There can be concluded that for turbulent flow regimes magnetic force direction has no significant influence on internal heat transfer. For smaller temperature differences, case W1B and W3A, magnetic force does influence measurements. CaseW1B shows steady flow regime first and for higher magnetic field strengths fluid plumes start to rise and sink due to magnetic force. Case W3A shows a very clear transition from turbulence to oscillating flow. Small temperature differences cause large measurement errors and internal heat transfer is assumed to be constant. Recommendations for further research is to get a better impression of fluid structures and temperatures in the enclosure. Fluid behaviour can be visualized with liquid crystals and velocity fields can be determined by using PIV on these visualizations. The velocities can be compared to simulations. To get realistic simulations, fluid properties need to be measured for different temperatures and if necessary differentmagnetic field strengths.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:ad7a0a8b-55dd-4990-8f0c-c0e099dad6ee","http://resolver.tudelft.nl/uuid:ad7a0a8b-55dd-4990-8f0c-c0e099dad6ee","Inhibition of a Gold-Based Catalyst in Benzyl Alcohol Oxidation: Understanding and Remediation","Skupien, E.; Berger, R.J.; Santos, V.P.; Gascon, J.; Makkee, M.; Kreutzer, M.T.; Kooyman, P.J.; Moulijn, J.A.; Kapteijn, F.","","2014","Benzyl alcohol oxidation was carried out in toluene as solvent, in the presence of the potentially inhibiting oxidation products benzaldehyde and benzoic acid. Benzoic acid, or a product of benzoic acid, is identified to be the inhibiting species. The presence of a basic potassium salt (K2CO3 or KF) suppresses this inhibition, but promotes the formation of benzyl benzoate from the alcohol and aldehyde. When a small amount of water is added together with the potassium salt, an even greater beneficial effect is observed, due to a synergistic effect with the base. A kinetic model, based on the three main reactions and four major reaction components, is presented to describe the concentration-time profiles and inhibition. The inhibition, as well as the effect of the base, was captured in the kinetic model, by combining strong benzoic acid adsorption and competitive adsorption with benzyl alcohol. The effect of the potassium salt is accounted for in terms of neutralization of benzoic acid.","gold; catalysis; benzyl alcohol; oxidation; deactivation; inhibition; mechanism; kinetics; modeling; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:8813575a-0abc-4286-91bb-b27a3241c150","http://resolver.tudelft.nl/uuid:8813575a-0abc-4286-91bb-b27a3241c150","Nanowire Field-Effect Transistors: Sensing Simplicity?","Mescher, M.","Sudhölter, E.J.R. (promotor)","2014","Silicon nanowires are structures made from silicon with at least one spatial dimension in the nanometer regime (1-100 nm). From these nanowires, silicon nanowire field-effect transistors can be constructed. Since their introduction in 2001 silicon nanowire field-effect transistors have been studied because of their promising application as selective sensors for biological and chemical species. Their large surface-to-volume ratio promises an increased sensitivity compared to conventional, planar field-effect transistors. Selectivity can be added by smart modification of the surface of the nanowire. The application of nanowire field-effect transistors as chemical sensors for ions is studied in this thesis. After briefly discussing the working principle of field-effect transistors, an extensive review on reported state-of-the-art surface modification techniques is presented. By far, most of this work covers the covalent attachment of molecules to the silicon oxide layer that is typically present on as-prepared silicon nanowires. In addition, some examples on non-covalent approaches have been reviewed. Alternatively, the oxide layer can be removed to attach molecules directly onto silicon. Nanowire field-effect transistors are prepared using top-down fabrication techniques. Nanowires with a width of 20 to 2000 nanometer, a length of 3 to 5 micrometer and a height of 50 to 100 nanometer are etched from silicon-on-insulator wafers. Using a newly developed complementary metal-oxide-semiconductor compatible process, nanowire field-effect transistors are obtained. This process allows for the use of a broad variety of front oxides, which enables selective surface modification of the nanowires and the implementation of materials with different dielectric constants. Furthermore, the presence of a silicon nitride passivation layer on the area around the nanowire provides the possibility to modify only the nanowire surface. Chips typically consist of 28 individual nanowire field-effect transistors. The devices are characterized in air and the variation of the threshold voltage over the wafer is mapped. It is shown that the electrical characteristics make the devices suitable for sensing experiments. The nanowire field-effect transistors are electrically characterized while exposed to water using a newly developed flow cell. A pulsed gate potential is applied as method for stable characterization. While most methods reported in literature use a reference electrode, the pulsed method can be applied without it. Using the sensitivity towards protons of the Si-OH groups at the SiO2 surface, the pH of aqueous solutions is determined using this pulsed gate potential method. It is found that upon increasing pH the threshold voltage increases, which is as expected. The nanowire field-effect transistors are studied using two types of gating: back gating and front gating through the liquid via an Ag/AgCl electrode. It is found that both methods can be used to gate the device, and that in general smaller potentials are needed for front gating compared to back gating. Using this front-gate method, the influence of the non-aqueous solvent 1,4-dioxane on the device characteristics is studied by exposing the devices to different water-1,4-dioxane mixtures. The dependency of the threshold voltage on the mixture composition is found to be related to the decreased dissociation of the surface silanol groups and the electrical conductivity of the mixture used. In the final experiments, the nanowire field-effect transistors are covered with an ionophore-containing polymer membrane via drop casting. This membrane consists of a silicon rubber polymer (Siloprene), embedding the ionophore valinomycin, which has a K+/Na+ selectivity of ~10^5. Using a setup with liquid gating and an Ag/AgCl reference electrode, accurate potassium ion concentrations are determined. Upon exposure of the membrane modified device to sodium ions at a fixed potassium ion concentration, the potential of the device only changes at very high sodium ion concentrations. This confirms the high ion selectivity of the membrane modified device. These results are comparable in line with those obtained using a conventional ion-selective electrode setup. In conclusion, the experiments presented in this PhD thesis lead to an increased understanding of the electrical behavior of nanowire field-effect transistors under different circumstances. This will support the construction and operation of nanowire field-effect sensors, facilitating the further development of advanced sensors.","nanowires","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:079468c7-122e-4bbd-8452-042621127202","http://resolver.tudelft.nl/uuid:079468c7-122e-4bbd-8452-042621127202","Bifunctional catalysts for the direct production of liquid fuels from syngas","Sartipi, S.","Kapteijn, F. (promotor)","2014","Design and development of catalyst formulations that maximize the direct production of liquid fuels by combining Fischer-Tropsch synthesis (FTS), hydrocarbon cracking, and isomerization into one single catalyst particle (bifunctional FTS catalyst) have been investigated in this thesis. To achieve this aim, a second functionality (other than FTS) has to be added to the catalyst formulation to break the limitation of a classical Anderson-Schulz-Flory (ASF) distribution of FTS products. Since upgrading the FTS hydrocarbons is mostly based on acid-catalyzed reactions, zeolites are potential candidates for this approach. In this relation, recent literature highlights the use of H-ZSM-5 for the following reasons: (1) it is one of the few zeolites industrially produced and applied for acid-catalyzed hydrocarbon conversion reactions, (2) due to its narrow channel type structure and well distributed acid sites, it represents a (relatively) stable catalytic performance, especially at low-temperature Fischer-Tropsch process conditions, and (3) besides acid-catalyzed cracking, it has a fair isomerization and oligomerization activity at low temperatures which is essential to increase the octane number in case of gasoline cut and improve the cold flow properties of diesel (Chapter 1). All the FTS experiments in this thesis were performed on a homemade lab-scale unit described in Chapter 2. The experimental setup is based on ‘six-flow fixed-bed microreactor’ concept which offers an increased experimental throughput as well as accuracy. The latter is due to equal conditions (in terms of process temperature, feed composition, equipment conditions, etc.) under which the six parallel experiments are performed. The condition is that all the reactors (flows) should behave identical, i.e., provide similar results employing the same catalyst. Design and operation of such piece of equipment confirm that indeed it is possible to obtain reproducible activity and selectivity data within an acceptable experimental error (Chapter 2). Incorporation of separate mass flow and pressure controllers as well as product separation units in each flow allows running reactions with high production of liquid fractions (as in conventional single-flow operations). This is crucial for a complete quantification of FTS product compositions and will represent an advantage over high-throughput setups with more than ten flows where such instrumental considerations lead to elevated equipment volume, cost, and operation complexity. Therefore, a six-flow fixed-bed microreactor unit combines the advantages of high-throughput and conventional FTS setups at the lab-scale (Chapter 2). In Chapter 3, combination of cobalt FTS active phase and acid functionality of H-ZSM-5 zeolite is explored in two different catalyst configurations: (i) H-ZSM-5 as catalytic coating on Co and (ii) H-ZSM-5 as catalytic support for Co. Spherical shaped Co/SiO2 is chosen as a conventional FTS catalyst for comparison and used as precursor to synthesize the H-ZSM-5-coated Co-catalyst. In the first case, various silicalite-1 and H-ZSM-5-coated reference samples were prepared by subjecting Co/SiO2 to a direct hydrothermal procedure (state of the art method to prepare zeolite coatings). Silica in the Co/SiO2 catalyst transforms into the zeolite when subjected to the hydrothermal synthesis while the original shape of the support is preserved after the transformation. By this synthesis approach, Co3O4 agglomerates are enwrapped in an H-ZSM-5 coating on a nanometer scale. The resulting bifunctional catalyst considerably lowers the production of FTS wax (C21+), as compared with Co/SiO2. The membrane effect of this coating, however, results in mass transport limitations that lower the productivity. In the absence of acid functionality, accumulation of carbonaceous species deactivates the silicalite-1-coated reference catalyst. The H-ZSM-5-coated Co-catalyst shows lower CO conversion levels than the conventional Co/SiO2 due to the membrane coating. This lower activity and modification of Co crystallites because of the hydrothermal treatment should be considered as the major drawbacks of this approach. On the other hand, systematic comparison of catalytic performances between physically mixed, coated catalyst, and non-acidic coated catalysts shows that the close proximity between the FTS and acid components is essential for improving the bifunctionality of the catalyst to increase the selectivity towards liquid products and eliminate the FTS heavy hydrocarbons (Chapter 3). Such contact can be maximized when Co is directly dispersed over the zeolite (configuration (ii)). Since the Co accessibility is better in this configuration, limitations associated with the membrane effect of a zeolite coating can be overcome while preserving the important close proximity of the two functionalities. To compensate for the relatively low intrinsic activity of FTS catalysts and to increase their productivity, high metal loadings are typically required in FTS catalyst formulations. In general, microporous zeolites are devoid of mesopore surface area, essential for an optimal dispersion of Co particles at high metal loadings. On the other hand, formation of metal clusters in the micropores is undesired, as Co particles smaller than 6 nm are not optimal for FTS in terms of activity and selectivity. Therefore, mesoporous H-ZSM-5 (‘mesoH-ZSM-5’) is studied as carrier for Co-based FTS catalysts in Chapters 4 to 7. Synthesis optimization of mesoH-ZSM-5 involved demetalation via consecutive base and acid treatments. NaOH (alkaline) and tetrapropylammonium hydroxide (TPAOH, organic) bases were employed as desilicating agents. Consecutive basic-acid treatments provides H-ZSM-5 with high mesopore surface areas and volumes. Under similar treatment conditions, NaOH results in a more severe desilication than TPAOH, creating mesostructures with pore sizes and volumes very similar to the amorphous SiO2 reference support. A more controlled desilication with TPAOH gives rise to more mesoporosity suggesting a higher degree of hierarchy with large cavities communicated with smaller mesopores. Further, TPAOH is preferred over NaOH, since Na+ is a well-known poison for Co-based FTS catalysts and trace amounts results in a lower FTS activity as compared with the organic base treated samples (Chapter 4). The consecutive acid treatment (with HNO3) removes the produced extraframework aluminum, caused by zeolite desilication, and boosts the FTS activity. Moreover, the acid treatment restores the Brønsted acidity of mesoH-ZSM-5 (Chapter 5). The large mesopore surface area of mesoH-ZSM-5 improves the metal dispersion at elevated Co loadings. The Co/mesoH-ZSM-5 catalyst is a much more active catalyst than Co/H-ZSM-5 and the conventional Co/SiO2. Moreover, time-on-stream stability of Co/mesoH-ZSM-5 and Co/SiO2 is comparable in terms of CO conversion, during 140 h of FTS reaction. As compared with Co/H-ZSM-5, the improved transport properties of mesoH-ZSM-5 increase the selectivity of the supported Co-catalyst towards liquid hydrocarbons and lowers that to methane. The high selectivity to liquid hydrocarbons over H-ZSM-5-supported catalysts is visible as a cutoff in the molar distribution above C11 in terms of the ASF distribution of conventional catalysts (e.g., Co/SiO2). Measurements after 140 h on-stream show that Co/mesoH-ZSM-5 is ca. three times more selective than Co/SiO2 towards the C5–C11 cut, producing a large fraction of unsaturated hydrocarbons, other than ?-olefins. Moreover, wax production is considerably suppressed over the zeolite-containing catalyst (513 K, 15 bar total pressure, feed composition H2/CO = 1, and GHSV = 12 m3STP kg-1cat h-1) (Chapters 5 and 6). Origins of methane selectivity over zeolite-supported Co-catalysts are also investigated. mesoH-ZSM-5 was used as carrier for a series of Co-based FTS catalysts of different loadings with ZrO2 and/or Ru added as promoters. By means of advanced catalyst characterization techniques (including quasi in situ dark field transmission electron microscopy, CO adsorption-diffuse reflectance infrared fourier transform spectroscopy, synchrotron-based X-ray absorption spectroscopy (EXAFS and XANES), etc.) in addition to a detailed catalyst performance assessment, a relationship is drawn between structural characteristics of Co (when supported on the zeolite) and its FTS activity and selectivity. Addition of either ZrO2 or Ru considerably increases the Co reducibility upon activation at 773 K and improves the FTS activity during the first 80 h of reaction after which the activity is returned to that of the unpromoted catalyst. This catalyst promotion does not significantly affect the product selectivity (Chapter 6). Methane selectivity over the zeolite-supported Co-catalysts originates from direct CO hydrogenation and hydrocarbon hydrogenolysis as the most important side reactions on coordinatively unsaturated Co sites, which are stabilized as consequence of a strong metal-zeolite interaction (Chapters 5 and 6). In addition to mesoH-ZSM-5, other zeolite topologies were investigated as FTS catalyst carriers: delaminated MWW (H-ITQ-2) and mesoporous FAU (Chapter 7). All the zeolite supports were carefully characterized for their number and strength of acid sites by temperature-programmed NH3 desorption and pyridine adsorption. To explore the role of acid-catalyzed reactions, including hydrocracking and isomerization, in the altered product distribution of zeolite-containing catalysts (with respect to conventional ones), acid-catalyzed model reactions of C6 (n-hexane or 1-hexene) were performed. Zeolite acid density and strength are essential parameters to tune the FTS product selectivity towards liquid hydrocarbons. Only strong acid sites, active for hydrocracking at the operating temperature window of Co-based FTS catalysts, give rise to deviations from a conventional ASF product distribution (Chapter 7). On purpose (partial) deactivation of Brønsted acidity in mesoH-ZSM-5 by carbonaceous species (during catalyst synthesis) decreases the iso- to n-paraffin ratio and selectivity to gasoline fraction which further confirms the above-mentioned role of acid-catalyzed reactions in tuning the product selectivity (Chapter 5). When acid site domains are in a close vicinity of FTS sites at a nanometer scale, ?-olefins, which are primary FTS products, may crack or isomerize before they are hydrogenated. Indeed 1-hexene conversion is considerably higher than that of n-hexane over mesoH-ZSM-5 (Chapter 6). The classical mechanism of such acid-catalyzed reactions, through rearrangement of a secondary carbocation into a protonated dialkylcyclopropane or through a bimolecular mechanism, increases the hydrocarbons’ degree of branching. Since FTS may mainly produce linear ?-olefins, considerable amounts of other unsaturated hydrocarbons in the liquid products are formed over the acid sites. Altogether, our results demonstrate that the use of mesoporous zeolites as FTS supports holds many promises for the direct synthesis of liquid fuels from syngas. The challenges that still need to be addressed include a better control over the product selectivity of bifunctional catalysts. In this respect, it is essential to tackle the aforementioned origin(s) of methane production on the zeolite-supported Co-catalysts. In addition, more insight is required to further separate and define the contributions of ‘the metal’ and ‘the zeolite/acid’ functions in the overall product spectrum of these catalysts. While neglected or poorly described in the open literature, such insight is necessary for further catalyst optimization in relation to the product spectrum and practical applications. Detailed acid-catalyzed hydrocarbon conversion studies, under conditions relevant to that of FTS, together with reference experiments and detailed kinetic investigations are considered essential for a better understanding of bifunctional FTS systems. Finally, the long term stability of these catalysts is largely unexplored. As an ongoing research, a new PhD project has recently started on this topic at the Catalysis Engineering section of Delft University of technology.","catalyst; fuel; FischerTropsch synthesis; zeolite; cobalt; mesoporous materials; syngas","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:7b2c27d3-8a5b-4471-a575-d55181d28c51","http://resolver.tudelft.nl/uuid:7b2c27d3-8a5b-4471-a575-d55181d28c51","High charge carrier mobility and efficient charge separation in highly soluble perylenetetracarboxyl-diimides","Günba?, D.D.; Xue, C.; Patwardhan, S.; Fravventura, M.C.; Zhang, H.; Jager, W.F.; Sudhölter, E.J.R.; Laurens, D.A.; Siebbeles, L.D.A.; Savenije, T.J.; Jin, S.; Grozema, F.C.","","2014","In this communication we report on the synthesis and charge mobility of highly soluble perylenebisimid derivatives.We show that introduction of alkylester side chains results in compounds combining a high solubility with charge mobilities up to 0.22 cm2 V_1 s_1. These materials are therefore interesting as an electron acceptor for solution-processed organic photovoltaics.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:748de818-c728-438e-96d8-ac02351f3812","http://resolver.tudelft.nl/uuid:748de818-c728-438e-96d8-ac02351f3812","Methods for assessing basic particle properties and cytotoxicity of engineered nanoparticles","Kalantzi, O.I.; Biskos, G.","","2014","The increasing penetration of materials and products containing engineered nanoparticles (ENPs) to the market is posing many concerns regarding their environmental impacts. To assess these impacts, there is an urgent need of techniques for determining the health-related properties of ENPs and standards for assessing their toxicity. Although a wide number of systems for characterizing nanoparticles in different media (i.e., gases and liquids) is already commercially available, the development of protocols for determining the cytotoxicity of ENPs is still at an infant stage, drawing upon existing knowledge from general toxicology. In this regard, differences in the preparation of ENP-containing solutions for cytotoxicity testing, as well as in the steps involved in the tests can result in significant deviations and inconsistencies between studies. In an attempt to highlight the urgent need for assessing the environmental impacts of nanotechnology, this article provides a brief overview of the existing methods for determining health-related properties of ENPs and their cytotoxicity.","nanotechnology; engineered nanoparticles; cytotoxicity; human exposure","en","journal article","MDPI","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:f9121754-98bb-4616-a60e-727c51059aa2","http://resolver.tudelft.nl/uuid:f9121754-98bb-4616-a60e-727c51059aa2","Nanoparticle emissions from traditional pottery manufacturing","Voliotis, A.; Bezantakos, S.; Giamarelou, M.; Valenti, M.; Kumar, P.; Biskos, G.","","2014","Traditional pottery manufacturing involves firing of the ceramics in kilns, a process that leads to high concentrations of airborne particles that are harmful to human health. In order to assess the associated exposure levels and the involved risks, here, for the first time, we investigate the size, the concentration and the elemental composition of the particles emitted during the different stages of the ceramic firing process. Number size distributions of the emitted particles, having diameters in the range from 10 nm to 20 ?m, were measured in a traditional small-sized pottery studio using a Scanning Mobility Particle Sizer (SMPS) and an Optical Particle Counter (OPC). The measurements showed dominance of the nanoparticle mode (i.e., particles smaller than 100 nm) when the kiln reached temperatures above 600 °C. The mean size of the particles ranged from 30 to 70 nm and their peak number concentration was 6.5 × 105 cm?3 during the first stage of the firing process where the ceramics were unpainted and unglazed. During the second stage of the firing process, where the ceramics were painted and glazed, the mean particle size ranged from 15 to 40 nm and their number concentration peaked at 1.2 × 106 cm?3. Elemental analysis of individual particles collected during the two firing stages and studied by Energy-Dispersive X-ray (EDX) spectroscopy showed that the emitted nanoparticles contain significant amounts of lead. These findings provide new information for understanding the health impacts of traditional pottery manufacturing, and underline the need for adopting adequate measures to control nanoparticle emissions at the source.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:6a1ec1b8-3b55-4946-8c59-da5951f0a16d","http://resolver.tudelft.nl/uuid:6a1ec1b8-3b55-4946-8c59-da5951f0a16d","Large Eddy Simulations of Electromagnetic Control of a Quasi-2D Jet","Hollander, J.","Kleijn, C.R. (mentor); Kenjeres, S. (mentor); Tummers, M.J. (mentor); Van der Plas, D. (mentor)","2014","This research aims to accurately predict the flow of electromagnetically conducting liquids liquid steel in a thin cavity. A thin cavity, with a thickness « width, is relevant as a model for a continuous steel caster mould. A turbulent jet flow enters the cavity, leading to a quasi-two-dimensional flow. Using large eddy simulations with the dynamic Smagorinsky model with cell face-averaging the filtered velocity field is solved. The model is validated using experimental data before the flow of liquid steel is simulated.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:d2b30d39-3883-40d5-b283-033053d2f62f","http://resolver.tudelft.nl/uuid:d2b30d39-3883-40d5-b283-033053d2f62f","Self-Assembly of Facial Oligothiophene Amphiphiles","Janeliunas, D.","Van Esch, J.H. (promotor)","2014","Organized ?-conjugated oligothiophene structures in water are highly promising building blocks to create a vast variety of smart and functional electronic systems. Such materials already found application in biological and chemical sensors, organic light-emitting diodes and photovoltaic devices. The high level of molecular order in such devices is crucial for their efficiency, but cannot be easily achieved by common lithography. Fortunately, nature developed a powerful tool to spontaneously organize isolated molecular components into ordered structures. Ubiquitous nano and micro architectures can be obtained by self-assembly. Hence, extending the design and knowledge of self-assembly to oligothiophenes in water opens doors to achieve new functional materials and devices. In this work the development of new and easily accessible self-assembling facial oligothiophene amphiphile systems is described. To arrive at a better understanding of the processes involved, we pioneered the use of the Martini coarse-grained molecular dynamic simulation model to investigate the self-assembly behavior of these systems.","self-assembly; thiophene; amphiphile; coarse-grained; molecular dynamics; Martini force-field; dynamic polyimines; conjugated","en","doctoral thesis","","","","","","","","2014-02-18","Applied Sciences","Chemical Engineering","","","",""
"uuid:bf8c966e-bf65-4d7f-a339-cadc493a0422","http://resolver.tudelft.nl/uuid:bf8c966e-bf65-4d7f-a339-cadc493a0422","Charge generation and recombination in nanostructured photovolatic materials","Dharmapura Hanumantharaya, M.K.","Siebbeles, L.D.A. (promotor); Savenije, T.J. (promotor)","2014","","","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:2890cf31-9bab-4072-a743-1aab672db56f","http://resolver.tudelft.nl/uuid:2890cf31-9bab-4072-a743-1aab672db56f","Energetics of charges in organic semiconductors and at organic donor–acceptor interfaces","Gorczak, N.; Swart, M.; Grozema, F.C.","","2014","We calculated the energy landscape of charged molecules that is determined by electrostatic and induction interaction using the fully polarizable force field DRF90 in the bulk and at interfaces of the electron accepting material C60, and two exemplary electron donating materials pentacene and phthalocyanine. In particular, we compared the energy of a non-interacting electron–hole pair (NI-EH) without mutual electrostatic interactions to the energy of a Coulomb-bound interfacial charge-transfer state (CT). Our calculations show that due to electrostatic interactions with the environment a NI-EH state is destabilized on the phthalocyanine–C60 interface, whereas it is stabilized on the interface between pentacene and C60, even without the interaction with the counter charge. Upon adding the mutual electrostatic interaction between the opposite charges the electrostatic term overall stabilizes the CT state in both systems. This stabilization is not compensated by the reduced induction term. The resulting binding energy of the CT state amounts to several tenths of an eV, which contradicts the evidence of working solar cells based on these systems. The overestimated CT state binding energy for charges localized on a single molecule suggests that charge delocalization over multiple molecules might play an important role. Nevertheless, our results indicate clear opportunities to engineer electrostatic interactions at the interface that might lead to destabilization of NI-EH and hence to a lower binding energy of CT.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:864a6030-ad02-4c50-aeab-189bacb48259","http://resolver.tudelft.nl/uuid:864a6030-ad02-4c50-aeab-189bacb48259","Influence of Conductivity and Dielectric Constant of Water–Dioxane Mixtures on the Electrical Response of SiNW-Based FETs","Mescher, M.; Brinkman, A.G.M.; Bosma, D.; Klootwijk, J.H.; Sudhölter, E.J.R.; De Smet, L.C.P.M.","","2014","In this study, we report on the electrical response of top-down, p-type silicon nanowire field-effect transistors exposed to water and mixtures of water and dioxane. First, the capacitive coupling of the back gate and the liquid gate via an Ag/AgCl electrode were compared in water. It was found that for liquid gating smaller potentials are needed to obtain similar responses of the nanowire compared to back gating. In the case of back gating, the applied potential couples through the buried oxide layer, indicating that the associated capacitance dominates all other capacitances involved during this mode of operation. Next, the devices were exposed to mixtures of water and dioxane to study the effect of these mixtures on the device characteristics, including the threshold voltage (VT). The VT dependency on the mixture composition was found to be related to the decreased dissociation of the surface silanol groups and the conductivity of the mixture used. This latter was confirmed by experiments with constant conductivity and varying water–dioxane mixtures.","silicon nanowire; field-effect transistor; liquid gate; back gate; conductivity","en","journal article","MDPI","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:dfc81084-c9aa-4ed4-a68b-42d15bf40a3b","http://resolver.tudelft.nl/uuid:dfc81084-c9aa-4ed4-a68b-42d15bf40a3b","Numerical Study of Wetting of a 2D Cylinder by an Impacting Jet","Zwinkels, S.","Kleijn, C.R. (mentor); Steijn, V. (mentor)","2014","In many processes, for example trickle-bed reactors, it is important to completely wet small spheres, or particles. (Baussaron, et al., 2007) Ideally, a small stream of liquid on such a particle would create a film around the particle, completely wetting it. It is therefore interesting to investigate which factors influence the formation of this film and to what effect. To this end, a simpler 2D case is investigated in this project: a small cylinder.","","en","bachelor thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Transport Phenomena","",""
"uuid:3d972e83-b31b-4755-9a04-cacc588ac53f","http://resolver.tudelft.nl/uuid:3d972e83-b31b-4755-9a04-cacc588ac53f","Dynamic chemical process modelling and validation: Theory and application to industrial and literature case study","Schmal, J.P.","Heijnen, J.J. (promotor); Verheijen, P.J.T. (promotor)","2014","Dynamic chemical process modelling is still largely considered an art. In this thesis the theory of large-scale chemical process modelling and validation is discussed and initial steps to extend the theory are explored. In particular we pay attention to the effect of the level of detail on the model simulation and optimisation performance. We investigate the liquid-filled tubular reactor, HIDiC and optimize the start-up from the cold state of part of a (open literature) plant. Furthermore, an industrial plant was modelled and validated for which model building times are reported.","large-scale dynamic modelling; dynamic validation; chemical process modelling; level of detail; HIDiC; start-up optimisation","en","doctoral thesis","","","","","","","","2014-01-20","Applied Sciences","Chemical Engineering","","","",""
"uuid:9b9e5b2d-c418-4f87-8f8c-f9fa8552d754","http://resolver.tudelft.nl/uuid:9b9e5b2d-c418-4f87-8f8c-f9fa8552d754","Poly(3-alkylthiophene)s show unexpected second-order nonlinear optical response","Deckers, S.; Vandendriessche, S.; Cornelis, D.; Monnaie, F.; Koeckelberghs, G.; Asselberghs, I.; Verbiest, T.; Van der Veen, M.A.","","2014","Regioregular poly(3-hexylthiophene)s with chain lengths varying from 5 to 100 monomers are synthesized. Poly(3-hexylthiophene)s show in solution an unexpectedly significant second-order nonlinear optical response. The increase in transition dipole moment upon oligomerisation causes the significant second-order nonlinear optical response.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:00cbb443-659e-4384-ab57-bc0d115ec52b","http://resolver.tudelft.nl/uuid:00cbb443-659e-4384-ab57-bc0d115ec52b","Catalysis engineering of bifunctional solids for the one-step synthesis of liquid fuels from syngas: A review","Sartipi, S.; Makkee, M.; Kapteijn, F.; Gascon, J.","","2014","The combination of acidic zeolites and Fischer–Tropsch synthesis (FTS) catalysts for one-step production of liquid fuels from syngas is critically reviewed. Bifunctional systems are classified by the proximity between FTS and acid functionalities on three levels: reactor, catalyst particle, and active phase. A thorough analysis of the published literature on this topic reveals that efficiency in the production of liquid fuels correlates well with the proximity of FTS and acid sites. Moreover, possible side reactions over the FTS metal, including direct CO hydrogenation and hydrocarbon hydrogenolysis, are addressed. The contribution of these side reactions should carefully be considered and separated from that of the zeolite function when evaluating the performance and product spectrum of zeolite-containing catalysts.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:bf295221-4e6e-4663-b046-79da13325243","http://resolver.tudelft.nl/uuid:bf295221-4e6e-4663-b046-79da13325243","Bulk Dynamics of Droplets in Liquid-Liquid Axial Cyclones","Van Campen, L.J.A.M.","Mudde, R.F. (promotor); Hoeijmakers, H.W.M. (promotor)","2014","Separation of oil and water is an essential step in the treatment of the production streams from fossil oil wells. Settling by gravity is a robust though voluminous process and therewith expensive method at remote locations, leading to a need for smaller separation equipment. In this thesis, we describe the research performed on the development of an inline axial cyclone for oil/water separation. This work is part of ISPT project OG-00-004 and has an experimental nature: a flowrig has been constructed to test different cyclones at flow rates up to 60 m3/h in a 10 cm diameter tube in which brine and low-viscosity lubricant oil can be mixed in almost any proportion. Results are compared with numerical datasets resulting from the same ISPT project. Three different swirl elements have been developed for this project: a strong swirl element and a weak swirl element with 10 cm diameter, and one element with a 26 cm diameter in combination with a tapered tube section. For all three swirl elements, the velocity profile of water has been measured with Laser Doppler Anemometry (LDA). The strong swirl element has a swirl number of 3.7, the weak of 2.3 and the large diameter element of 3.9. The axial velocity profile normalized with the bulk velocity shows vortex breakdown (upstream flow in the center), where the severeness of the breakdown normalized with the upstream bulk velocity shows proportionality with the swirl number. For the azimuthal velocity, the velocity profile was proportional to the bulk velocity. The non-dimensional azimuthal velocity was similar for all three swirl elements in the region |r/D| < 0.2. Outside that region the relative velocity is strongly influenced by the swirl element. Time series obtained with single phase LDA studies were used to estimate the effect of turbulent dispersion on droplet trajectories. A simplified equation of motion based on centrifugal buoyancy, drag and turbulent dispersion was solved for many fictitious droplet paths. The measured, chaotic axial velocity time series was used to mimic the radial component of the velocity fluctuations. With this model, we can predict the smallest droplet size that can be separated with a certain cyclone and the largest droplet size before it is broken by the flow. Model results show good agreement with overall bulk data obtained in the experimental flow rig. With an intrusive endoscope technique, we measured the droplet size distribution at various positions in the axial cyclone. From this, Hinze’s theory for the droplet size in turbulent pipe flow is confirmed. Furthermore, the inverse correlation between azimuthal velocity and median droplet size is shown and quantified: a lower velocity allows larger droplets to survive. Different designs were tested to understand which parameters have a large influence on the industrially relevant parameter of separation performance. This question is answered by variation of the swirl element, swirl tube length, pickup tube diameter, flow rate and droplet size. Changes that affect the droplet size have a severe effect on separation, these are the swirl element and flow rate. Changes that increase the droplet size lead to better phase separation. The other geometrical changes can be used to optimize performance, but are not identified as parameters leading to breakthrough improvements. Two non-dimensional numbers can be used to explain the behavior of the cyclone: the Weber number (We) based on the droplet size upstream of the swirl element and the maximum velocity obtained in the gaps of the swirl element, and the Reynolds number (Re_?) for the droplets downstream of the swirl element based on their median diameter and the azimuthal liquid velocity. Separation is better for a smaller We number, because droplets are less vulnerable for breakup under that condition. A large Re? number is beneficial since the droplets then experience a large centrifugal acceleration which is larger than turbulent dispersion. Both trends are confirmed with experimental data obtained in this project. We propose that there is a function for the maximum possible separation efficiency based on both non-dimensional numbers. The inverse coupling between We and Re_? via the azimuthal velocity makes optimization of separation efficiency difficult. Application of a large diameter swirl element (low velocity and therefore limited droplet breakup) in combination with a gradual tapering of the tube (increasing the azimuthal velocity) is a possibility to obtain both a large We and Re? number. Another option is to place multiple axial cyclones in series, with a stepwise increase of the swirl strength in each subsequent cyclone. In such a configuration, each step is capable of separating smaller droplets than the previous step, without immediate breakup of large droplets. This method should increase the overall quality of the phase separation.","swirling flow; cyclones; oil; turbulence; experimental methods; separation; multiphase flows","en","doctoral thesis","","","","","","","","2014-01-08","Applied Sciences","Chemical Engineering","","","",""
"uuid:ef5daad0-3b75-48b9-b87e-cacd9313ecc1","http://resolver.tudelft.nl/uuid:ef5daad0-3b75-48b9-b87e-cacd9313ecc1","Interfacial interactions and mass transfer at the interfacial region of bituminous hydrocarbon mixtures","Van Lent, D.Q.","Molenaar, A.A.A. (promotor); Picken, S.J. (promotor)","2014","The adhesion between bitumen and aggregate is a complex process with numerous of variables. To improve the understanding of the bond between bitumen and aggregates in road applications, this research focuses on preferential adsorption, which is one aspect of bitumen-aggregate adhesion. The main objective is to find out whether there is preferential adsorption or segregation at the aggregate and the air interface. The investigation of the preferential adsorption was done on the bitumen as it is used in road applications. So in this research the bitumens were not diluted and the bitumens were not characterized by selected molecules in the bitumen. To determine whether preferential adsorption can occur, the surface energy of common road construction aggregates was measured by means of sorption experiments. The measurements of the aggregates showed that the dominant polar component is significantly large enough. So if bitumen would consist of non-polar and polar components, then the potential interaction energy of the polar components will be larger than the non-polar components with the measured aggregates. The difference in interaction energy could lead to preferential adsorption of specific bitumen particles on the aggregates. The next step was to determine the surface energy of bitumens and bitumen components. This was done by means of contact angle measurements. It was found that the components have a difference in surface energy relatively to each other. This means that preferential adsorption can occur and that, if preferential adsorption really takes place, the interaction energy at the bitumen surface could be different at different interfaces. The adsorption of bitumen at an aggregate was investigated by means of refractometric measurements. Comparison of the calculated index of refraction of the not adsorbed reference bitumen with the measured index of refraction of adsorbed reference bitumen suggested that preferential adsorption took place on the crystal, but that it was certainly not clear. The index of refraction of bitumen at the crystal interface, at both 20°C and 90°C, has a high correlation with the penetration grade. Ellipsometric measurements were used to investigate the bitumen-air interface. In general the bitumens showed a larger difference in results between the ellipsometric measurements and the refractometric measurements compared to materials that are not expected to show interfacial mass transfer. Most bitumens have on average more molecules that give smaller indices of refraction at the bitumen-air interface in comparison with the bitumen-aggregate interface. It was found that the results of the ellipsometric measurements for bitumens were depending on the cooling rate of the bitumen samples during preparation and on time. The preparation temperature also showed to have effect on the results for some bitumens. The difference found between the bitumen at the crystal interface and the bitumen at the air interface was investigated by means of Fourier transform infrared spectroscopy. A chemical characterization for the difference between the bitumen at the crystal interface and the bitumen at the air interface could not be made. The measurement inaccuracies made the chemical characterization of the reference bitumen at the air interface unreliable. Also no preferential adsorption of bitumen onto the crystal surface was observed with the infrared measurements.","bitumen; interface; interactions; preferential adsorption; mass transfer","en","doctoral thesis","","","","","","","","2014-01-22","Civil Engineering and Geosciences / Applied Sciences","Structural Engineering / Chemical Engineering","","","",""
"uuid:86c4c6b9-4bd8-4521-9176-716c8af9ab11","http://resolver.tudelft.nl/uuid:86c4c6b9-4bd8-4521-9176-716c8af9ab11","Electronic and vibronic properties of a discotic liquid-crystal and its charge transfer complex","Haverkate, L.A.; Zbiri, M.; Johnson, M.R.; Carter, E.; Kotlewski, A.; Picken, S.J.; Mulder, F.M.; Kearley, G.J.","","2014","Discotic liquid crystalline (DLC) charge transfer (CT) complexes combine visible light absorption and rapid charge transfer characteristics, being favorable properties for photovoltaic (PV) applications. We present a detailed study of the electronic and vibrational properties of the prototypic 1:1 mixture of discotic 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT6) and 2,4,7-trinitro-9-fluorenone (TNF). It is shown that intermolecular charge transfer occurs in the ground state of the complex: a charge delocalization of about 10?2 electron from the HAT6 core to TNF is deduced from both Raman and our previous NMR measurements [L. A. Haverkate, M. Zbiri, M. R. Johnson, B. Deme, H. J. M. de Groot, F. Lefeber, A. Kotlewski, S. J. Picken, F. M. Mulder, and G. J. Kearley, J. Phys. Chem. B116, 13098 (2012)], implying the presence of permanent dipoles at the donor-acceptor interface. A combined analysis of density functional theory calculations, resonant Raman and UV-VIS absorption measurements indicate that fast relaxation occurs in the UV region due to intramolecular vibronic coupling of HAT6 quinoidal modes with lower lying electronic states. Relatively slower relaxation in the visible region the excited CT-band of the complex is also indicated, which likely involves motions of the TNF nitro groups. The fast quinoidal relaxation process in the hot UV band of HAT6 relates to pseudo-Jahn-Teller interactions in a single benzene unit, suggesting that the underlying vibronic coupling mechanism can be generic for polyaromatic hydrocarbons. Both the presence of ground state CT dipoles and relatively slow relaxation processes in the excited CT band can be relevant concerning the design of DLC based organic PV systems.","","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:99585204-0362-490c-a2a4-3b00dc566399","http://resolver.tudelft.nl/uuid:99585204-0362-490c-a2a4-3b00dc566399","Silicon nanowire-based devices for gas-phase sensing","Cao, A.; Sudhölter, E.J.R.; De Smet, L.C.P.M.","","2013","Since their introduction in 2001, SiNW-based sensor devices have attracted considerable interest as a general platform for ultra-sensitive, electrical detection of biological and chemical species. Most studies focus on detecting, sensing and monitoring analytes in aqueous solution, but the number of studies on sensing gases and vapors using SiNW-based devices is increasing. This review gives an overview of selected research papers related to the application of electrical SiNW-based devices in the gas phase that have been reported over the past 10 years. Special attention is given to surface modification strategies and the sensing principles involved. In addition, future steps and technological challenges in this field are addressed.","silicon nanowire; field effect transistor; resistor; gas; vapor; volatile organic compound","en","journal article","MDPI","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:ed13fd2a-a0df-4877-8769-89bb09d4ac6e","http://resolver.tudelft.nl/uuid:ed13fd2a-a0df-4877-8769-89bb09d4ac6e","Six-flow operations for catalyst development in Fischer-Tropsch synthesis: Bridging the gap between high-throughput experimentation and extensive product evaluation","Sartipi, S.; Jansma, H.; Bosma, D.; Boshuizen, B.; Makkee, M.; Gascon, J.; Kapteijn, F.","","2013","Design and operation of a “six-flow fixed-bed microreactor” setup for Fischer-Tropsch synthesis (FTS) is described. The unit consists of feed and mixing, flow division, reaction, separation, and analysis sections. The reactor system is made of five heating blocks with individual temperature controllers, assuring an identical isothermal zone of at least 10 cm along six fixed-bed microreactor inserts (4?mm inner diameter). Such a lab-scale setup allows running six experiments in parallel, under equal feed composition, reaction temperature, and conditions of separation and analysis equipment. It permits separate collection of wax and liquid samples (from each flow line), allowing operation with high productivities of C5+ hydrocarbons. The latter is crucial for a complete understanding of FTS product compositions and will represent an advantage over high-throughput setups with more than ten flows where such instrumental considerations lead to elevated equipment volume, cost, and operation complexity. The identical performance (of the six flows) under similar reaction conditions was assured by testing a same catalyst batch, loaded in all microreactors.","","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:4f62ae3a-7176-4028-93f4-d4d845f30dc3","http://resolver.tudelft.nl/uuid:4f62ae3a-7176-4028-93f4-d4d845f30dc3","Chemical composition and hygroscopic properties of aerosol particles over the Aegean Sea","Bezantakos, S.; Barmpounis, K.; Giamarelou, M.; Bossioli, E.; Tombrou, M.; Mihalopoulos, N.; Eleftheriadis, K.; Kalogiros, J.; Allan, J.D.; Bacak, A.; Percival, C.J.; Coe, H.; Biskos, G.","","2013","The chemical composition and water uptake characteristics of sub-micrometre atmospheric particles over the region of the Aegean Sea were measured between 25 August and 11 September 2011 within the framework of the Aegean-Game campaign. High temporal-resolution measurements of the chemical composition of the particles were conducted using an airborne compact time-of-flight aerosol mass spectrometer (cToF-AMS). These measurements were performed during two flights from the island of Crete to the island of Lemnos and back. A hygroscopic tandem differential mobility analyser (HTDMA) located on the island of Lemnos was used to measure the ability of the particles to take up water. The HTDMA measurements showed that the particles in the dominant mode were internally mixed, having hygroscopic growth factors that ranged from 1.00 to 1.59 when exposed to 85% relative humidity. When the aircraft flew near the ground station on Lemnos, the cToF-AMS measurements showed that the organic volume fraction of the particles ranged from 43 to 56%. These measurements corroborate the range of hygroscopic growth factors measured by the HTDMA during that time. Good closure between HTDMA and cToF-AMS measurements was achieved when assuming that the organic species were less hygroscopic and had an average density that corresponds to aged organic species. Using the results from the closure study, the cToF-AMS measurements were employed to determine vertical profiles of a representative aerosol hygroscopic parameter ?mix. Calculated ?mix values ranged from 0.19 to 0.84 during the first flight and from 0.22 to 0.80 during the second flight. Air masses of different origin as determined by back trajectory calculations can explain the spatial variation in chemical composition and ?mix values of the particles observed in the region.","","en","journal article","European Geosciences Union","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:016854ac-6322-44a4-927a-0329e5b690d2","http://resolver.tudelft.nl/uuid:016854ac-6322-44a4-927a-0329e5b690d2","Optimal ionic strength for nonionically initiated polymerization","Dobrowolska, M.E.; Koper, G.J.M.","","2013","Surfactant-free emulsion polymerization involving a nonionic, and hence uncharged initiator presents a new approach towards environmentally friendly procedures to synthesize latex particles. Under optimal solvent conditions, notably pH and ionic strength, the latex particles are stabilized by the natural development of ionic charge at the surface of the particles. We emphasize that the present process does not at all involve the addition of stabilizers such as surfactants or the creation of surface-active species from ionic initiators. The width of the size distribution is found to vary strongly with experimental conditions, notably the ionic strength and to a much lesser extent pH. The phenomenon is explained by a critical ionic strength dependence of the aggregation of the just nucleated primary particles into larger secondary particles, the so-called “coagulative nucleation” step.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:88cc689a-7cbb-4a51-9dd8-52e9e71eeb9b","http://resolver.tudelft.nl/uuid:88cc689a-7cbb-4a51-9dd8-52e9e71eeb9b","Interacting Living Polymers Confined between Two Surfaces","Besseling, N.A.M.; Korobko, A.V.","","2013","We present predictions on the equilibrium behavior of solutions of living polymers confined in a gap between surfaces, including the ensuing potential of mean force between those surfaces (the disjoining potential). We highlight the occurrence of a transition upon narrowing the gap, which arises from a cooperative simultaneous increase of the local density and degree of polymerization. At this transition, many properties of the confined solution, including the disjoining potential, change by orders of magnitude over a minute change of the surface separation. These results were obtained owing to two extensions to a previously introduced self-consistent field–propagator formalism. (i) We derive this formalism from a free-energy functional of the distribution of chain lengths and configurations. This enables evaluation of thermodynamic properties, including the disjoining potential. (ii) We solved for a system confined between two surfaces.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:cd4ae843-7ed1-4865-a234-3d35e1b006ba","http://resolver.tudelft.nl/uuid:cd4ae843-7ed1-4865-a234-3d35e1b006ba","Covalently, Non-Covalently and Non Functionalized Networked Graphitic Structures as robust catalyst support in PEM electrodes (abstract)","Negro, E.; De Vries, M.; Latsuzbaia, R.; Koper, G.J.M.","","2013","","","en","conference paper","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:8e9ed02f-2fee-4613-8d85-4ed12b54fa52","http://resolver.tudelft.nl/uuid:8e9ed02f-2fee-4613-8d85-4ed12b54fa52","Design of Photocatalytic Reactors","Motegh, M.","Kreutzer, M.T. (promotor); Van Ommen, J.R. (promotor)","2013","Photocatalysis is a photochemical reaction induced by photon–absorption of a solid material, a ""photocatalyst"", that remains unchanged during the reaction. Photocatalysis has a wide variety of applications, e.g., degrading contaminants in aqueous solutions and in air, oxidizing liquid hydrocarbons, and reducing carbon dioxide into valuable hydrocarbons. It has been successfully applied at lab scale and many advancements are achieved with respect to photocatalyst development and the effect of different parameters such as pH, temperature, catalyst loading, and light intensity on the photoreaction kinetics of various compounds. Yet, there are several issues to be resolved for the technology to be widely implemented at large scale. The current limited industrial application of the technology is attributed to, among other factors, the difficulty of quantifying and predicting the photonic efficiency at different steps of the chain of photocatalytic events. Moreover, the strategies for the scale–up of photocatalytic reactors are scarce. There is a lack of guidelines on how to carry out experimental studies, and how to design and operate photocatalytic reactors. This thesis focuses on addressing these issues in multiphase slurry photocatalytic reactors. In this work, we first focused on providing experimentalists with simple guidelines to properly measure kinetic data in well-mixed slurry photoreactors. Whereas in such reactors concentrations are independent of location, the light distribution may still be inhomogeneous. As the light travels through the photoreactor, it is scattered and absorbed by the photocatalyst particles and its intensity drops; since photons initiate the photoreaction, this results in a non–uniform reaction rate in the photoreactor. We calculated the local volumetric rate of photon absorption based on a so-called two-flux model. This model assumes that photocatalyst particles absorb and scatter photons, but scattering happens only in a direction opposite to the incident light. Based on the analysis of the rate of photon absorption, we developed analytical expressions that calculate the minimum optical thickness that is required to ensure no photon transmits through the reactor unused, both for low and for high photon fluxes. We concluded that for a reliable determination of the photoreaction rate, an optically differential photoreactor is needed. In such a photoreactor, the optical thickness is sufficiently small for the gradient in the rate of photon absorption to be less than 5%. In a photocatalytic reaction, the absorbed photons excite the electrons in photocatalyst particles, generating electron–hole pairs. The electron–hole pairs then initiate a set of redox reactions, or recombine to lose the absorbed energy to heat. Many photocatalytic processes require a supply of oxygen for the progression of the photocatalytic chain of events. The role of oxygen is to remove the excited electrons in order to suppress the recombination of electron–hole pairs. In practice, the aeration is done either externally in a recirculating–flow photoreactor, or internally via sparging air or oxygen into the slurry photoreactor. Considering that bubbles scatter photons significantly, the main research question was whether there is any advantage to separating the aeration and photoreaction units in a photoreactor setup. Thus, we aimed to determine at what gas fractions and bubble diameters, bubbles start having a significant effect on the photonic efficiency in a bubbly slurry photocatalytic reactor. Bubbles scatter the light mainly in the forward direction, and the two–flux model fails to consider that. To capture the scattering characteristics of bubbles, we developed a new optical model. We devised a bidirectional scattering model that accounts for scattering in both forward and backward directions. Based on the photon balances, we showed that for typical values of gas fraction and bubble diameter in bubbly slurry photoreactors, the effect of bubbles on the photon–absorption and photoreaction rate is negligible. Therefore, there is no advantage to separating the aeration and photoreaction units in a photoreactor setup. Moreover, the same guidelines for design and operation of two–phase slurries can be applied to bubbly slurry photocatalytic reactors. Following the analysis of photonic efficiencies in well–mixed photoreactors, we looked into the extent of diffusion limitations in unstirred photoreactors. As mentioned previously, the gradient in the rate of photon absorption results in a gradient in the photoreaction rate throughout the photoreactor. This consequently leads to a non-uniform concentration field in the photoreactor. Of course, vigorous stirring can eliminate such concentration gradients, but we find many examples of unstirred photocatalytic reactors for which neither forced nor natural convection is reported. Obviously, when the mass transport is not fast enough to keep up with photocatalysis, the overall reaction rate changes, and the measured kinetic data are obscured by diffusion limitations. Similar criteria were also developed for optically thin reactors. By applying a two–flux model, we showed that the effect of diffusion limitation in rectangular optically thick photoreactors is negligible when the Damkohler number based on reactor depth in the direction of incident light is smaller than the 10% of the product of optical thickness and the exponent that describes how the reaction rate varies with intensity. Finally, this thesis presents a case study for the scale–up of photocatalytic reactors for water remediation purposes. A successful implementation of photocatalysis at large–scale calls for an interdisciplinary view over the interplay between all the important parameters that affect the capture and utilisation of photons in a photoreactor Moreover, the engineering aspects of photocatalysis in terms of contacting patterns and mass transfer rates must be optimized to develop useful design procedures for the scale–up of photocatalytic reactors. In this case study, we chose the reactor configuration (i.e., rectangular slurry bubble column) as such to ensure a good mass transfer rate, a high photocatalytic surface area per reactor volume, and a high reactor surface–area–to–volume ratio for a good capture of sunlight. By implementing a bidirectional scattering model, we calculated the local rate of photon absorption and the photonic efficiencies for different steps of the photoreaction. The outcome of photonic efficiency studies revealed that the electron–hole trapping at the surface of the photocatalyst, and the surface reaction efficiency are the bottlenecks of the overall photonic efficiency. Future research efforts must be focused on improving these efficiencies. Despite the low photonic efficiencies, we showed that implementing the principles of process intensification, the large scale degradation of cyanide to below its allowable emission threshold set by European legislation is achievable. Throughout this thesis, we focused on implementing and developing simple models to capture the most relevant phenomena in (bubbly) slurry photocatalytic reactors. We developed analytical expressions and a set of easy-to-calculate criteria for the design and operation of photoreactors. Based on such criteria, this study helps answering some of the main questions related to analysis, design and scale–up of photocatalytic reactors. Finally, based on the analysis of photonic efficiencies, the limiting steps in the overall photonic efficiency were identified. Future research shall indeed focus on improving the efficiency of these limiting steps to make photocatalysis feasible for large–scale applications.","Photocatalytic Reactors; Design","en","doctoral thesis","Uitgeverij BOXPress","","","","","","","2014-07-15","Applied Sciences","Chemical Engineering","","","",""
"uuid:1275f74a-95d4-431b-8ce1-449bfb55cc2b","http://resolver.tudelft.nl/uuid:1275f74a-95d4-431b-8ce1-449bfb55cc2b","Networked Graphitic Structures Grown from Dense Microemulsions as High Performance Electrode Material (abstract)","Negro, E.; Dieci, M.; Sordi, D.; Koper, G.J.M.","","2013","","","en","conference paper","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:9acd4ea3-6774-4dba-b8b9-75d271f73cf0","http://resolver.tudelft.nl/uuid:9acd4ea3-6774-4dba-b8b9-75d271f73cf0","Responsive polyelectrolyte hydrogels and soft matter micromanipulation","Glazer, P.J.","Lemay, S.G. (promotor); Mendes, E. (promotor)","2013","This dissertation describes experimental studies on the mechanisms underlying the dynamic response of polyelectrolyte hydrogels when submitted to an external electric potential. In addition, we explore the possibilities of miniaturization and manipulation of responsive gels and other soft matter systems by using microfabrication techniques. Furthermore, a novel biocompatible hydrogel electro-active in biological fluids is developed. The possibilities of using this electro-responsive hydrogel system in bio-medical applications are investigated by studying it under in vitro conditions. By means of microfabrication techniques, we are able to miniaturize the hydrogel as a large array of responsive cilia, considerably increasing its response speed. Such cilia are also made bi-responsive by inclusion of magnetic particles. Finally, by mastering the microfabrication techniques we develop novel methods for micelle-based nanowire formation and soft-matter objects manipulation.","hydrogel; microfabrication; soft matter; gel; polymers; nanowires; micelles","en","doctoral thesis","Uitgeverij BOXPress, s-Hertogenbosch","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:27dc842b-689f-4f63-ba22-60511401d327","http://resolver.tudelft.nl/uuid:27dc842b-689f-4f63-ba22-60511401d327","Synthesis of Durable Platinum Catalyst for Proton Exchange Membrane Fuel Cells in Bicontinuous Microemulsion (abstract)","Latsuzbaia, R.; Nergo, E.; Koper, G.J.M.","","2013","","","en","conference paper","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:7a1ec0a6-2836-49b7-8879-5a40e651a508","http://resolver.tudelft.nl/uuid:7a1ec0a6-2836-49b7-8879-5a40e651a508","Reversible Nanoparticle Formation As a Potential Strategy for PEMFC Catalyst Regeneration (abstract)","Latsuzbaia, R.; Negro, E.; Koper, G.J.M.","","2013","","","en","conference paper","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:9b24aa3c-4356-4072-9332-fec3a26b28d9","http://resolver.tudelft.nl/uuid:9b24aa3c-4356-4072-9332-fec3a26b28d9","Insights into the Catalytic Performance of Mesoporous H-ZSM-5-Supported Cobalt in Fischer–Tropsch Synthesis","Sartipi, S.; Alberts, M.; Santos, V.P.; Nasalevich, M.; Gascon, J.; Kapteijn, F.","","2013","Mesoporous H-ZSM-5 (mesoH-ZSM-5) was used as a carrier for a series of bifunctional Co-based catalysts for Fischer–Tropsch synthesis with ZrO2 and/or Ru added as promoters. The reducibility of the catalysts was studied in detail by using temperature-programmed reduction and X-ray absorption spectroscopy. A comparison of the catalytic performance of Co/mesoH-ZSM-5 and Co/SiO2 (a conventional catalyst), after 140?h on stream, reveals that the former is two times more active and three times more selective to the C5–C11 fraction with a large content of unsaturated hydrocarbons, which is next to ?-olefins. The acid-catalyzed conversion of n-hexane and 1-hexene, as model reactions, demonstrates that the improvement in the selectivity toward gasoline range hydrocarbons is due to the acid-catalyzed reactions of the Fischer–Tropsch ?-olefins over the acidic zeolite. The formation of methane over the zeolite-supported Co catalysts originates from direct CO hydrogenation and hydrocarbon hydrogenolysis on coordinatively unsaturated Co sites, which are stabilized as a consequence of a strong metal–zeolite interaction. Although the addition of either ZrO2 or Ru increases the catalyst reducibility considerably, it does not affect the product selectivity significantly.","alkenes; cobalt; FischerTropsch synthesis; mesoporous materials; zeolites","en","journal article","Wiley","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:1ba78553-e1f9-47ae-abb8-9b8f238aa51b","http://resolver.tudelft.nl/uuid:1ba78553-e1f9-47ae-abb8-9b8f238aa51b","A Lattice Boltzmann Approach to Multi-Phase Surface Reactions with Heat Effects","Kamali, M.R.","Van den Akker, H.E.A. (promotor); Sundaresan, S. (promotor)","2013","The aim of the present research was to explore the promises and shift the limits of the numerical framework of lattice Boltzmann (LB) for studying the physics behind multi-component two-phase heterogeneous non-isothermal reactive flows under industrial conditions. An example of such an industrially relevant topic is the Fischer-Tropsch Synthesis (FTS) in the Gas-to-Liquid (GtL) conversion process of methane. The research described in this thesis was carried out in the context of a twin project supported by Shell and STW on structured reactors for Fischer-Tropsch and the meso-scale flow and transport phenomena and catalysis aspects therein. The complexity of such multi-component two-phase heterogeneous reactive flow systems with thermal effects was a good reason for splitting the topic up into a number of constitutive elements which were tackled individually. The various LB methods available in the literature dealing with all these separate elements were studied; the most promising methods were identified, improved where needed, and implemented in a three-dimensional code structure which was then validated against theory and/or experiment. At the start of the development of this numerical infrastructure, we implemented an incompressible single-phase LB based flow solver. This was used for analysing in 2-D the flow and for detecting stagnation zones in cross-flow structured packings for tubular fixed bed reactors. This study was combined with an experimental and modelling investigation comparing the heat transfer characteristics of different types of packings in such reactors. Further details of this analysis are provided in Chapter 2 of this thesis. Then, the LB approach was extended for dealing with multi-component gas-liquid flows over solid surfaces. The pseudo-potential concept due to Shan and Chen (1993) was identified as being the promising method, as it describes the interaction of components and interaction in more fundamental terms and does not require a separate equation for tracking the phase interfaces. In this concept, the various components each have their own particle distribution function governed by an own Boltzmann equation. Inter-particle forces are defined in the format of potential functions for each of the components; the interactions between the various components and phases are controlled by parameters denoted as coupling strength. These potential functions should reflect some equation of state (EOS). For the interaction of fluid components with the solid boundaries, a similar approach was considered. These component-component and component-wall pseudo potentials and the pertinent coupling strengths are responsible for phase separation, surface tension, density ratio between phases, contact angle and so on; the values of all these continuum variables follow from the selected potential functions and coupling strengths. The original Shan & Chen concept was introduced for two EOSs only (ideal gas and Van der Waals) and suffered from numerical instabilities for density ratios in excess of, say, 10. More recently, Yuan and Schaefer (2006) came up with improvements allowing the use of different EOSs (such as Carnahan-Starling and Redlich-Kwong) with a positive effect on the numerical stability at higher density ratios. Implementing such modifications resulted in successful simulations of two-phase systems with density ratios as high as 1,000 - depending on the EOS used and on the reduced temperature. The code developed so far was capable of dealing with single- and multiple-component systems with various density ratios and wettability properties. It was used for studying a variety of cases including a spontaneous phase separation process between two phases, the rise of a single bubble in a liquid pool, fully wetting (Taylor) and partially wetting segmented flows in a straight tube, and almost non-wetting/partially wetting droplet flow in inclined micro-channels. The outcome of these simulations compared favourably with available literature data or experiments. Particularly with respect to the motion of a Taylor bubble through a tube, a comprehensive quantitative analysis was performed tackling different aspects of the bubble and its motion. This validation study comprised the analysis of the variations of liquid film thickness, bubble to liquid velocity ratio, and bubble shape with the Capillary number; also the pressure field in the thin liquid film between bubble and tube wall was evaluated. Further background on this multi-component multi-phase flow solver and the details of the validation studies performed are described in Chapters 3-4 of this thesis. Solving the energy conservation equation in two-phase systems with phase change phenomena included was another step in improving the potential of the current LB approach with the view of the project objectives. In this approach, next to the ones used in the multi-component system, an additional distribution function was introduced for a pseudo-temperature scalar variable $\rho T$. This variable recovers the macroscopic conservation of energy in two-phase mixtures. The rest of the distribution functions take care of the mass and the momentum conservation of the multi-component system. Heats of reaction, enthalpy change associated with phase change, and diffusive transport of enthalpy are all taken into account; the dependence of enthalpy on pressure, which is usually a small effect in most non-isothermal flows encountered in chemical reaction systems, is ignored however. The energy equation was coupled with the LB equations for species transport and the pseudo-potential interaction forces through the EOS by using the local pseudo-temperature field. In order to control the noise associated with the fluctuations in the pseudo-temperature in the vicinity of the diffused interface, a robust regularized spline algorithm was introduced in the coupling between pseudo-temperature and density. The proposed scheme was used for simulating some benchmark problems the results of which were validated against available analytical solutions. An extensive explanation on this thermal two-phase model and its applications are provided in Chapter 5 of this thesis. As another important element of this research, the potential of the current multi-component LB methodology for solving the advection-diffusion equation for multiple species was assessed. This study showed - for various velocities and for various values of the ratio of the diffusivities of solvent and solute - that the accuracy of our multi-component LB methodology is high. Of course, this accuracy depends on the spatial resolution, expressed in terms of the diffusion depth per grid spacing. Furthermore, we investigated the accuracy of this model by simulating the mass transfer of a gas-like component across a gas-liquid interface at a moderate density ratio of the two phases and at a moderate value of Henry's coefficient. Further details can be found in Chapter 6 of this thesis. Finally, the current approach was used for simulating the complex interplay of diffusion and surface reaction in a multi-component gas-liquid catalytic chemical reactor under (for the time being) isothermal conditions. The current lattice Boltzmann technique was capable of reproducing quite realistically, at satisfactory temporal and spatial resolution, the combination of species transport across a phase interface, a chemical reaction at a catalytic surface, and the resulting phase change due to the surface reaction. This was observed after careful comparison of the simulation data with analytical models. We simulated a simplified isothermal 1-D Fischer-Tropsch Synthesis in which hydrogen and carbon monoxide reacted to water and paraffin $C_{15}$ at a catalytic flat surface with an educated simplification of the reaction kinetics. This four-component gas-liquid surface reaction with a liquid film covering a catalytic surface from the very beginning resulted in a gradually increasing thickness of the liquid layer as well as in quite realistic species concentration profiles in liquid and gas phases. In our simulated model, the tracked hydrocarbon was representative of all the possible carbon chain products in such a reaction. In the end, by combining all temporally resolved species concentrations with empirical Anderson-Schulz-Flory (ASF) model and by determining the chain growth probabilities, the pertinent carbon chain products were calculated for the range $C_1 - C_{60}$. The extensive description of this multi-component multi-phase surface reaction study is given in Chapter 7 of this thesis. Finally, Chapters 8 and 9 present the overall conclusions of this project and an outlook for further work.","","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:f805fc41-e87e-4f35-8685-05056ab1a50f","http://resolver.tudelft.nl/uuid:f805fc41-e87e-4f35-8685-05056ab1a50f","Hot Spot Formation in Trickle Bed Reactors","Mousazadeh, F.","Mudde, R.F. (promotor); Van den Akker, H.E.A. (promotor)","2013","","trickle bed reactor; hot spot formation; CFD simulation","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:cac43094-6191-49d4-a53b-131f6f940885","http://resolver.tudelft.nl/uuid:cac43094-6191-49d4-a53b-131f6f940885","Forced convection mass deposition and heat transfer onto a cylinder sheathed by protective garments","Ambesi, D.; Kleijn, C.R.; Den Hartog, E.A.; Bouma, R.H.B.; Brasser, P.","","2013","In chemical, biological, radiological, and nuclear protective clothing, a layer of activated carbon material in between two textile layers provides protection against hazardous gases. A cylinder in cross flow, sheathed by such material, is generally used to experimentally test the garment properties. This is, however, complicated and predictive models are needed. We present a computational fluid dynamics model for the initial phase in which the carbon filter material is not yet saturated. The textiles are modeled as chemically inactive porous layers, the carbon filter particles have been resolved explicitly. The model has been validated against experimental data. We demonstrate that (1) computational fluid dynamics simulations can be used for the efficient design and optimization of protective garments, and (2) the addition of a highly porous active carbon layer highly increases the chemical protection capabilities, while having relatively little negative impact on the thermal comfort of protective garments.","chemical; biological; radiological; and nuclear protective garments; cylinder; active carbon filter; heat transfer; mass transfer; computational fluid dynamics; turbulence; time-dependent Reynolds-averaged Navier-Stokes","en","journal article","Wiley","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:43f2f172-c5ac-4371-aca8-5237a828f931","http://resolver.tudelft.nl/uuid:43f2f172-c5ac-4371-aca8-5237a828f931","Breakup of confined droplets in microfluidics","Hoang, A.D.","Kleijn, C.R. (promotor); Kreutzer, M.T. (promotor)","2013","Segmented-flow microreactors have emerged as an attractive tool for fine chemical synthesis and (bio)chemical analysis, owing to their high heat and mass transfer rate, low axial dispersion, as well as rapid mixing. A key challenge for the use of segmented-flow microreactors in large-scale processing is their low throughput. This can be overcome by applying the concept of numbering-up in which several microreactors are placed and operated in parallel. A challenging aspect of this approach is to distribute segmented flows over those parallel microreactors with a high uniformity in the size and the speed of the fluid compartments. In this thesis, we propose to use a bubble-splitting distributor where a single stream of fluid compartments is recursively split into smaller ones via a series of T-junctions. We first investigate the fundamental physics of the breakup of droplets in a single T-junction using CFD simulations. Being able to explain the mechanism of the droplet breakup leads us to a more applied question, how to design a bubble/droplet distributor and what are the optimum operating conditions. We present theoretical and experimental analyses of the uniformity of the distribution of bubbles/droplets using the proposed distributor and provide guidelines to operate it for different flow conditions. The thesis ends with a discussion on how some of our main findings can be generalized and opportunities for future research.","bubbles; droplets; breakup; scale-up; CFD; experiment","en","doctoral thesis","","","","","","","","2013-10-16","Applied Sciences","Chemical Engineering","","","",""
"uuid:0d10c8b5-102a-4be7-9b3c-1d0aa434adf1","http://resolver.tudelft.nl/uuid:0d10c8b5-102a-4be7-9b3c-1d0aa434adf1","Destabilization of magnesium hydride through interface engineering","Mooij, L.P.A.","Dam, B. (promotor)","2013","The aim of this thesis is to study the thermodynamics of hydrogenation of nanoconfined magnesium within a thin film multilayer model system. Magnesium hydride is a potential material for hydrogen storage, which is a key component in a renewable energy system based on hydrogen. In bulk form, magnesium hydride is very stable, which means that hydrogen is released only at elevated temperature. Furthermore, the kinetics of hydrogen sorption is slow, which further hampers the practical use of this hydrogen storage material. A solution to both these issues may be found in nanoconfinement. At the nanoscale, the contribution of the surface (or interface) energy starts to play a large role and potentially destabilizes magnesium hydride. The kinetics is expected to improve due to the increased surface area and shorter diffusion lengths. With a thin film model system, the confinement of magnesium can be directly controlled by changing the magnesium layer thickness, as well as by changing the interfacing materials of the magnesium layer. The effect of the interface energy and further effects from nanoconfinement such as nucleation and growth, mechanical anisotropy and alloying are all investigated. These findings provide valuable insights for the optimization of nanosized hydrogen storage systems, thus paving the road to thin layered nanostructures enabling hydrogen desorption at 1 bar at room temperature.","hydrogen storage; metal hydride; nanoconfinement; magnesium; interface energy","en","doctoral thesis","","","","","","","","2013-10-01","Applied Sciences","Department of Chemical Engineering","","","",""
"uuid:39c17490-18ae-457c-8493-9bf2303b97a8","http://resolver.tudelft.nl/uuid:39c17490-18ae-457c-8493-9bf2303b97a8","The Stabilizer-Free Emulsion Polymerization","Dobrowolska, M.E.","Van Esch, J.H. (promotor)","2013","The research described in this thesis has been performed with the goal to understand and develop a method for stabilizer-free emulsion polymerization. In order to develop rules for this method, three main issues had to be understood: colloidal stability, emulsification method and polymerization procedure. By definition, emulsion polymerization is a process that starts with an emulsion made out of monomer dispersed in water, usually involves stabilization agent, and upon addition of initiator it polymerizes to create fine polymer particles. As the main disadvantage of this method is the contamination with stabilizing agent in the final product, the goal was to find a method, which does not require the additional stabilizing agent. For that purpose species that is naturally present in water have been used for electrostatic stabilization.","stabilizer-free; emulsion polymerization","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:99236514-8ff6-4053-b317-9a9bb0f9438d","http://resolver.tudelft.nl/uuid:99236514-8ff6-4053-b317-9a9bb0f9438d","Enhancing optical absorption of metal–organic frameworks for improved visible light photocatalysis","Nasalevich, M.A.; Goesten, M.G.; Savenije, T.J.; Kapteijn, F.; Gascon, J.","","2013","NH2-MIL-125(Ti) has been post-synthetically functionalized with dye-like molecular fragments. The new material (methyl red-MIL- 125(Ti)) exhibits improved light absorption over a wide range of the visible spectrum, and shows enhanced photocatalytic oxidation activity under visible light illumination. The consequences of functionalization and the bottlenecks in MOF photochemistry are studied in detail.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:9caa4ef4-cd88-4d70-9ab8-52fe9ae92860","http://resolver.tudelft.nl/uuid:9caa4ef4-cd88-4d70-9ab8-52fe9ae92860","Hydrogel based occlusion systems","Stam, F.A.; Jackson, N.; Dubruel, P.; Adesanya, K.; Embrechts, A.; Mendes, E.; Neves, H.P.; Herijgers, P.; Verbrugghe, Y.; Shacham, Y.; Engel, L.; Krylov, V.","","2013","A hydrogel based occlusion system, a method for occluding vessels, appendages or aneurysms, and a method for hydrogel synthesis are disclosed. The hydrogel based occlusion system includes a hydrogel having a shrunken and a swollen state and a delivery tool configured to deliver the hydrogel to a target occlusion location. The hydrogel is configured to permanently occlude the target occlusion location in the swollen state. The hydrogel may be an electro-activated hydrogel (EAH) which could be electro-activated with a delivery system to control the degree of swelling/shrinking.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:555501f2-a7cf-4cc2-8fbc-b8bc075073ce","http://resolver.tudelft.nl/uuid:555501f2-a7cf-4cc2-8fbc-b8bc075073ce","Fascinating chemistry or frustrating unpredictability: Observations in crystal engineering of metal–organic frameworks","Goesten, M.G.; Kapteijn, F.; Gascon, J.","","2013","Reticular design is a highly attractive concept, but coordination chemistry around the tectonic units of metal– organic frameworks (MOFs) and additional interplay with anionic and solvent species provide for dazzling complexity that effectively rules out structure prediction. We can however study the chemistry around pre-existing clusters, and assemble novel materials correspondingly, using a priori information about the connectivity of an investigated metal cluster. Studies, often spectroscopic of nature, have in recent years solved many puzzles in MOF crystallization. The obtained knowledge opens new doors in crystal engineering, but more research on MOF coordination chemistry has to be carried out.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:dc13c65d-5a00-401a-bec3-5dc38c702967","http://resolver.tudelft.nl/uuid:dc13c65d-5a00-401a-bec3-5dc38c702967","Assessing the performance of ground source heat pumps in neighboring medium-size households","Alvarez Gallardo, M.D.P.","Korevaar, G. (mentor); Vardon, P.J. (mentor)","2013","The Master's programme Industrial Ecology is jointly organised by Leiden University and Delft University of Technology. This research project was done during an internship of 8 months completed with Royal Dutch Shell within the department of Future Energy Technologies of The Netherlands. It is focused on a case study of a medium size house (2202) situated in The Hague, NL and the neighboring households with the same characteristics along the same street. Homes in the Netherlands are likely to have their heat requirements fulfilled by conventional natural gas systems due to the relatively cheap cost compared to other systems (installation and investment wise) that could have a lower carbon footprint. However, innovative installations could make other more environmentally friendly systems as accessible as conventional systems. The Netherlands as one of the European member states have the goal of reducing CO2 emissions to accomplish their Kyoto targets; however, The Netherlands was not able to meet this target by 3.24% (target of 200.4 megaton CO2-eq). Besides, there is a general lack of financial incentives, making it in many cases an obvious decision to keep and use standard fossil fuel energy systems (both large- and small-scale) regardless of the environmental impact they may have. The building energy consumption sector provides a great opportunity and focus area for trying to reduce even more those emissions, and efforts have been made to introduce into the market more environmentally friendly systems. Until now, exploitation of geothermal shallow energy using a Ground Source Heat Pump (GSHP) has generally been limited to large commercial / industrial units. One reason for this is that the technology used for obtaining the geothermal energy and raising it to an appropriate temperature for the heat requirements of a typical house requires a big space for its installation which in turn proves to be a disruptive and complex process that requires the use of heavy and bulky machinery which immediately translates in a restriction for small homes. Innovations for installations of Ground Source heat pumps are starting to appear in the market, giving the possibility and the opportunity to install those systems in smaller areas, with less disruption and lower investment costs, although some concerns may arise when considering the thermal interference between the boreholes. This project examined the geological characteristics of the case study as determined by a Thermal Response Test (TRT) where parameters such as the thermal conductivity, the thermal resistance and the thermal diffusivity of the ground were obtained. Furthermore, the heat requirements of the test house were calculated with real data obtained during a year between 2012 and 2013 in order to determine the size of the system that would be required for each one of the houses assuming they all have the same demand throughout the year, having a peak demand for a winter day of 16 KW and an average demand of 10 KW in the winter months. Calculations of the length required of every Borehole Heat Exchanger (BHE) and the distance between them were made for the area of each house assuming no thermal interference. The first set of results indicated that a BHE length of 268 m would be needed, and with borehole thermal interference introducing a temperature penalty calculated with an analytical model, the length required increased to 332 m, 68 m more. After this a proposed design of borehole arrangement is suggested for the test house considering the space constraints. Calculations on the Economic and Environmental advantage from Ground Source Heat Pump (GSHP) compared to a Gas Boiler is done, taking into consideration two scenarios for the GSHP, 1) with a Seasonal Performance Factor (SPF) of 3.5 and 2) with a SPF of 3.0. Domestic gas and electricity price fluctuations over the past years were included, extrapolating this behavior for the years 2015 and 2020. Gas prices are considered to have changed 9% per year given the data from 1996 – 2013. Having extrapolated the prices, calculations are done on running costs and investment cost, to give the payback times when considering current power and gas prices for 2015 and 2020. The current situation (2013) seems the more expensive moment for having the system with a payback time of 24 years however a GSHP system in 2020 with electricity and gas prices following a 9% increase for gas prices would take just 8 years to have the investment back. For the environmental performance the Dutch footprint of power generation is calculated for the average predicted trends of different scenarios in the future for European power generation where GSHP with a SPF of 3.5 in 2020 seems to have the best Carbon Footprint advantage of all with 59% advantage of the compared systems. Recommendations are made in order to come up with connected scenarios of Dutch power and natural gas to have a coherent and timely understanding of GSHP and other renewable systems in the Dutch heating market for the coming years. Further recommendations are made in order to have a clear understanding on all the interrelated factors that have an impact on the efficiency, feasibility and performance of GSHP systems and how this research project could be broadened.","ground source heat pumps; renewable energy","en","master thesis","","","","","","","","","Technical University of Technology","Chemical Engineering","","Industrial Ecology","",""
"uuid:691abb5b-c315-440a-bdc3-08b43091d61d","http://resolver.tudelft.nl/uuid:691abb5b-c315-440a-bdc3-08b43091d61d","Disorder strongly enhances Auger recombination in conductive quantum-dot solids","Gao, Y.; Suchand Sandeep, C.S.; Schins, J.M.; Houtepen, A.J.; Siebbeles, L.D.A.","","2013","Auger recombination (AR) can be an important loss mechanism for optoelectronic devices, but it is typically not very efficient at low excitation densities. Here we show that in conductive quantum-dot solids, AR is the dominant charge carrier decay path even at excitation densities as low as 10?3 per quantum dot, and that AR becomes faster as the charge carrier mobility increases. Monte Carlo simulations reveal that this efficient AR results from charge carrier congregation in ‘Auger hot spots’: lower-energy sites that are present because of energy disorder. Disorder-enhanced AR is a general effect that is expected to be active in all disordered materials. The observed efficient AR is an issue of concern for devices that work at charge carrier densities in excess of ~10?3 charge carriers per quantum dot. At the same time, efficient carrier congregation could be exploited for fast optical switching or to achieve optical gain in the near infrared.","physical sciences; condensed matter; materials science","en","journal article","Nature Publishing Group","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:d0484cc2-1ba2-4872-90c2-0ca6fefe850d","http://resolver.tudelft.nl/uuid:d0484cc2-1ba2-4872-90c2-0ca6fefe850d","Lattice-Boltzmann-based two-phase thermal model for simulating phase change","Kamali, M.R.; Gillissen, J.J.J.; Van den Akker, H.E.A.; Sundaresan, S.","","2013","A lattice Boltzmann (LB) method is presented for solving the energy conservation equation in two phases when the phase change effects are included in the model. This approach employs multiple distribution functions, one for a pseudotemperature scalar variable and the rest for the various species. A nonideal equation of state (EOS) is introduced by using a pseudopotential LB model. The evolution equation for the pseudotemperature variable is constructed in such a manner that in the continuum limit one recovers the well known macroscopic energy conservation equation for the mixtures. Heats of reaction, the enthalpy change associated with the phase change, and the diffusive transport of enthalpy are all taken into account; but the dependence of enthalpy on pressure, which is usually a small effect in most nonisothermal flows encountered in chemical reaction systems, is ignored. The energy equation is coupled to the LB equations for species transport and pseudopotential interaction forces through the EOS by using the filtered local pseudotemperature field. The proposed scheme is validated against simple test problems for which analytical solutions can readily be obtained.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:e81e5ed8-1608-47c0-a668-3be25e04c039","http://resolver.tudelft.nl/uuid:e81e5ed8-1608-47c0-a668-3be25e04c039","Towards Highly Efficient Bias-Free Solar Water Splitting","Abdi, F.F.","Dam, B. (promotor); Van de Krol, R. (promotor)","2013","Solar water splitting has attracted significant attention due to its potential of converting solar to chemical energy. It uses semiconductor to convert sunlight into electron-hole pairs, which then split water into hydrogen and oxygen. The hydrogen can be used as a renewable fuel, or it can serve as a feedstock material to form hydrocarbons. However, the development of an adequate semiconductor material for solar water splitting still remains a challenge. This thesis work aimed at developing new, multinary metal oxides: bismuth vanadate (BiVO4). BiVO4 was synthesized using a low-cost spray deposition process. By systematically optimizing the deposition parameters, high quality thin films of BiVO4 photoanodes with quantum efficiencies close to 90% were reproducibly produced. To further increase the performance, a thorough analysis was performed to determine its performance limiting factors, which are poor catalytic activity and slow carrier transport. Cobalt-phosphate catalyst was then deposited on BiVO4 surface to solve the first limitation, and a gradient concentration of tungsten as a dopant was introduced to solve the latter problem. As a result, the photocurrent of BiVO4-based photoanode has been increased up to 4.0 mA/cm2 under 1 sun irradiation, which is the highest value ever reported for this material. Considering that only a photocurrent of <0.2 mA/cm2 was achieved prior to the start of this thesis work, this is a significant ~20-fold improvement of the performance. This state-of-the-art BiVO4 photoanode was then combined with a thin film amorphous silicon solar cell to fabricate a complete solar water splitting device. As a result, a device with ~5% solar-to-hydrogen (STH) efficiency was produced, which is the current world-record for a device based on a metal-oxide photoanode. Finally, the significant progress achieved through this thesis shows that the ideal semiconductor material for solar water splitting, which is cheap, abundant, stable, and showing the 10% efficiency target, could be developed within the next few years.","solar water splitting; bismuth vanadate; spray pyrolysis; photoelectrochemistry","en","doctoral thesis","","","","","","","","2013-08-24","Applied Sciences","Chemical Engineering","","","",""
"uuid:9bcc29cf-eb26-4978-9f6a-2aaa42183d90","http://resolver.tudelft.nl/uuid:9bcc29cf-eb26-4978-9f6a-2aaa42183d90","High charge-carrier mobility enables exploitation of carrier multiplication in quantum-dot films","Suchand Sandeep, C.S.; Ten Cate, S.; Schins, J.M.; Savenije, T.J.; Liu, Y.; Law, M.; Kinge, S.; Houtepen, A.J.; Siebbeles, L.D.A.","","2013","Carrier multiplication, the generation of multiple electron–hole pairs by a single photon, is of great interest for solar cells as it may enhance their photocurrent. This process has been shown to occur efficiently in colloidal quantum dots, however, harvesting of the generated multiple charges has proved difficult. Here we show that by tuning the charge-carrier mobility in quantum-dot films, carrier multiplication can be optimized and may show an efficiency as high as in colloidal dispersion. Our results are explained quantitatively by the competition between dissociation of multiple electron–hole pairs and Auger recombination. Above a mobility of ~1?cm2?V?1?s?1, all charges escape Auger recombination and are quantitatively converted to free charges, offering the prospect of cheap quantum-dot solar cells with efficiencies in excess of the Shockley–Queisser limit. In addition, we show that the threshold energy for carrier multiplication is reduced to twice the band gap of the quantum dots.","physical sciences; nanotechnology; optical physics","en","journal article","Nature Publishing Group","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:fa4719d8-742c-49ae-85b0-63d904fe9e8a","http://resolver.tudelft.nl/uuid:fa4719d8-742c-49ae-85b0-63d904fe9e8a","Spark ablation device","Schmidt-Ott, A.; Pfeiffer, T.V.","","2013","A spark ablation device for generating nanoparticles comprising a spark generator; the spark generator comprising first and second electrodes, wherein the spark generator further comprises at least one power source which is arranged to be operative at a first energy level for maintaining a discharge between the first and second electrodes, which power source is arranged for repetitively increasing the energy of the discharge to a predetermined secondary level that is higher than the first energy level for ablating a portion of the electrodes.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:44c6c49a-3d20-4ca5-952e-3f26c04985f3","http://resolver.tudelft.nl/uuid:44c6c49a-3d20-4ca5-952e-3f26c04985f3","Engineering of Metal Organic Framework Catalysts","Juan-Alcaniz, J.","Kapteijn, F. (promotor)","2013","The last few decades have witnessed the unprecedented explosion of a new research field built around Metal-Organic Frameworks (MOFs). MOFs are crystalline porous solids consisting of metal ions (also named clusters) coordinated to often rigid organic molecules (also called ligands) to form one- two-, or three- dimensional structures. This combination of organic and inorganic building blocks into highly ordered, crystalline structures offers an almost infinite number of combinations, enormous flexibility in pore size, shape and structure, and plenty of opportunities for facile tuning by functionalization, grafting and/or encapsulation. This field has rapidly evolved from an early stage, in which the main scope was the discovery of new structures, to a more mature stage in which dozens of applications are currently being explored like gas storage, separation, sensing or drug delivery. Last but not least, its tunable morphology, pore size, and adsorption properties, along with its intrinsic hybrid nature, all point at MOFs as very promising heterogeneous catalyst. This dissertation describes the development of a new generation of hybrid catalysts based on Metal-Organic Frameworks decorated with active functionalities and the study of its implementation into challenging catalytic processes. Metal clusters with unsaturated sites, organic functionalities and encapsulation of macromolecules or nanoparticles in the pores of these tunable crystalline structures are among the methods investigated in this dissertation. This work investigates from the design of the catalysts to the final application: from the molecular to the reactor scale. The research presents a deep insight in successful methodologies for future multifunctional systems and the catalytic performance of such active sites when confined into highly ordered structures, supported by extensive characterization.","heterogeneous catalysis","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering / Catalysis Engineering","","","",""
"uuid:56e51e81-dc55-4e8d-9b78-351ab1787f1b","http://resolver.tudelft.nl/uuid:56e51e81-dc55-4e8d-9b78-351ab1787f1b","Multidimensionality in Fluidized Nanopowder Agglomerates","De Martin, L.; Bouwman, W.G.; Van Ommen, J.R.","","2013","recent years, the interest in fluidization as a mean to process nanoparticles is strongly increasing. Due to the small size of the nanoparticles, which makes van der Waals forces predominate, they do not fluidize as single particles but as agglomerates. Various researchers using settling experiments and bed expansion measurements conclude that fluidized agglomerates are fractal structures with a single fractal dimension of 2.5. Based on microscopy results, Wang et al. “Powder Technology 124, 152–C159 (2002)” propose a hierarchical structure, which seems in contradiction with the use of only one fractal dimension as a descriptor of the whole structure. Moreover, it is not clear whether the structure presented by the agglomerates ex-situ is the same during fluidization. Hence, in this work we have characterized in-situ the internal structure of fluidized agglomerates by means of spin-echo small-angle neutron scattering (SESANS). We show that the structure of the agglomerates present at least two fractal dimensions. One of them is ? 2.1 and characterizes the primary strong agglomerates. The second one is ? 2.8 and characterizes the larger agglomerates formed by the primary agglomerates.","flow measurement; fluidisation; fluidised beds; fractals,; nanoparticles; two-phase flow; van der Waals forces","en","conference paper","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:b4dba21a-1dac-473c-9429-3226c7472afb","http://resolver.tudelft.nl/uuid:b4dba21a-1dac-473c-9429-3226c7472afb","Towards acid MOFs – catalytic performance of sulfonic acid functionalized architectures","Juan-Alcaniz, J.; Gielisse, R.; Lago, A.B.; Ramos-Fernandez, E.V.; Serra-Crespo, P.; Devic, T.; Guillou, N.; Serre, C.; Kapteijn, F.; Gascon, J.","","2013","In this work, the inclusion of free sulfonic acid groups in highly stable MOFs is explored. The synthesized catalysts have been applied in a model esterification reaction. Two metal organic frameworks bearing sulfonic acid moieties are investigated: HSO3-MIL-101(Cr) synthesized following different approaches and a new structure based on HSO3-bdc and Zr. The acidic properties, catalytic performance, deactivation and stability of the different structures are critically evaluated. In the case of MIL-101(Cr), deactivation of the sulfonic groups via formation of butanol sulfonic esters has been observed. Due to the strong interaction between –SO3 _ and the Cr open metal site where usually fluorine (F_) is located in the structure, the HSO3-MIL-101(Cr) catalysts are not stable under acidic regeneration conditions. When using Zr as a metal node, a new and stable sulfonic acid containing porous structure was synthesized. This structure showed high activity and full re-usability in the esterification of n-butanol with acetic acid. In this case, deactivation of the catalyst due to sulfonic ester formation could be reversed by reactivation under acidic conditions.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:b3546fc9-550a-4d13-9fcf-c4bddf569a08","http://resolver.tudelft.nl/uuid:b3546fc9-550a-4d13-9fcf-c4bddf569a08","Metal hydrides for smart window and sensor applications","Yoshimura, K.; Langhammer, C.; Dam, B.","","2013","The hydrogenation of metals often leads to changes in optical properties in the visible range. This allows for fundamental studies of the hydrogenation process, as well as the exploration of various applications using these optical effects. Here, we focus on recent developments in metal hydride-based optical fiber and plasmonic sensors and smart windows. Both applications benefit from the existence of a reflective metallic state, which is lost on hydrogenation and allows for large reversible optical changes. In this article, we review the status of both technologies and their prospects for applications.","","en","journal article","Cambridge University Press","","","","","","","2014-06-30","Applied Sciences","Chemical Engineering","","","",""
"uuid:643b5fa6-86be-4bb1-9aec-eac53e10b49b","http://resolver.tudelft.nl/uuid:643b5fa6-86be-4bb1-9aec-eac53e10b49b","Kinetics of chemisorption and physisorption in liquid phase using a microfluidic ATR-FTIR flow cell","Renckens, T.J.A.","Kreutzer, M.T. (promotor); Mul, G. (promotor)","2013","This thesis describes the development and application of an Attenuated Total Reflection Fourier Transform-Infrared (ATR FT-IR) microflow cell for the study of liquid-solid sorption kinetics, relevant for heterogeneous (photo)catalysis.","","en","doctoral thesis","Ridderprint","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:6aaf7d6f-fb6e-466e-826c-bba406e5cc42","http://resolver.tudelft.nl/uuid:6aaf7d6f-fb6e-466e-826c-bba406e5cc42","Stimulated-healing of proton exchange membrane fuel cell catalyst","Latsuzbaia, R.; Negro, E.; Koper, G.J.M.","","2013","Platinum nanoparticles, which are used as catalysts in Proton Exchange Membrane Fuel Cells (PEMFC), tend to degrade after long-term operation. We discriminate the following mechanisms of the degradation: poisoning, migration and coalescence, dissolution, and electrochemical Ostwald ripening. There are two ways to tackle this problem. The first option involves formulation of durable catalyst, which can resist harsh fuel cell conditions, and this is the conventional route. The second option is reactivation by dissolution and then redeposition of the catalyst nanoparticles, which is an unprecedented method for platinum catalyst regeneration/stimulated-healing and the one we shall discuss. Dissolution of platinum can be achieved electrochemically, by potential cycling of the fuel cell electrode impregnated with platinum nanoparticles in oxygen enriched acidic electrolyte according to following reactions [1]: Pt + H2O?PtO + 2H+ + 2e- (1) PtO + 2H+?Pt2+ + H2O (2) During the potential cycling, platinum oxides are formed at each positive cycle and subsequently dissolved as platinum ions in the electrolyte on the negative cycle. These cycles are alternated continuously. The partial dissolution of platinum nanoparticles results in a decrease in particles size and oxidation of the poisonous species on the platinum surface. The process of dissolution is monitored in-situ via cyclic voltammetry technique. The concentration of dissolved platinum is measured with Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The next step of the regeneration procedure is redeposition of the dissolved platinum back onto the carbon support of the fuel cell electrode. This can be realized by means of electrodeposition. A negative potential is applied to an electrode from where the platinum was dissolved and this results in a reduction of the dissolved platinum ions. Regenerated nanoparticles are characterized by AFM, TEM and XRD. The activity of the catalyst will be checked via voltammetric techniques.","fuel cell; platinum nanoparticles; self-healing; dissolution; deposition","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:2cefee5b-8d34-492d-92a1-20c480450338","http://resolver.tudelft.nl/uuid:2cefee5b-8d34-492d-92a1-20c480450338","Dissipative self-assembly: A novel self-healing mechanism for functional materials","Koper, G.J.M.; Boekhoven, J.; Hendriksen, W.E.; Eelkema, R.; Van Esch, J.H.","","2013","Self-assembled systems formed of micelles or vesicles have frequently been discussed as model systems for self-healing materials because their structure is dictated by thermodynamics and hence they quickly restore upon perturbation. In this aspect, they mimic many natural systems such as biological cells. However, in contrast to most synthetic self-assembling systems the natural systems are not equilibrium processes. Attention is therefore now focusing on dissipative selfassembling systems where energy input is required to sustain the self-assembled state. These systems have the potential to adapt themselves and enter into different self-assembled states depending on the rates of environmental reactions whereas their equilibrium counterparts can only assemble or disassemble depending on the environmental equilibrium condition. Recently, we have constructed some dissipative self-assembling systems using chemical fuels and presently more examples are being worked on. During this presentation some important aspects of these systems will be discussed in relation to their capabilities of being self-healing.","self-assembly; dissipation; self-healing; functional materials","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:eae2517c-277f-4f63-b161-9e847f02b88b","http://resolver.tudelft.nl/uuid:eae2517c-277f-4f63-b161-9e847f02b88b","Self-healing supramolecular polymer nanocomposites","Liu, Z.; Besseling, N.A.M.; Mendes, E.; Picken, S.J.","","2013","Polyborosiloxanes (PBSs) are viscoelastic, transparent, colourless, self-healable polymer matrices, synthesized by reacting linear polydimethylsiloxanes (PDMSs) with boric acid (BA) above 150°C. BA takes part not only in cleaving the PDMS chains, but also contributes boronic-acid like moieties to the cleaved chain ends, which provide supramolecular self-healing capabilities. PBSs can be regarded as supramolecular elastomers, owing to the reversible cross links formed by the abundant hydroxyl groups. Therefore they are able to recover both the microscopic and macroscopic fractures intrinsically via hydrogen-bonds. Additionally, a glass transition temperature (Tg) as low as -90°C ensures chain mobility to PBSs molecules to heal cracks autonomously without extra heat supply. Compared to traditional carbon-based polymeric materials, PBSs provide a higher resistance to heat and light owing to the siloxane backbone. Upon increasing the degree of modification, PBSs get stronger on the one hand. However, PBSs also become less adhesive and start suffering from brittle fracture. Interestingly, the addition of nano-clay (Cloisite 30B) solves this problem. It does not make PBSs more brittle as it does in traditional thermal plastics. Instead, it renders PBSs ductile but strong. Comparing to PBSs, the PBSs/Cloisite 30B nanocomposites even exhibit an additional filler-induced mechanical relaxation at high frequency. This phenomenon implies that PBSs/Cloisite 30B nanocomposites can be applicable as self-healing shock absorber. Further investigations will be focusing on characterization of the selfhealing capacity, on strengthening the composites and on tuning the position of the filler-induced rheological response. Upon applying other (nano-sized) reinforcements, PBSs can be endowed with wide variety of targeted functionalities, for instance, stiffness by nano-clay; thermal conductivity by graphite or boron nitride; piezoelectric properties by lead zirconate titanate (PZT), etc. The presence of particles is also advantageous for the adhesive properties of the composites, because particles lower the number of hydrogen-bonds by, either isolating molecules or forming particle-molecule interaction.","polyborosiloxane (PBS); hydrogen-bonding; self-healing","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:39948771-d5b8-4892-9a24-de601d86b87c","http://resolver.tudelft.nl/uuid:39948771-d5b8-4892-9a24-de601d86b87c","Dynamics of Single Rising Bubbles in Neutrally Buoyant Liquid-Solid Suspensions","Hoosyar, N.; Van Ommen, J.R.; Hamersma, P.J.; Sundaresan, S.; Mudde, R.F.","","2013","We experimentally investigate the effect of particles on the dynamics of a gas bubble rising in a liquid-solid suspension while the particles are equally sized and neutrally buoyant. Using the Stokes number as a universal scale, we show that when a bubble rises through a suspension characterized by a low Stokes number (in our case, small particles), it will hardly collide with the particles and will experience the suspension as a pseudoclear liquid. On the other hand, when the Stokes number is high (large particles), the high particle inertia leads to direct collisions with the bubble. In that case, Newton’s collision rule applies, and direct exchange of momentum and energy between the bubble and the particles occurs. We present a simple theory that describes the underlying mechanism determining the terminal bubble velocity.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:e418f9fe-c7f1-44b4-828b-5953612e7513","http://resolver.tudelft.nl/uuid:e418f9fe-c7f1-44b4-828b-5953612e7513","Structure-Property Relationship of Thermoset Nanocomposites","Faraz, M.I.","Picken, S.J. (promotor)","2013","In this thesis we report the synthesis, characterization and thermo-mechanical properties of a high-temperature resistant themoset nanocomposite system based on an aero-space-grade Bismaleimide resin. Various processing techniques with various fillers are used. The emphasis is on establishing the relationship between the structure and mechanical properties of nanocomposite systems. We characterized the nanocomposite systems experimentally using rheology, X-ray diffraction, Thermo-mechanical and microscopic techniques. The mechanical properties e.g. viscoelastic properties are interpreted in terms of the microstructure and explained by using micromechanical and viscoelastic models. In order to get insight into the structure of clay particles in the form of suspension we studied the rheology of organoclay dispersions before curing. We investigated the development of organoclay dispersions over time with the help of rheometry by applying small amplitude oscillatory deformation. Dispersions evolve over time with distinct stages into a percolating network. In most of the cases with various clay concentrations the behavior of dispersions was elastic solids-like. There is a critical threshold concentration of clay particles at which the dispersions initially behave as elastic solids and below which they form viscous fluids. This critical threshold seems to coincide with overlap concentration of the bodies of revolution of the particles, which is at a low clay concentration (of the order of 0.5% w/w). This overlapping of the bodies of revolution of particles may also limit the degree of exfoliation. Complete exfoliation is hardly ever achieved, as usually the concentration of particles used is much larger than the critical threshold concentration. Moreover, surprisingly, the frequency dependency of the mechanical moduli of the dispersions resemble that of a critical gel (a system just at the cross over between a visco-elastic solid and a visco-elastic fluid), normally reported for cross-linking polymers. This aspect has not been highlighted yet for clay dispersions. Interestingly the critical gel-like behavior of the dispersions persisted throughout the evolution over time. Thermo-mechanical properties of nanocomposite systems prepared with both carbon nanofiber and organoclay were investigated. The matrix itself and the nanocomposite system show excellent thermal properties and reasonable mechanical properties, better than the normal engineering polymers. The use of carbon nanofiber did not produce significant improvement in mechanical properties due to the poor adhesion of the fiber with the matrix. However, the use of organo clays shows systematic increase in mechanical properties and heat deflection temperature with the concentration of clay particles. The evaporation of solvent during curing leads to alignment of clay particles, which may also be beneficial for the properties of the nanocomposite. The stiffness of the nanocomposite was modeled by the Halpin-Tsai model. The model reproduces the data reasonably well. XRD results and the apparent aspect ratio obtained by Halpin-Tsai fitting indicate that the nanocomposite system is not completely exfoliated, and that the degree of exfoliation decreases with increasing particle concentration. We also investigated creep behavior of the nanocomposite system. The matrix shows very good creep stability and the use of nanofiller further enhances it. Application of the Findley power law and the Burgers model, which are widely used to describe the creep behavior of polymers, is critically evaluated. Their limitations to describe the creep behavior of thermoset matrices are discussed. We used a modified form of Burgers’ model which we named the ‘stretched Burgers model’ (SB) to describe the creep behavior of thermoset matrix and the nanocomposite. The stretched Burgers model reproduces the time-dependent creep compliance remarkably well. We made assumptions in fitting the data that retardation time scale distribution should be independent of filler concentration. The very good fitting of data supports the assumption. This means that the dynamics of the nanocomposite system is mainly governed by the dynamics of the matrix. This is an interesting assumption in our study and never highlighted in creep studies of nanocomposites. We believe that this finding is helpful for developing a better understanding of the mechanics of nanocomposites and of the role of filler on the dynamics of the matrix, which is greatly debated. The stretched Burgers model appears to be very suitable for describing the creep behavior of thermoset systems both from a physical point of view and concerning the quality of the fits.","nanocomposites; thermoset; polymer nanocomposites; mechanical properties","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:9f99dd6f-9036-426a-98b9-5c98f7f5270a","http://resolver.tudelft.nl/uuid:9f99dd6f-9036-426a-98b9-5c98f7f5270a","Flow, heat and mass transfer through CBRN protective clothing","Ambesi, D.","Kleijn, C.R. (promotor)","2013","","carbon particles; gas filters; protection factor","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:2e8e2d71-2f42-448b-919e-4f0d51249a70","http://resolver.tudelft.nl/uuid:2e8e2d71-2f42-448b-919e-4f0d51249a70","On the fabrication of PDMS micromodels by rapid prototyping, and their use in two-phase flow studies","Karadimitriou, N.K.; Musterd, M.; Kleingeld, P.J.; Kreutzer, M.T.; Hassanizadeh, S.M.; Joekar-Niasar, V.","","2013","Micromodels have been increasingly employed in various ways in porous media research, to study the pore-scale behavior of fluids. Micromodels have proven to be a valuable tool by allowing the observation of flow and transport at the micron scale in chemical, biological, and physical applications. They have helped to improve our insight of flow and transport phenomena at both microscale and macroscale. Up to now, most micromodels that have been used to study the role of interfaces in two-phase flow were small, square, or nearly square domains. In this work, an elongated PDMS micromodel, bearing a flow network with dimensions 5×30 mm2 was manufactured. The pore network was designed such that the REV size was around 5×7 mm2. So, our flow network was considered to be nearly four times the REV size. Using such micromodels, we established that the inclusion of interfacial area between the wetting and the nonwetting fluids models the hysteretic relationship between capillary pressure and saturation in porous media. In this paper, we first present the procedure for manufacturing PDMS micromodels with the use of soft lithography. Then, we describe an innovative and novel optical setup that allows the real-time visualization of elongated samples. Finally, we present the results obtained by quasi-static, two-phase flow experiments.","PDMS; micromodels; two-phase flow; capillary pressure; hysteresis; interfacial area","en","journal article","American Geophysical Union","","","","","","","2013-10-23","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:dbfc5e39-4ace-4839-bd2a-321fd8769b89","http://resolver.tudelft.nl/uuid:dbfc5e39-4ace-4839-bd2a-321fd8769b89","Block-and-break generation of microdroplets with fixed volume","Van Steijn, V.; Korczyk, P.M.; Derzsi, L.; Abate, A.R.; Weitz, D.A.; Garstecki, P.","","2013","We introduce a novel type of droplet generator that produces droplets of a volume set by the geometry of the droplet generator and not by the flow rates of the liquids. The generator consists of a classic T-junction with a bypass channel. This bypass directs the continuous fluid around the forming droplets, so that they can fill the space between the inlet of the dispersed phase and the exit of the bypass without breaking. Once filled, the dispersed phase blocks the exit of the bypass and is squeezed by the continuous fluid and broken off from the junction. We demonstrate the fixed-volume droplet generator for (i) the formation of monodisperse droplets from a source of varying flow rates, (ii) the formation of monodisperse droplets containing a gradation of solute concentration, and (iii) the parallel production of monodisperse droplets.","biomedical equipment; bioMEMS; drops; microchannel flow; two-phase flow","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:eb02394d-4321-47c1-b79c-086e393f7307","http://resolver.tudelft.nl/uuid:eb02394d-4321-47c1-b79c-086e393f7307","Predicting the diffusivity of CO2 in substituted amines","Masy, E.","Balaji, S.P. (mentor)","2013","The experimental determination of the diffusivity of carbon dioxide (CO2) in an amine solvent is difficult as the CO2 diffuses and reacts simultaneously when absorbed into an amine solvent. As the knowledge of the diffusivity and solubility of CO2 is essential to design the absorption units based on amine solvents, the nitrous oxide (N2O) analogy is used in practice to estimate them. It consists of evaluating those physical properties by substituting the reacting CO2 with an inert gas of a similar structure, N2O. The diffusion of CO2 in amine solvents is investigated using molecular dynamics (MD) simulation. Unlike experiments, MD simulation allows a direct measurement of the CO2 diffusivity. In MD simulations, the reaction between CO2 and the amine can be switched off. The Fick diffusion coeffcients are derived from the Maxwell-Stefan diffusivities and the thermodynamic factors. Different amine solvents like monoethanolamine, diethanolamine, methyl-diethanolamine and ethylamine are investigated. The N2O analogy in the monoethanolamine-water solution has been validated.","diffusion; amine; CO2 absorption; N2O analog; Maxwell-Stefan diffusivity; thermodynamic factor; molecular dynamic simulations","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","ETh","",""
"uuid:fab19f3c-d8f9-4080-95ef-924fcc663ed8","http://resolver.tudelft.nl/uuid:fab19f3c-d8f9-4080-95ef-924fcc663ed8","Visualizing MOF Mixed Matrix Membranes at the Nanoscale: Towards Structure-Performance Relationships in CO 2 /CH 4 Separation Over NH 2 -MIL-53(Al)@PI","Rodenas, T.; Van Dalen, M.; Garcia-Perez, E.; Serra-Crespo, P.; Zornoza, B.; Kapteijn, F.; Gascon, J.","","2013","Mixed matrix membranes (MMMs) composed of metal organic framework (MOF) fi llers embedded in a polymeric matrix represent a promising alternative for CO 2 removal from natural gas and biogas. Here, MMMs based on NH 2 -MIL-53(Al) MOF and polyimide are successfully synthesized with MOF loadings up to 25 wt% and different thicknesses. At 308 K and ? P = 3 bar, the incorporation of the MOF fi ller enhances CO 2 permeability with respect to membranes based on the neat polymer, while preserving the relatively high separation factor. The rate of solvent evaporation after membrane casting proves key for the fi nal confi guration and dispersion of the MOF in the membrane. Fast solvent removal favours the contraction of the MOF structure to its narrow pore framework confi guration, resulting in enhanced separation factor and, particularly, CO 2 permeability. The study reveals an excellent fi llerpolymercontact, with ca. 0.11% void volume fraction, for membranes based on the amino-functionalized MOF, even at high fi ller loadings (25 wt%). By providing precise and quantitative insight into key structural features at the nanoscale range, the approach provides feedback to the membrane casting process and therefore it represents an important advancement towards the rational design of mixed matrix membranes with enhanced structural features and separation performance.","","en","journal article","Wiley","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:542afb49-b482-4a23-9b33-49f6a86fa19f","http://resolver.tudelft.nl/uuid:542afb49-b482-4a23-9b33-49f6a86fa19f","Simultaneous hydrolysis and hydrogenation of cellobiose to sorbitol in molten salt hydrate media","Li, J.; Soares, H.S.M.P.; Moulijn, J.A.; Makkee, M.","","2013","The hydrolysis and hydrogenation of cellobiose (4-O-b-D-glucopyranosyl-D-glucose) in ZnCl2_4H2O solvent was studied to optimize the conditions for conversion of lignocellulose (the most abundant renewable resource) into sorbitol (D-glucitol). Water at neutral pH does not allow hydrolysis of cellobiose under the conditions of the experiments (up to 125 1C, 4 h), but relatively fast hydrogenation of cellobiose into 3-b-D-glucopyranosyl-D-glucitol over a Ru/C catalyst in the presence of H2 takes place. In ZnCl2_4H2O hydrolysis does take place in the range of temperatures studied (75–125 1C) and simultaneously hydrogenation (H2, Ru/C), though at a lower rate than that in neutral water. Thus, a one-pot conversion of cellobiose into sorbitol is possible. The hydrolysis is the rate limiting reaction, but the selectivity to sorbitol is determined by the rate of hydrogenation. Under optimal conditions the yield of sorbitol is Z95%. The kinetic pathways are discussed.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:8d645f6b-0b22-483d-86ab-6cf0db463e46","http://resolver.tudelft.nl/uuid:8d645f6b-0b22-483d-86ab-6cf0db463e46","Sorbitol dehydration into isosorbide in a molten salt hydrate medium","Li, J.; Spina, A.; Moulijn, J.A.; Makkee, M.","","2013","The sorbitol conversion in a molten salt hydrate medium (ZnCl2; 70 wt% in water) was studied. Dehydration is the main reaction, initially 1,4- and 3,6-anhydrosorbitol are the main products that are subsequently converted into isosorbide; two other anhydrohexitols, (1,5- and 2,5-), formed are in less amounts and do not undergo further dehydration. Besides dehydration, depending on the temperature, sorbitol was partly epimerized into galactitol, which was further converted to anhydrohexitols or di-anhydrohexitols (mainly isoidide). Epimerization of galactitol into sorbitol was not observed. Temperature (150 to 220 1C) is a crucial factor; at low temperature the reaction rate is low but the selectivity is high, at elevated temperature (over 200 1C) the rate is high but extensive amounts of byproducts were produced. At the optimal temperature range, without using any co-catalysts, full conversion is achieved, and the isosorbide percent yield is above 85% on a molar basis; (1,5- and 2,5-) anhydrohexitols are the major byproducts. The sorbitol conversion reaction pathway has been investigated.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:d338a9ff-af6e-4cc5-a153-9e8d95f4cf05","http://resolver.tudelft.nl/uuid:d338a9ff-af6e-4cc5-a153-9e8d95f4cf05","Atomic layer deposition of platinum clusters on titania nanoparticles at atmospheric pressure","Goulas, A.; Van Ommen, J.R.","","2013","We report the fabrication of platinum nanoclusters with a narrow size distribution on TiO2 nanoparticles using atomic layer deposition. With MeCpPtMe3 and ozone as reactants, the deposition can be carried out at a relatively low temperature of 250 degrees C. Our approach of working with suspended nanoparticles at atmospheric pressure gives precise control of the material properties, high efficiency of the use of the platinum precursor, and the possibility for large scale production of the nanostructured particles.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:b65710fd-66fa-4943-a4f5-74b83babe41b","http://resolver.tudelft.nl/uuid:b65710fd-66fa-4943-a4f5-74b83babe41b","Viscoelastic flow simulations through an array of cylinders","Gillissen, J.J.J.","","2013","Polymer solution flow is studied numerically in a periodic, hexagonal array of cylinders as a model for a porous medium. We use a lattice Boltzmann method supplemented by a polymer stress, where the polymers are modeled as finitely extensible, nonlinear, elastic dumbbells. The simulated, nonmonotonic behavior of the effective viscosity ?eff as a function of the Weissenberg number We is in qualitative agreement with experiments in the literature. An analytical model, which replaces the flexible polymers by rods and that replaces the flow field in the porous medium by a superposition of shear and elongation, correctly reproduces the simulated ?eff as a function of the polymer extensibility parameter b in the limit of large We.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:01501155-474a-4275-8651-25be92721b66","http://resolver.tudelft.nl/uuid:01501155-474a-4275-8651-25be92721b66","Dynamics of droplet breakup in a T-junction","Hoang, D.A.; Portela, L.M.; Kleijn, C.R.; Kreutzer, M.T.; Van Steijn, V.","","2013","The breakup of droplets due to creeping motion in a confined microchannel geometry is studied using three-dimensional numerical simulations. Analogously to unconfined droplets, there exist two distinct breakup phases: (i) a quasi-steady droplet deformation driven by the externally applied flow; and (ii) a surface-tension-driven three-dimensional rapid pinching that is independent of the externally applied flow. In the first phase, the droplet relaxes back to its original shape if the externally applied flow stops; if the second phase is reached, the droplet will always break. Also analogously to unconfined droplets, there exist two distinct critical conditions: (i) one that determines whether the droplet reaches the second phase and breaks, or it reaches a steady shape and does not break; and (ii) one that determines when the rapid autonomous pinching starts. We analyse the second phase using stop–flow simulations, which reveal that the mechanism responsible for the autonomous breakup is similar to the end-pinching mechanism for unconfined droplets reported in the literature: the rapid pinching starts when, in the channel mid-plane, the curvature at the neck becomes larger than the curvature everywhere else. The same critical condition is observed in simulations in which we do not stop the flow: the breakup dynamics and the neck thickness corresponding to the crossover of curvatures are similar in both cases. This critical neck thickness depends strongly on the aspect ratio, and, unlike unconfined flows, depends only weakly on the capillary number and the viscosity contrast between the fluids inside and outside the droplet.","breakup/coalescence; drops and bubbles; micro-/nano-fluid dynamics; microfluidics","en","journal article","Cambridge University Press","","","","","","","2014-02-05","Applied Sciences","Chemical Engineering","","","",""
"uuid:ddbc2271-24bf-4f84-9862-716a85141d4a","http://resolver.tudelft.nl/uuid:ddbc2271-24bf-4f84-9862-716a85141d4a","All-aqueous compartmentalized structures by microfluidics","Ziemecka, I.","Van Esch, J.H. (promotor); Kreutzer, M.T. (promotor); Van Steijn, V. (promotor)","2013","","","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:865e9591-dd0b-4dca-964e-61faaabf616e","http://resolver.tudelft.nl/uuid:865e9591-dd0b-4dca-964e-61faaabf616e","Turbulent drag reduction using fluid spheres","Gillissen, J.J.J.","","2013","Using direct numerical simulations of turbulent Couette flow, we predict drag reduction in suspensions of neutrally buoyant fluid spheres, of diameter larger than the Kolmogorov length scale. The velocity fluctuations are enhanced in the streamwise direction, and reduced in the cross-stream directions, which is similar to the more studied case of drag reduction using polymers. Despite these similarities, the drag reduction mechanism is found to originate in the logarithmic region, while the buffer region contributes to a slight drag increase, which is opposite to polymer-induced drag reduction. Another striking difference is the reduction of the turbulent energy at the large scales and an enhancement at the small scales.","drag reduction; multiphase and particle-laden flows; turbulent boundary layer","en","journal article","Cambridge University Press","","","","","","","2014-01-25","Applied Sciences","Chemical Engineering","","","",""
"uuid:e3ba1b09-e097-4f1e-bf06-0dbd0e78415d","http://resolver.tudelft.nl/uuid:e3ba1b09-e097-4f1e-bf06-0dbd0e78415d","Resonant optical absorption and defect control in Ta3N5 photoanodes","Dabirian, A.; Van de Krol, R.","","2013","In this study, we explore resonance-enhanced optical absorption in Ta3N5 photoanodes for water splitting. By using a reflecting Pt back-contact and appropriate Ta3N5 film thickness, the resonance frequency can be tuned to energies just above the bandgap, where the optical absorption is normally weak. The resonance results in a significant improvement in the photoanode's incident photon-to-current efficiency. The Ta3N5 films are made by high-temperature nitridation of Ta2O5. The nitridation time is found to be critical, as extended nitridation result in the formation of nitrogen vacancies through thermal reduction. These insights give important clues for the development of efficient (oxy)nitride-based photoelectrodes.","anodes; light absorption; nitridation; photochemistry; platinum; tantalum compounds; vacancies (crystal)","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:1516431c-0823-4a68-a235-21ff5e5cf9e1","http://resolver.tudelft.nl/uuid:1516431c-0823-4a68-a235-21ff5e5cf9e1","Hydrodynamics of Structured Slurry Bubble Columns","Hooshyar, N.","Mudde, R.F. (promotor)","2013","","","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:326a44e0-1e70-45df-9d18-b26dacbfd05a","http://resolver.tudelft.nl/uuid:326a44e0-1e70-45df-9d18-b26dacbfd05a","Interphasial energy transfer and particle dissipation in particle-laden wall turbulence","Zhao, L.; Andersson, H.I.; Gillissen, J.J.J.","","2013","Transfer of mechanical energy between solid spherical particles and a Newtonian carrier fluid has been explored in two-way coupled direct numerical simulations of turbulent channel flow. The inertial particles have been treated as individual point particles in a Lagrangian framework and their feedback on the fluid phase has been incorporated in the Navier–Stokes equations. At sufficiently large particle response times the Reynolds shear stress and the turbulence intensities in the spanwise and wall-normal directions were attenuated whereas the velocity fluctuations were augmented in the streamwise direction. The physical mechanisms involved in the particle–fluid interactions were analysed in detail, and it was observed that the fluid transferred energy to the particles in the core region of the channel whereas the fluid received kinetic energy from the particles in the wall region. A local imbalance in the work performed by the particles on the fluid and the work exerted by the fluid on the particles was observed. This imbalance gave rise to a particleinduced energy dissipation which represents a loss of mechanical energy from the fluid–particle suspension. An independent examination of the work associated with the different directional components of the Stokes force revealed that the dominating energy transfer was associated with the streamwise component. Both the mean and fluctuating parts of the Stokes force promoted streamwise fluctuations in the near-wall region. The kinetic energy associated with the cross-sectional velocity components was damped due to work done by the particles, and the energy was dissipated rather than recovered as particle kinetic energy. Componentwise scatter plots of the instantaneous velocity versus the instantaneous slip-velocity provided further insight into the energy transfer mechanisms, and the observed modulations of the flow field could thereby be explained.","multiphase and particle-laden flows; turbulence simulation","en","journal article","Cambridge University Press","","","","","","","2014-01-09","Applied Sciences","Chemical Engineering","","","",""
"uuid:ba788632-ae88-4791-a311-7d94035301b4","http://resolver.tudelft.nl/uuid:ba788632-ae88-4791-a311-7d94035301b4","A reliable, sensitive and fast optical fiber hydrogen sensor based on surface plasmon resonance","Perrotton, C.; Westerwaal, R.J.; Javahiraly, N.; Slaman, M.; Schreuders, H.; Dam, B.; Meyrueis, P.","","2013","We report for the first time on the experimental response of a Surface Plasmon Resonance fiber optic sensor based on wavelength modulation for hydrogen sensing. This approach of measuring the hydrogen concentration makes the sensor insensitive to intensity fluctuations. The intrinsic fiber sensor developed provides remote sensing and enables the possibility of multi-points sensing. The sensor consists of a multilayer of 35 nm Au / 180 nm SiO2/ Pd deposited on a step- index multimode fiber core. The sensitivity and selectivity of the sensor are optimal at a Pd thickness of 3.75 nm. The sensor is sensitive to a hydrogen concentration ranging between 0.5 and 4% H2 in Ar, with a response time less than 15 s.","","en","journal article","Optical Society of America","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:b5f7139a-f58b-4d5a-8ec3-7c7f4049fcc2","http://resolver.tudelft.nl/uuid:b5f7139a-f58b-4d5a-8ec3-7c7f4049fcc2","The Impact of MOF Flexibility Using an Amino Functionalized MOF in Mixed Matrix Membranes for CO2 Separation","Zornoza, B.; Rodenas, T.; Tellez, C.; Coronas, J.; Gascon, J.; Kapteijn, F.","","2012","","","en","journal article","Elsevier","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:dcdfd4e0-b090-4e20-9c13-da0dd5a00e55","http://resolver.tudelft.nl/uuid:dcdfd4e0-b090-4e20-9c13-da0dd5a00e55","Precise positioning of functional elements in nanopatterns by self-assembly","Gobbo, C.","Van Esch, J. (promotor)","2012","","","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:ec2e7aa9-c197-4f4f-8d79-895e8d57f352","http://resolver.tudelft.nl/uuid:ec2e7aa9-c197-4f4f-8d79-895e8d57f352","Pt/Al2O3 Catalyzed 1,3-Propanediol Formation from Glycerol using Tungsten Additives","Ten Dam, J.; Djanashvili, K.; Kapteijn, F.; Hanefeld, U.","","2012","Screening of four commercial catalysts (Pt/Al2O3, Pt/SiO2, Pd/Al2O3, and Pd/SiO2) and four acidic additives (hydrochloric, tungstic, phosphotungstic, and silicotungstic acids) shows that the combination of a platinum hydrogenation catalyst with tungsten containing acidic additives yields 1,3-propanediol from aqueous glycerol. The performance of the best catalytic system Pt/Al2O3 with silicotungstic acid as an additive was optimized by experimental design, capturing the influence of reaction time, glycerol concentration, acid concentration, pressure, and temperature on the formation of 1,3-propanediol from glycerol. High 1,3-propanediol yield in an aqueous batch system can be achieved (49?% conversion, 28?% selectivity) with excellent 1,3-propanediol to 1,2-propanediol ratios. A mechanistic interpretation is given for this bifunctional system, supported by the relative stability of 1,3-propanediol in comparison with 1,2-propanediol under the chosen reaction conditions.","elimination; glycerol; heterogeneous catalysis; hydrogenation; hydrogenolysis; tungsten","en","journal article","Wiley-VCH Verlag","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:55930a1e-61ba-4bec-8fd8-0d96eaca5db3","http://resolver.tudelft.nl/uuid:55930a1e-61ba-4bec-8fd8-0d96eaca5db3","Multiscale Structure-Performance Relationships in Supported Palladium Catalysis for Multiphase Hydrogenations","Bakker, J.J.W.","Moulijn, J.A. (promotor); Kapteijn, F. (promotor); Kreutzer, M.T. (promotor)","2012","The performance of heterogeneous catalysts in multiphase reactions in general is governed by different types of extrinsic and intrinsic structural effects on all length scales, i.e., on the macro- (m to cm), meso- (mm to µm), and microlevel (nm). This PhD research, with a catalysis-engineering approach, focused on several of these multiscale structure-performance relationships of supported palladium (Pd) catalysts applied in, industrially important, multiphase hydrogenations. The structure-performance relationships were studied in various batch and continuous reactors of which most are related to important topics in process intensification such a monolithic reactors and flow chemistry. The performance of monolithic Pd catalysts was enhanced by combining a new type of structured highly porous monoliths with a pressure pulse generating gas-liquid flow (i.e., Taylor flow). This induced a convective flow inside the ‘open’ monolith walls thereby enhancing the mass exchange with the Pd catalyst. This favourable result opens the avenue to higher catalyst loadings without increasing internal mass transfer limitations. Furthermore, a proof of concept study showed that a cheap and readily available gas chromatography capillary, wall-coated with an alumina-supported Pd catalyst and operated in the Taylor flow regime, can be used to synthesize high-value products and to rapidly produce (visual) information about catalytic hydrogenations. This Pd capillary flow device is an excellent alternative for expensive microchip technology and bulky round-bottom flasks. Finally, the intrinsic property of Pd to absorb hydrogen into its crystal lattice was shown to have a strong influence on its performance in the hydrogenation of aromatic nitriles. The transformation into stable Pd ?-hydride above a certain threshold hydrogen pressure induced a persistent change in activity and by-product selectivity.","Heterogeneous catalysis; Hydrogenation; Structured reactors; Palladium; Monoliths; Flow chemistry; Catalyst performance; Nitriles; Azides; Alkynes; Taylor flow; Residence time distribution; process intensification; Multiphase hydrogenation","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:30da8c21-2e45-45e4-8c84-b52e3389ccd4","http://resolver.tudelft.nl/uuid:30da8c21-2e45-45e4-8c84-b52e3389ccd4","Breaking the Fischer–Tropsch synthesis selectivity: Direct conversion of syngas to gasoline over hierarchical Co/H-ZSM-5 catalysts","Sartipi, S.; Parashar, K.; Makkee, M.; Gascon, J.; Kapteijn, F.","","2012","We report the combination of Fischer–Tropsch catalyst with acid functionality in one single catalyst particle. The resulting bifunctional catalyst is capable of producing gasoline range hydrocarbons from synthesis gas in one catalytic step with outstanding activities and selectivities.","","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:f4ed61b6-fdc4-4d6c-af47-b896f7025d82","http://resolver.tudelft.nl/uuid:f4ed61b6-fdc4-4d6c-af47-b896f7025d82","Energy spectra and turbulence generation in the wake of magnetic obstacles","Kenjeres, S.","","2012","Numerical simulations and analysis of flow and heat transfer of an electrically conducting fluid past magnetic obstacles are reported. We studied the channel flow configuration with electrically and thermally insulated horizontal walls containing a single or multiple (two or three) magnetic dipoles. Different values of the interactive parameter 0 ? N ? 50 and with a fixed value of Re = 103 are simulated. Detailed insights into energy spectra and turbulence generation in the wake of magnetic obstacles are provided. Although the temperature is a passive scalar, strong dissimilarities between mechanisms of production of the turbulent kinetic energy and temperature variance are observed. The long-term averaged second moments of velocity and temperature revealed the presence of anisotropic turbulence and countergradient diffusion of turbulent heat fluxes. It is concluded that configurations with multiple magnetic dipoles can be utilized in practical applications where the local generation of turbulence and intensification of mixing and heat transfer are required.","channel flow; electrohydrodynamics; external flows; flow simulation; heat transfer; magnetohydrodynamics; method of moments; mixing; turbulent diffusion; wakes","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:83b1d146-55e1-4b7b-8993-6cc88791f5bf","http://resolver.tudelft.nl/uuid:83b1d146-55e1-4b7b-8993-6cc88791f5bf","Catalytic dehydrogenations of ethylbenzene to styrene","Nederlof, C.","Kapteijn, F. (promotor); Makkee, M. (promotor)","2012","This research work on the catalytic dehydrogenation of ethylbenzene (EB) to styrene (ST) had a primary goal of developing improved catalysts for dehydrogenation processes both in CO2 as well as with O2 that can compete with the conventional dehydrogenation process in steam. In order to achieve this goal, all these processes need to be properly understood. After having worked on catalytic dehydrogenation reactions in steam, in nitrogen, in carbon dioxide and with oxygen, it appeared that these reactions show many parallels. Carbon deposit formation on the catalyst is closely connected to all dehydrogenation reactions of ethylbenzene to styrene. They always go hand-in-hand and cannot be separated. Yes, these coke deposits will also be a cause of deactivation. But foremost the coke is an active ingredient of the ‘catalyst’ in the ethylbenzene (EB) dehydrogenation reactions. In the oxidative dehydrogenation it is without any doubt that the selective dehydrogenation reaction proceeds over the deposited coke on the catalyst or support. The dehydrogenations experiments in CO2 or N2 in this thesis and characterizations of the samples also clearly show the involvement of coke in the dehydrogenation reaction to styrene (ST). Also in the direct dehydrogenation in steam, coke deposits play an important role in the dehydrogenation, based on literature and our experiments presented in this thesis (Ch. 2). By applying catalyst- and technology developments, a competitive process with O2 appears to be within reach. This process applies a P/SiO2 catalyst and staged feeding of O2, whereby the stability of the catalyst as a function of the time on stream still remains a topic of concern.","Ethylbenzene; Styrene; Dehydrogenation; oxidative; carbon dioxide; steam; coke; staged feeding; water gas shift; catalysis","en","doctoral thesis","BOXPress","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:c95df5af-2ce4-4c61-8901-71d7016702a4","http://resolver.tudelft.nl/uuid:c95df5af-2ce4-4c61-8901-71d7016702a4","Particle Imaging and Flow Visualization of In-situ TEM Nanoreactors","Puspitasari, I.; Saputra, P.; Morana, B.; Mele, L.; Santagata, F.; Creemer, J.F.; Kapteijn, F.; Kooyman, P.J.","","2012","","","en","journal article","Cambridge University Press","","","","","","","2013-11-23","Applied Sciences","Chemical Engineering","","","",""
"uuid:9442760e-ab58-4faf-8818-43f05e6dd536","http://resolver.tudelft.nl/uuid:9442760e-ab58-4faf-8818-43f05e6dd536","Current-induced nanogap formation and graphitization in boron-doped diamond films","Seshan, V.; Arroyo, C.R.; Castellanos-Gomez, A.; Prins, F.; Perrin, M.L.; Janssens, S.D.; Haenen, K.; Nesládek, M.; Sudhölter, E.J.R.; De Smet, L.C.P.M.; Van der Zant, H.S.J.; Dulic, D.","","2012","A high-current annealing technique is used to fabricate nanogaps and hybrid diamond/graphite structures in boron-doped nanocrystalline diamond films. Nanometer-sized gaps down to ?1?nm are produced using a feedback-controlled current annealing procedure. The nanogaps are characterized using scanning electron microscopy and electronic transport measurements. The structural changes produced by the elevated temperature, achieved by Joule heating during current annealing, are characterized using Raman spectroscopy. The formation of hybridized diamond/graphite structure is observed at the point of maximum heat accumulation.","annealing; boron; diamond; elemental semiconductors; energy gap; graphite; graphitisation; nanofabrication; nanostructured materials; Raman spectra; scanning electron microscopy","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:6db9a759-a930-482b-a5f5-0ccbeafb3e58","http://resolver.tudelft.nl/uuid:6db9a759-a930-482b-a5f5-0ccbeafb3e58","Self-similar drag reduction in plug-flow of suspensions of macroscopic fibers","Gillissen, J.J.J.; Hoving, J.P.","","2012","Pipe flow experiments show that turbulent drag reduction in plug-flow of concentrated suspensions of macroscopic fibers is a self-similar function of the wall shear stress over the fiber network yield stress. We model the experimental observations, by assuming a central fiber network plug, whose radius is determined by the yield stress. According to the model the plug constrains the size of the turbulent eddies in the surrounding annulus, with the effect of a reduced friction factor as compared to Newtonian flow.","boundary layer turbulence; drag reduction; fibres; fractals; pipe flow; shear turbulence; suspensions; yield stress","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:30cb1688-6c85-4815-af77-6a5d76e88c11","http://resolver.tudelft.nl/uuid:30cb1688-6c85-4815-af77-6a5d76e88c11","Fluorinated building blocks for next-generation polymer electrolyte membrane fuel cells","Wadekar, M.N.","Picken, S.J. (promotor); Jager, W.F. (promotor)","2012","The purpose of this thesis is to design, create and study basic building blocks for the construction of self-assembled nanostructured electrodes and membranes for PEMFC. The research described deals with the synthesis of polymerizable fluorosurfactant (1) and its non-polymerizable analogue (2) and the study of their self-assembly properties. Similarly, the (co)polymerization behavior of 1 and the polymer properties are described. The design of the polymerizable fluorosurfactant, 1 and the synthetic routes to obtain the desired functionalities and molecules are discussed in Chapter 1. The reaction pathways to create –SO3¯ as well as styryl groups are described. The syntheses of compounds 1 and 2 are described in Chapter 3. The key reactions viz. the copper mediated cross-coupling reactions to attach fluorocarbon molecules to aromatic moieties and the Wittig reactions to obtain styryl functionalities are described. The micellization properties of 1 and 2 are deliberated in Chapter 4. Unlike, several fluorinated sulfonic acid salt surfactants, both surfactants were soluble in water at room temperature. This is due to their hybrid character and the presence of bulky aromatic moieties in the surfactant tails. Both compounds 1 and 2 display comparable cmc values ~30 mM, and form spherical shaped micelles. The Gibbs energy of micellization of 1 and 2 are in the range of -24 to -26 kJ mol-1. The micelles were characterized by low aggregation numbers, in the range of 25 to 35. Entropy driven micelle formation and a U-shaped relation was observed between the Gibbs energy of micellization and experiment temperatures were observed. The LLC phase behavior of 2-water mixtures is described in Chapter 5 and two lyotropic phases in the range of 63 to 84 wt% 2 were identified and investigated. An unprecedented supramolecular columnar (Cs) phase made up by self-assembly of “Leek” shaped aggregates was observed in the concentration regime between 63 and 70 wt% 2, and a lamellar (L?) phase was observed from 70 to 84 wt% 2. The “Leeks” were shown to be formed by wrapping up of the 2-water bilayers. An interdigitated and/or tilted assembly of 2 molecules was suggested for both LLC phases based on SAXS data analysis. Homo and copolymers of compound 1 with model the perfluorinated comonomer, 3 or styrene were prepared by free radical method, and are discussed in Chapter 6. The strong incompatability of ionic groups and fluorocarbon moieties of poly-1 severely hampered the molecular weight determination by GPC. Homopolymer of 3 is insoluble in most of the polar as well as nonpolar solvents. 19F NMR experiments revealed that there are inhomogeneities within the copolymer samples synthesized from 1 and 3 because of the large compositional drifts with respect to the comonomer feed ratios occurred during the polymerization. Thermal stabilities of all polymers were slightly better compared to the thermal stability of polystyrene. Cryo-TEM P1-water solution revealed the formation of elongated worm-like micelles with ~5 nm diameter and length of up to 400 nm. These micelles were suggested to be formed by the lateral self- assembly of 2-3 extended polymer chains of P1.","polymerizable fluorosurfactant; PEMFC; self-assembly; nanostructured","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:89fd8b1d-e47b-4fd0-ac14-8d871456a684","http://resolver.tudelft.nl/uuid:89fd8b1d-e47b-4fd0-ac14-8d871456a684","Rheological properties of magneto-responsive copolymer gels","An, H.","Picken, S.J. (promotor)","2012","New magneto rheological systems that respond mechanically to external homogeneous magnetic fields, namely, physically cross-linked magneto rheological (MR) gels, were synthesized and investigated. Various aspects of the rheological behavior were considered such as linear viscoelastic response for various pre-aligned sample geometries, transient dynamic response under stepwised magnetic field, nonlinear rheology under large amplitude oscillation shear (LAOS) and cyclic stress hardening behavior in the presence of magnetic fields. The rheological properties are heavily influenced by the fact that the particle network still has some freedom to locally rearrange under magnetic field and/or shear, as compared to MR elastomers and MR fluids. Direct microscopic observation of structure rearrangements under magnetic field and shear suggest that the mechanical properties of the surrounding gel matrix are also modified during rearrangement, resulting in nonhomogeneous gel matrix and highly non-linear overall MR gel response. It is difficult to explain the particle rearrangement by a simple combination of the magnetic forces and average elastic forces from the pure gel matrix. Our approach of direct observation of local rearrangements under magnetic field and shear may help theoreticians to develop highly non-linear models that are apparently needed to describe local and macroscopic response of these systems.","","en","doctoral thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:a95f9245-8ff2-4507-91cb-3363b3e6cea6","http://resolver.tudelft.nl/uuid:a95f9245-8ff2-4507-91cb-3363b3e6cea6","Micro-imaging of transient guest profiles in nanoporous host systems of cylindrical symmetry","Binder, T.; Hibbe, F.; Chmelik, C.; Kärger, J.; Martinez-Joaristi, A.; Gascon, J.; Kapteijn, F.; Ruthven, D.","","2012","Nanoporous host materials giving rise to transient guest profiles of cylindrical symmetry during molecular uptake and release are shown to provide particularly advantageous conditions for the study of guest diffusion by micro-imaging. Considering zeolites of structure type DDR (Deca-dodecasil 3R) as a host system and short-chain length hydrocarbons as guest molecules, the benefits thus attainable in micro-imaging studies using interference microscopy are shown to include the determination of transient concentration profiles with improved accuracy, the option to overcome the disturbing impact of surface imperfections, and easy access to concentration-dependent diffusivities.","diffusion; nanoporous materials; organic compounds; zeolites","en","journal article","American Institute of Physics","","","","","","","","Electrical Engineering, Mathematics and Computer Science","ChemE/Chemical Engineering","","","",""
"uuid:ac907049-96d0-4304-a5d1-5b2661741ab1","http://resolver.tudelft.nl/uuid:ac907049-96d0-4304-a5d1-5b2661741ab1","Photogeneration Diffusion and Decay of Charge Carriers in Quantum-Dot Solids","Gao, Y.","Siebbeles, L.D.A. (promotor); Van der Zant, H.S.J. (promotor)","2012","Semiconductor nanocrystals (NCs), which can have a variety of sizes, shapes and chemical compositions, will be a large and important family of future advanced materials.This thesis focuses on colloidal semiconductor NC solids, also called quantum-dot (QD) solids, which are promising materials for many applications, such as photo-detectors, field-effect transistors, solar cells, light-emitting diodes, and lasers. The thesis presents studies on the charge carrier properties of PbSe QD solids, going through the charge carrier photogeneration, thermalization, diffusion and decay, which together are the ``life and fate'' of the charge carriers. Diverse tools have been utilized to reveal the whole picture of the ``life and fate''. The most important ones are: femtosecond transient absorption spectroscopy (TA) (Chapter 2, 3, 4), picosecond Terahertz spectroscopy (THz) (Chapter 2), the nanosecond time-resolved microwave conductivity technique (TRMC) (Chapter 2-5), and Monte Carlo simulations (Chapter 4).","quantum dot; Auger Decay; charge carrier conductivity; semiconductor","en","doctoral thesis","Posen & Looijen","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:5c406756-cf5c-417a-929e-bd503ea95381","http://resolver.tudelft.nl/uuid:5c406756-cf5c-417a-929e-bd503ea95381","Hydrogen storage in metal organic frameworks","Yang, J.","Dingemans, T.J. (promotor); Mulder, F.M. (promotor)","2012","","","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:356c7cd7-9fb6-45cd-9369-4355354e8893","http://resolver.tudelft.nl/uuid:356c7cd7-9fb6-45cd-9369-4355354e8893","New composite PEM for high temperature fuel cells (abstract)","Cordova, M.E.; Sleczka, A.E.; Kelder, E.M.; Picken, S.J.","","2012","","","en","conference paper","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:21fa8237-f1ac-424f-b62e-5a47bf842523","http://resolver.tudelft.nl/uuid:21fa8237-f1ac-424f-b62e-5a47bf842523","Performance Limiting Factors in Co-Pi Catalyzed, Spray-Deposited BiVO4 Photoanodes (abstract)","Abdi, F.F.; Firet, N.; Van de Krol, R.","","2012","","","en","conference paper","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:59bb1686-58b9-4523-aec0-694fb3c94afc","http://resolver.tudelft.nl/uuid:59bb1686-58b9-4523-aec0-694fb3c94afc","Effect of Cr-oxide partial coating on the electrochemical behavior of thin film high-voltage spinel (abstract)","Garcia-Tamayo, E.; Ros, J.; Kaas, A.; Fredon, R.; Kelder, E.M.","","2012","","","en","conference paper","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:7698bf0f-0f82-4ec6-9be8-59754ab18f19","http://resolver.tudelft.nl/uuid:7698bf0f-0f82-4ec6-9be8-59754ab18f19","Maximum drag reduction simulation using rodlike polymers","Gillissen, J.J.J.","","2012","Simulations of maximum drag reduction (MDR) in channel flow using constitutive equations for suspensions of noninteracting rods predict a few-fold larger turbulent kinetic energy than in experiments using rodlike polymers. These differences are attributed to the neglect of interactions between polymers in the simulations. Despite these inconsistencies the simulations correctly reproduce the essential features of MDR, with universal profiles of the mean flow and the shear stress budgets that do not depend on the polymer concentration.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:e217d888-bbce-480f-b73d-3e5aa9bba736","http://resolver.tudelft.nl/uuid:e217d888-bbce-480f-b73d-3e5aa9bba736","Lignocellulosic Biomass Conversion into Platform Chemicals in Molten Salt Hydrate Media","Li, J.","Moulijn, J.A. (promotor); Makkee, M. (promotor)","2012","","","en","doctoral thesis","Delft University of Technology","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:b2384bea-872f-4e92-b13c-53afe14af297","http://resolver.tudelft.nl/uuid:b2384bea-872f-4e92-b13c-53afe14af297","Nano LEGO®","Kowlgi, N.K.K.","Picken, S.J. (promotor); Koper, G.J.M. (promotor)","2012","Self-Assembly has predominantly been nature's unique tool for building remarkable entities. This thesis shows how this versatile tool can be utilised for building devices that are useful to mankind. Starting with advanced fuel cells which produce clean energy in a highly efficient way; continuing on to carbon nano networks which are one of the strongest materials known to man; and finally supermagnets which have the potential to revolutionise the medical and electronics industry.","Self-Assembly; nano; nanoparticle; fuel cell; carbon nano network; supermagnet","en","doctoral thesis","","","","","","","","2012-12-14","Applied Sciences","Chemical Engineering","","","",""
"uuid:542098cd-ca8e-408b-a803-2d35119d3b74","http://resolver.tudelft.nl/uuid:542098cd-ca8e-408b-a803-2d35119d3b74","Selective Photocatalytic Reduction of NOx with Fe-doped TiO2: A New Approach Towards Photocatalyst Design","Wu, Q.","Dam, B. (promotor); Van de Krol, R. (promotor)","2012","Conventional TiO2 based photocatalysts oxidize NOx to nitrates which do not automatically desorb and have to be washed away from the catalyst surface. To avoid this, the research described in this thesis aims to design new photocatalysts that can photo-reduce NO into N2 and O2. Previous efforts in the literature have shown that catalysts prepared by depositing isolated titanium oxide clusters (TiO4, tetrahedra) inside the cavities of zeolite-Y using ion beam implantation technology show high activity for N2 and O2 formation. However, large scale application of zeolites using ion beam technology is economically unattractive. We aim to create a large number of oxygen vacancies in TiO2 to ‘artificially’ create TiO4 species. The basic principles of photocatalysis and the overall approach taken in this thesis have been described in Chapter 1. The following chapters describe how a series of Fe-doped TiO2 nanoparticles were prepared and systematically investigated for creating and stabilizing oxygen vacancies for changing the photocatalytic selectivity from the oxidation to the reduction of NO. The synthesis and characterization of Fe-doped TiO2 nanoparticles with different Fe concentrations have been described in Chapter 2. A simple, template free sol-gel method was used for synthesizing pure TiO2 and Fe-doped TiO2 nanoparticles. After drying the as-synthesized samples at 373 K , most iron is located at the surface. However, after firing at 773 K, the iron diffuses into the bulk of the TiO2 up to a 10% Fe doping concentration. No evidence for phase segregation was found. For the XRD patterns, the anatase (101) peak position shifts towards smaller d values with increasing Fe concentration. The observed shift is linear with the amount of Fe. This is in accordance with Vegard’s law and this indicates the incorporation of Fe into TiO2 lattice. However, the decrease in lattice constant is contrary to what one might initially expect, since the radius of Fe3+ ions (0.65 ?) is slightly larger than Ti4+ radius (0.61 ?) for six-fold coordinated ions. The formation of Fe4+, can be ruled out from Fe K-edge XANES spectra. Instead, we attribute the decrease in lattice spacing to a high concentration of oxygen vacancies. These oxygen vacancies are formed in order to compensate the effective negative charge of the Fe acceptor dopant. The presence of oxygen vacancies is further confirmed by Raman spectra. A similar linear shift at the strongest anatase (Eg mode) is observed by comparing Fe-doped TiO2 with reduced TiO2-x from Parker et al.. This confirms that oxygen vacancies are indeed present in our material. The surprisingly high solubility of Fe is mainly due to the fact that the ionic radii of Ti4+ and Fe3+ are nearly equivalent. In addition, there is an energetically favorable Coulomb attraction between the negatively charged Fe acceptor and the positively charged oxygen vacancies. Intriguingly, XANES measurements indicate that the coordination geometry of Ti is changed from octahedral to tetrahedral at high oxygen vacancy concentrations. The tetrahedrally coordinated TiO4 clusters are presumably present at the surface, where the lattice symmetry constraints are more relaxed. The phenomenon that the coordination geometry can be changed by creating large number of oxygen vacancies provides a new way for designing highly selective photocatalyst. The first step of photocatalysis, NO adsorption and release at Fe3+ sites in Fe/TiO2 nanoparticles, is studied by in-situ Diffuse Reflection Infrared Fourier Transformed spectroscopy coupled with Mass Spectrometry (DRIFT, Chapter 3). In this chapter, Fe3+ ions are found to be highly effective NO adsorption sites after in-situ heat treatment. Upon exposure to trace amounts of H2O, up to ~ 89 ?mol/g NO can be released from the surface of 10% Fe-doped TiO2. This can be explained by the much larger dipole moment of H2O as compared to that of NO. In addition, the phenomenon that adsorbed H2O can effectively block NO adsorption explains why Fe3+-NO species are often not observed. In addition, a new IR band at 1840 cm-1 is assigned to the stretch vibration of N-O bond over Fe3+ site. This is the first clear evidence for the presence of Fe3+-NO on Fe-doped TiO2 nanoparticles. While easy replacement of NO by H2O molecules is clearly undesirable for practical use of photocatalysts, the controllable adsorption and release of NO may lead to new NO storage and release applications based on Fe-doped TiO2. In order to identify the contribution of oxygen vacancies to catalytic selectivity, photocatalytic measurements of pure TiO2 after annealing in air (unreduced TiO2) and in a 2% H2/Ar atmosphere (reduced TiO2) are compared. The photocatalytic activities are now evaluated by a combination of an NOx analyzer and gas chromatography (GC). With UV light irradiation, 1% NO photo-reduction was detected after reaching catalytic equilibrium, while no photo-reduction can be found for unreduced TiO2. This indicates that oxygen vacancies contribute to photo-reduction selectivity. To further prove the role of oxygen vacancies, Fe doped TiO2 with different oxygen vacancy concentrations are further evaluated for NO decomposition. For 1% Fe-doped TiO2, 3% NO photo-reduction is found in air after achieving the photocatalytic equilibrium. The reduction activity is a three times improvement over reduced TiO2 at the same experimental conditions. Furthermore, a 4.5% NO photo-reduction is found in pure N2 atmosphere. This is a higher efficiency than that in air. This strongly supports our interpretation of the photo-reduction process in Fe-doped TiO2. In this case, the formation of gas phase NO2 is now completely suppressed. This is consistent with our observation from in-situ DRIFT spectra. In addition, we find that the photoreduction activity increases with an increasing concentration of oxygen vacancies. The direct evidence for NO photo-reduction is provided by GC measurements. For 1% Fe-doped TiO2, almost the same amount of N2 and O2 are produced after reaching catalytic equilibrium. This excludes the possibility of N2O formation. Pure TiO2 shows no formation of N2 and O2 at the same experimental conditions. Two possible explanations are provided for the formation of N2 and O2 in chapter 4. One of the possible explanations is that a small amount of tetrahedrally coordinated Ti-oxides are formed. However, the formation of tetrahedrally coordinated Ti would require two oxygen vacancies to be present on the same Ti sites. As positively charged oxygen vacancies would repel with each other and very low oxygen vacancy concentrations are present up on 1% Fe doping, the formation of tetrahedrally coordinated Ti is not very likely. A more likely explanation is that oxygen vacancies may act as catalytic centers for trapping O atom of NO molecules, thus lowering the bond energy of NO. The trapped nitric molecules have no net charges. This allows mobile oxygen vacancies to closely approach these species, after which a second NO species can be adsorbed directly next to the first one. When both nitrogen end-species combine to form N2, the energy released may easily knock out the trapped oxygen species, resulting in the release of O2. Although the mechanism of photocatalytic reduction is still not yet exactly clear, the contribution of oxygen vacancies to NO photo-reduction selectivity provides a promising way for designing new and highly selective photocatalysts. To confirm the reaction mechanism from Chapter 4, the photon-assisted NO adsorption-desorption and reaction species on the surface of the samples are investigated in Chapter 5. The combination of DRIFT spectra and on-line NOx analysis confirms that Fe dopant can actually suppress the formation of NO2 during photocatalytic process. The suppression of NO2 formation is caused due to the reduction of Fe3+ to Fe2+ by photo-generated electrons. In addition, the photon-assisted NO adsorption shows a new IR band at 1805 cm-1, which is attributed to N=O stretch vibration in a Fe2+-(NO)2 complex. After turning off the UV light, on-line NOx analysis shows that the NO desorbs again. XPS data indicates that this coincides with the re-oxidation of Fe2+ to Fe3+ presumably by photo-generated hydroxyl radicals. The re-oxidation triggers the release of NO due to its weak bonding to Fe3+, which is consistent with the results presented in chapters 3 and 4.","Fe doped TiO2; photocatalysis; oxygen vacancies; photo-reduction; NOx","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:9e217367-b237-47c0-9ebe-9a49ee3a6265","http://resolver.tudelft.nl/uuid:9e217367-b237-47c0-9ebe-9a49ee3a6265","Experimental study of particle-driven secondary flow in turbulent pipe flows","Belt, R.J.; Daalmans, A.C.L.M.; Portela, L.M.","","2012","In fully developed single-phase turbulent flow in straight pipes, it is known that mean motions can occur in the plane of the pipe cross-section, when the cross-section is non-circular, or when the wall roughness is non-uniform around the circumference of a circular pipe. This phenomenon is known as secondary flow of the second kind and is associated with the anisotropy in the Reynolds stress tensor in the pipe cross-section. In this work, we show, using careful laser Doppler anemometry experiments, that secondary flow of the second kind can also be promoted by a non-uniform non-axisymmetric particle-forcing, in a fully developed turbulent flow in a smooth circular pipe. In order to isolate the particle-forcing from other phenomena, and to prevent the occurrence of mean particle-forcing in the pipe cross-section, which could promote a different type of secondary flow (secondary flow of the first kind), we consider a simplified well-defined situation: a non-uniform distribution of particles, kept at fixed positions in the ‘bottom’ part of the pipe, mimicking, in a way, the particle or droplet distribution in horizontal pipe flows. Our results show that the particles modify the turbulence through ‘direct’ effects (associated with the wake of the particles) and ‘indirect’ effects (associated with the global balance of momentum and the turbulence dynamics). The resulting anisotropy in the Reynolds stress tensor is shown to promote four secondary flow cells in the pipe cross-section. We show that the secondary flow is determined by the projection of the Reynolds stress tensor onto the pipe cross-section. In particular, we show that the direction of the secondary flow is dictated by the gradients of the normal Reynolds stresses in the pipe cross-section, and . Finally, a scaling law is proposed, showing that the particle-driven secondary flow scales with the root of the mean particle-forcing in the axial direction, allowing us to estimate the magnitude of the secondary flow.","multiphase and particle-laden flows; turbulent flows","en","journal article","Cambridge University Press","","","","","","","2013-08-24","Applied Sciences","Chemical Engineering","","","",""
"uuid:146c65c0-9602-45b6-a9db-503e57ecabc1","http://resolver.tudelft.nl/uuid:146c65c0-9602-45b6-a9db-503e57ecabc1","Mechanics of Granular Materials: Constitutive Behavior and Pattern Transformation","Göncü, F.","Luding, S. (promotor); Schmidt-Ott, A. (promotor)","2012","From pharmaceutical to mining or traveling desert dunes to earthquakes, granular materials are at the heart of many industries and natural phenomena. Improving the efficiency of the machines handling them or, constructing safer buildings requires a critical understanding of their behavior. However, this is not a straightforward task as opposed to what one might think due to the abundance of particulate matter. From a fundamental point of view, it has been only recently realized that they cannot be easily classified as a solid or liquid or even a gas as they are able to mimic all of these states under slightly different conditions. The challenge of the scientific research today, is to establish the link between the collective behavior and properties of individual particles composing granular materials.Such a relation would enable to characterize them with only a few parameters in contrast to billions of particles typically found in practice. In the first part of this thesis, we study the mechanical behavior of idealized sphere packings with discrete element simulations. The polydispersity and coefficient of friction of the particles are varied systematically to characterize their influence on the macroscopic stress strain response. In isotropically deformed packings, the critical volume fraction marking the transition from a solid to fluid like state increases with polydispersity, whereas it decreases with the coefficient of friction. The coordination number, i.e. average number of contact per particle, is discontinuous at this density. During decompression it drops from its isostatic value to zero and obeys a power law at higher volume fractions. The effect of polydispersity on the pressure is determined by the ratio of critical volume fraction and the contact density which is equal to the trace of the fabric times a correction factor that depends only on the moments of the particle size distribution. Using the micromechanical definition of the stress tensor, we derive an incremental constitutive model for the pressure which includes changes of fabric. With one fit parameter the linear regime of lower pressure is described, while with two parameters, the model captures well the non-linear pressure evolution in isotropically deformed polydisperse, frictionless and frictional packings. Anisotropic deformations are studied with triaxial test simulations. The shear strength of the packings is measured by the deviatoric stress ratio which first increases then saturates with increasing particle coefficient of friction. Volumetric strain also depends on the particle friction albeit in a non monotonic way. The maximum compaction after which packings start to dilate, is achieved at a relatively small coefficient of friction. The stress strain response depends indirectly on the polydispersity which determines initial packing conditions. When initially the volume fraction is fixed, the pressure as well as the shear strength decrease with polydispersity. The opposite is observed when the initial pressure is imposed, although the effect of polydispersity on the stress-strain behavior is less significant in this case. Finally, a hypoplastic constitutive model is calibrated with simulation results and the resulting material coefficients are related to particle properties. Most granular materials are amorphous and disordered as realized up to now. However,crystal structures can be built by placing uniform particles on a regular lattice. The second part of the thesis is about pattern transformation in two-dimensional granular crystals composed of bi-disperse soft and hard cylindrical particles. We show with experiments and simulations that upon uniaxial compression the particles undergo structural rearrangements from an initial square to hexagon-like lattice. It is found that the characteristics of the transformation strongly depend on the size ratio of the particles rather than their material properties. If the ratio is small enough the transformation is homogeneous and practically reversible. The band structure of the granular crystal changes due to the pattern transformation. Using a linearized contact force model, we compute the dispersion relation at different levels of deformation and show that band gaps open and close as the structure of the crystal changes.This could find applications in tunable acoustic devices such as filters or vibration isolators. In short, this thesis concerns the mechanics of granular materials subject to different modes of deformation. The constitutive behavior of disordered sphere packings and pattern transformation in regular arrays of cylinders have been studied.","granular materials; pattern transformation; discrete element method","en","doctoral thesis","Ipskamp Drukkers","","","","","","","2012-10-02","Applied Sciences","Chemical Engineering","","","",""
"uuid:15a9036f-988d-4de9-933b-220868546659","http://resolver.tudelft.nl/uuid:15a9036f-988d-4de9-933b-220868546659","Thermo-physical characterization of Pharmacoatr 603, Pharmacoatr 615 and Mowiolr 4-98","Perfetti, G.; Alphazan, T.; Wildeboer, W.J.; Meesters, G.M.H.","","2012","","formulation; HPMC; PVA; adsorption; desorption; thermo-physical analysis","en","journal article","Springer-Verlag","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:4310f877-1bf6-403b-bf41-8261d9effa74","http://resolver.tudelft.nl/uuid:4310f877-1bf6-403b-bf41-8261d9effa74","Silver-functionalized carbon nanofiber composite electrodes for ibuprofen detection","Manea, F.; Motoc, S.; Pop, A.; Remes, A.; Schoonman, J.","","2012","The aim of this study is to prepare and characterize two types of silver-functionalized carbon nanofiber (CNF) composite electrodes, i.e., silver-decorated CNF-epoxy and silver-modified natural zeolite-CNF-epoxy composite electrodes suitable for ibuprofen detection in aqueous solution. Ag carbon nanotube composite electrode exhibited the best electroanalytical parameters through applying preconcentration/differential-pulsed voltammetry scheme.","carbon nanofiber composite electrodes; Ssilver particles; electrochemical determination; ibuprofen","en","journal article","SpringerOpen","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:a3acd125-e859-4b9e-a02a-b7320c23cdcc","http://resolver.tudelft.nl/uuid:a3acd125-e859-4b9e-a02a-b7320c23cdcc","Thermodynamic properties, hysteresis behavior and stress-strain analysis of MgH2 thin films, studied over a wide temperature range","Pivak, Y.; Schreuders, H.; Dam, B.","","2012","Using hydrogenography, we investigate the thermodynamic parameters and hysteresis behavior in Mg thin films capped by Ta/Pd, in a temperature range from 333 K to 545 K. The enthalpy and entropy of hydride decomposition, ?Hdes = ?78.3 kJ/molH2, ?Sdes = ?136.1 J/K molH2, estimated from the Van't Hoff analysis, are in good agreement with bulk results, while the absorption thermodynamics, ?Habs = ?61.6 kJ/molH2, ?Sabs = ?110.9 J/K molH2, appear to be substantially affected by the clamping of the film to the substrate. The clamping is negligible at high temperatures, T > 523 K, while at lower temperatures, T < 393 K, it is considerable. The hysteresis at room temperature in Mg/Ta/Pd films increases by a factor of 16 as compared to MgH2 bulk. The hysteresis increases even further in Mg/Pd films, most likely due to the formation of a Mg-Pd alloy at the Mg/Pd interface. The stress–strain analysis of the Mg/Ta/Pd films at 300–333 K proves that the increase of the hysteresis occurs due to additional mechanical work during the (de-)hydrogenation cycle. With a proper temperature correction, our stress–strain analysis quantitatively and qualitatively explains the hysteresis behavior in thin films, as compared to bulk, over the whole temperature range.","hydrogenography; MgH2 thin films; thermodynamics; clamping; hysteresis; stress-strain model","en","journal article","MDPI","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:2592406a-960a-4aae-8ef6-0e53d6493090","http://resolver.tudelft.nl/uuid:2592406a-960a-4aae-8ef6-0e53d6493090","Copper-decorated carbon nanotubes-based composite electrodes for nonenzymatic detection of glucose","Pop, A.; Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.","","2012","The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite electrode (Cu/CNT-epoxy) exhibited the highest sensitivity to glucose determination.","multiwall carbon nanotubes composite electrodes, copper particles, glucose, electrochemical determination","en","journal article","Springer-Verlag","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:875d52ca-852a-4c32-b929-9d7d02839bda","http://resolver.tudelft.nl/uuid:875d52ca-852a-4c32-b929-9d7d02839bda","Electrochemical Determination of Pentachlorophenol in Water on a Multi-Wall Carbon Nanotubes-Epoxy Composite Electrode","Remes, A.; Pop, A.; Manea, F.; Baciu, A.; Picken, S.J.; Schoonman, J.","","2012","The aim of this study was the preparation, characterization, and application of a multi-wall carbon nanotubes-epoxy composite electrode (MWCNT-EP) with 25%, wt. MWCNTs loading for the voltammetric/amperometric determination of pentachlorophenol (PCP) in aqueous solutions. The structural and morphological aspects of the MWCNT-EP composite electrode were examined by scanning electron microscopy. The electrical properties were characterized by direct-current conductivity measurements in relation with the percolation threshold. The electrochemical behavior of PCP at the MWCNT-EP composite electrode was investigated using cyclic voltammetry in 0.1 M Na2SO4 supporting electrolyte in order to establish the parameters for amperometric/voltammetric determination of PCP. The linear dependence of current vs. PCP concentrations was reached in a wide concentration range from 0.2 to 12 ?M PCP using cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry, chronoamperometry, and multiple-pulsed amperometry techniques. The best electroanalytical performances of this composite electrode were achieved using a pre-concentration/square-wave voltammetric technique and also multiple-pulsed amperometry techniques envisaging the practical applications. The ease of preparation, high sensitivity, and stability of this composite electrode should open novel avenues and applications for fabricating robust sensors for detection of many important species.","multi-wall carbon nanotubes-epoxy composite electrode; electrochemical determination; pentachlorophenol; square-wave voltammetry; cyclic voltammetry","en","journal article","MDPI","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:1d9702c6-5365-49a3-93db-70e350688093","http://resolver.tudelft.nl/uuid:1d9702c6-5365-49a3-93db-70e350688093","HDS for fuel cell applications","Alsolami, B.H.","Moulijn, J.A. (promotor); Makkee, M. (promotor)","2012","The objective of this chapter is to investigate the feasibility of developing a catalytic hydrodesulfurization (HDS) process operating under low pressure and high temperature conditions to produce a near-zero sulfur content diesel suitable for fuel cell applications. As expected, it was found that decreasing the operating pressure will reduce the adsorbed hydrogen content on the catalyst surface and hence the percentage of sulfur removal (i.e. HDS activity). This is compensated by increasing the temperature which increases the catalytic activity and the hydrogen solubility, but at the same local bulk phase conditions the hydrogen coverage is decreased. Furthermore, the choice of the feedstock is an important factor. This chapter includes a comparison with other commercialized and under-development desulfurization processes, besides the conventional catalytic HDS process. Light is shed on types of HDS catalysts used to achieve low sulfur specifications.","","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:5416e239-bc6c-466c-96e1-53b864687e60","http://resolver.tudelft.nl/uuid:5416e239-bc6c-466c-96e1-53b864687e60","Upconversion: Kinetics of a model system","Van Sebille, M.","Grozema, F. (mentor); Aulin, Y. (mentor)","2012","Photochemical upconversion is a process upon which the photons of low energy are converted into photons of higher energy by means of sensitized triplet triplet annihilation. Photochemical upconversion has a potential application in the eld of photovoltaics, where it can signicantly improve the eciency of solar cells by exploiting the energy of near infrared band of solar radiation. In order to design highly ecient chromophores for photochemical upconversion, better understanding of the elementary processes is crucial. Current thesis is an attempt to do so by studying the kinetics and eciency of photochemical upconversion in a model system metal-OEP/DPA utilizing time resolved transient absorption and photoluminescence spectroscopic techniques.","upconversion","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Opto-electronic Materials","",""
"uuid:abb00472-bc4b-4eee-9127-dd4275680670","http://resolver.tudelft.nl/uuid:abb00472-bc4b-4eee-9127-dd4275680670","Multicomponent and Dissipative Self-Assembly Approaches: Towards functional materials","Boekhoven, J.","Van Esch, J.H. (promotor); Eelkema, R. (promotor)","2012","The use of self-assembly has proven to be a powerful approach to create smart and functional materials and has led to a vast variety of successful examples. However, the full potential of self-assembly has not been reached. Despite the number of successful artificial materials based on self-assembly, the corresponding structures do not compete with the highly sophisticated and functional architectures found in natural systems. The aim of the research described in this thesis is to increase the functionality of artificial self-assembled materials. In order to do so we implement different ways of self-assembly, inspired by natural self-assembly, in artificial systems. With that, the aim is to to extend the current toolbox, to open routes to the creation of new functional and complex materials and to learn from natural self-assembled systems.","supramolecular chemistry; self-assembly; chemistry; dissipative; multicomponent","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:d9fad926-e61f-4b6d-aa6e-3ca13521d170","http://resolver.tudelft.nl/uuid:d9fad926-e61f-4b6d-aa6e-3ca13521d170","Slow growth of the Rayleigh-Plateau instability in aqueous two phase systems","Geschiere, S.D.; Ziemecka, I.; Van Steijn, V.; Koper, G.J.M.; Van Esch, J.H.; Kreutzer, M.T.","","2012","This paper studies the Rayleigh-Plateau instability for co-flowing immiscible aqueous polymer solutions in a microfluidic channel. Careful vibration-free experiments with controlled actuation of the flow allowed direct measurement of the growth rate of this instability. Experiments for the well-known aqueous two phase system (ATPS, or aqueous biphasic systems) of dextran and polyethylene glycol solutions exhibited a growth rate of 1 s-1, which was more than an order of magnitude slower than an analogous experiment with two immiscible Newtonian fluids with viscosities and interfacial tension that closely matched the ATPS experiment. Viscoelastic effects and adhesion to the walls were ruled out as explanations for the observed behavior. The results are remarkable because all current theory suggests that such dilute polymer solutions should break up faster, not slower, than the analogous Newtonian case. Microfluidic uses of aqueous two phase systems include separation of labile biomolecules but have hitherto be limited because of the difficulty in making droplets. The results of this work teach how to design devices for biological microfluidic ATPS platforms.","adhesion; biochemistry; biological fluid dynamics; flow instability; microfluidics; molecular biophysics; polymer solutions; surface tension; viscosity","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:7bac3b46-9065-4309-b8bc-b926017239a0","http://resolver.tudelft.nl/uuid:7bac3b46-9065-4309-b8bc-b926017239a0","Wet ammonia Synthesis of Semiconducting N:Ta2O5, Ta3N5 and ?-TaON Films for Photoanode Applications","Dabirian, A.; Van 't Spijker, H.; Van der Krol, R.","","2012","Tantalum oxynitride (?-TaON) is a promising photoanode material for photoelectrochemical water splitting. However, the synthesis of phase-pure ?-TaON films is a challenging task. This paper describes a novel approach to achieve this by the controlled nitridation of Ta2O5 films under a flow of ammonia gas (ammonolysis), which was obtained by bubbling argon through an aqueous ammonium hydroxide solution followed by a 5 Å molecular sieve to remove the water. Depending on the nitridation conditions, either nitrogen-doped Ta2O5 or Ta3N5 was obtained as a thermodynamically stable phase. The evolution of the nitridation process was monitored in-situ using optical transmission spectroscopy, which revealed that the transformation of Ta2O5 to Ta3N5 occurred within minutes, through a series of intermediate oxynitride phases. This suggested the possibility of synthesizing the desired ?-TaON phase by quenching the sample at the right time during the nitridation process. By choosing the right ammonolysis conditions (750 °C, flow rate 50 ml/min.), we were able to slow down the nitridation process and terminate it before the oxide was fully converted to Ta3N5. A post-nitridation heat treatment at 800 °C indeed resulted in the formation of the desired ?-TaON phase.","tantalum oxynitride; photoanodes; water splitting; optical monitoring; tantalum nitride; ammonolysis","en","journal article","Elsevier","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:4f7c7a42-eb0e-4f06-ad7a-c30768bebc20","http://resolver.tudelft.nl/uuid:4f7c7a42-eb0e-4f06-ad7a-c30768bebc20","Quality of Coated Particles: Physical - Mechanical Characterization of Polymeric Film Coatings","Perfetti, G.","Schmidt-Ott, A. (promotor); Meesters, G.M.H. (promotor)","2012","All coated particle producers, when applying the coating layer(s) would like to know precisely what is the best coating system to use in order to answer customer’s requests. It is, therefore, of very high relevance for many industries, to have a clear understanding of what are the parameters I need to trigger in order to generate the requested quality. Such understanding was the target of this work. The specific equipments designed at Delft University of Technology enabled us to measure the resistance to attrition and the resistance to abrasion of both reference coating agents and commercially pre-mixed coating systems. The resistance to attrition was directly related to the intrinsic properties of the coating material, to the process parameters used to apply the coating layer (fluid bed coating in this case) and to the conditions in which the particles are stored. The viscoelastic properties of the coating layers were measured by using nano indentation. Very good correlation between the viscoelasticity term, tan ?, and the resistance to attrition was found. Cast and sprayed films were produced as representation of the coating film. The morphology and the structure of coating layers were mimicked much better by sprayed films which could be obtained by novel equipment designed during this work. To assess the quality of the coating layer and determine how efficient the coating process was, X-Ray micro tomography in combination with image analysis was used. This gave us a very robust set of data which could be used to correlate the quality of the coating layer to the parameters chosen during coating process and those two with the final performance of the coated particles in respect of resistance to attrition/abrasion. Finally commercially available pre-mixed coating systems were used as case study. By comparing them with the reference coating agents we could proof and quantify how important are the additives, plasticisers in primis, in increasing the coating quality and, therefore, the resistance to mechanical stresses.","","en","doctoral thesis","","","","","","","","2012-04-28","Applied Sciences","Chemical Engineering, ChemE","","","",""
"uuid:f6eb90e4-6ded-4b4b-ab3a-cd313972829d","http://resolver.tudelft.nl/uuid:f6eb90e4-6ded-4b4b-ab3a-cd313972829d","Carbon nanostructures and networks produced by chemical vapor deposition","Kowlgi, N.K.K.; Koper, G.J.M.; Van Raalten, R.A.D.","","2012","The invention pertains to a method for manufacturing crystalline carbon nanostructures and/or a network of crystalline carbon nanostructures, comprising: (i) providing a bicontinuous micro-emulsion containing metal nanoparticles having an average particle size between 1and 100nm; (ii) bringing said bicontinuous micro-emulsion into contact with a substrate; and (iii) subjecting said metal nanoparticles and a gaseous carbon source to chemical vapor deposition, thus forming carbon nanostructures and/or a network of carbon nanostructures. Therewith, it is now possible to obtain crystalline carbon nanostructures networks, preferably carbon nanotubes networks","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:5426c528-72b6-4b12-bfd9-13de930597ec","http://resolver.tudelft.nl/uuid:5426c528-72b6-4b12-bfd9-13de930597ec","The assembly of flexible polystyrene-block-poly(ethylene oxide) wormlike micelles from chloroform droplets by the ‘emulsification and solvent evaporation’ method","Nuijten, M.P.","Van Steijn, V. (mentor); Hamersma, P. (mentor); Mendes, E. (mentor); Embrechts, A. (mentor); Glazer, P. (mentor)","2012","Flexible wormlike micelles show promising results in their application as drug carriers in the field of targeted drug delivery. A method introduced to produce wormlike micelles is the ‘emulsification and solvent evaporation’ method, but the formation mechanism behind this method is not yet fully understood. The aim of this work is to study whether the lengths of the wormlike micelles formed depends on the size of the droplets in the emulsion. Wormlike micelles were formed by dissolving polystyrene-block-poly(ethylene oxide), or PS-PEO, in chloroform, and mixing this into an emulsion with water containing NaCl through vigorous stirring. Interfacial instabilities between the water and chloroform phase caused by increased concentrations of polymer lead to the formation of wormlike micelles. Effects of varying stirring rates and times on the size of the chloroform droplets in the emulsion as well as the lengths of wormlike micelle sizes were studied by analysis through optical and fluorescence microscopy. The droplets were found to be polydisperse and stable for timescales up to a few minutes, but the diameters decrease during the course of mixing the emulsion. Wormlike micelles start to form directly when the chloroform and water phases are brought in contact. When mixing occurs more vigorously the average length of wormlike micelles increases and their distributions becomes broader. Interestingly, wormlike micelles produced using this method grow to lengths up to 1 mm.","wormlike micelles; self-assembly; emulsification and solvent evaporation; polystyrene-block-poly(ethylene oxide)","en","bachelor thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Product and Process Engineering","",""
"uuid:129c7bfa-7664-4c5a-98ca-af8f6651d800","http://resolver.tudelft.nl/uuid:129c7bfa-7664-4c5a-98ca-af8f6651d800","Fluidization of nanopowders: A review","Van Ommen, J.R.; Valverde, J.M.; Pfeffer, R.","","2012","Nanoparticles (NPs) are applied in a wide range of processes, and their use continues to increase. Fluidization is one of the best techniques available to disperse and process NPs. NPs cannot be fluidized individually; they fluidize as very porous agglomerates. The objective of this article is to review the developments in nanopowder fluidization. Often, it is needed to apply an assistance method, such as vibration or microjets, to obtain proper fluidization. These methods can greatly improve the fluidization characteristics, strongly increase the bed expansion, and lead to a better mixing of the bed material. Several approaches have been applied to model the behavior of fluidized nanopowders. The average size of fluidized NP agglomerates can be estimated using a force balance or by a modified Richardson and Zaki equation. Some first attempts have been made to apply computational fluid dynamics. Fluidization can also be used to provide individual NPs with a thin coating of another material and to mix two different species of nanopowder. The application of nanopowder fluidization in practice is still limited, but a wide range of potential applications is foreseen.","nanoparticles; agglomerates; fluidized beds; assisted fluidization; modeling nanofluidization; literature review","en","journal article","Springer","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:6b040d3f-850c-40e7-9704-06826743b687","http://resolver.tudelft.nl/uuid:6b040d3f-850c-40e7-9704-06826743b687","Turbulence anisotropy and coherent structures in electromagnetically generated vortex patterns","Kenjeres, S.","","2011","","","en","conference paper","IOP Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:e585bab3-fa14-49e1-a001-6e831e6144d6","http://resolver.tudelft.nl/uuid:e585bab3-fa14-49e1-a001-6e831e6144d6","Transients and turbulence pockets in thermal convection of paramagnetic fluid subjected to strong magnetic field gradients","Kenjeres, S.; Wrobel, W.; Pyrda, L.; Fornalik-Wajs, E.; Szmyd, J.S.","","2011","We performed combined experimental and numerical studies of the flow and heat transfer of a paramagnetic fluid inside a differentially heated cubical enclosure subjected to various strong non-uniform magnetic field gradients. Two different heating scenarios are considered: unstable (heated from below) and stable (heated from above) initial thermal stratification. In contrast to the previously reported studies in literature, which observed solely laminar flow regimes, we investigated also appearance and sustenance of the periodic- and fully transient-flow motions for the very first time. This was consequence of using significantly stronger magnetic field strength (up to 10 T experimentally, and up to 15 T numerically) than those used in previous studies (up to 5 T). Detailed comparison between experiments and numerical simulations are performed and generally very good agreements were obtained.","","en","conference paper","IOP Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:831a4110-0146-4e26-ad71-e819c0200386","http://resolver.tudelft.nl/uuid:831a4110-0146-4e26-ad71-e819c0200386","Review of the various CO2 mineralization product forms","Verduyn, M.; Geerlings, J.J.C.; Van Mossel, G.; Vijayakumari, S.","","2011","Two experimental modes of operation, a sequence of batch and a continuous one, have demonstrated the technical feasibility of Shell’s proposed slurry-based direct flue gas mineralization concept on the basis of activated serpentine. The base case mineralization concept can be simplified yielding a variety of product forms and significantly reduced CO2 abatement costs. Combined with a positive first assessment of the sustainability of the various mineralization product forms, all mineralization concepts deserve to be further investigated. To optimally take advantage of integration opportunities so as avoid parasitic CO2 emissions and minimize cost, this should be done over the complete technology chain.","mineralization; flue gas; feasibility; product form; sustainability","en","journal article","Elsevier","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:a69b784a-4bac-499d-aee4-9642f997847d","http://resolver.tudelft.nl/uuid:a69b784a-4bac-499d-aee4-9642f997847d","Towards H2 selective porous inorganic membranes: Pore size control through combined Sol-Gel and Atomic Layer Deposition Processes","Tran, T.H.Y.","Schoonman, J. (promotor); Haije, W.G. (promotor)","2011","Carbon capture and storage (CCS) can significantly contribute to the reduction of the emission of the greenhouse gas CO2. Capture by means of CO2 sorption or membrane-based separation processes is a promising way for achieving decarbonization of fuel or flue gas cleaning. In the field of separation and also purification of hydrogen, membrane separation technology has been and still is a focal point for Research and Development (R&D) due to its promising energy-efficiency, inherent selectivity and continuous operation. Research is being devoted to the development of membranes for H2 separation from CO and CO2 containing gas mixtures with high permeance and selectivity for conversion to electricity via fuel cells or directly in gas turbines. Currently, most membranes are being developed to separate H2 from the underlying reaction mixtures obtained via coal gasification, steam-methane reforming, and water gas-shift processes. The key advantage of membrane separation, but also sorbent-based separation, is the possibility to go beyond the thermodynamic conversion limits set by the equilibrium constant of these H2 production reactions. The in-situ separation of H2 from the gas mixture through membranes shifts the equilibrium toward higher production of H2 by preventing the back reaction. At the same time a stream of CO2 is produced, pure enough for storage in geological reservoirs (empty oil and gas fields or deep saline aquifers) or for use in enhanced oil or gas recovery processes. Inorganic microporous membranes are considered promising for H2 separation in high-temperature H2 production processes because of their high thermal and chemical stability. The major objective of the thesis is dedicated to fabricate and study a microporous non-silica based membrane system, consisting of an ?-alumina macroporous support, a mesoporous intermediate layer, and a microporous ?-Al2O3, or TiO2 top layer, for H2 separation from a gas mixture with CO and CO2. We have studied the possibility to incorporate Al2O3, TiO2, and ZrO2 into the envisioned structure using the synthesis concept of a combination of sol-gel and Atomic Layer Deposition (ALD) processes. The foremost goal of the ALD related membrane research was to provide enhanced H2 selectivity of the synthesized membranes. Tests on the H2/CO2 separation were carried out on these synthesized membranes. The H2 permeance and H2/CO2 selectivity of these membranes are ~1-2x10?7 mol.m?2.s?1.Pa?1 and ~ 5.8-10.9 at 175 °C and 105 Pa pressure difference, respectively. It was shown that ALD can elegantly be coupled with the sol-gel synthesis to fabricate microporous membranes on a large scale.","hydrogen; ceramic membrane; sol-gel; atomic layer deposition","en","doctoral thesis","","","","","","","","2012-01-11","Applied Sciences","Chemical Engineering","","","",""
"uuid:4e3aa6d8-8b54-4aba-ad5e-052244646ff7","http://resolver.tudelft.nl/uuid:4e3aa6d8-8b54-4aba-ad5e-052244646ff7","Synthesis, Mesophase Behaviour and Charge Mobility of Phenyl-Thiophene Pentamers","Kuiper, S.","Picken, S.J. (promotor); Dingemans, T.J. (promotor); Jager, W.F. (promotor)","2011","The performance of opto-electronic devices based on semi-conducting organic molecules, dependence on the molecular order of the semi-conducting molecules. To get high charge transportation through the material a high order of the material is needed. In our research we used liquid crystalline phases to get relative high order over large distances. A series of all-aromatic phenyl-thiophene pentamers and a series of alkoxy terminated phenyl-thiophene pentamers have been synthesized. The mesophase behaviour and the UV-vis absorption have been determined. In the nematic phase the molecules possess only orientational order. It was found that the orientational order, in the nematic phase of p-quinquephenyl, determined by wide angle x-ray diffraction is less, due to temperature dependent fluctuations of the director at a macroscopic scale. The exact temperature dependence of the orientational order was determined by birefringence measurements and could be fitted with the predicted temperature dependence of the orientational order by the Maier-Saupe model. In the smectic phases the molecules possess orientational order as well as positional order. The charge mobility was determined by time resolved microwave conductivity. In the nematic phase the charge mobility is dependent on the orientational order. Hardly any charge mobility could be observed in the higher ordered smectic phases, because the concentration of charges is reduced.","Liquid Crystal; Charge Mobility; Orientational Order; p-quinquephenyl; Phenyl-Thiophene Pentamers; Maier-Saupe Model","en","doctoral thesis","","","","","","","","2011-12-12","Applied Sciences","Chemical Engineering","","","",""
"uuid:f0c17569-493f-4e4e-8b36-cbbd991d7f76","http://resolver.tudelft.nl/uuid:f0c17569-493f-4e4e-8b36-cbbd991d7f76","Aberration-Corrected STEM Investigation of Metallic Ti Cluster Formation in Mg-Ti Hydrides","Kepaptsoglou, D.M.; Jensen, I.J.T.; Sarahan, M.; Ramasse, Q.M.; Schreuders, H.; Dam, B.; Diplas, S.; Løvvik, O.M.; Taftø, J.","","2011","Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.","","en","journal article","Cambridge University Press","","","","","","","2012-10-31","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:228e2b45-791c-4983-9ae6-5e7111269b5f","http://resolver.tudelft.nl/uuid:228e2b45-791c-4983-9ae6-5e7111269b5f","Microfluidic systems for the analysis of viscoelastic fluid flow phenomena in porous media","Galindo-Rosales, F.J.; Campo-Deano, L.; Pinho, F.T.; Van Bokhorst, E.; Hamersma, P.J.; Oliveira, M.S.N.; Alves, M.A.","","2011","In this study, two microfluidic devices are proposed as simplified 1-D microfluidic analogues of a porous medium. The objectives are twofold: firstly to assess the usefulness of the microchannels to mimic the porous medium in a controlled and simplified manner, and secondly to obtain a better insight about the flow characteristics of viscoelastic fluids flowing through a packed bed. For these purposes, flow visualizations and pressure drop measurements are conducted with Newtonian and viscoelastic fluids. The 1-D microfluidic analogues of porous medium consisted of microchannels with a sequence of contractions/expansions disposed in symmetric and asymmetric arrangements. The real porous medium is in reality, a complex combination of the two arrangements of particles simulated with the microchannels, which can be considered as limiting ideal configurations. The results show that both configurations are able to mimic well the pressure drop variation with flow rate for Newtonian fluids. However, due to the intrinsic differences in the deformation rate profiles associated with each microgeometry, the symmetric configuration is more suitable for studying the flow of viscoelastic fluids at low De values, while the asymmetric configuration provides better results at high De values. In this way, both microgeometries seem to be complementary and could be interesting tools to obtain a better insight about the flow of viscoelastic fluids through a porous medium. Such model systems could be very interesting to use in polymer-flood processes for enhanced oil recovery, for instance, as a tool for selecting the most suitable viscoelastic fluid to be used in a specific formation. The selection of the fluid properties of a detergent for cleaning oil contaminated soil, sand, and in general, any porous material, is another possible application.","microfluidics; porous media; rheology; contraction-expansion; viscoelastic fluids","en","journal article","Springer","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:e753441c-365f-4f69-a6b6-8cd7ed182310","http://resolver.tudelft.nl/uuid:e753441c-365f-4f69-a6b6-8cd7ed182310","Development of an Electroactive Membrane for Lithium Recovery by Electrochemical Means","Locati, C.; Kelder, E.M.","","2011","","","en","journal article","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:f6686931-67c5-474c-acb5-beea4857d76f","http://resolver.tudelft.nl/uuid:f6686931-67c5-474c-acb5-beea4857d76f","An Electrochemical Study of High Voltage Cathode Materials in Contact with Mixtures of Ionic Liquids and Commercial Electrolytes","Locati, C.; Kelder, E.M.","","2011","","","en","journal article","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:bc89728f-2f75-4faa-9dc6-6cef5bc37a9c","http://resolver.tudelft.nl/uuid:bc89728f-2f75-4faa-9dc6-6cef5bc37a9c","In situ HRTEM of a catalyst using a nanoreactor at 1 bar","Vendelbo, S.B.; Creemer, J.F.; Helveg, S.; Morana, B.; Mele, L.; Molenbroek, A.M.; Sarro, P.M.; Zandbergen, H.W.; Kooyman, P.J.","","2011","Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.","","en","journal article","Cambridge University Press","","","","","","","2012-10-07","Applied Sciences","Chemical Engineering","","","",""
"uuid:0720fa11-fc97-4596-8a44-2a1f5996f5e6","http://resolver.tudelft.nl/uuid:0720fa11-fc97-4596-8a44-2a1f5996f5e6","Fiber optic Surface Plasmon Resonance sensor based on wavelength modulation for hydrogen sensing","Perrotton, C.; Javahiraly, N.; Slaman, M.J.; Dam, B.; Meyrueis, P.","","2011","A new design of a fiber optic Surface Plasmon Resonance (SPR) sensor using Palladium as a sensitive layer for hydrogen detection is presented. In this approach, a transducer layer is deposited on the outside of a multimode fiber, after removing the optical cladding. The transducer layer is a multilayer stack made of a Silver, a Silica and a Palladium layer. The spectral modulation of the light transmitted by the fiber allows to detect the presence of hydrogen in the environment. The sensor is only sensitive to the Transverse Magnetic polarized light and the Traverse Electric polarized light can be used therefore as a reference signal. A more reliable response is expected for the fiber SPR hydrogen sensor based on spectral modulation instead of on intensity modulation. The multilayer thickness defines the sensor performance. The silica thickness tunes the resonant wavelength, whereas the Silver and Palladium thickness determine the sensor sensitivity. In an optimal configuration (NA = 0.22, 100 ?m core radius and transducer length = 1 cm), the resonant wavelength is shifted over 17.6 nm at a concentration of 4% Hydrogen in Argon for the case of the 35 nm Silver/ 100 nm Silica/ 3 nm palladium multilayer.","fiber optics sensors; sensors; surface plasmons","en","journal article","Optical Society of America","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:f4a530ff-9b72-4562-8a68-0bbbdd499827","http://resolver.tudelft.nl/uuid:f4a530ff-9b72-4562-8a68-0bbbdd499827","Influence of carrier density on the electronic cooling channels of bilayer graphene","Limmer, T.; Houtepen, A.J.; Niggebaum, A.; Tautz, R.; Da Como, E.","","2011","We study the electronic cooling dynamics in a single flake of bilayer graphene by femtosecond transient absorption probing the photon-energy range 0.25–1.3 eV. From the transients, we extract the carrier cooling curves for different initial temperatures and densities of the photoexcited electrons and holes. Two regimes of carrier cooling, dominated by optical and acoustic phonons emission, are clearly identified. For increasing carrier density, the crossover between the two regimes occurs at larger carrier temperatures, since cooling via optical phonons experiences a bottleneck. Acoustic phonons, which are less sensitive to saturation, show an increasing contribution at high density.","acoustic emission; carrier density; graphene; photoacoustic effect; photoexcitation","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:5dc59703-3c85-456f-9163-4708b05dbe2f","http://resolver.tudelft.nl/uuid:5dc59703-3c85-456f-9163-4708b05dbe2f","Increased carrier generation rate in Si nanocrystals in SiO2 investigated by induced absorption","De Boer, W.D.A.M.; Trinh, M.T.; Timmerman, D.; Schins, J.M.; Siebbeles, L.D.A.; Greogorkiewicz, T.","","2011","We report on investigations of optical generation of carriers in Si nanocrystals embedded in SiO2 matrix by time-resolved induced absorption technique. Results obtained for excitation below and above twice the bandgap energy h??2Eg and h??>?2Eg show very similar decay characteristics (within ?resolution ? 100 fs). When intensity of the signal is correlated to number of generated excitons, it is found that for the high photon energy excitation, carrier generation rate is considerably enhanced. These results are discussed in terms of carrier multiplication reported previously for semiconductor nanocrystals and photoluminescence quantum yield measurements for similar materials.","elemental semiconductors; energy gap; nanostructured materials; photoluminescence; silicon; silicon compounds","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:afecbacd-0ac1-4a01-b7ab-db1ba0c42f50","http://resolver.tudelft.nl/uuid:afecbacd-0ac1-4a01-b7ab-db1ba0c42f50","Model Reduction in Chemical Engineering: Case studies applied to process analysis, design and operation","Dorneanu, B.","Grievink, J. (promotor); Bildea, C.S. (promotor)","2011","During the last decades, models have become widely used for supporting a broad range of chemical engineering activities, such as product and process design and development, process monitoring and control, real time optimization of plant operation or supply chain management. Although tremendous advancements continue to take place in the development of numerical techniques and the acceleration of the computing speed, these advancements have been outpaced by the tendency to make rigorous models of much more complicated and extensive systems. Such rigorous models cannot always be effectively used for design and optimisation. A reduction of the model size and complexity is required to make a model-based solution practical. Many current numerical approaches in systems engineering apply order-reduction to a model in its entirety, without preserving the underlying network structure of the process or its multi-scale decomposition. Retaining these meaningful structural features of a process in a reduced model is a necessity for numerous applications. This is the motivation for the research and the results presented in this thesis. The novelty of this thesis is in systematizing and exploiting the essential structural features of a process in model reduction. The model reduction approach aims first at simplifying the physical and the behavioural structure, as well as the systemic level of the chemical process in the model. Only then additional mathematical and numerical (scheme) reductions are selectively applied to individual compartments or units. In the following step, the reduced models of the individual units are connected at system level and the reduced model of the full process is obtained. In this way, the model reduction procedure is able to preserve the essential structural features of the process. Moreover, the physical meaning of the variables and equations is kept as much as possible. The feasibility and the advantages of the approach are presented for two types of applications: (1) the iso-butane alkylation process, an example of a complex process with relatively simple (one-phase) products; and (2) the freezing step in ice cream manufacture, an example of a single process unit with a complex product. The model reduction procedures works well for the cases considered. The resulting models are solved in acceptable amounts of time. Moreover, they are successfully used for applications such as assessment of the plantwide control structures and the dynamic optimization of the plant operation for the iso-butane alkylation process, and the sensitivity analysis of the model’s parameters in the case of the ice cream freezing process. However, the issue of the optimality with respect to the level of the multi-scale decomposition when developing the reduced model is still open.","model reduction; process modelling; plantwide control; dynamic optimization; alkylation; ice cream freezing","en","doctoral thesis","CPI Wohrmann Print Service","","","","","","","2011-07-05","Applied Sciences","Chemical Engineering","","","",""
"uuid:c4a6a02d-9d2e-4439-80c2-72c166843c31","http://resolver.tudelft.nl/uuid:c4a6a02d-9d2e-4439-80c2-72c166843c31","Silicon nanoparticles produced by spark discharge","Vons, V.A.; De Smet, L.C.P.M.; Munao, D.; Evirgen, A.; Kelder, E.M.; Schmidt-Ott, A.","","2011","On the example of silicon, the production of nanoparticles using spark discharge is shown to be feasible for semiconductors. The discharge circuit is modelled as a damped oscillator circuit. This analysis reveals that the electrode resistance should be kept low enough to limit energy loss by Joule heating and to enable effective nanoparticle production. The use of doped electrodes results in a thousand-fold increase in the mass production rate as compared to intrinsic silicon. Pure and oxidised uniformly sized silicon nanoparticles with a primary particle diameter of 3–5 nm are produced. It is shown that the colour of the particles can be used as a good indicator of the oxidation state. If oxygen and water are banned from the spark generation system by (a) gas purification, (b) outgassing and (c) by initially using the particles produced as getters, unoxidised Si particles are obtained. They exhibit pyrophoric behaviour. This continuous nanoparticle preparation method can be combined with other processing techniques, including surface functionalization or the immediate impaction of freshly prepared nanoparticles onto a substrate for applications in the field of batteries, hydrogen storage or sensors.","silicon nanoparticles; spark discharge; nanoparticle production; aerosol; synthesis","en","journal article","Springer","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:4f4d737a-3a2b-4059-b8fa-f70bd581e4ff","http://resolver.tudelft.nl/uuid:4f4d737a-3a2b-4059-b8fa-f70bd581e4ff","Erratum: Interpretation of ultrafast pump-probe terahertz experiments in the time domain: How to exploit two-dimensional correlations [Phys. Rev. B 83, 205111 (2011)]","Schins, J.M.","","2011","","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:95854074-fe4a-4c32-85af-82068a92a0f8","http://resolver.tudelft.nl/uuid:95854074-fe4a-4c32-85af-82068a92a0f8","Self-healing supramolecular polymer and polymer nanocomposites (poster abstract)","Liu, Z.; Besseling, N.A.M.; Mendes, E.; Picken, S.J.","","2011","","self-healing; supramolecular polymers; nanocomposite; mechanical testing","en","conference paper","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:9cb199a4-6359-4c73-a053-8cd57fc5d703","http://resolver.tudelft.nl/uuid:9cb199a4-6359-4c73-a053-8cd57fc5d703","Charge Carriers and Excited States in Supramolecular Materials","Patwardhan, S.","Siebbeles, L.D.A. (promotor)","2011","The field of organic electronics has been thriving for the last decades due to growing commercial interest. One of the advantages of using organic materials as semiconductors is the possibility to tune their optoelectronic properties by modifying the chemical structure and organization of the building blocks. In this thesis, the properties of charge carriers and excited states in a variety of organic supramolecular materials were studied in relation to the chemical structure and organization of their building blocks. The charge transport properties were studied by pulse radiolysis time-resolved microwave conductivity (PR-TRMC) measurements and theoretical calculations. The excited state properties were investigated by combining optical spectroscopy with exciton theory calculations.","supramolecular electronics; charge transport; excited states; chlorophylls; DNA; covalent organic framework; liquid crystal; time-resolved microwave conductivity; exciton theory","en","doctoral thesis","Ipskamp Drukkers B.V.","","","","","","","2011-08-01","Applied Sciences","Chemical Engineering","","","",""
"uuid:95984f33-94ce-418d-ad88-71de975ee5e5","http://resolver.tudelft.nl/uuid:95984f33-94ce-418d-ad88-71de975ee5e5","Conductive response of a photo-excited sample in a radio-frequent driven resonance cavity","Schins, J.M.; Talgorn, E.","","2011","An expression is derived for the perturbative response of a lumped resonance circuit to a sudden change in the circuit parameters. This expression is shown to describe also the photo-induced conductivity of a semiconductor mounted in a single-mode microwave cavity. The power dissipated in the cavity is measured in the two dimensions corresponding to time (after photo-excitation of the sample) and frequency (of the microwave driving source). Analysis of the experimental data for different semiconductor materials demonstrates the general applicability of the presented analytical expression here, by retrieving the time dependence of the sample's photo-induced conductivity.","photoconductivity,; photoexcitation; RLC circuits; semiconductor materials","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:99ed452a-b7bb-44b5-8c39-fe1e3f1e3ccc","http://resolver.tudelft.nl/uuid:99ed452a-b7bb-44b5-8c39-fe1e3f1e3ccc","Interpretation of ultrafast pump-probe terahertz experiments in the time domain: How to exploit two-dimensional correlations","Schins, J.M.","","2011","Optical-pump-terahertz-probe spectroscopy has the potential to distinguish between several classes of carrier motion, among others high-frequency oscillatory motion, free motion, and quasifree motion within bounded domains. We present a simplified formalism, applicable to thin samples, which allows identification of these three classes of photoexcited species on basis of the two-dimensional correlations in the time-domain experimental data.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:29e75d56-5771-4782-a629-baee09595404","http://resolver.tudelft.nl/uuid:29e75d56-5771-4782-a629-baee09595404","Reaction-diffusion analysis for one-step plasma etching and bonding of microfluidic devices","Rosso, M.; Van Steijn, V.; De Smet, L.C.P.M.; Sudhölter, E.J.R.; Kleijn, C.R.; Kreutzer, M.T.","","2011","A self-similar reaction front develops in reactive ion etching when the ions penetrate channels of shallow height h. This relates to the patterning of microchannels using a single-step etching and bonding, as described by Rhee et al. [Lab Chip 5, 102 (2005)] . Experimentally, we report that the front location scales as xf ? ht1/2 and the width is time-invariant and scales as ? ? h. Mean-field reaction-diffusion theory and Knudsen diffusion give a semiquantitative understanding of these observations and allow optimization of etching times in relation to bonding requirements.","fractals; Knudsen flow; microchannel flow; reaction-diffusion systems; sputter etching; OA-Fund TU Delft","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:71328a81-260a-4ced-a9db-5b06a58ba6a9","http://resolver.tudelft.nl/uuid:71328a81-260a-4ced-a9db-5b06a58ba6a9","Optimization of Pd Surface Plasmon Resonance sensors for hydrogen detection","Perrotton, C.; Javahiraly, N.; Slaman, M.; Schreuders, H.; Dam, B.; Meyrueis, P.","","2011","A design to optimize a fiber optic Surface Plasmon Resonance (SPR) sensor using Palladium as a sensitive layer for hydrogen detection is presented. In this approach, the sensitive layer is deposited on the core of a multimode fiber, after removing the optical cladding. The light is injected in the fiber with a given wavelength and all fiber modes are equally excited. The intensity modulation at the fiber output is measured to estimate the presence of hydrogen absorbed by the Pd, and consequently the Hydrogen concentration in the environment. The sensor response depends on both the Transverse Magnetic (TM) polarization (magnetic field perpendicular to incidence plane) and the Transverse Electric (TE) polarization (electric field perpendicular to incidence plane). The response for the Transverse Electric polarization is opposite with respect to the Transverse Magnetic polarization. The objective here is to optimize the Pd-SPR hydrogen sensor design in order to increase its sensitivity. We introduce an analysis of the sensor response as a function of the Pd thickness. Finally, a new design based on a multilayer system is proposed to enhance the SP ’effect’.","fiber optic sensor; hydrogen sensor; surface plasmon; palladium","en","conference paper","SPIE","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:239568db-562f-4c44-8fa9-c60c6310e3c2","http://resolver.tudelft.nl/uuid:239568db-562f-4c44-8fa9-c60c6310e3c2","Testing facility for hydrogen storage materials designed to simulate application based conditions","Westerwaal, R.J.; Nyqvist, R.G.; Haije, W.G.","","2011","For the daily use of hydrogen storage materials, not only their intrinsic storage properties are important, but also equally important is the performance under practical conditions. Besides the techniques already available for the fundamental characterization of storage materials, there is a growing need to test storage materials under conditions resembling day-to-day use. For that we developed and tested a downscaled hydrogen storage reactor with which it is possible to monitor the hydrogenation behavior under nonideal conditions. Here we present a characterization of the developed reactor setup which enables a fast screening of storage materials. For characterization and calibration purposes, we use the rather well-documented LaNi5–Al alloy as reference. The found experimental results agree well with the properties of LaNi5–Al as reported in literature. Our results show that this reactor setup enables an efficient screening of new developed storage alloys under realistic conditions and is therefore complementary to the already existing characterization setups.","aluminium alloys; calibration; chemical reactors; hydrogen storage; hydrogenation; lanthanum alloys; nickel alloys; process monitoring; test facilities","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:ccc3f705-2abe-48df-8d02-10abdcbcc103","http://resolver.tudelft.nl/uuid:ccc3f705-2abe-48df-8d02-10abdcbcc103","Testing facility for hydrogen storage materials designed to simulate application based conditions","Westerwaal, R.J.; Nyqvist, R.G.; Haije, W.G.","","2011","For the daily use of hydrogen storage materials, not only their intrinsic storage properties are important, but also equally important is the performance under practical conditions. Besides the techniques already available for the fundamental characterization of storage materials, there is a growing need to test storage materials under conditions resembling day-to-day use. For that we developed and tested a downscaled hydrogen storage reactor with which it is possible to monitor the hydrogenation behavior under nonideal conditions. Here we present a characterization of the developed reactor setup which enables a fast screening of storage materials. For characterization and calibration purposes, we use the rather well-documented LaNi5–Al alloy as reference. The found experimental results agree well with the properties of LaNi5–Al as reported in literature. Our results show that this reactor setup enables an efficient screening of new developed storage alloys under realistic conditions and is therefore complementary to the already existing characterization setups.","","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:105474cc-6e92-434b-b402-1aab4d3c229e","http://resolver.tudelft.nl/uuid:105474cc-6e92-434b-b402-1aab4d3c229e","Influence of point defects on the performance of InVO4 photoanodes","Van de Krol, R.; Ségalini, J.; Enache, C.S.","","2011","The properties of thin film InVO4 photoanodes for water splitting have been studied. Compact films of InVO4 were prepared by spray pyrolysis and are found to be stable between pH 3 and 11. Although the indirect bandgap is 3.2 eV, a modest amount of visible light absorption is observed. The origin of this absorption is attributed to the presence of deep donor states at ?0.7 eV below the conduction band. These donor states presumably correspond to oxygen vacancies, which form as a result of small but unavoidable deviations of In:V from the ideal 1:1 stoichiometry during the wet-chemical synthesis process. Shallow donors are absent in this material, in contrast to what is normally observed for metal oxides. The deep donor model explains the much stronger visible light absorption of powders compared to thin films. The defect chemical reactions that lead to the formation of the deep donors are shown, and are supported by photoluminescence data","InVO4; photoelectrochemistry; photoanode; water splitting; defect chemistry; photoluminescence","en","journal article","SPIE","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:8f51b282-b8a4-4800-847d-9577df38264d","http://resolver.tudelft.nl/uuid:8f51b282-b8a4-4800-847d-9577df38264d","Charge Transport in Disordered Molecular Systems","Kocherzhenko, A.A.","Siebbeles, L.D.A. (promotor)","2011","How does classical reality emerge from quantum mechanics? When does an electron in a molecule stop behaving as a wave and start behaving as a particle? What is the best way to describe the intermediate regime? Can quantum mechanical effects be put to practical use in molecular electronics? These are the questions that this thesis asks and attempts to answer. The topics covered include quantum interference and decoherence in molecular systems, band-like and incoherent hopping charge transport in polymers, the effects of the molecular environment on single-molecule charge transport and supramolecular control of charge transport.","charge transport; open quantum systems; conjugated polymers; donor-bridge-acceptor systems","en","doctoral thesis","","","","","","","","2011-03-21","Applied Sciences","Chemical Engineering","","","",""
"uuid:945e26d0-f523-472c-8e7f-da1d7b40c7a3","http://resolver.tudelft.nl/uuid:945e26d0-f523-472c-8e7f-da1d7b40c7a3","Optical response of the sodium alanate system: GW0-BSE calculations and thin film measurements","Van Setten, M.J.; Gremaud, R.; Brocks, G.; Dam, B.; Kresse, G.; De Wijs, G.A.","","2011","We calculate from first principles the optical spectra of the hydrides in the sodium alanate hydrogen storage system: NaH, NaAlH4, and Na3AlH6. In particular we study the effects of systematic improvements of the theoretical description. To benchmark the calculations we also measure the optical response of a thin film of NaH. The simplest calculated dielectric functions are based upon independent electrons and holes, whose spectrum is obtained at the G0W0 level. Successive improvements consist of including partial self-consistency (so-called GW0) and account for excitonic effects, using the Bethe-Salpeter equation (BSE). Each improvement gives a sizable blue shift or red shift of the dielectric functions, but conserves the trend in the optical gap among different materials. Whereas these shifts partially cancel at the highest (GW0-BSE) level of approximation, the shape of the dielectric functions is strongly modified by excitonic effects. Calculations at the GW0-BSE level give a good agreement with the dielectric function of NaH extracted from the measurements. It demonstrates that the approach can be used for a quantitative interpretation of spectra in novel hydrogen storage materials obtained via, e.g., hydrogenography.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:6f818741-23a0-4c4b-af26-588739157a56","http://resolver.tudelft.nl/uuid:6f818741-23a0-4c4b-af26-588739157a56","Influence of point defects on the performance of InVO4 photoanodes","Van de Krol, R.; Ségalini, J.; Enache, C.S.","","2010","The properties of thin film InVO4 photoanodes for water splitting have been studied. Compact films of InVO4 were prepared by spray pyrolysis and are found to be stable between pH 3 – 11. Although the indirect bandgap is 3.2 eV, a modest amount of visible light absorption is observed. The origin of this absorption is attributed to the presence of deep donor states at ~0.7 eV below the conduction band. Shallow donors are absent in this material, in contrast to what is normally observed for metal oxides. The deep donor model explains the much stronger visible light absorption of powders compared to thin films, and is supported by photoluminescence data. The origin of the deep donors is attributed to deviations in the In:V ratio, and the corresponding defect-chemical reactions will be discussed.","InVO4, photoelectrochemistry, photoanode, water splitting, defect chemistry, photochemical stability","en","conference paper","SPIE","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:098c4c1f-f9bc-4bdd-99dc-fa52cbab6ace","http://resolver.tudelft.nl/uuid:098c4c1f-f9bc-4bdd-99dc-fa52cbab6ace","Photo-catalytic oxidation of cyclohexane over TiO2: A novel interpretation of temperature dependent performance","Almeida, A.R.; Berger, R.; Moulijn, J.A.; Mul, G.","","2010","The rate of cyclohexane photo-catalytic oxidation to cyclohexanone over anatase TiO2 was studied at temperatures between 23 and 60ºC by in situ ATR-FTIR spectroscopy, and the kinetic parameters were estimated using a microkinetic model. At low temperatures, surface cyclohexanone formation is limited by cyclohexane adsorption due to unfavorable desorption of H2O, rather than previously proposed slow desorption of the product cyclohexanone. Up to 50ºC, the activation energy for photocatalytic cyclohexanone formation is zero, while carboxylates are formed with an activation energy of 18.4 ± 3.3 kJ mol-1. Above 50ºC, significant (thermal) oxidation of cyclohexanone contributes to carboxylate formation. The irreversibly adsorbed carboxylates lead to deactivation of the catalyst, and are most likely the predominant cause of the non-Arrhenius behavior at relatively high reaction temperatures, rather than cyclohexane adsorption limitations. The results imply that elevating the reaction temperature of photocatalytic cyclohexane oxidation reduces selectivity, and is not a means to suppress catalyst deactivation.","","en","journal article","Royal Society of Chemistry","","","","","","","2011-12-14","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:0a2d99bc-c13b-4de7-a4a8-b65ad3397ae9","http://resolver.tudelft.nl/uuid:0a2d99bc-c13b-4de7-a4a8-b65ad3397ae9","Single molecule charge transport: From a quantum mechanical to a classical description","Kocherzhenko, A.A.; Grozema, F.C.; Siebbeles, L.D.A.","","2010","This paper explores charge transport at the single molecule level. The conductive properties of both small organic molecules and conjugated polymers (molecular wires) are considered. In particular, the reasons for the transition from fully coherent to incoherent charge transport and the approaches that can be taken to describe this transition are addressed in some detail. The effects of molecular orbital symmetry, quantum interference, static disorder and molecular vibrations on charge transport are discussed. All of these effects must be taken into account (and may be used in a functional way) in the design of molecular electronic devices. An overview of the theoretical models employed when studying charge transport in small organic molecules and molecular wires is presented.","","en","journal article","Royal Society of Chemistry","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:73fb553b-2a3f-486e-a4c2-17081274ff61","http://resolver.tudelft.nl/uuid:73fb553b-2a3f-486e-a4c2-17081274ff61","Secondary Industrial Minerals from Coal Fly Ash and Aluminium Anodising Waste Solutions","Nugteren, H.W.","Witkamp, G.J. (promotor); Kreutzer, M.T. (promotor)","2010","Minerals that are extracted from the earth’s crust to be directly used for their properties are called industrial minerals. This research shows that such minerals can also be produced from industrial residues, hence the name secondary industrial minerals. In this thesis coal fly ash is chosen as one of the industrial residues to work with. Since reuse of coal fly ash is restricted by its technical and environmental quality, the first approach was to improve its quality and thereby extend its applications. Significant fractions of heavy metals were removed from the ash by chemical extraction, but full compliance with leaching regulations could not be obtained. Since this method is tedious and costly and polluted effluents result, this is not the way to do it. A waste solution from the aluminium anodising industry is the other residue and is used as precursor for the synthesis of industrial minerals. Zeolites, dawsonite, ettringite and hydrotalcite were successfully synthesised from these effluents by using common other raw materials. This recovers most of the aluminium and other raw materials that would be otherwise lost and pollute the environment. The resulting effluents have pollutant concentrations below the accepted discharge levels. Zeolites can as well be synthesised by conversion of fly ash, however this yields mixtures of zeolites and ash. By extracting silica and alumina from fly ash and adding extra aluminium from the anodising waste solutions, commercial interesting zeolites could be synthesised with almost no input of primary raw materials. Another way of using both industrial residues together is the production of inorganic polymers, often referred to as geopolymers. Geopolymers with compressive strength of over 100 MPa were first made by activation of fly ash with potassium hydroxide and silicate solutions. Moreover, it is demonstrated that activation can also be done by using the aluminium anodising waste solutions. In this way an ‘all-waste’ geopolymer immobilising all hazardous components from its precursors is produced. The research shows that the production of secondary industrial minerals is an appropriate approach to simultaneously recover valuable materials from industrial residues, save primary resources and decrease emissions to the environment.","industrial minerals; coal fly ash; aluminium anodising; zeolite; geopolymer","en","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:c9fc2a31-5c30-48fe-8c30-39121fc59c63","http://resolver.tudelft.nl/uuid:c9fc2a31-5c30-48fe-8c30-39121fc59c63","Photoconductivity of Quantum Dot Films Towards Third-Generation Solar Cells","Talgorn, E.C.V.","Siebbeles, L.D.A. (promotor); Houtepen, A.J. (promotor)","2010","Colloidal semiconductor nanoparticles, also called quantum dots, have unique opto-electronic properties that make them promising candidates for many applications such as solar cells, light–emitting diodes, lasers, or biological imaging. One of the most interesting features is that the bandgap energy can be tuned by changing the particle size. This allows the design of solar cells with optimized absorption of the solar spectrum, resulting in improved power conversion efficiency. Quantum-dot-based opto-electronic devices require photoconductive nanocrystal assemblies, i.e. assemblies in which charge carrier photogeneration and transport are efficient. However, in assemblies of colloidal quantum dots, both the yield for charge carrier photogeneration and the charge mobility are initially low. This is due to the presence of long (1-2 nanometer), insulating molecules that are present at the surface of the dots for particle stabilization and surface passivation. The goal of this thesis was to produce photoconductive films of quantum dots and to understand the mechanisms governing charge generation, transport and decay in those films. Three options to increase the film photoconductivity were investigated in this thesis: capping removal (Chapter 2), capping exchange with short, organic molecules (Chapter 3, 5 and 6), and capping exchange with short, inorganic molecules (Chapter 4). Mobilities greater than 1 cm2/Vs were achieved in films of CdSe and PbSe quantum dots (Chapter 4 and 5), and in some cases, unity quantum yields of charge carrier photogeneration were attained (Chapter 5). Furthermore, charge extraction from quantum dot layers has been demonstrated with encouraging efficiency (Chapter 2). Those results show that quantum dots fulfill the requirements for use as the active material in solar cells.","colloidal nanoparticle; quantum confinement; quantum dot; thin film; solar cell; mobility; photogeneration quantum yield; photoconductivity; Time-Resolved Microwave Conductivity (TRMC)","en","doctoral thesis","","","","","","","","","Applied Sciences","Department of Chemical Engineering","","","",""
"uuid:981a234b-66fa-4cde-8ffb-19aec8e79842","http://resolver.tudelft.nl/uuid:981a234b-66fa-4cde-8ffb-19aec8e79842","Next Generation Steam Cracking Reactor Concept","Van Goethem, M.W.M.","Grievink, J. (promotor); Moulijn, J.A. (promotor); Verheijen, P.J.T. (promotor)","2010","The steam cracking process is an important asset in the hydrocarbon processing industry. The main products are lower olefins and hydrogen, with ethylene being the world's largest volume organic chemical at a worldwide capacity of ~ 120 million tonnes per year. Feed stocks are hydrocarbons such as: ethane, LPG, naphtha's, gas condensates and gas oil. The research goal of this thesis is to search for the intrinsic optimal steam cracking reaction conditions, pushing the olefin yields to the maximum that the fundamental reaction kinetic models allow for. To get to that goal we have: firstly, identified and assessed alternative process concepts published in the literature. Secondly, developed the concepts and software for an equation based modelling tool suitable for optimisation of large scale reaction kinetic models. Thirdly, developed a new reactor concept, d-RMix for homogeneous reactions with distributed feed allocation, product removal and macro-mixing. Fourthly, applied the optimisation tool to the new reactor concept model and an advanced reaction kinetic model for steam cracking, SPYRO(r). For four different feed stocks optimisations of ethylene yield and of ethylene plus propylene yields have been carried out. For the cracking of ethane a linear-concave unconstrained temperature profile with a (free) maximum temperature of ~1260 K proves optimal. For propane and heavier feed stocks an isothermal profile at the upper temperature bound is optimal, with dips at the beginning and the middle of the reaction volume coordinate. For these heavier hydrocarbon feeds a distribution along the reactor volume coordinate does result in higher yields. Having established that the steam cracking chemistry offers a potential for significantly higher olefins yields, these equipment engineering considerations pose a significant challenge to actually realise this potential and arrive at a next generation steam cracking reactor.","steam cracking; ethylene; propylene; ethene; propene; mixing; rinetics; attainable region; d-RMix; Distributed reaction mixing; spyro","en","doctoral thesis","M.W.M. van Goethem","","","","","","","2010-11-23","Applied Sciences","Chemical Engineering","","","",""
"uuid:df42ebaf-c77e-4fbd-b305-34d056a25569","http://resolver.tudelft.nl/uuid:df42ebaf-c77e-4fbd-b305-34d056a25569","Self-assembly and semiconductivity of an oligothiophene supergelator","Pratihar, P.; Ghosh, S.; Stepanenko, V.; Patwardhan, S.; Grozema, F.C.; Siebbeles, L.D.A.; Würthner, F.","","2010","A bis(trialkoxybenzamide)-functionalized quaterthiophene derivative was synthesized and its self-assembly properties in solution were studied. In non-polar solvents such as cyclohexane, this quaterthiophene ?-system formed fibril aggregates with an H-type molecular arrangement due to synergistic effect of hydrogen bonding and ?-stacking. The self-assembled fibres were found to gelate numerous organic solvents of diverse polarity. The charge transport ability of such elongated fibres of quaterthiophene ?-system was explored by the pulse radiolysis time resolved microwave conductivity (PR-TRMC) technique and moderate mobility values were obtained. Furthermore, initial AFM and UV-vis spectroscopic studies of a mixture of our electron-rich quaterthiophene derivative with the electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) revealed a nanoscale segregated assembly of the individual building blocks in the blend.","charge transport; hydrogen bonding; oligothiophene; organogel; self-assembly","en","journal article","Beilstein-Institut","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:092bfa3f-f61b-4d19-9e14-86950616e186","http://resolver.tudelft.nl/uuid:092bfa3f-f61b-4d19-9e14-86950616e186","Thin-sample limit for time-resolved terahertz spectroscopy","Schins, J.M.","","2010","The retrieval of the primary (subpicosecond) photoproducts in small-band two-dimensional time-domain terahertz spectroscopy has succeeded only in a few model systems, due to the complicated correlation between the two time parameters. We show that the nature of the primary photoproducts is revealed upon differentiating the measured time-domain spectra with respect to the pump-probe delay. An analytical treatment is given in the thin-sample limit, which distinguishes unambiguously between excitons and free charge carriers. This treatment gives a fair description of the data even for thick samples, including the subpicosecond timescale.","excitons; gallium arsenide; III-V semiconductors; optical pumping; semiconductor thin films; terahertz spectroscopy; terahertz wave spectra; time resolved spectra; time resolved spectroscopy","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:c32d353f-358c-48ad-a3f2-720656510f4b","http://resolver.tudelft.nl/uuid:c32d353f-358c-48ad-a3f2-720656510f4b","Electrical conductivity and defect chemistry of BaxSr1 - xCoyFe1 - yO3 - dBaxSr1?xCoyFe1?yO3? perovskites","Yáng, Z.; Harvey, A.S.; Infortuna, A.; Schoonman, J.; Gauckler, L.J.","","2010","Bulk BaxSr1 - xCoyFe1 - yO3 - dBaxSr1?xCoyFe1?yO3? compositions (BSCF) were synthesized by the solid-state reaction method. The electrical conductivity of ceramic bars was measured using a dc four-probe method as a function of temperature in air up to 970 °C. All compositions showed thermally activated p-type semi-conductivity up to ~450 °C and then a transition to metal-like conductivity. The small-polaron hopping p-type semi-conductivity depends on the oxygen nonstoichiometry, which increases with increasing temperature. Metal-like conductivity is attributed to the overlap of the transition metal d-electron orbitals with the oxygen p-orbitals. Strontium-rich compositions show higher conductivity. The Co/Fe ratio does not influence much the p-type semi-conduction. Iron-rich compositions revealed more metal-like conduction behavior. The degree of overlap between transition metal d-orbitals and oxygen p-orbitals depends on the Ba/Sr as well as on the Co/Fe ratios.","electrical conductivity; BSCF; mixed ionic and electronic conduction; perovskite; metal-insulator transition; cathode; solid oxide fuel cell; catalysis","en","journal article","Springer","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:af57d24c-3b26-42a4-b07c-073578da4ffe","http://resolver.tudelft.nl/uuid:af57d24c-3b26-42a4-b07c-073578da4ffe","Proton binding by linear, branched, and hyperbranched polyelectrolytes","Koper, G.J.M.; Borkovec, M.","","2010","This article reviews our understanding of ionization processes of weak polyelectrolytes. The emphasis is put on a general introduction to site binding models, which are able to account for many experimental features of linear and branched polyelectrolytes, including dendrimers. These models are fully compatible with the classical description of acid-base equilibria. The review further discusses the nature of the site-site interaction and role of conformational equilibria. Experimental charging data of numerous weak polyelectrolytes are discussed in terms of these models in detail.","proton binding; weak polyelectrolytes; conformation","en","journal article","Elsevier","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:c7c61f73-1552-4892-8676-a09012c7af53","http://resolver.tudelft.nl/uuid:c7c61f73-1552-4892-8676-a09012c7af53","Spark Discharge Generated Nanoparticles for Hydrogen Storage Applications","Vons, V.A.","Schmidt-Ott, A. (promotor)","2010","One of the largest obstacles to the large scale application of hydrogen powered fuel cell vehicles is the absence of hydrogen storage methods suitable for application on-board of these vehicles. Metal hydrides are materials in which hydrogen is reversibly absorbed by one or more metals or combinations of metals with non-metallic elements. Due to their high volumetric hydrogen content metal hydrides offer an alternative to traditional methods for hydrogen storage like high pressure gaseous or liquid hydrogen storage. In order to be successful, potential metal hydride systems depend on very small particle sizes, proper mixing of different components, and the addition of well dispersed catalyst(s). All of this can be achieved by spark discharge nanoparticle generation (SDG). In SDG, a high voltage power supply is used to generate sparks between two electrodes. The interaction of the sparks with the electrodes results in erosion of the electrodes, and the metal vapour that is thus formed condenses to form very small nanoparticles. Spark discharge offers an interesting alternative to current production methods for metal hydrides like ball milling, as very small and highly pure nanoparticles can be generated. The process is continuous, can be operated at atmospheric pressure and has the potential to be scaled up. The simplicity of adding a range of different catalysts and the high dispersion that can be achieved by mixing in the aerosol phase further add to the potential benefits of spark discharge. In this thesis results are presented on using spark discharge as a new method for generating metal hydride based hydrogen storage materials. It is the first part of a long term research effort at Delft University of Technology into new materials for hydrogen storage produced using this method.","Spark Discharge; Metal Hydride; Nanoparticles; Magnesium; Palladium","en","doctoral thesis","","","","","","","","2010-09-26","Applied Sciences","Chemical Engineering","","","",""
"uuid:2d5b608e-9b04-451d-94ec-d7c305612737","http://resolver.tudelft.nl/uuid:2d5b608e-9b04-451d-94ec-d7c305612737","Apparatus and process for atomic or molecular layer deposition onto particles during pneumatic transport","Van Ommen, J.R.","","2010","The invention provides a process for depositing a coating onto particles being pneumatically transported in a tube. The process comprising the steps of providing a tube having an inlet opening and an outlet opening; feeding a carrier gas entraining particles into the tube at or near the inlet opening of the tube to create a particle flow through the tube; and injecting a first self-terminating reactant into the tube via at least one injection point downstream from the inlet opening of the tube for reaction with the particles in the particle flow. The process is suitable for atomic layer deposition and molecular layer deposition. An apparatus for carrying out the process is also disclosed.","","en","patent","European Patent Office","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:24e4a62b-70ba-45ee-8777-28008c718772","http://resolver.tudelft.nl/uuid:24e4a62b-70ba-45ee-8777-28008c718772","Synthesis and Deposition of Nanostructured Lithium Nickel Manganese Film as Material for 3D Microbatteries","Garcia Tamayo, E.; Kelder, E.M.; Anastasopol, A.; Lafont, U.; Walpot, H.","","2010","","","en","journal article","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:e142d38b-d0ed-4560-8569-10254fd26dc6","http://resolver.tudelft.nl/uuid:e142d38b-d0ed-4560-8569-10254fd26dc6","Electrochemical Performance of Nanocomposite Fe2O3 and CuO Negative Electrodes for Li-Ion Batteries","Valvo, M.; Garcia Tamayo, E.; Lafont, U.; Kelder, E.M.","","2010","","","en","journal article","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:fb6db27d-f7f1-48fb-81cf-b784625adfc8","http://resolver.tudelft.nl/uuid:fb6db27d-f7f1-48fb-81cf-b784625adfc8","New Insight on the Failure Mechanism of Nano-Si Based Anodes for Li-Ion Batteries","Munaò, D.; Valvo, M.; Van Erven, J.; Kelder, E.M.","","2010","","","en","journal article","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:d9b47ed2-e950-459c-8c01-7c865a12b03d","http://resolver.tudelft.nl/uuid:d9b47ed2-e950-459c-8c01-7c865a12b03d","Cloud droplet activation of mixed organic-sulfate particles produced by the photooxidation of isoprene","King, S.M.; Rosenoern, T.; Shilling, J.E.; Chen, Q.; Wang, Z.; Biskos, G.; McKinney, K.A.; Pöschl, U.; Martin, S.T.","","2010","The cloud condensation nuclei (CCN) properties of ammonium sulfate particles mixed with organic material condensed during the hydroxyl-radical-initiated photooxidation of isoprene (C5H8) were investigated in the continuous-flow Harvard Environmental Chamber. CCN activation curves were measured for organic particle mass concentrations of 0.5 to 10.0 ?g m?3, NOx concentrations from under 0.4 ppbv up to 38 ppbv, particle mobility diameters from 70 to 150 nm, and thermodenuder temperatures from 25 to 100 °C. At 25 °C, the observed CCN activation curves were accurately described by a Köhler model having two internally mixed components, namely ammonium sulfate and secondary organic material. The modeled physicochemical parameters of the organic material were equivalent to an effective hygroscopicity parameter ?ORG of 0.10±0.03, regardless of the C5H8:NOx concentration ratio for the span of >200:0.4 to 50:38 (ppbv:ppbv). The volatilization curves (i.e., plots of the residual organic volume fraction against temperature) were also similar for the span of investigated C5H8:NOx ratios, suggesting a broad similarity of particle chemical composition. This suggestion was supported by limited variance at 25 °C among the particle mass spectra. For example, the signal intensity at m/z 44 (which can result from the fragmentation of oxidized molecules believed to affect hygroscopicity and CCN properties) varied weakly from 6 to 9% across the range of investigated conditions. In contradistinction to the results for 25 °C, conditioning up to 100 °C in the thermodenuder significantly reduced CCN activity. The altered CCN activity might be explained by chemical reactions (e.g., decomposition or oligomerization) of the secondary organic material at elevated temperatures. The study's results at 25 °C, in conjunction with the results of other chamber and field studies for a diverse range of conditions, suggest that a value of 0.10±0.05 for ?ORG is representative of both anthropogenic and biogenic secondary organic material. This finding supports the use of ?ORG as a simplified yet accurate general parameter to represent the CCN activation of secondary organic material in large-scale atmospheric and climate models.","","en","journal article","Copernicus Publications","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:b39e4e3f-2289-42d3-9e5b-61e3f5fecbc3","http://resolver.tudelft.nl/uuid:b39e4e3f-2289-42d3-9e5b-61e3f5fecbc3","Formation and Transport of Bubbles in Microfluidic Systems","Van Steijn, V.","Kleijn, C.R. (promotor); Kreutzer, M.T. (promotor)","2010","Precise manipulation of minute volumes of fluids is at the heart of microfluidics and opens up an exciting route to miniaturize processes in the areas of chemistry, biology and medicine. An attractive way to transport small fluid samples through the channels of microfluidic devices is by enclosing these samples inside containers in the form of microbubbles or microdroplets. The work described in this thesis is motivated by the need to reliably form such microbubbles and microdroplets and robustly transport them through networks of microchannels at high throughput. One of the central questions addressed in this thesis is how bubbles form at T-junctions under conditions typical to bubble-based microfluidic systems. The basic question how large bubbles grow is resolved by studying the fundamentals of bubble formation and pinch-off using experimental techniques, such as micro Particle Image Velocimetry. Another key question addressed in this thesis is how bubbles are transported in confined geometries. We hereby considered transport of bubbles through simple microchannel networks as found in for instance micro reactors and laboratories-on-chips, as well as through more complex microchannel networks comparable to for instance the pore structure in micro packed beds or oil reservoirs.","microfluidics; multiphase flow; bubble; droplet; segmented flow; micro Particle Image Velocimetry; lab-on-a-chip; droplet microfluidics","en","doctoral thesis","","","","","","","","","Applied Sciences","Multi-Scale Physics / Chemical Engineering","","","",""
"uuid:7f2823ff-07b9-442b-9c77-68144075f484","http://resolver.tudelft.nl/uuid:7f2823ff-07b9-442b-9c77-68144075f484","Start en wedergeboorte van de Delftse Hortus","Van Mourik, P.; Van der Veen, G.","","2010","De Botanische Tuin TU Delft werd begin vorige eeuw aangelegd om te voorzien in technische gewassen voor onderwijs en onderzoek aan de toenmalige TH Delft. Die functie heeft de tuin binnen de TU Delft nog steeds, maar de laatste jaren is de publieke functie ook belangrijk geworden. Jaarlijks bezoeken enige tienduizenden mensen de Delftse hortus.","Botanische Tuin TU Delft","nl","journal article","Erfgoed Delft","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:35aaff85-6073-4d21-8e64-b5410f3c7b15","http://resolver.tudelft.nl/uuid:35aaff85-6073-4d21-8e64-b5410f3c7b15","Solving the Heat Transport Issue in Multiphase Fixed Bed Reactors","Pangarkar, K.V.","Moulijn, J.A. (promotor); Kapteijn, F. (promotor)","2010","","","en","doctoral thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:d4cacbbd-052c-444d-ad2a-a29465f2b8e8","http://resolver.tudelft.nl/uuid:d4cacbbd-052c-444d-ad2a-a29465f2b8e8","Breakage of Agglomerates: Attrition, Abrasion and Compression","Van Laarhoven, B.","Schmidt-Ott, A. (promotor)","2010","In many industries particulate solids are handled in different forms. When producing particles breakage is an important wanted, in the case of grinding, or unwanted phenomenon. Granules often consist of more than one component and multiple phases. This means that granules are strongly anisotropic and inhomogeneous which makes mechanical characterization difficult, so the strength is difficult to measure. The objective of this thesis is to develop and validate new particle breakage testers from an industrial point of view. The philosophy behind the breakage testers is to isolate the forces that cause damage to the particles. This requires repeated stress cycles to be transfered to the test particles. To validate the improved attrition tester with an industrial application, the damage per unit energy is compared to the damage caused during dilute phase pneumatic conveying. Wear observed during Pneumatic conveying correlates well with results from the improved attrition tester for particles having surface asperities. But only during the so called rounding off phase. The asperities act as a fracture buffer absorbing energy from the impact. First the attrition process removes asperities. Then fracture occurs. Besides the validation of the attrition tester a new breakage tester testing tangential forces is developed in this work. The abrasion tester, is based on a particle box following a planetary motion. This motion causes the particles to rotate continuously over the particle box wall. The particle wear during abrasion testing, expressed in mass loss over transferred kinetic energy is in the same order as during attrition testing. This is explained by the same efficiency at which the kinetic energy is converted into particle deformation. The kinetic energy is converted into newly created surface energy. And the efficiency at which this occurs is a particle property. The major difference between abrasion and attrition testing is the absence of the accelerated removal of surface asperities. A qualitative difference between abrasion and attrition testing is also presented. Abrasion is characterized by the gentle polishing of the particles. Whereas attrition testing results in the removal of the asperities and ""craters"" are visible of the impact sites of the particle with the wall. Often granules are coated with a water soluble polymeric coating in order to improve the mechanical strength. The question arises what polymeric properties are important to form a mechanically strong coating on a particle? The work of Rowe is cited about the adhesion of the coatings to the particles. Rowe found an inverse relation between coating thickness and film adhesion. Indicating that a thick coating does not necessarily leads to stronger granules. To study the influence of different coating polymers on the overall particle strength, particle formulations are made using fluidised bed coating. The formulated particles are then tested using the developed attrition, abrasion and compression tester. Three attrition sub regimes are identified, the peeling, erosion and layer fatigue modes. The conclusion is that for an elastic deforming brittle polymer, the layer fatigue attrition sub mechanism is expected. Applying a plastic deforming coating leads to a reservoir system where the fragments are held together by the plastic deforming coating. A plastic deforming coating on sodium benzoate shows the erosion mechanism during attrition testing. The coated granules are abrasion tested. A linear relation between remaining mass and transfered energy is observed. During abrasion testing it was not possible to remove all the coating completely. Apparently the rate of strain in the abrasion tester is not high enough for the coatings to be removed. Applying higher strain rates by increasing the centripetal force could overcome this. At this moment it is mechanically not possible. Also the coated particles are much stronger towards abrasion testing than to attrition testing. This is explained by the perceived thickness of the coating. The compression strength of coated granules is not easy to quantify since there is a large spread in the observed critical stress. This large spread is due to the heterogeneous nature of the granules. Weibull statistics are successfully applied to statistically describe the observed strength of the coated granules. Using Weibull statistics a ranking can be made between the coatings and the compression strength. A plastic deforming coating tends to hold the particle together as a reservoir upon compression. An elastic deforming coating has a higher initial strength without regions of plastic deformation. Individual failure of different layers is observed. This compares also to the layer fatigue attrition mechanism where initially no attrition is observed but after a while the granules start to fail.","attrition; abrasion; abrasion tester; breakage tester","en","doctoral thesis","Uitgeverij Boekenplan","","","","","","","2010-03-08","Applied Sciences","Chemical engineering","","","",""
"uuid:d02df51d-ddbc-43a4-8da0-086a4491cece","http://resolver.tudelft.nl/uuid:d02df51d-ddbc-43a4-8da0-086a4491cece","Photoconductance of conjugated materials for organic electronics","Grzegorczyk, W.J.","Siebbeles, L.D.A. (promotor)","2010","The photogeneration and mobility of charge carriers in organic thin films, including bulk heterojunctions (BHJs), have been studied with the time resolved microwave photo-conductance technique (TRMC). The TRMC technique allows the electrodeless measurement of the photoconductance with nanosecond time resolution. The research focuses on the way in which molecular structure and film morphology affect the optical and the photoconductive properties. Chapter 2 describes the effects of annealing of pDA2T:PCBM BHJ thin films on the nanomorphology and optoelectronic properties. It is shown, that upon annealing extensive phase segregation of the pDA2T and PCBM and crystallization of the polymer domains occur. The segregation leads to a reduced charge separation efficiency and long lifetime of charge carriers. These results show that annealing is an efficient method for manipulating the photophysics of polymer:PCBM BHJs. Chapter 3 presents the relationship of the nanomorphology and the photoconductive properties of several blends based on different poly(thienothiophene) co-polymers and PCBM. Annealing of pDA2T:PCBM and of pBTTT:PCBM at 120 °C (for molecular structures see page 9) leads to phase segregation of the polymer and PCBM. Interestingly, annealing of pBTCT:PCBM at 120 °C and of pBTTT:PCBM at 165 °C results in a multiple bilayer structure, in which PCBM molecules intercalate between polymer chains. The highest photoconductance is obtained for the BHJs exhibiting phase segregation. This is associated with efficient generation of electrons in the PCBM domains. Though in BHJs with a multiple bilayer structure efficient photoluminescence quenching is observed, fast charge carrier recombination results in low photoconductance. Chapter 4 describes studies on thin-film BHJs of poly(3-hexyl thiophene) and soluble oligomers of siloxane substituted with naphthalene diimide (NDIS) moieties, prepared by spin-coating from chloroform (CHCl3) or from ortho-dichlorobenzene (ODCB). CHCl3 derived samples exhibit no phase segregation in TEM images. By contrast, for ODCB derived blends phase segregation occurs with an extent that increases with the molecular weight of the NDIS molecules and the weight content of NDIS. The formation of large NDIS clusters is essential for efficient photogeneration of charges. Chapter 5 addresses the mechanism of photogeneration of charge carriers in P3HT:PCBM bulk heterojunctions. This study has been performed using TRMC and femtosecond transient optical absorption spectroscopy at temperatures ranging from 10 K to 298 K. It is inferred that charge generation does not occur via the Onsager-Braun model. The absence of an effect of temperature on the quantum yield of charges can be due to coupling of the initially hot exciton with excess vibrational energy. The magnitude of the photoconductance is found to be strongly dependent on the film preparation procedure. Chapter 6 reports a study of the relation between the nanomorphology and the mobility of charge carriers in thin films of a liquid crystalline terthiophene derivative. The anisotropy of the optical absorption is much higher than for the mobility. This result can be understood on basis of quantum chemical calculations of electronic couplings for charge transport in different directions.","bulk heterojunction; conjugated polymer; photoconductance; time-resolved microwave conductance; nanomorphology; molecular crystals; organic solar cells; organic field-effect transistors; polythiophenes","en","doctoral thesis","","","","","","","","2010-02-23","Applied Sciences","Chemical Engineering","","","",""
"uuid:3e31f289-9f5c-4b24-a7d9-21c41d6a9a4d","http://resolver.tudelft.nl/uuid:3e31f289-9f5c-4b24-a7d9-21c41d6a9a4d","Electrosprayed Metal Oxide Semiconductor Films for Sensitive and Selective Detection of Hydrogen Sulfide","Ghimbeu, C.M.; Lumbreras, M.; Schoonman, J.; Siadat, M.","","2009","Semiconductor metal oxide films of copper-doped tin oxide (Cu-SnO2), tungsten oxide (WO3) and indium oxide (In2O3) were deposited on a platinum coated alumina substrate employing the electrostatic spray deposition technique (ESD). The morphology studied with scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows porous homogeneous films comprising uniformly distributed aggregates of nano particles. The X-ray diffraction technique (XRD) proves the formation of crystalline phases with no impurities. Besides, the Raman cartographies provided information about the structural homogeneity. Some of the films are highly sensitive to low concentrations of H2S (10 ppm) at low operating temperatures (100 and 200 °C) and the best response in terms of Rair/Rgas is given by Cu-SnO2 films (2500) followed by WO3 (1200) and In2O3 (75). Moreover, all the films exhibit no cross-sensitivity to other reducing (SO2) or oxidizing (NO2) gases.","semiconductor metal oxide; electrostatic spray depositio; gas sensors; pollutant gases","en","journal article","MDPI AG","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:9c600f27-e4be-403a-b312-9a0c2174ce0b","http://resolver.tudelft.nl/uuid:9c600f27-e4be-403a-b312-9a0c2174ce0b","Defect Properties and Photoelectrochemical Performance of BiVO4 Photoanodes","Liang, Y.; Kleijn, S.; Mooij, L.; Van de Krol, R.","","2009","","","en","journal article","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:2f2d917d-19e1-40cc-9cd2-d6153d2dd1c2","http://resolver.tudelft.nl/uuid:2f2d917d-19e1-40cc-9cd2-d6153d2dd1c2","Lichtkloverij: Interview met Prof. dr. L.D.A. Siebbeles","De Vries, G.","","2008","“Waarom leggen we de daken niet vol zonnecellen? Dan is het energieprobleem zo opgelost.” Een aantrekkelijke gedachte, maar nog steeds geen praktijk. Dat komt door hoge productiekosten en een relatief laag rendement. In het Joint Solar Programme van FOM wordt gewerkt aan materialen die een groter deel van het erop vallende licht omzetten in elektrische energie.","","nl","journal article","Delft University of Technology","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:75ab7d41-fd77-4fdc-aab2-301d1a0ca59b","http://resolver.tudelft.nl/uuid:75ab7d41-fd77-4fdc-aab2-301d1a0ca59b","Voltammetric Detection of Urea on an Ag-Modified Zeolite- Expanded Graphite-Epoxy Composite Electrode","Manea, F.; Pop, A.; Radovan, C.; Malchev, P.G.; Bebeselea, A.; Burtica, G.; Picken, S.J.; Schoonman, J.","","2008","In this paper, a modified expanded graphite composite electrode based on natural zeolitic volcanic tuff modified with silver (EG-Ag-Z-Epoxy) was developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer and a good stability of the electrode in 0.1 M NaOH supporting electrolyte. This modified electrode exhibited moderate electrocatalytic effect towards urea oxidation, allowing its determination in aqueous solution. The linear dependence of the current versus urea concentration was reached using square-wave voltammetry in the concentrations range of urea between 0.2 to 1.4 mM, with a relatively low limit of detection of 0.05 mM. A moderate enhancement of electroanalytical sensitivity for the determination of urea at EG-Ag-Z-Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric/amperometric quantification.","urea determination; expanded graphite-Ag-zeolite-epoxy composite electrode; electrocatalytic effect","en","journal article","MDPI AG","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:0d5d8575-10d7-4645-a754-7833b63c2f18","http://resolver.tudelft.nl/uuid:0d5d8575-10d7-4645-a754-7833b63c2f18","Phase behavior of flowerlike micelles in a SCF cell model","Sprakel, J.; Besseling, N.A.M.; Cohen Stuart, M.A.; Leermakers, F.A.M.","","2008","We study the interactions between flowerlike micelles, self-assembled from telechelic associative polymers, using a molecular self-consistent field (SCF) theory and discuss the corresponding phase behavior. In these calculations we do not impose properties such as aggregation number, micellar structure and number of bridging chains. Adopting a SCF cell model, we calculate the free energy of interaction between a central micelle surrounded by others. Based on these results, we predict the binodal for coexistence of dilute and dense liquid phases, as a function of the length of the hydrophobic and hydrophilic blocks. In the same cell model we compute the number of bridges between micelles, allowing us to predict the network transition. Several quantitative trends obtained from the numerical results can be rationalized in terms of transparent scaling arguments.","Self-assembly; Phase separation and segregation in colloidal systems; Self-consistent-field methods","en","journal article","Springer","","","","","","","","Applied Sciences","Department of Chemical Engineering","","","",""
"uuid:0fdb47d8-2140-4abb-8325-9b59c1cab2b4","http://resolver.tudelft.nl/uuid:0fdb47d8-2140-4abb-8325-9b59c1cab2b4","Carbon-based Composite Electrodes: Preparation, Characterization and Application in Electroanalysis","Corb, I.; Manea, F.; Radovan, C.; Pop, A.; Burtica, G.; Malchev, P.G.; Picken, S.J.; Schoonman, J.","","2007","Electrodes based on carbon, i.e., expanded graphite (20%, wt.)-epoxy composite (20EG-Epoxy) and expanded graphite (20%, wt.)-polystyrene composite (20EG-PS) have been prepared, characterized using scanning electron microscopy (SEM) and cyclic voltammetry (CV), and tested as anodic sensors. The electrodes exhibited good mechanical resistance and low electrical resistances. Scan rate dependent cyclic voltammetry responses at 20EG-Epoxy and 20EG-PS composite electrodes, which were exemplified for thiourea (TU), a toxic sulphur organic compound selected as testing target analyte in 0.1 M Na2SO4 supporting electrolyte, were investigated. The obtained voltammetric data were in accordance with those for a random array of microelectrodes. The voltammetric and chronoamperometric detection results of TU in tap water samples, without a supplementary addition of supporting electrolyte, at 20EG-Epoxy electrode proved its use for direct analysis of environmental samples.","carbon-based composite electrode; microelectrode array behavio; thiourea; electroanalysis","en","journal article","MDPI AG","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:438d37b6-9e09-44bd-a2ad-61080662045a","http://resolver.tudelft.nl/uuid:438d37b6-9e09-44bd-a2ad-61080662045a","Direct numerical simulation of deformable bubbles in wall-bounded shear flows","Sousa, F.S.; Portela, L.M.; Mudde, R.F.; Mangiavacchi, N.","","2006","We present a method for fully-resolved simulations of bubbly flows using a front-tracking/front-capturing technique. The method is a modification of a marker-and-cell method developed previously for free-surface flows. The basic approach is somehow similar to the front-tracking method of Tryggvason: the continuity and Navier-Stokes equations are solved in a single Eulerian grid, and the interface is represented by an unstructured Lagrangian grid moving through the Eulerian grid, with the velocities at the Lagrangian grid obtained by interpolation from the Eulerian grid. However, contrary to Tryggvason's method, our method uses a sharp interface between the gas and the liquid, since it ""captures"" the interface within one cell of the Eulerian grid. The surface tension is expressed as a body-force in the Eulerian grid, and is computed using a least-squares fit, together with a mass-conserving filter to remove sub-grid oscillations. The Navier-Stokes equations are solved using a finite difference scheme on the Eulerian grid and the continuity is enforced using a standard projection technique, with the resulting Poisson equation being solved by a conjugate gradient method. We present some results of the simulations of single bubbles of different sizes in laminar wall-bounded uniform-shear flows at moderate Reynolds numbers (bubble-Reynolds-number in the range of 20-50). In wall-bounded shear flows, it has been observed experimentally that depending on the bubble size the lift force can push the bubble either towards or away from the wall. Our simulations show a good agreement with the experiments, both qualitatively and quantitatively, and an explanation for the lift inversion mechanism is provided based on the analysis of the forces acting on the bubble.","Direct Numerical Simulation; front-tracking; front-capturing; bubbly flows; shear flow; lift force","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:5b866a24-cdbd-43d8-87d2-409227bf317d","http://resolver.tudelft.nl/uuid:5b866a24-cdbd-43d8-87d2-409227bf317d","Impedance Simulation of a Li-Ion Battery with Porous Electrodes and Spherical Li+ Intercalation Particles","Huang, R.W.J.M.; Chung, F.; Kelder, E.M.","","2006","We present a semimathematical model for the simulation of the impedance spectra of a rechargeable lithium batteries consisting of porous electrodes with spherical Li+ intercalation particles. The particles are considered to have two distinct homogeneous phases as a result of the intercalation and deintercalation of Li+ during charge and discharge. The diffusion of Li+ ions in the two phases and the charge transfer at the solid electrolyte interface (SEI) are described with a mathematical model. The SEI and the electrolyte are modeled using passive electronic elements. First, this model is derived for a single intercalation particle consisting of two different solid phases. This model is then transformed to a continuous model and applied to a single porous electrode, where the sizes of the particles are assumed to have on average two grain sizes where the radii are Gaussian distributions. Finally, this model is further developed to simulate the impedance of a rechargeable lithium-ion battery.","lithium; secondary cells; electrochemical electrodes; porous materials; intercalation compounds; solid electrolytes; diffusion; charge exchange; particle size; grain size; Gaussian distribution; electric impedance","en","journal article","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:15360042-dd7c-4694-91cd-71ec0fab7bb9","http://resolver.tudelft.nl/uuid:15360042-dd7c-4694-91cd-71ec0fab7bb9","Secondary nucleation attributable to the combined effects of crystal-impeller and crystal-crystal collisions","Van Beusichem, R.","Kramer, H.J.M. (mentor); Jansens, P.J. (mentor)","2006","","secondary nucleation models; CSD; attrition","en","master thesis","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","Laboratory for Process and Energy","",""
"uuid:fbc3c36f-696b-4728-a818-af9780e43886","http://resolver.tudelft.nl/uuid:fbc3c36f-696b-4728-a818-af9780e43886","Electrochemical Properties of Imidiazolium-based Ionic Liquids","Best, A.S.; Nerkar, J.Y.; Ooms, F.G.B.; Picken, S.J.","","2005","","","en","journal article","The Electrochemical Society","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:6a58bb6d-a842-4e15-943a-c593c5c07773","http://resolver.tudelft.nl/uuid:6a58bb6d-a842-4e15-943a-c593c5c07773","Extraction of silicon and aluminium from coal fly ash","Sebastia Garcia, Eva","Nugteren, H.W. (mentor)","2000","","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and of Materials Science","","Applied Thermodynamics and Phase Behaviour","",""
"uuid:1d55ba5e-1317-48b7-b601-9e842df6fd1c","http://resolver.tudelft.nl/uuid:1d55ba5e-1317-48b7-b601-9e842df6fd1c","The Mechanisms of Combined Granulation and Drying of Aspartame in a Turbo Dryer","Smit, Martin","Scarlett, B. (mentor); Meesters, G.M.H. (mentor); Vercoulen, P. (mentor); Verkoeijen, D. (mentor); Slangen, H. (mentor)","2000","","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and of Materials Science","","Applied Thermodynamics and Phase Behaviour","",""
"uuid:056b6aa8-4ec2-40fd-a07b-2908b5e80f6a","http://resolver.tudelft.nl/uuid:056b6aa8-4ec2-40fd-a07b-2908b5e80f6a","Anisotropy in Powder Flow Behavior","Raharja, Andreas","Janssen, R.J.M. (mentor); Scarlett, B. (mentor)","1999","Depending on the properties and the process that is applied, a powder may be capable of forming anisotropic structure. Understanding on this behavior may help one to design equipment and to interpret measurement results obtained with different testers. In this project, anisotropy in powder flow behavior has been investigated by the use of a Jenike shear cell and a Flexible Wall Biaxial Tester (FWBT). The FWBT is operated in a strain controlled manner and its performance in conducting this operation is also investigated. The strength anisotropy of three different powders has been measured with the Jenike shear cell. The powders are BCR limestone (4 |xm) , glass beads (60 pm), and a mixture composed of l%w aerosil R-812 and 99%w BCR limestone. In the experiments the consolidation and preshear are performed as normally, but the shear is carried out in different directions than that of the preshear. For each direction a yield locus can be constructed to obtain the corresponding unconfmed yield strength. The plot of unconfined yield strength as a function of shear direction represents the degree of the strength anisotropy of the powder. The results shows that BCR limestone is strongly anisotropic. The effect is less with the mixture and is not seen with the glass beads...","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and of Materials Science","","","",""
"uuid:7e0129a7-9384-4c22-8279-f8f969b9e23f","http://resolver.tudelft.nl/uuid:7e0129a7-9384-4c22-8279-f8f969b9e23f","The Effects of Moisture Content on the Kinetics of Agglomeration and Consolidation of Copper Ore in a Batch Rotating Drum Granulator","van de Water, R.","Scarlett, B. (mentor); Meesters, G.M.H. (mentor); Wauters, P.A.L. (mentor); Litster, J.D. (mentor); Cameron, I. (mentor)","1999","This research was aimed at investigating the influence of moisture content on the kinetics of growth and consolidation behaviour of copper chalcopyrite in a rotating batch drum granulator. The material exhibited typical induction growth behaviour [9], in the moisture range of 10 to 12%. With increasing moisture content in the aforementioned interval the induction time decreased and the end granule size increased. Systems with moisture contents below this interval remained in the nucleation region, whereas systems with moisture contents above this interval exhibited rapid growth behaviour. This is in agreement with the granulation behaviour described in literature. With increasing moisture content it was found that the maximum pore saturation (Smax) increased as well as the Stokes deformation number (Stdef), also being in agreement with literature. The results of the experiments were used to further develop and validate the regime map proposed by Iveson and Litster [9]. This regime map postulates that the type of granule growth is a function of the systems liquid content, represented by Smax and the granule deformation during collision, represented by Stdef. The plotted results all lie in the induction region and it was observed that increasing the moisture content shifted the system from the induction stage to the rapid growth stage. Although the results are promising and the regime map potential has the potential to aid in design and control of granulation systems, more experiments have to be carried out for further validation. Analysis of the experiments carried out on the continuos pilot plant showed that even with knowledge of granule growth behaviour of a material, it is extremely difficult to control granulation in a continuous manner. Besides the influence of moisture content, a range of other variables, like the wetting characteristics of the material and equipment, influenced the process remarkably. The operation of granulation still heavily relies on the experience of operator experience.","","","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:1a95cffc-8201-4f20-bc45-bc30e8e8cd3f","http://resolver.tudelft.nl/uuid:1a95cffc-8201-4f20-bc45-bc30e8e8cd3f","Promoting capabilities of some in water insoluble components on the formation of gas hydrates: Experiments and Modelling","van den Heuvel, M.","Peters, C.J. (mentor); de Swaan Arons, J. (mentor)","1999","Gas hydrates are a special case of clathrate hydrates, which are ice-like crystalline inclusion compounds. They can be formed in systems of water and small molecules like methane, ethane or propane, for example. The small molecules are encapsulated in structures of hydrogen bonded water molecules and stabilise the structure in this way. The stabilisation makes the existence of gas hydrates possible above the freezing temperature of water, at elevated pressures...","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:ab726df9-2bfb-408c-9471-cef3f41d619e","http://resolver.tudelft.nl/uuid:ab726df9-2bfb-408c-9471-cef3f41d619e","The Effect Of Sodium Chloride On The Hydrate Equilibrium in the System Methane+ Water+ 1,3-Dioxolane + NaC1: Experiments and modelling","Reuvers, M.","Peters, C.J. (mentor); de Swaan Arons, J. (mentor)","1998","Systems of water and small molecules form ice-like crystal structures at low temperatures and high pressures. The hydrogen-bonded water molecules form a lattice that is stabilised by the presence of the encaged molecules. The incentive for hydrate research at this laboratory is the possibility to store natural gas in the form of hydrates in underground salt caverns. From earlier investigations it became apparent that sodium chloride had a strong hydrate inhibiting effect with as a consequence unacceptably high equilibrium pressures in the caverns. Recently it was found that addition of small amounts of certain organic compounds show the opposite effect, i.e., a hydrate promoting effect. Therefore, the main purpose of this study was to investigate which and to what extent these organic compounds reduce the equilibrium pressures to such a low level that storage of natural gas in salt caverns again is an option to consider. To achieve this objective, hydrate equilibrium conditions have been measured with Cailletet equipment. 1,3-Dioxolane has been used as a hydrate promotor. In addition, the results obtained along with those obtained by De Deugd on the salt-free system have been modelled using an edited version of an existing mathcad program. This program is based on the Van der Waals and Platteeuw theory. The UNIF AC group contribution method has been used to calculate the activity coefficients of water and 1,3-dioxolane. The effect of the sodium chloride has been introduced by adding the extended Debye-Hilckel electrolyte model to the prediction program. The results show that the hydrate equilibrium pressures are calculated correctly for the three component system water + 1,3-dioxolane + methane. However, the equilibrium conditions of the system containing salt have not been calculated correctly, probably due to an incorrect relation for the activity coefficient of water and 1,3-dioxolane. The conclusions of this study are that the Cailletet equipment can be used to measure hydrate equilibrium conditions for systems containing salt and that the mathcad prediction program is able to calculate hydrate equilibrium conditions for systems without salt, but needs improvement for calculations on systems containing salt.","","; en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:e2ee5584-2722-4833-9902-5fd93cce5624","http://resolver.tudelft.nl/uuid:e2ee5584-2722-4833-9902-5fd93cce5624","Sustainability of Palm Oil Production: A Thermodynamical Approach","van den Berg, Michiel M.D.","de Swaan Arons, J. (mentor); van der Kooi, H.J. (mentor); Vis, J.C. (mentor); Broekhoff, J.C.P. (mentor)","1998","In the environment report of 1998 [2] Unilever’s Environment Policy is stated: ‘Unilever is committed to meeting the needs of customers and consumers in an environmentally sound and sustainable manner, through conscious improvement in environmental performance in all our activities.” [2]. Environmental problems are part of the trilemma the world faces, which is a trade off among economic growth, consumption of energy and resources and conservation of the environment. As the solution for the trilemma the concept of sustainable development or sustainability is introduced, as defined by the UN commission Brundtland in 1987. To be able to scientifically work through to a solution of environmental problems, it is necessary to give concrete form to the term sustainability. Thermodynamics was thought to be able to play a key role in this process. The goal of this project was: ‘Performing an exergy analysis, parallel to an existing life cycle analysis, of the process route of a Unilever product made from one of the strategic crops and using the results of this analysis as the basis for the development of a sustainability parameter, based on thermodynamics, with the purpose of being able to trace sources of environmental impact better and thus contributing to an efficient and scientifically justifiable minimisation of the total environmental impact of Unilever’s activities.'...","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Phase Equilibria and Applied Thermodynamics","",""
"uuid:0a74917e-3275-4289-b87c-c31c245e7e48","http://resolver.tudelft.nl/uuid:0a74917e-3275-4289-b87c-c31c245e7e48","Modeling phase behavior of polymer/solvent/anti-solvent systems for design of supercritical anti-solvent separation processes for polymer mixtures: Calculation of the influence of anti-solvents on the phase behavior of polymer/solvent systems using the SAFT equation of state","ter Horst, M.H.","de Swaan Arons, J. (mentor); de Loos, W. (mentor); Arlt, W. (mentor); Sadowski, G. (mentor); Behme, S. (mentor)","1998","To predict phase behavior of the polymer/cyclohexane/anti-solvent systems, binary interaction parameters for the constituent component pairs had to be found by fitting the equation of state on binary literature data. Predicted cloud-point curves of ternary systems subsequently were compared to experimental curves and, if necessary, the polymer/gas interaction parameters were adjusted to improve the predictions. The resulting parameters were used to calculate the minimum pressure and amount of anti-solvent to reach a desired separation (product streams: almost pure cyclohexane + 25%wt polymer/75%wt cyclohexane solution) at a chosen temperature…","","","student report","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:71238daa-7e7f-4da6-8c63-808264eb3cc0","http://resolver.tudelft.nl/uuid:71238daa-7e7f-4da6-8c63-808264eb3cc0","Measurements and modelling of liquid-liquid equilibria: of ɛ-caprolactam + water + solvent + ammonium sulfate systems","van Bochove, G.","Wijtkamp, M. (mentor); de Loos, W. (mentor); de Swaan Arons, J. (mentor)","1998","Ɛ-Caprolactam. the monomer of Nylon-6, is obtained from the production process as an aqueous solution of ammonium sulfate and ɛ -caprolactam. The crude Ɛ-Caprolactam is purified by extraction with an organic solvent. To be able to model this extraction process, thermodynamic modelling of liquid-liquid equilibria of Ɛ-Caprolactam + water + solvent + ammonium sulfate is required. Since the number of models in literature is scarce, a dedicated model for the description of liquid-liquid equilibria of mixed solvent electrolyte systems has to be developed. In this work liquid-liquid equilibria were experimentally determined for the systems Ɛ-Caprolactam + water + 1-heptanol + ammonium sulfate at 20°, 40° and 60°C. In addition to this experimental work, a program was developed to correlate experimental liquid-liquid equilibrium data of mixed solvent electrolyte systems. The program is based on an activity coefficient model, that consists of a nonelectrostatic contribution and an electrostatic contribution. The Non Random Two Liquid (NRTL) theory is used to describe the nonelectrostatic contribution. The statistical mechanical Mean Spherical Approximation (MSA) theory is used to account for the electrostatic interactions. The MSA is a physically more correct model than the Debye-Hückel model, since it takes into account ion size effects. The new NRTL-MSA activity coefficient model is compared with the existing electrolyte NRTL models of Chen and Liu. The experimental work showed that 1-heptanol may be a suitable solvent for the extraction of Ɛ-Caprolactam. The presence of ammonium sulfate in the system favours the dissolution of Ɛ-Caprolactam in the organic phase and salts out the aqueous phase. At increasing temperature, the solubility of Ɛ-Caprolactam in 1-heptanol increases to a greater extent than the solubility in water. The NRTL-MSA model, built up from an electrolyte NRTL contribution and an electrostatic MSA contribution without explicit hard sphere contribution produces promising results for the representation of liquid-liquid equilibria of mixed solvent electrolyte systems. For the system water + 2-propanoI + sodium chloride, an average deviation of 0.006 w/w could be reached. It might be concluded carefully that the NRTL-MSA performs better than the electrolyte NRTL. However, the model still needs more testing. It is also recommended to extend and apply the nonprimitive MSA to mixed solvent systems and compare it with the results of the NRTL-MSA model, presented here.","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:877e157d-c224-4a6b-9b5e-824e88b111ce","http://resolver.tudelft.nl/uuid:877e157d-c224-4a6b-9b5e-824e88b111ce","Modeling of Complex Reaction Systems: Steam Cracker","Goethem, M.W.M. Van","Van Leeuwen, C. (mentor); Verheijen, P.J.T. (mentor)","1998","Steam pyrolysis of ethane and naphtha is an important chemical bulk process. It produces ethylene and propylene, which are important base chemicals. In order to be competitive, crackers have to be operated at near optimal conditions. Hence, a simulation program of the process, particularly of the pyrolysis is very helpful. KTI uses and licenses such a program called SPYRO*. Development of this program has started over 20 years ago. Consequently, it uses a closed model. It has been the objective of this study to investigate the feasibility of the development of an open version of SPYRO. Here open means that the equations are written in residual form .This enhances the flexibility of the program very much. For our studies we have used the model of Froment for ethane cracking because the documentation to make an open SPYRO model was insufficient. This Froment model has been modified as to improve the modeling of the bends. It has been checked, whether the solution of this model would pose any problems. It was found that the index might become more than 1 during integration. As yet no sound physical explanation has been found for this phenomena. It also follows from investigation of the index that a start-up problem of the numerical integration exists for the original set of differential equations. We have found a more elegant method to circumvent this problem than Froment. Moreover, we were able to solve the set of equations for bad initial conditions (equal to the boundary conditions). The ordinary differential equations of the model are turned into algebraic equations using orthogonal collocation on finite elements. This allows the model to be solved with an equation solver. The results were compared with various commercial numerical integrators. Excellent agreement was found for limited numbers of sections and collocation points. The speed of solution of the linearized set of modal equations depends on the size, the sparsity and structure of the Jacobian. The latter has an enormous effect on the fill-in of the L and U decomposition matrices. We found a very satisfying structure by modification of the equations and proper arrangement in the Jacobian. On the basis of the above results we may draw the following conclusions regarding the feasibility of the development of an Open SPYRO model. Unfortunately we had to use a simple model of Froment rather than the SPYRO equations themselves. Nevertheless, we have concluded that such a development is feasible. Within a reasonable time an accurate solution will be found even with bad starting values. The computation time can be further reduced with a smart initialization procedure.","kinetic systems; simulation","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:1c25523f-2271-4d28-8bbb-77d8116f60dc","http://resolver.tudelft.nl/uuid:1c25523f-2271-4d28-8bbb-77d8116f60dc","Exergy Analysis as a Thermodynamic Tool for Gaining New Insights into Chemical Processes: Demonstrated on the SNC Pernis Isopropylalcohol Process","Blokker, W.R.; Molenaar, P.","de Swaan Arons, J. (mentor); van der Kooi, H.J. (mentor); Mooiweer, A.L. (mentor); Iwema, K.A. (mentor); Schoonakker, M.C. (mentor); van Diepen, P.B.J. (mentor); Donkers-Dijken, M.R.G. (mentor); Scholes, G. (mentor)","1998","This thesis demonstrates how exergy analysis can be used to gain new insights into chemical processes. Exergy analysis has been applied to the SNC Pernis Isopropylalcohol process in order to introduce the concepts of exergy and exergy analysis together with its applications to Shell personnel and to show the strength and the usefulness of an exergy analysis in the chemical industry. These objectives have been met by using exergy analysis as a tool for identifying the weaknesses of the SNC Pernis Isopropylalcohol process (COF/3) with regard to exergy utilization by locating and quantifying the main exergy losses, by interpreting and understanding the reasons and causes of excessive exergy losses and by introducing and investigating possible solutions to reduce those losses and to conserve exergy as long as possible. Exergy analysis has proved to be an invaluable thermodynamic, diagnostic tool for process analysis. Exergy analysis provides clear insights into a chemical process and should therefore preferably be used in the design phase of new process designs. The strength of exergy analysis lies in the fact that it is able to direct research and new thinking in order to develop new processes based on minimal exergy consumption and that it covers all aspects relating to process. Analysis of the exergy utilization of the IPA-cbm/IPA section of the COF/3 plant shows that the main exergy losses arise as a result of the original process design: the choice of a reaction route with low conversion to isopropylalcohol and the maintenance of a large water recycle in the separation sections. Potential improvements include, the choice of a reaction route based on the partial oxidation of propane; to reduce the size of the water recycle, a unique combination of a membrane and a heat-pump is proposed. As far as is known such a combination has never been applied on an industrial scale; the use of membranes as an end-of-pipe solution to break the water/IPA azeotrope; the installation of a hot water plant possibly in combination with a heat transformer and the installation of heat pumps. The analysis of the DMK/MIBK section of the COF/3 plant shows that, from an exergetic point of view, the use of DMK originating from the cumene oxidation process is unfavourable compared to the DMK produced in the COF/3. Also a capacity enlargement of the after reactor rather than the direct route reactor should be preferred for the production of MIBK. Finally the replacement of the current heat integration to drive the reboiler of the finished DMK column has been investigated. The essential conclusion of this graduation project is that exergy analysis provides a more fundamental approach to the analysis of chemical processes.","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","","",""
"uuid:3ec4bd01-9fa8-47ad-a121-ee8fe580e535","http://resolver.tudelft.nl/uuid:3ec4bd01-9fa8-47ad-a121-ee8fe580e535","Microstructure of Concentrated Acrylic Dispersions Thickened with Triblock Polymer Surfactants: Studied by Means of Rheometry, Light Scattering and Light Transmission Techniques","Cai, R.","Reuvers, A.J. (mentor); te Nijenhuis, K. (mentor); Zohrehvand, S. (mentor)","1997","This study has been performed as part of the phenomenology project of Technology Center Waterborne coatings (TCWB) of Akzo Nobel Coatings, with the aim of developing waterborne topcoats with extended open time and improved leveling behavior. Another part of this study has been performed as part of the innovation oriented research program. Innovatie gericht Onderzoek Programma Verf (IOP-Verf), which is focused on aqueous dispersion coatings. The goal of the current study is to investigate the microstructure of concentrated acrylic dispersions thickened with triblock polymer surfactants by means of rheometry, light scattering and light transmission techniques. In this report we have been able to show the microstructure of concentrated acrylic dispersions thickened with triblock polymer surfactants, i.e. Hydrophobically modified ethoxylated urethane (HEUR) thickeners, as a function of the particle volume fraction where two concentration area can be separated: Concentration area I, where still no coalescence takes place; Concentration area II, where coalescence does take place.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering & Material Science","","","",""
"uuid:d95505a3-57f9-43c0-ad2d-9a9309d3e7c3","http://resolver.tudelft.nl/uuid:d95505a3-57f9-43c0-ad2d-9a9309d3e7c3","Recycling of Plastics: Plastic waste streams, separation methodes, end use markets for recycled plastics","Dekker, M.","Willemse, R. (mentor)","1997","This report is about plastics. It mentions the existing plastic solid waste streams, describes techniques for the mechanical separation of plastic mixtures into then- own species and discusses the problems of reprocessing recycled thermoplastics into new products…","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Material Science","","Recycling","",""
"uuid:87597c2c-13cc-4173-9473-d407874fbf5f","http://resolver.tudelft.nl/uuid:87597c2c-13cc-4173-9473-d407874fbf5f","Superabsorbent polymers: literature study","Schippers, Marjan","van Turnhout, J. (mentor)","1997","In this literature study the most important characteristics of superabsorbent polymers are described. Also some attention has been paid to conventional absorbing materials such as nonwovens made of cellulose fibres. First a classification and some examples of hydrogels are given. The swelling behaviour of the gels has been dealt with and also the external conditions that influence the absorption. In general, the equilibrium swelling of the gels depends on three contributions: elastic retractive forces, polymer-swelling agent interactions and ionic interactions. Additionally a phase diagram constructed on the basis of this equilibrium swelling theory is described. Conditions that affect the absorption are for instance the temperature of the system, the solvent composition (pH of swelling agent and presence of salts), application of electrical fields, irradiation and the degree of crosslinking. For the new application of hydrogels in heat and cold storage media, the thermal behaviour of water is also described. Furthermore, some attention was paid to the addition of Glauber’s salt and the usage of paraffin. Finally an overview of existing applications is given, which comprises sealing agents (water-swollen rubber and water-blocking tape), actuators, sensors, drug release systems, water retainers in agriculture and horticulture, separation and concentration methods.","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","","",""
"uuid:23bdb1dd-725a-48c0-b2d6-b1fc3c1455bc","http://resolver.tudelft.nl/uuid:23bdb1dd-725a-48c0-b2d6-b1fc3c1455bc","Coated Particles Experiments and Preparation","v.d. Welle, M.","Oostra, W. (mentor); Weiss, M. (mentor); Scarlett, B. (mentor)","1996","The aim of this master project was to prepare coated particles for experiments with the time-of-flight mass spectrometer and for thermophoresis experiments. Firstly, a coated particle was modeled in the computer program SEPRAN to simulate heat conducting behaviour of particle and layer. This yielded particle characteristics for the thermophoretic experiment: a highly conducting core with a low conducting layer. Following experiments involved the preparation of polystyrene particles with different silica layers. A coated particle was made in three reaction steps: the preparation of a core particle of polystyrene, adsorption of small silica particles on the surface of the core and as last a chemical seeding with TEOS, to achieve a smooth silica layer around the particle. A quantitative recipe for the preparation of a smooth silica layer around a polystyrene particle was yielded. These prepared particles in suspension, were used for aerosol experiments. The suspensions were atomized in a nebulizer, the produced airosol stream was used for measurements with the time-of-flight mass spectrometer. Experiments for different particles and different intensities of the excimer laser were performed. The aerosol stream was also used for experiments to show thermophoresis. The last experiment involved the modeling of a nebulizer, this resulted in mathematical model describing concentration as function of time.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","","",""
"uuid:393549b8-cf38-4f35-bc09-2ce68b9a2b9a","http://resolver.tudelft.nl/uuid:393549b8-cf38-4f35-bc09-2ce68b9a2b9a","The influence of methane on the phase behaviour of water+oil+nonionic surfactant systems","Bovendeert, M.J.","Rudolph, E.S.J. (mentor); de Loos, W. (mentor); de Swaan Arons, J. (mentor)","1996","One of the proposed enhanced oil recovery methods is surfactant flooding. During this process a surfactant is injected into an oil reservoir to cause a decrease in the interfacial tension between the water and the oil phase in the reservoir pores. This improves the oil mobility and results in an increase in the oil recovery factor. The knowledge of the phase behaviour of water+oil+surfactant systems is of great importance for these processes. So far, the research was concentrated on the determination of the phase behaviour of water+""heavy"" oil+nonionic surfactant systems. In this master's project the phase behaviour of systems of water, nonionic surfactant and mixtures of methane and n-decane (as a model live oil) is determined. This master's project is performed within the scope of the Ph. D. project of Dipl. Ing. E.S.J. Rudolph...","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:6f21443d-1900-4168-aa31-3b36b55a3b2a","http://resolver.tudelft.nl/uuid:6f21443d-1900-4168-aa31-3b36b55a3b2a","The influence of intermediate compounds on the solidification behaviour of heavy constituents in hyperbaric reservoir model fluids","Hollanders, B.","de Swaan Arons, J. (mentor); de Loos, W. (mentor); Floter, E. (mentor)","1996","During recent years numerous discoveries of oil and gas accumulations at unusual high reservoir depth have been made. As a result of this unusual depth these reservoirs show some features different from most oil and gas fields. The so-called hyperbaric reservoirs might exhibit pressures over 100 MPa, reservoir temperatures up to 470 K, and a particular composition. Apart from high methane concentrations (mole fraction> 0.60), the hyperbaric reservoir fluids also contain a significant amount of heavy hydrocarbons. During production precipitation of the solid heavy hydrocarbons (wax formation) can occur due to either decreasing temperatures or pressures. Hyperbaric reservoir fluids are complex multicomponent mixtures. However, many features of the phase behaviour of these fluids can be studied by investigating the phase behaviour of simple asymmetric model fluids. In this work experimental vapour-liquid and solid-fluid phase equilibrium data of the ternary systems (methane+ n-docosane + n-tetracosane) and (methane+ propane+ ntetracosane) are presented at pressures up to 200 MPa. These phase equilibria have been measured for 20 different mixtures of the ternary system (methane+ n-docosane + ntetracosane) and for 6 different mixtures of the ternary system (methane+ propane+ ntetracosane). The experiments were carried out with a high pressure autoclave with sapphire windows. Phase equilibrium data were collected according to the synthetic method. Additionally, D.S.C. measurements were performed on the binary system (n-docosane + ntetracosane) at atmospheric pressure. The main focus of this work is centered on the thermodynamical description of the solid-fluid phase equilibria in solutions of n-docosane and n-tetracosane in methane at high pressure. The phase behaviour of this ternary system is very interesting. The results show that the solid phase, which is formed at high pressures, exhibits different mixed crystal structures. The D.S.C. measurements of the binary system (n-docosane + n-tetracosane) at atmospheric pressure also show regions of mixed crystals. In general, a fairly good description of the solidfluid phase equilibria of the ternary system is obtained. Further, the influence of propane on the phase behaviour of the binary model fluid (methane+ n-tetracosane) is shown. With an increasing amount of propane both the solidfluid and the vapour-liquid phase equilibria curves shift towards lower temperatures and pressures. The experimental results were modelled with the Peng-Robinson equation of state with one binary interaction parameter.","","; en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:9f386eba-5613-4b36-989b-60f4b42f27b3","http://resolver.tudelft.nl/uuid:9f386eba-5613-4b36-989b-60f4b42f27b3","Influence of high concentrations on the diffusion coefficient: Literature survey","Breimer, B.C.","Willemse, A.W. (mentor); Merkus, H.G. (mentor); Scarlett, B. (mentor)","1996","Relations between the diffusion coefficient and the particle size in concentrated suspensions are necessary to make full use of the possibilities of Photon Correlation Spectroscopy. In this report several models for these relations are described. Also a number of papers are described in which measured relations are explained. These can be used as an comparison. Most models for concentrated suspensions are in reasonable agreement with the models coming from the measurements.","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","","",""
"uuid:19eb29aa-4394-4503-ac04-bf655bcca8e9","http://resolver.tudelft.nl/uuid:19eb29aa-4394-4503-ac04-bf655bcca8e9","Microstructuur en kinetiek tijdens het partieel gloeien van twee commerciële niet-hardbare aluminiumlegeringen","Söntgerath, J.A.H.; Van Mourik, P.; Van der Zwaag, S.; Korevaar, B.M.","","1996","","aluminium legeringen; microstructuur; gloeien","nl","journal article","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:d9828988-f170-4fa6-86a9-1885ab48518c","http://resolver.tudelft.nl/uuid:d9828988-f170-4fa6-86a9-1885ab48518c","High pressure fluid phase behavior of the systems CF4 - H2O and CF4 - H2O - NaCl","Smits, R.J.A.","de Swaan Arons, J. (mentor); Peters, C.J. (mentor); Smits, P.J. (mentor); Poot, W. (mentor); Grondel, J.H.F. (mentor); van der Plas, A. (mentor)","1996","Supercritical Water Oxidation (SCWO) is a highly efficient method to destruct all kinds of toxic wastes, such as explosives and freons. Destruction efficiencies of 99.9 % can be reached. In order to study model systems for SCWO processes, high pressure phase equilibria of CF 4 - H2O and CF 4 - H2O - NaCl mixtures have been measured in the pressure range from 20 to 200 MPa and in the temperature range from 580 to 673 K. The measurements were performed in a high-pressure autoclave with sapphire windows and magnetic stirring, with visual observation of the bubble point...","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:e7fc822b-e030-4226-a87f-f1cfe7694340","http://resolver.tudelft.nl/uuid:e7fc822b-e030-4226-a87f-f1cfe7694340","High pressure phase behavior of binary water - light organic and ternary water – light organic - salt systems: A literature review, and a theoretical treatment of the salt effect","Smits, R.J.A.","de Swaan Arons, J. (mentor); Peters, C.J. (mentor); Smits, P.J. (mentor)","1995","In order to develop Supercritical Water Oxidation (SCWO) processes for the destruction of ChloroFluoroCarbohydrates (CFC's), more experimental data on the phase behavior of water-CFC and water-CFC-salt systems is needed. First a general review is given of high pressure phase equilibria, according to the classification of van Konynenburg and Scott. A general description of waterhydrocarbon mixtures will follow that. Since no data were found on water-CFC and water-CFC-salt systems at near critical conditions of water, the attention was focused on water-organic and waterorganic-salt systems with light organic compounds. For this purpose the phase behavior of binary water mixtures of methane, ethane and carbon dioxide are investigated at near critical conditions. For these binary systems the location of the critical curve is described, as well as other characteristic aspects of these systems. The location of the three phase curve and the upper critical endpoint are also discussed, for the mixtures containing ethane and carbon dioxide. In the water-methane system no three phase curve, and consequently no upper critical endpoint, are present. The phase behavior of ternary water mixtures with methane and sodium chloride, methane and calcium chloride, ethane and sodium chloride, and carbon dioxide and sodium chloride are discussed. For these ternary systems the effect of salt on the resulting phase behavior is described. Finally an extensive treatment of the salt effect is given.","","; en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:d9eebad8-9ecc-4d08-815c-6c0a92f95f87","http://resolver.tudelft.nl/uuid:d9eebad8-9ecc-4d08-815c-6c0a92f95f87","Simplified-Perturbed-Hard-Chain Theory: Modifications in Prigogine's c-parameter and the effect on vapour-liquid equilibria in pure fluids and binary mixtures","Muiderman, M.","de Swaan Arons, J. (mentor); Peters, C.J. (mentor)","1995","on two simple potential functions. The hard sphere potential, leading to the accurate CarnahanStarling equation is used for the repulsive part. The attractive term is a local composition model for square-well molecules. The SPHCT equation is suitable for the prediction of the phase behaviour of chain molecules, such as n-alkanes. For a pure component, there are three parameters: the hard-core volume, v·, the energy parameter, T' and the number of external degrees of freedom, 3c. In this thesis, there are two modifications of the SPHCT developed. The first modification is a combination of two improvements of the SPHCT: the fact that Prigogine's c-parameter is density dependent (1987 SPHCT) is combined with a better description of the hard-sphere structure in the attractive term (1992 SPHCT). As an extra adjustment, Ciocca's parameters, n and λ are considered to be linear with the hard-core volume, v·. The saturated pressure and liquid volume of pure n-alkanes are predicted slightlymore accurate than with the 1992 SPHCT equation of state. Unfortunately, this modification doesn't lead to a better description of vapour-liquid equilibria in binary mixtures of n-alkanes. Furthermore, the mixing rule for the c-parameter is adjusted to yield better results for the vapour-liquid equilibria in binary mixtures. It appears that the linear mixing rule gives an overestimation for the average value of c. A small adjustment in the mixing rule gives an enormous improvement in the prediction of the vapour-liquid equilibria for asymmetric mixtures of n-alkanes. If the components in the binary mixture have similar values of c, such as the methane/ethane binary, the new mixing rule gives the same estimations as the old mixing rule. So this new mixing rule can be used instead of the commonly used linear mixing rule for the prediction of vapour-liquid equilibria in all types of binary fluid mixtures.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:ff9eb3ee-ef22-422e-9e4a-395f14918ac6","http://resolver.tudelft.nl/uuid:ff9eb3ee-ef22-422e-9e4a-395f14918ac6","The simplified perturbed hard chain theory: Development, performance and modifications","Muiderman, M.","Peters, C.J. (mentor); de Swaan Arons, J. (mentor)","1995","The Simplified Perturbed Hard Chain Theory (SPHCT) developed by Kim et al. (1986) is an equation of state based on the Generalized van der Waals Theory (Vera and Prausnitz, 1972, Sandler, 1985). The SPHCT is accurate in describing thermodynamic properties of chain molecules. This in contrast with the common used Peng-Robinson or Redlich-Kwong equations of state. The SPHCT is a simplification of the Perturbed Hard Chain Theory (PHCT). The PHCT is described in chapter 2. Donohue and Prausnitz (1978) treated all density dependent (external) rotations and vibrations equivalent to translations. Prigogine (1957) postulated that a molecule has 3c degrees of freedom that are density dependent (3 translational and 3c-3 external rotational/vibrational degrees of freedom). These two assumptions form the basis for the PHCT. The SPHCT developed by Kim et al. (1986) uses the same assumptions. Point of difference is the replacement of the potential energy term. While Donohue and Prausnitz used a term that was based on computer simulation data by Alder et al. (1972), Kim et al. developed an expression for the potential energy based on the local composition model, following Lee et al. (1985). This derivation is given in chapter 3. The SPHCT is in the first place derived for chain molecules like n-alkanes. The performance of the SPHCT is given in chapter 4 (pure components) and chapter 5 (mixtures). It appears that also polar molecules can be described reasonably well with the SPHCT equation of state. The SPHCT has been modified (chapter 6) to give better predictions of thermodynamic properties. The modifications make the SPHCT more complex, by implementing theoretical or empirical relations.","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:525f7a4c-a6bb-46c3-95e3-62ab23b17498","http://resolver.tudelft.nl/uuid:525f7a4c-a6bb-46c3-95e3-62ab23b17498","A Study on the Ejection and Cracking Behaviour of Alumina Green Compacts: Effects of Compaction Parameters","Smaling, C.M.","Briscoe, B.J. (mentor); Scarlett, B. (mentor)","1995","","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and of Materials Science","","Applied Thermodynamics and Phase Behaviour","",""
"uuid:858f80a9-ab90-4337-a9b8-d3f21feefa08","http://resolver.tudelft.nl/uuid:858f80a9-ab90-4337-a9b8-d3f21feefa08","Verification of the FET Object Model: Implementation of Reactors and Separation Processes","Kerkhove, D.","","1995","The Front End Tools (FET) Project's goal is to create a software application which should aid the process engineer in creative design of process plants. Since this application will be written using object-oriented techniques, an object model has been designed by Akzo-Nobel Engineering. This document describes the verification procedure of this object model, which should be able to contain chemical engineering process design data and methods. During this verification (which included examining separation processes and reactors as well as writing two C++ applications) several elements of the original model have been modified. The conclusions made at the end of the project state that the currently developed object model can be used for its intended purpose. Apart from this conclusion, several concepts were proposed for further development in conjunction with the FET project.","Process Systems Engineering","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:2aefcdef-9ed0-4ebb-8b88-bab4c7d8b0f9","http://resolver.tudelft.nl/uuid:2aefcdef-9ed0-4ebb-8b88-bab4c7d8b0f9","Dielectric Characterisation of Anisotropic Gels","Hesselink, S.J.A.","Seppen, A. (mentor); van Turnhout, J. (mentor)","1994","Liquid Crystal (LC) systems working on the principle of light scattering, for example Polymer Dispersed Liquid Crystals, are of great interest. A recently developed gel system containing a low molecular weight liquid crystal and a liquid crystalline polymer (LCP) network can also be used for electrically induced scattering. The gel system can be formed by interconnecting phases of free LC-molecules and crosslinked network molecules. In order to induce isotropic light scattering a homeotropic oriented gel system was developed. The structure and the concentration of the network was found to have an effect on the resultant light scattering and optical measurements showed the existence of little domains in the gels. To study these domains dielectric measurements were used to characterise the gel system and to find more information about the domains. The presence of the domains give rise to the socalled Maxwell-Wagner effects: accumulation of charges at the interface of the domains will give an increase in the dielectric constant and this can be measured using dielectric relaxation measurements. To support the characterisation of the gel system DSC-measurements were performed, which showed the characteristic transitions of the LC and the LCP network. Using a standard cell with circular electrodes of ITO and Au dielectric measurements were performed. Electrode polarisation was observed in all samples (pure lc and gels containing 7 w/w% LCP-network), which is caused by ion conductivity in the sample. Activation energies of the observed relaxations are close to values found for ion conductivity. The model found for the observed relaxations with Boukamp Equivalent Circuits fits the model known for electrode polarisation. Maxwell-Wagner effects due to the presence of the domains were not observed. They were probably overruled by the electrode polarisation. A higher conductivity was observed after curing with a UV-source for both the pure LC and the gels. The increase in conductivity can not fully be explained by the increase of conductivity of the pure LC. ITO-electrodes caused disturbtion in the measurements and deflected results were obtained. Electrode polarisation in ionic conducting materials might be avoided using a bias during the dielectric measurements. The ions will be trapped in the sample by the electric field and the epsilon perpendicular will be measured. The observed relaxations will be due to the sample and not due to the mobility of the ions. Measurements with the gels system could give useful information about the domains as the electrode polarisation is not occurring. Further experiments should be focussed on the use of a bias during these measurements.","","en","master thesis","","","","","","","","","Applied Sciences","Materials Science and Chemical Engineering","","Polymers and Organic Chemistry, Technologie van Macromoleculaire Stoffen","",""
"uuid:6125aa58-e94b-4617-97f4-10c9ca57e362","http://resolver.tudelft.nl/uuid:6125aa58-e94b-4617-97f4-10c9ca57e362","Deeltjesoplossen tijdens homogeniseren van aluminiumlegeringen","Vermolen, F.J.; Van Mourik, P.; Van der Zwaag, S.","","1994","","homogeniseren; deeltjesoplossen; aluminiumlegeringen","nl","journal article","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:e0919f45-26d5-46a3-b0bf-d172f6aa8be2","http://resolver.tudelft.nl/uuid:e0919f45-26d5-46a3-b0bf-d172f6aa8be2","Polymer Dispersed Liquid Crystal Films Based on E7","Hesselink, S.J.A.","van de Leur, R.H.M. (mentor); van Turnhout, J. (mentor)","1994","Polymeric materials containing dispersed microdroplets of liquid crystal (Polymer Dispersed Liquid Crystals, PDLC's) can be used as displays. PDLC's are translucent due to scattering of light by the liquid crystal (LC) droplets. Using an electric field the LC-molecules align parallel to the applied field, which will cause transparency if the refractive indices of the liquid crystal and the transparent polymer matrix match each other...","","en","master thesis","","","","","","","","","Applied Sciences","Materials Science and Chemical Engineering","","Functional Properties and Applications","",""
"uuid:eda3e080-0896-402c-90c4-1c08123f9340","http://resolver.tudelft.nl/uuid:eda3e080-0896-402c-90c4-1c08123f9340","Some observations on precipitation in a Al-Si-Cu-Mg alloy with Al2O3 particles","Bronsveld, P.M.; Starink, M.J.; De Hosson, J.; Van Mourik, P.","","1994","","precipitation; particle-reinforced; aluminium alloys","en","conference paper","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:f251aa8c-384a-4ff2-a4e2-560b9428880b","http://resolver.tudelft.nl/uuid:f251aa8c-384a-4ff2-a4e2-560b9428880b","Calculation of fluid phase equilibria in binary systems","Nugroho, M.J.","de Swaan Arons, J. (mentor); de Loos, W. (mentor); Stamoulis, D.P. (mentor)","1993","The most common problems in the phase equilibrium calculations are convergence failures and the need for good initial estimates. In this work one of the computational methods is evaluated. The method was tried and extended by Stamoulis (1993). The method is based on the construction of closed loop curves formed when the independent field variables determining the equilibrium are plotted against each other. In this case the µ1 - µ2 plot is constructed. It solves the equilibrium problems without convergence and initial estimate difficulties. In this work the reliability of the plot method is tested. For that purpose calculations of three phase curves, critical curves, Px- and Tx-sections for the binary systems of the CO2 + n-alkanes, the C4F10 + n-alkanes and the C4F10 + n alcanols families are performed. For the calculations the Peng-Robinson equation of state with adjustable k and l parameters was used. Optimum values of k and l are selected to represent as close as possible the critical endpoints of three phase curves. The transition mechanisms between the various types of fluid phase equilibria according to the classification of Scott and van Konynenburg are studied by means of the PTx-space and their projections on appropriate planes for several systems. It was shown that the calculations with the cubic equation of state predicts a wider range of type IV behaviour than it was found experimentally.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Behaviour","",""
"uuid:1f19c606-2c74-450a-8507-4cf9c1259898","http://resolver.tudelft.nl/uuid:1f19c606-2c74-450a-8507-4cf9c1259898","The Phase Behaviour of the β-Lactoglobulin / Dextran / Water System","Schoenmakers, W.P.J.M.","Ming, Y. (mentor); de Swaan Arons, J. (mentor); Weisenborn, P.C.M. (mentor)","1993","This project was started with the intention to gather more accurate data for one specific protein-polysaccharide system, which should help building and optimizing a theoretical model, based on the experimental observations of Tolstoguzov for other protein-polysaccharide systems. The ternary system chosen is ß-lactoglobulin/Dextran/Water, because ß-lactoglobulin is the most important milk protein and therefore a very important food protein. This choice is supported by the suggestion of Tolstoguzov that incompatibility (liquid-liquid phase separation) is a general phenomenon, no matter what kind of conformation (globular or coil-like) the protein has. Surprisingly the phase separation measurements do not fully support this suggestion, because the system shows a more complex phase behaviour. In the lower concentration range the system is homogeneous. In the higher concentration range the system separates into two liquid phases (as Tolstoguzov suggested). In the range between the system separates into a solid and a liquid phase or even into a three phase system (solid-liquid-liquid system). The three phase region has not been found experimentally by others, but should theoretically be possible for particle/coil systems. A lot of measurements have been done to determine the whole phase diagram, but some problems have arisen during the experiments due to the complexity (high viscosity and multicomponent nature) of the samples. Therefore the data in the phase diagram are not in complete agreement with each other. The experiments however give a good idea of the geometry of the phase diagram and, accordingly, can be a good guide for the modelling work. In order to get more insight to the observed phase behaviour of this system osmotic pressure measurements have been done for B-lactoglobulin solutions and for Dextran T-500 solutions, which determine parameters like the molecular weight, MN, and the second virial coefficient, A2. The next step in these measurements should be the determination of the cross-virial coefficient, A3, by measuring the osmotic pressure of mixtures of B-lactoglobulin and Dextran T-500.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and of Material Science","","Applied Thermodynamics","",""
"uuid:87510a10-9f94-4bda-8459-30ae33c93606","http://resolver.tudelft.nl/uuid:87510a10-9f94-4bda-8459-30ae33c93606","Études calorimétriques différientielles de la précipitation dans quelques alliages d'aluminium","Van Mourik, P.; Starink, M.J.","","1993","","differential scanning calorimetry; precipitation; aluminium alloys","fr","conference paper","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:29802d6c-8fdf-40bb-8cbb-361b172104ed","http://resolver.tudelft.nl/uuid:29802d6c-8fdf-40bb-8cbb-361b172104ed","Modeling of the phase behaviour of industrially important mixtures from the associated perturbed anisotropic chain theory","Blindenbach, W.L.","de Swaan Arons, J. (mentor); Peters, C.J. (mentor)","1993","In the last twenty years, the interest in the phase behavior of mixtures of polar, associating and ionic compounds has been grown and subsequently the interest in equations of state for these mixtures. A new field of equations of state has been developed, based on statistical thermodynamic grounds. The most successful thermodynamic theory for pure components and mixtures of components is perturbation theory. Donohue and co-workers developed a practical equation of state using perturbation theory for associating and polar components, the Associated Perturbed Anisotropic Chain Theory (APACT). In this work, pure component molecular parameters for the APACT have been calculated. It is clear that APACT is able to describe the pure component properties with less than one percent error. Furthermore, it is clear that the molecular parameters for the APACT have a physical basis and are related to the size, dispersion energy and shape of the molecules. Two systems have been described (ethanol-hexane and water-carbon dioxide) with the APACT. For the system ethanol-hexane the APACT was able to describe the entire phase behavior accurately and furthermore it predicts the azeotrope. This is in contrast to the PengRobinson (PR) equation of state, which is not able to describe the phase behavior of this system, even with a binary interaction parameter. For the system water-carbon dioxide, a binary interaction parameter was necessary for the APACT. In addition to Vapor-Liquid- Equilibria, also Liquid-Liquid-Equilibria have been calculated with the APACT. Finally, the phase behavior for a number of freon mixtures has been calculated with the PACT and the predictions are compared with the PR equation of state and the Soave-RedlichKwong equation of state. The PACT was able to describe the mixtures approximately two times better than the PR equation of state. Introduction of a binary interaction parameter results in the same results for all the equations of state used. It is clear that for systems that exhibit hydrogen bonding and polar interactions the APACT works better than the cubic equations of state and that for extrapolation or prediction purposes, the APACT should be used.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:208a7069-7a5d-402d-a64c-aa0f9a1341cc","http://resolver.tudelft.nl/uuid:208a7069-7a5d-402d-a64c-aa0f9a1341cc","Reactive Distillation: A literature review of existing applications","Strijk, F.H.A.","de Swaan Arons, J. (mentor)","1993","The literature on reactive distillation can be divided into two groups. One category approaches the problem from a distillation point of view: can the separation of a mixture with close boiling components be improved by adding a reactive facet to the conventional distillation column ? The second group treats the subject from a reaction perspective: can the conversion of an equilibrium reaction be increased by adding distillation techniques to the normal reactor ? ...","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:0a05107d-7112-4587-945c-de9628f8b7b5","http://resolver.tudelft.nl/uuid:0a05107d-7112-4587-945c-de9628f8b7b5","Reactive Distillation: A literature review of existing applications","Strijk, F.H.A.","de Swaan Arons, J. (mentor)","1993","","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:42d36d7a-cc22-4786-8fd6-87509454ede6","http://resolver.tudelft.nl/uuid:42d36d7a-cc22-4786-8fd6-87509454ede6","An overview of equations of state for polar, associating and ionic mixtures: Literature thesis","Blindenbach, W.L.","de Swaan Arons, J. (mentor); Peters, C.J. (mentor)","1993","In this literature thesis an overview of equations of state for polar, associating and ionic mixtures is given. Many of the cubic equations of state, like the Soave-Redlich-Kwong equation of state or the Peng-Robinson equation of state, are often used to describe the phase behaviour of mixtures containing polar, associating or ionic components. When using these equations of state for such mixtures, large errors are created and large temperature or composition dependent binary interaction parameters are needed. Better results are obtained when using an equation of state with specific terms to describe the polar, associating and ionic contribution. Only these equations of state, with specific terms for one of these non-idealities, are described and discussed in this overview. For polar mixtures most of the equations of state with a specific term to describe the anisotropic interactions are based on the PHCT. Of these equations of state, the PACT equation of state is the most well-known. Another familiar equation of state for polar mixtures, not based on the PHCT, is the BACK equation of state. For associating mixtures, three classes of theories have been developed specifically to treat hydrogen-bonding systems. The three theories (chemical, quasi-chemical and physical theory) result in different equations of state, which have the same functional form for both pure components and for mixtures. The most widely used equations of state for hydrogen-bonding mixtures are the APACT equation of state and the SAFT equation of state. For more complex calculations there is also the APACT-2 equation of state. When calculating the phase behaviour at low reduced densities the ESD equation of state is often used. Electrolytes are mostly described by an activity model and not by an equation of state. However, a few equations of state have been developed specially to treat binary liquid mixtures containing salts.","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:978dd80e-420a-4a33-9342-3f9eec56c80c","http://resolver.tudelft.nl/uuid:978dd80e-420a-4a33-9342-3f9eec56c80c","Liquid-liquid-vapour phase equilibria in the system methane + ethane + eicosane: Retrograde behaviour of the heavy liquid phase (Master thesis + appendices)","Smits, P.J.","de Loos, W. (mentor); Gregorowicz, J. (mentor); de Swaan Arons, J. (mentor)","1992","Liquid-liquid-vapour equilibrium experiments were conducted with model reservoir fluids comprising the ternary system methane + ethane + eicosane, with special emphasis on the phenomenon of retrograde condensation of the second heavier liquid phase L1 in the presence of a vapour phase V and a lighter liquid phase L1. P,Tsections for mixtures of constant composition were determined according to the synthetic method for several constant molar ratios of ethane and eicosane and for different mole fractions of methane. The temperature range investigated was 290-307 K and the pressure range 5.0-6.4 MPa. The three phase L1L2V areas were found at lower temperatures in comparison with the locations of the three phase curve of the binary subsystem ethane + eicosane, as was expected. Some of the ternary mixtures studied were found to exhibit retrograde condensation of the heavier liquid phase over a narrow range of temperature and concentration of eicosane. The experimental phase boundary data were modelled with the Peng-Robinson equation of state, using two binary interaction parameters per binary, in combination with a three phase flash routine. Retrograde condensation of the heavier liquid phase can not be predicted in the composition range investigated using this calculation procedure. The agreement between the locations and the shapes of the experimentally determined and the calculated three phase areas is qualitative. A slight improvement in the agreement between the experimental data and the calculations is observed in comparison with the same calculation procedure using only one binary interaction parameter per binary.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Equilibria","",""
"uuid:d895b64c-8e2f-47ec-9524-b52653c99136","http://resolver.tudelft.nl/uuid:d895b64c-8e2f-47ec-9524-b52653c99136","Precipitatie in aluminium-metaal matrix composieten","Starink, M.J.; Van Mourik, P.","","1992","","precipitation; Al metal matrix composites","nl","journal article","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:fbf4c96d-45d9-4996-9e6a-c139899319ac","http://resolver.tudelft.nl/uuid:fbf4c96d-45d9-4996-9e6a-c139899319ac","The Physical Properties of Lactic Acid and Derivatives: A literature review","van Lieshout, G.P.","","1992","Lactic acid is an important chemical, used in food-technology, medicine and cosmetics. It’s 2-hydroxypropionic acid. This paper deals with the physical properties of lactic acid and it’s derivatives. There’s not much known about the physical properties of pure lactic acid, because lactic acid appears mainly in the form of aqueous solutions. When physical properties of these solutions have been estimated one should consider that lactic acid in solution undergoes intermolecular esterification spontaneously, resulting after some time in an equilibrium solution containing, lactic acid, lactoyllactic acid, poly lactic acid and a very little dilactide. When it’s not mentioned whether intermolecular esters are present in lactic acid solutions, physical properties of these solutions are not that reliable. Also physical properties of lactic with other solvents than water are considered, like distribution coefficients, ternary phase diagrams and critical solution temperatures. The optical activity of lactic acid doesn’t have any influence on the physical properties, except the melting point. Racemic lactic acid has a lower melting point than optical active lactic acid, 25-27°C and 52.7-52.8°C respectively. Also the physical properties of the intermolecular esters and some derivatives are described. Not much is known about these esters. More is known about some common esters of lactic acid, like alkyl lactates. The physical properties of alkali and ammonium lactates, salts of lactic acid, are mentioned shortly. Some short articles deal with spectra of lactic acid. Here ultraviolet, infrared and microwave spectra are briefly discussed. Most of the data presented were published more than 40 years ago, one article was even published in 1894. Unfortunately there aren’t any recent articles about physical properties of lactic acid and derivatives.","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and of Materials Science","","Applied Thermodynamics and Phase Behaviour","",""
"uuid:195f5fc8-41af-4ebe-ab80-f21219cfee02","http://resolver.tudelft.nl/uuid:195f5fc8-41af-4ebe-ab80-f21219cfee02","The granular bed filter as a model of the lower parts of the human lung: Literature study","van der Put, S.","Bibo, B.H. (mentor); Scarlett, B. (mentor); Lemkowitz, S.M. (mentor); Marijnissen, J.C.M. (mentor); Stoop, H.C. (mentor)","1991","In this paper, the fiber deposition in the lower parts of the lung (8-23rd generation of Weibel) during inspiration is compared with the deposition of fibers in a granular bed filter with similar dimensions and equal air flow rate. It is found that very little experimental and theoretical research has been done on deposition of fibers in the deeper parts of the human lung. The model of Harris and Fraser (1976) is the only model that predicts regional deposition as a function of breathing conditions and fiber dimensions. This model however, has many shortcomings. Literature on fiber deposition in granular bed filters is scanty as well. For that reason the model of Boulaud (1991) for deposition of spherical aerosol particles in a granular bed filter has been modified in this paper to make a rough estimate of fiber deposition in this type of filters. Geometry of the lung, fluid dynamics and deposition probabilities have been compared in both systems with the help of the model of Harris and Fraser and the model of Boulaud. It is succeeded to translate the Weibel model for geometry of the human lung into a trumpet-like granular bed filter with varying granule size in which the dimensions of the air spaces and the air velocity in a layer are similar to those in an airway generation. As shape and dimensions of the voids in the granular bed filter differ from those in the respiratory system, differences in air flow patterns between both systems will exist, that will have their effect on deposition. Efficiencies depend on the same dimensionless numbers in both systems. Investigations in a granular bed filter will be useful to find out relationships between fiber dimensions and orientation, air velocity, residence time and geometrical dimensions of the air spaces on one hand and fiber deposition on the other hand. Results obtained with granular bed filters can be applicable to the deeper parts of the human lung when differences in geometry of the airspaces and in velocity patterns are accounted for. Further experimental and theoretical research is needed to improve and validate the model for fiber deposition in a granular bed filter derived in this paper, to make a more detailed comparison of geometry of the airspaces and velocity profiles in both systems and to improve the deposition model of Harris and Fraser.","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Particle Technology","",""
"uuid:69162614-fd74-480f-aed6-ca716a0920b3","http://resolver.tudelft.nl/uuid:69162614-fd74-480f-aed6-ca716a0920b3","The automation of uniform droplet production: Tailor-made droplets","Van Woerden, Marnix J.","Meesters, G.M.H. (mentor); Scarlett, B. (mentor)","1990","Software and hardware have been developed in order to control an apparatus producing uniform droplets. The droplets are made by means of longitudinal vibration of a liquid jet originating from a non-oscillating orifice. Software run from a personal computer can control frequency and liquid velocity and can measure the weight of droplets produced. It can therefore produce defined droplets of variable sizes. Hence, a defined particle size distribution can be produced semi-automatically. A new high-pressure apparatus was used, which can produce uniform droplets using liquids having a high viscosity. For aqueous sodium alginate solutions up to 1600 cP, regions of uniform droplets have been determined. Smaller uniform regions are obtained than for low-viscous liquids due to non-linear wave growth, which causes irregularities during jet break-up. Droplets were produced ranging in diameter between 500 µm and 2000 µm The droplets can be produced smaller if the liquid is clean enough, so that the nozzle is not blocked by impurities. Image analysis of solidified mono-sized droplets shows that droplets can be produced with 98% of the droplets within the range [x-0.03x, x+0.03x]. The real volume distribution is even closer due to non-sphericity of the droplets, which troubles the analysis. ""Tailor-made"" particle size distributions were made using 2%w/w and 3%w/w sodium alginate in water. Errors in the distribution are caused by the fact that the jet velocity can not be measured fast and precise enough, by the fact that resonance effects interfere with the jet break-up and finally because the shrinkage factor of the droplets is size dependent. Better control over the jet velocity can be obtained by enabling on-line velocity measurement or by using a precise pump. The producible droplets ranges between two to three times the nozzle diameter. To obtain a broader distribution a way has to be found to change nozzles automatically. Recommendations are made for improvement of the apparatus and how to obtain a tailor-made particle size distribution fully automatic.","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","","",""
"uuid:46b4977a-30dc-4b15-86e9-a0757de71da6","http://resolver.tudelft.nl/uuid:46b4977a-30dc-4b15-86e9-a0757de71da6","A comparitive study on heat effects in an Al-Cu alloy reinforced with silicon particles and in a binary Al-Cu alloy","Starink, M.J.; Van Mourik, P.","","1990","Preprint","heat effects; Al-Cu alloys; silicon reinforcement","en","conference paper","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:938733f1-a3e0-485f-9f49-0e15e483a6b7","http://resolver.tudelft.nl/uuid:938733f1-a3e0-485f-9f49-0e15e483a6b7","Gas Saturation Measurements and Phase Behaviour of the system Methane - Benzene","Hathie, M.","de Swaan Arons, J. (mentor); Peters, C.J. (mentor)","1990","The solubility of benzene in the methane gasphase was experimentally determined at pressures ranging from O. 2 to 25 MPa as a function of the temperature ( 7 to 42 °C). For this purpose a gassaturation apparatus was used. Each measurement was carried out in triplicate and the repeatability was generally better than 2%. From these measurements the retrograde condensation behaviour of the system methane - benzene can be fully explained. The validity of the measurements has been established by successfully calculating vapor pressures of benzene, computation of second and third virial pressures of benzene, computation isotherms, reproduction of experimental data with the virial equation of state and comparison with data previously reported in literature. The Peng-Robinson and the Simplified-Perturbed-Hard-Chain-Theory equations of state were applied to describe measured dewpoint and reported bubblepoint data. These equations are optimized pure component parameters. Both equations are capable of reproducing vapor pressures of benzene as well as the pVT behaviour of methane. On the other hand, predicted p-(x,y) diagrams from both equations poorly reproduce measured data even if the use of a binary interaction parameter is incorporated. In the case the predicitions are limited to a pressure equal or less than 10 MPa the reproduction of the data is improved. The description however remains insufficiently accurate with the applied form of the Peng-Robinson and the Simplified-Perturbed-Hard-Chain-Theory equations of state.","","","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science, Inorganic and Physical Chemistry","","Applied Thermodynamics and Phase Behaviour","",""
"uuid:7a40a7ee-447a-461b-ae59-4c86eb32c1ee","http://resolver.tudelft.nl/uuid:7a40a7ee-447a-461b-ae59-4c86eb32c1ee","Precipitatieverschijnselen en spanningseffecten in geavanceerde aluminiumlegeringen","Van Mourik, P.; Van Rooijen, M.","","1990","","precipitation; stress effects; aluminium alloys","nl","journal article","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:449e2ad1-44ec-46d0-9018-8f8f85235da0","http://resolver.tudelft.nl/uuid:449e2ad1-44ec-46d0-9018-8f8f85235da0","The Gibbs method: Literature thesis","van Leeuwen, Monica E.","Peters, C.J. (mentor)","1989","The Gibbs method, proposed by Panagiotopoulos (1987), directly determines two-phase equilibria through Monte Carlo simulations, using the Gibbs ensemble as statistical ensemble. The Gibbs ensemble consists of systems (NVtT or NpT fixed), which are divided in two separate sub-systems with variable volumes and variable number of particles...","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Applied Thermodynamics and Phase Behavior","",""
"uuid:71982af1-e89d-4b55-ac1f-eba2da211d40","http://resolver.tudelft.nl/uuid:71982af1-e89d-4b55-ac1f-eba2da211d40","The production of uniformly sized droplets by means of a longitudinally vibration technique","Onderwater, M.F.J.","Meesters, G.M.H. (mentor); Scarlett, B. (mentor)","1989","Research has been done on the production of uniformly sized droplets by means of longitudinally vibration. Experimental results have been compared with literature...","","en","master thesis","","","","","","","","","Applied Sciences","Chemical Engineering and Materials Science","","Particle Technology Group","",""
"uuid:9a2272f2-fd5f-4684-8480-4cc60e04c2b2","http://resolver.tudelft.nl/uuid:9a2272f2-fd5f-4684-8480-4cc60e04c2b2","Electrostatically Enhanced Granular Bed Filtration: Choosing Materials + Filter Modelling","Brons, J.F.J.","Zevenhoven, C.A.P. (mentor); Scarlett, B. (mentor)","1989","As a part of the project on Pressurized Fluidized bed Combustion of Coal / High Temperature Gas Cleaning, a six-month period was spent investigating a number of granular materials on their applicability as granular material in an Electrostatically Enhanced Granular Bed Filter, to be applied as the final cleaning step of the off-gas. Impedance Spectroscopy was used as technique to obtain information on the electrical behaviour of the materials in AC electric fields. Quartz granules showed a conductivity of 1-2 orders of magnitude greater than alumina granules, both with and without fly ash loadings. Barium titanate still remains an interesting material, despite its high-power consumption. Pelletized BaTiO3 granules should be investigated in the near future. The existing EV-model for granular bed filtration was scrutinized, modified and translated from Fortran to Pascal to yield an interactive and user-friendly program for the PC. The model is now expected to give reliable information on filtering efficiencies and the transition between surface filtration and deep bed filtration.","","en","student report","","","","","","","","","Applied Sciences","Chemical Engineering","","Particle Technology Group","",""
"uuid:32190305-a02b-45df-b6f7-b4d4ad0d67ec","http://resolver.tudelft.nl/uuid:32190305-a02b-45df-b6f7-b4d4ad0d67ec","Misfit strains and excess vacancies in liquid-quenched and solid-quenched Al-Si alloys on ageing","Van Mourik, P.; De Keijser, T.H.; Mittemeijer, E.J.","","1986","","misfit strains; rapid quenching; solid quenching; ageing","en","conference paper","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:df555dbc-c2cf-42ab-a8fe-6af9f09eb452","http://resolver.tudelft.nl/uuid:df555dbc-c2cf-42ab-a8fe-6af9f09eb452","Consolidation and resulting tensile strength of melt-spun Al-Mg and Al-Si alloys","Van Rooyen, M.; Van der Hoeven, J.; Katgerman, L.; Van Mourik, P.; De Keijser, T.H.; Mittemeijer, E.J.","","1984","","rapid quenching; tensile strength; aluminium alloys; consolidation","en","conference paper","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:b3a4a2db-5f79-4ec9-adac-9aa0a99c0960","http://resolver.tudelft.nl/uuid:b3a4a2db-5f79-4ec9-adac-9aa0a99c0960","Thermodynamics of equilibria in the model development the phase and reaction system nh3-co2-h2o and parameter evaluation through optimization methods","Gogolides, E.","Ramasamy, K. (mentor); Tech, M. (mentor); van den Berg, P.J. (mentor)","1984","Urea is produced industrially through the reaction of ammonia and carbon dioxide. The synthesis, carried out at high pressures of around 140-250 bar and at temperatures ranging from 180 C-200 C₁can best be described as a two stage process, with ammonium carbamate being an intermediate product…","","; en","student report","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:0b4e638e-b1d6-488c-bf87-9019ef0ecd4e","http://resolver.tudelft.nl/uuid:0b4e638e-b1d6-488c-bf87-9019ef0ecd4e","Rapidly solidified (melt-spun) aluminium alloys: Morphology, texture and excess vacancies","Van Mourik, P.; Van Rooijen, M.; Van der Pers, N.M.; De Keijser, T.H.; Mittemeijer, E.J.","","1984","Abstract","aluminium alloys; rapid quenching; morphology; texture; vacancies","en","conference paper","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:9fc3dd61-3a24-4317-8f68-14681a0728ea","http://resolver.tudelft.nl/uuid:9fc3dd61-3a24-4317-8f68-14681a0728ea","Precipitation of Silicon in a Solid Quenched Aluminium- ilicon (1.3 at yo) Alloy Studied by Positron Annihilation","Seegers, D.; Van Mourik, P.; Van Wijngaarden, M.H.; Rao, B.M.","","1984","Doppler broadening of the positron annihilation line was measured for quenched and aged specimens of an aluminium-silicon (1.29 at%Si) alloy. One set of specimens was aged at room temperature (set A) and one set was isochronally (t = 30 min) aged at temperatures ranging from 347 to 884 K (set B). The lineshape parameter S measured in the as-quenched condition was larger than that of well-annealed pure aluminium. S decreased with time of ageing at room temperature, which might be ascribed to the formation of vacancy loops decorated with silicon atoms. After 1320 h at room temperature the specimens of set A were aged for 30 min at 353 K in vacuo. Then, thc lineshape parameter S decreased further, which is interpreted as due to a further disappearance of the earlier formed vacancy loops. The behaviour of the lineshape parameter S for set B can be described as follows: 1. 350 to 450 K. Constant value of S, about the same as found for pure aluminium. 2. 450 to 580 K. Increase of S, ascribed to precipitation of vacancies near the Si aggregateslmatrix interface relieving transformation strains. 3. above 580 I<. Decrease of S to the pure-aluminium value. This effect is ascribed to the growth of silicon precipitates accompanied by annihilation of vacancies. The misfit between the silicon precipitates and the Al-rich matrix is accommodated by dislocations.","precipitation; aluminium-silicon alloy; positron annihilation","en","journal article","Wiley","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:0b75cb7f-aed6-4e99-a553-72ea9f985d90","http://resolver.tudelft.nl/uuid:0b75cb7f-aed6-4e99-a553-72ea9f985d90","On precipitation in rapidly solidified Aluminium-Silicon alloys as studied by X-ray diffraction","Van Mourik, P.; Mittemeijer, E.J.; De Keijser, T.","","1983","","Al-Si alloys; rapid quenching; precipitation","en","conference paper","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:377f41dd-4b76-4101-bd81-9885ecb5cf8d","http://resolver.tudelft.nl/uuid:377f41dd-4b76-4101-bd81-9885ecb5cf8d","Al-Si Alloys Rapidly Quenched from the Melt","Delhez, R.; Katgerman, L.; De Keijser, T.; Mittemeijer, E.J.; Van Mourik, P.; Van der Pers, N.M.; Van Rooijen, M.; Zalm, W.E.","","1983","","Al-Si alloys; rapid quenching","en","journal article","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:eb9cd3a1-7281-4708-b469-c2a8b639b6ae","http://resolver.tudelft.nl/uuid:eb9cd3a1-7281-4708-b469-c2a8b639b6ae","Thermal investigation of unstable substances including a comparion of different thermal analytical techniques","Barendregt, R.B.","Van den Berg, P.J. (promotor)","1981","","","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Chemical Engineering and Material Sciences","","","",""
"uuid:e7066482-46a9-4eb4-850d-ef6f3bf11fc3","http://resolver.tudelft.nl/uuid:e7066482-46a9-4eb4-850d-ef6f3bf11fc3","TEM 'in situ' training and bulk studies of the selection of glide systems in F.C.C. single crystals","Kolkman, H.J.","Okkerse, B. (promotor)","1981","","","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Chemical Engineering and Material Sciences","","","",""
"uuid:d0446c4f-c40a-431c-8282-ad9cb97d65e1","http://resolver.tudelft.nl/uuid:d0446c4f-c40a-431c-8282-ad9cb97d65e1","Studies on overcrowding in organic molecules","Van de Graaf, B.","Wepster, B.M. (promotor)","1978","","","en","doctoral thesis","Delft University Press","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:2256c3e2-eb11-41a2-a6a4-9b05018261a9","http://resolver.tudelft.nl/uuid:2256c3e2-eb11-41a2-a6a4-9b05018261a9","Homogene katalyse van enige autoxydatiereacties door cobaltcomplexen","Hendriks, C.F.","Van Beek, H.C.A. (promotor); Heertjes, P.M. (promotor)","1977","","","nl","doctoral thesis","","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:095fc10a-e23c-4da1-9316-5794fc2f103f","http://resolver.tudelft.nl/uuid:095fc10a-e23c-4da1-9316-5794fc2f103f","De stromings dubbele breking van polystyreensmelten met kleine Hoeveelheden benzofenon","Laurijsen, P.","","1972","","","nl","student report","","","","","","","","","Applied Sciences","Chemical Engineering and of Materials Science","","Applied Thermodynamics and Phase Behaviour","",""
"uuid:e6e2de79-b998-4237-9dfd-feec0732e8e8","http://resolver.tudelft.nl/uuid:e6e2de79-b998-4237-9dfd-feec0732e8e8","Eye readable metal hydride based hydrogen tape sensor for health applications","Ngene, P.; Radeva, T.; Westerwaal, R.; Schreuders, H.; Dam, B.","","","Using the change in the intrinsic optical properties of YMg-based thin films upon exposure to hydrogen, we observe the presence of hydrogen at concentrations as low as 20 ppm just by a change in color. The eye-visible color change circumvents the use of any electronics in this device, thereby making it an inexpensive H2 detector. The detector shows high selectivity towards H2 in H2-O2 - mixtures, and responds within 20 s to 0.25% H2 in the presence of 18% O2.","tape sensor; Eye readable sensor; hydrogen sensor; breath analysis; lactose intolerance; yttriumhydride; thin film","en","conference paper","SPIE","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:cd5bfe29-81ba-4ce1-aad8-6854dd2164b3","http://resolver.tudelft.nl/uuid:cd5bfe29-81ba-4ce1-aad8-6854dd2164b3","Dynamics of droplet formation at T-shaped nozzles with elastic feed lines","Malsch, D.; Gleichmann, N.; Kielpinski, M.; Mayer, G.; Henkel, T.; Mueller, D.; Van Steijn, V.; Kleijn, C.; Kreutzer, M.T.","","","We describe the formation of water in oil droplets, which are commonly used in lab-on-a-chip systems for sample generation and dosing, at microfluidic Tshaped nozzles from elastic feed lines. A narrow nozzle forms a barrier for a liquid–liquid interface, such that pressure can build up behind the nozzle up to a critical pressure. Above this critical pressure, the liquid bursts into the main channel. Build-up of pressure is possible when the fluid before the nozzle is compressible or when the channel that leads to the nozzle is elastic. We explore the value of the critical pressure and the time required to achieve it. We describe the fluid flow of the sudden burst, globally in terms of flow rate into the channel and spatially resolved in terms of flow fields measured using micro-PIV. A total of three different stages—the lag phase, a spill out phase, and a linear growth phase—can be clearly discriminated during droplet formation. The lag time linearly scales with the curvature of the interface inside the nozzle and is inversly proportional to the flow rate of the dispersed phase. A complete overview of the evolution of the growth of droplets and the internal flow structure is provided in the digital supplement","segmented flow; droplet formation; micro particle image velocimetry (lPIV); micro channel; oil/water two phase flow; digital reaction technology; droplet-based microfluidics platform","en","journal article","Springer","","","","","","","","Applied Sciences","Chemical Engineering","","","",""