Enzymatic biodiesel production offers advantages in overcoming the limitations of base-catalyzed process that is sensitive to free fatty acid contents and acid-catalyzed process that requires high operating conditions. The present study is the first to explore the techno-economic viability of enzymatic biodiesel production from castor oil considering both conventional reactor-distillation and enzymatic reactive distillation (ERD) technologies. The ERD technology was assessed by previous studies for other chemical systems, while the ERD prospect for biodiesel process currently remains unknown. This work proposes a reliable thermodynamic model and a new power-law kinetic expression for the specific assessed system. The realistic approach of reactor and enzymatic reactive distillation design in this study suggests that compared to the ERD scheme, the conventional process achieves slightly higher conversion (99.65% vs 97.61%) at substantially lower specific energy use (1.50 vs 3.93 GJ/tonne FAME) and lower specific CO₂ emissions (0.12 vs 0.31 kg CO₂/tonne FAME), with comparable production costs (2.05 vs 2.11 USD/kg). Due to the inherent slow reaction in enzymatic systems and an unfavorable components’ volatility order in the biodiesel system, a standalone ERD without pre-reactors is not practically viable. Despite the fact that the reactive distillation scheme offers advantages of process integration in some chemical reaction systems, this study reveals that sometimes process intensification fails to outperform conventional processes, particularly in enzymatic biodiesel production.

Continuous neutral-alcohol and food-grade ethanol production is an energy-intensive process in which distillation and rectification alone account for 50–85% of total plant energy use. While significant advances in separation technology have emerged over the past two decades, the spirits industry continues to rely predominantly on multi-effect distillation configurations developed decades ago. This perspective paper evaluates intensified separation technologies for large-scale continuous production of food-grade ethanol. Special emphasis is on practical applicability within the constraints of spirit manufacturing, namely food-grade compatibility, congener management and retrofit feasibility. The ethanol–water azeotrope at 95.63 wt% (96.47 vol%) at atmospheric pressure remains the key thermodynamic challenge, though only for the high-strength distillate/neutral-alcohol stage as most finished spirits (bottled at ca 40 vol%) never approach it. Breaking or avoiding it without using (food-grade-incompatible) mass separating agents requires an actual rethinking of process design. Technologies are assessed against a technology readiness level (TRL) framework. Cyclic distillation and heat pump-assisted distillation are identified as near-term, deployment-ready solutions offering 30–70% energy savings at TRL 7–9. HIDiC, suitable for new plant designs, can reach up to 77% savings. Hybrid distillation–membrane separation is the most promising medium-term pathway combining high purity and low energy demand. Pass-through distillation emerges as a disruptive option enabling concurrent fermentation and alcohol recovery. A decision framework linking feed concentration, target purity, plant scale and capital constraints is proposed to guide technology selection for both new plants and retrofit applications. The findings highlight that the spirits sector is well positioned to reduce its carbon footprint and operating costs by adopting proven process intensification technologies that have demonstrated industrial viability in other sectors.

The evolution of artificial intelligence (AI), machine learning (ML), and neural networks (NN) is transforming the landscape of scientific and engineering modeling. It also prompts a debate on the role of first-principles modeling (FPM) in chemical engineering. While data-driven methods excel at interpolation and very rapid development, they often lack physical fidelity, interpretability, and reliable extrapolation capabilities. This article provides a personal academic and industrial perspective on the synergistic integration of FPM and AI-based methods, highlighting their complementary roles in process systems engineering. We argue that FPM (based on fundamental conservation laws and mechanistic understanding of phenomena), remains indispensable for ensuring robustness, safety, physical consistency, and adaptability of models in PSE. Moreover, we analyze the synergistic potential of hybrid approaches by deconstructing the model-building workflow. The latter is the primary lens to identify key decision points where integration delivers maximum value, moving beyond a simple paradigm comparison. Using this structured analysis of the model-building workflow, we identify several major opportunities for this integration, particularly where first-principles knowledge is incomplete. The discussion extends to practical strategies for model validation, scalability, and industrial applications, supported by case studies, as well as the potential of LLMs in assisting the future developments of FPM. Finally, we conclude that a physics-informed foundation for modeling is not obsolete but is instead critical for guiding the safe and reliable application of AI in chemical engineering.

This study advances the development of syngas fermentation by presenting the first industrial-scale process design for producing isopropanol (IPA) and acetone from steel mill off-gas, with a total production capacity of 46–50 ktonne per year. The process was rigorously developed in Aspen Plus, with a comprehensive techno-economic assessment and life-cycle analysis performed to evaluate the process performance. The developed process maximizes energy efficiency by utilizing the heat content of steel off-gas and implementing advanced heat pump systems. As a result, the process is thermally self-sufficient and can operate solely on renewable electricity. Efficient utilization of waste gases results in substantial reductions in global warming potential compared with petrochemical-based production (144–160% for IPA and 138–149% for acetone). The unit production cost of 0.58–0.74 $/kg_IPA/Ac and potential profit margins of 49–65% testify to the cost-effectiveness of the developed process. These findings demonstrate the environmental and economic sustainability of syngas fermentation from steel mill off-gas, establishing it as a potentially viable alternative to conventional petrochemical processes. This technology may hold great potential in reducing environmental impacts and carbon emissions in industrial chemical production.

The electrification of chemical processes and CO₂ utilization are key approaches to improving efficiency and reducing CO₂ emissions in the process industry. The development of electrolyzers has gathered momentum, enabling the potential introduction of renewable electrons into the manufacture of CO₂-based chemicals. While the performance of electrolyzers is subject to improvements driven by the experimental community, the generation of waste heat is unavoidable due to electrical resistances and process inefficiencies within the electrochemical cells. Nonetheless, reusing this waste heat has yet to be investigated for CO₂ electrolyzers. This novel work shows the potential for upgrading the electrolyzer waste heat by means of a heat pump, enabling its utilization in the separation processes downstream of the carbon dioxide electrolyzer. The product chosen is formic acid (60 kt/y), and for our system, the waste heat represents approximately 60 % of the power input to the electrochemical cells, and it can be upgraded from 50 °C to 120 °C to drive the azeotropic distillation of formic acid and water. This integration results in the electrification of 76 % of the separation energy duty, yielding a decrease in CO₂ emissions of 29–84 % compared to the conventional production, depending on the source of electricity. The results demonstrate that the use of traditional heating media in thermal separation processes can be offset and substituted with (renewable) electrical energy, allowing for an increased overall system efficiency. This approach can be readily extended to different productions based on carbon dioxide electroreduction, for example for methanol and ethanol manufacture. This eco-efficient process design leads to a deeper penetration of renewable energy into chemical manufacturing, as both reaction and separation are driven by electricity.

A fully electrified flash vapor circulation (FVC) distillation system for methanol/water separation is investigated, with a focus on identifying suitable self-optimizing controlled variables for minimizing electric power consumption. Starting from two published schemes (CS1 and CS2), four new control structures (CS3 – CS6) are developed to explain and remove the strongly asymmetric closed-loop behavior observed in the original designs. Closed-loop dynamic simulations are performed under ± 20% step disturbances in throughput and methanol composition. Control performance is assessed using product quality deviations, energy indicators, settling time, and integrated absolute error. The results show that controlling compressor discharge pressure in CS1 and CS2 is a poor choice because it over-constrains the series pressure loop of the FVC configuration, which drives excessive recycle, asymmetric responses, and COP deterioration. Eliminating this redundant pressure constraint in CS3 restores the available degrees of freedom and yields more symmetric behavior with lower compression power. Building on self-optimizing control, CS4 and CS5 select condenser outlet conditions as controlled variables to coordinate the trade-off between pressure lift and circulating vapor flow, giving similar energy performance. Finally, CS6 adds a distillate composition controller on top of CS4 to enforce the methanol specification and avoid both under and over purification, with only longer transients due to the slower composition loop. To generalize these findings, a three-step workflow is proposed as a transferable design procedure for heat pump assisted distillation systems.

The use of 1-methyl-2-pyrrolidone (NMP) as an entrainer in extractive distillation (ED) has raised safety and environmental concerns. This study investigated biobased and greener solvents as sustainable entrainers for the industrially relevant separations of an azeotropic n-hexane-ethanol (HEX-ETH) mixture and a close-boiling methylcyclohexane-toluene (MCH-TOL) mixture. A multi-stage entrainer selection framework integrating computational predictions, experimental validation, and process-level assessment was applied to identify effective greener entrainers. A comprehensive assessment for the economic and sustainability performances was conducted, including total annual cost (TAC), energy intensity, CO₂ emissions, and water consumption. Sensitivity analyses were further performed to evaluate the effect of recycled entrainer purity, payback period, and entrainer price on the TAC. The results indicate that the investigated greener entrainers generally achieve economic and sustainability performances comparable to those of NMP while offering substantially lower toxicity. Considering the estimated TAC uncertainty of approximately below 11%, greener entrainer-based ED processes exhibit TAC differences within the estimation uncertainty of the corresponding NMP-based processes. However, HEX-ETH-dimethyl isosorbide (DMI) and MCH-TOL-1-butylpyrrolidin-2-one (NBP), which show TAC increases of up to 14.2 and 15.1%, respectively, are mainly due to higher CAPEX for HEX-ETH-DMI and higher OPEX for MCH-TOL-NBP. Overall, the greener entrainers provide comparable economic and favorable sustainability performance relative to NMP, with an energy intensity ranging from 0.31 to 0.38 kWh/kg_products, CO₂ emissions decrease by 5.8% for MCH-TOL-gamma-valerolactone (GVL), while slightly higher 1.5–20.0% are observed in the other cases. Water consumption is similar for most systems, except for HEX-ETH-DMI and MCH-TOL-NBP, which show 25.0% higher values. Sensitivity analysis confirms that entrainer ranking remains robust under variations in entrainer purity constraint and payback periods, whereas entrainer price significantly affects economic competitiveness. Supporting analyses showed that selectivity exhibits better descriptive consistency with TAC trends than capacity, especially for MCH-TOL, whereas both metrics shows weaker descriptive consistency with TAC trends for the associating HEX-ETH mixture. Predictive models of UNIFAC and COSMO-SAC yielded TAC deviations below 31% and 32%, respectively, when compared with NRTL-based simulations. This indicates their suitability for early-stage entrainer screening for systems without strong association or that do not exhibit abnormal phase behavior. However, the COSMO-SAC prediction for the ethanol-DMI mixture produces nonphysical azeotropic behavior and leads to process convergence failure. This highlights the risk of applying COSMO-SAC to strongly associating mixtures without prior VLE validation. Therefore, validation with experimental data is required before applying predictive models in process-level simulations.

The industrial viability of bioenzymatic production pathways for value-added chemicals relies on the development of energy-efficient and economically feasible downstream processes. This study presents the design, simulation, and techno-economic assessment of a novel downstream separation and purification process for the bioenzymatic conversion of 5-hydroxymethylfurfural (HMF) into four value-added products, namely: 2,5-bis(hydroxymethyl)furan (BHMF), 5-(aminomethyl)-2-furanmethanol (AMFM), R-1-phenylethylamine (R-PEAM), and S-1-phenylethylalcohol (S-PEA). The newly proposed process integrates a heat pump-assisted vacuum distillation column (supplying 5.38 MW_th to drive water evaporation) with pinch-optimized heat exchanger networks, reducing the heat pump system's total cost of ownership by 3% relative to a classic 10 °C minimum temperature approach design (44.31 vs. 45.67 M$). Alternative separation routes for the amine products and their process intensification via dividing wall column (DWC) were systematically evaluated against the base case across economic and environmental metrics. The DWC implementation of Route 2 (Case c) achieved high amine recovery (>99.88%) at the production cost of 42.94 $/kg of pure product and lowest pollutant and toxic materials emissions of 0.469 kg_pt/kg_product, although at a marginal increase in material intensity (0.0425 vs. 0.0420 kg_waste/kg_product) relative to the base case. All four products were obtained at purities exceeding 98%wt for BHMF and 99.9%wt for the remaining products. Economic feasibility is primarily determined by the price ratio of AMFM to phenylsilane feedstock, with AMFM currently priced significantly above the estimated production cost. This work demonstrates that heat pump integration and process intensification via DWCs offer measurable (but system-specific) advantages for bioenzymatic downstream processes, providing a quantitative basis for industrial scale-up decisions.

Multi-stage mechanical vapor recompression (MVR) is a promising route to electrify and intensify distillation for wide-boiling separations, yet its deployment is often constrained by the requirements for effective inter-stage cooling and utilization of the associated sensible heat. This work proposes and evaluates liquid injection as a compact intensification alternative to conventional exchanger-based intercooling in a two-stage MVR system. Unlike prior work on the discretely heat integrated distillation column (D-HIDiC), this study introduces liquid injection directly into MVR systems, eliminating intercooler hardware while maintaining energy performance. Four configurations are examined: a two-stage MVR without intercooling (MVR #1), an intercooled MVR with internal heat recovery to an additional bottom reboiler (MVR #2), a liquid injection MVR without an intercooler (MVR #3), and a liquid injection MVR combined with pre-compressor splitting (MVR #4) to mitigate the increased second-stage compressor load caused by injection. Compared with conventional distillation (CDiC, 10,073 kW reboiler duty), all MVR cases reduce the final energy input to 1759–1850 kW (81.6–82.5% savings) with COP values of 5.445–5.727; MVR #4 achieves the lowest compressor power (1759 kW) and the highest COP (5.727). On a primary-energy basis (36.6% electricity conversion efficiency), the MVR schemes deliver 49.8–52.3% savings versus CDiC. Overall, liquid injection enables equipment simplification with competitive efficiency, while pre-compressor splitting provides a practical tuning degree of freedom to recover or improve performance without sacrificing compactness.

This study investigates the dynamics and control of discretely heat integrated distillation columns, focusing on two configurations: one utilizing a liquid pumparound loop and the other employing liquid injection for waste heat recovery in a multi-stage vapor recompression cycle. These innovative designs eliminate the need for vapor splitters, simplifying operation and enhancing control robustness. As case study, the methanol/water separation process was modelled to achieve 99.99 mol % purity for both products. Dynamic simulations were conducted in Aspen Dynamics to evaluate the control performance for ± 20 % throughput and composition disturbances. Results demonstrated that the proposed control structures, which rely on inferential temperature-based strategies, effectively maintain product specifications and ensure stable operation. This work provides valuable insights into the practical implementation of discretely heat integrated distillation columns, offering a pathway toward energy-efficient and operationally flexible distillation systems.

This study investigates the dynamics and control of a fully electrified heat pump assisted distillation system based on the flash vapor circulation (FVC) concept. The proposed configuration enables complete electrification without auxiliary steam. Two control structures are developed and evaluated in Aspen Dynamics under ± 20 % disturbances in throughput and composition. The first structure CS1 employs single-end temperature control with fixed reflux ratio and demonstrates satisfactory performance in most cases. However, it shows minor deviations in product purity under large composition changes. To address this, a second structure CS2 incorporates an additional composition controller to adjust the reflux ratio, achieving improved purity regulation and energy flexibility. The results confirm the dynamic feasibility and controllability of FVC-based distillation, supporting its integration in future sustainable and flexible separation systems.

Green solvents have emerged as promising green entrainers to substitute conventional entrainers in extractive distillation to separate azeotropic mixtures. However, the limited availability of thermodynamic data for green-solvent-containing mixtures continues to hinder their practical implementation in this process. This study is the first to report experimental vapor–liquid equilibrium (VLE) data for the n-hexane + ethanol azeotropic system containing the greener entrainer 1-butylpyrrolidin-2-one (NBP) alongside the benchmark entrainer 1-methylpyrrolidin-2-one (NMP). Using a Fischer Labodest VLE602 ebulliometer, VLE measurements were performed at pressures of 50.0 and 100.0 kPa and various entrainer-to-feed ratios (E/F). The reliability of the reported VLE data was tested and confirmed using the Van Ness thermodynamic consistency test. The results show that NBP enhances relative volatility and effectively eliminates the azeotrope, performing comparably to the benchmark entrainer NMP. The nonrandom-two-liquid (NRTL) model was utilized to regress the investigated VLE data and determine the optimum binary interaction parameters (BIPs). As a result, the NRTL model demonstrates good agreement with the experimental data. This thermodynamic modeling confirms the data’s reliability and suitability for process design, highlighting NBP’s potential as an environmentally friendly alternative entrainer in extractive distillation.

Fermentation can be used to obtain a wide variety of valuable high-boiling components. Among these components, microorganisms can produce aliphatic diols (e.g. propanediols, butanediols, etc.) in significant concentrations (e.g. 5–15 wt.%). Nonetheless, the high boiling points of these components, presence of microorganisms, and formation of by-products complicate recovery after fermentation. Hence, this perspective offers valuable insights into downstream processing options. A novel methodology was developed for recovering high-boiling components from dilute aqueous solutions, whereby both light and heavy impurities are present. The main steps in the proposed methodology are heat pump-assisted preconcentration and final purification in a dividing-wall column. These steps allow effective separation of high-purity product from water, light and heavy impurities. Furthermore, processes for recovery of 1,3-propanediol, 2,3-, 1,4- and 1,3-butanediol, designed according to the proposed methodology, were compared. Downstream processing performance is mainly determined by the product concentration in the fermentation broth, but is also influenced by the amount of impurities in the broth.

Distillation is widely used for separating liquid mixtures, but its high heating demand poses challenges for achieving net-zero emissions. This study presents an innovative approach to electrifying distillation for load adaptability and flexible operation, aligning with dynamic electricity markets driven by renewables. The approach integrates flash vapor circulation and thermal storage into the distillation to optimize power usage and capitalizes on economic opportunities from load-flexible operation in response to fluctuating electricity pricing. A methanol/water distillation case study, using two typical electricity pricing scenarios, demonstrates that the proposed approach is more economically efficient than mechanical vapor recompression distillation, especially in lowering operational costs when the latter operates under fixed electricity pricing. However, compressor capital costs significantly impact overall costs, with sensitivity analysis examining different cost models. This approach can be applied to general distillation, allowing integration with the power sector and demand response programs, while enhancing flexibility, decarbonization, and efficiency.

In this work, dimethyl isosorbide (DMI) and 1-butylpyrrolidin-2-one (NBP), as biobased and greener organic solvents, were used for the first time as entrainers in extractive distillation to separate a close-boiling mixture of methylcyclohexane and toluene. Vapor–liquid equilibrium (VLE) data were collected for pseudoternary mixtures consisting of methylcyclohexane and toluene in the presence of DMI and NBP at various entrainer-to-feed ratios (E/F) and pressures. The VLE measurements were conducted by using a Fischer Labodest VLE602 ebulliometer, and the thermodynamic consistency of the data was verified by using the Van Ness test. Both DMI and NBP were found to increase the relative volatility of methylcyclohexane to toluene, successfully eliminating close-boiling behavior. Compared to benchmark entrainers, both outperformed 1-methylpyrrolidin-2-one (NMP) and sulfolane under certain conditions. In comparison with other green entrainers, DMI and NBP showed similar performance to gamma-valerolactone (GVL) and Cyrene under specific conditions. The VLE data were accurately correlated by using the nonrandom two-liquid (NRTL) model.