Zeolite membranes exhibit considerable potential for gas separation; however, two critical challenges (low permeation flux and scaling-up fabrication) continue to hinder their practical implementation. Here, we propose an embryonic zeolite-mediated suture (EZMS) strategy to synthesize large-area zeolite membranes with stable gas separation performance. The membrane thickness is equivalent to that of the initial seed layer—a feature validated across three distinct zeolite frameworks (STT, CHA, and MFI). For high-silica CHA (also known as SSZ-13) zeolite membranes, the EZMS strategy enables a 5-fold thickness reduction, yielding a CO₂ permeance of 1.02 × 10^-6mol·m^-2·s^-1·Pa^-1 (3000 GPU) and a CO₂/CH₄ selectivity of 158 at 0.2 MPa. Scalability is validated by the successful synthesis of SSZ-13 zeolite membrane bundles with an individual area of 0.5 m² (40 cm in length). The membranes exhibited excellent high-pressure resistance (>4 MPa) and long-term stability (>220 d) for humid CO₂/CH₄ separation, representing a high-performance benchmark for biogas upgrading. The reliable synthesis protocol and improved performance highlight the industrial application potential of zeolite membranes.

Separation of hydrogen from carbon dioxide for sustainable H₂ production and CO₂ capture still faces great challenges due to the smaller size of H₂ and higher condensability of CO₂. Herein, a high-performance benzimidazole-linked polymer (BILP) membrane for hydrogen separation was directly prepared on α-Al₂O₃ substrate through a facile interfacial polymerization approach at room temperature. The separation performance of the BILP membrane were regulated by controlling the reaction time and the microstructure was systematically characterized. Molecular simulations were performed to deep understand the separation mechanism in the BILP membrane. The best performance membrane displays an extraordinary mixed gas selectivity of 40 for H₂/CO₂ together with outstanding H₂ permeance of 250 gas permeation units (GPU) at 473 K, far exceeding the Robeson's upper bound. Besides, the membrane can withstand high temperature and pressure, and also shows good H₂/N₂ and H₂/CH₄ selectivity. The excellent separation performance, coupled with high temperature and pressure resistance and easy preparation, render BILP membranes great potential for economic H₂ purification, H₂ recovery, and natural gas treatment.

Novel membrane materials for H₂ separation are wanted. How to overcome the “trade-off” between membrane permeability and selectivity is a tough challenge. Here we report new random organic framework membranes with benzimidazole and imine linkages to form hierarchical channels. Both high H₂-selective and fast H₂ transport pathways are created. The preparation parameters are thoroughly studied and the membrane structures are well characterized by SEM, AFM, NMR, XPS, gas sorption, etc. Effect of feed conditions on membrane performance, such as composition, pressure and temperature, is investigated. The membrane performance transcends the upper bounds of H₂/CO₂, H₂/N₂ and H₂/CH₄ with excellent stability.

Monitoring complex catalytic pathways under industrially-relevant conditions is one of the key challenges in catalysis chemistry and technology. Herewith we describe a direct technique called ‘fast scanning-pulse analysis’ (FASPA) that allows the direct characterization and detailed kinetic analysis of intimately interweaved catalytic pathways. The power and potential of the FASPA approach are demonstrated with an industrially relevant methanol-to-hydrocarbons (MTH) process over H-ZSM-5 zeolite. This reaction proceeds via a hydrocarbon pool (HCP) mechanism producing olefins and aromatics. The HCP is built-up upon exposure to methanol during the induction period, followed by a transition regime to a quasi steady-state MTH operation. This FASPA technique allows (sub-)second resolution of the full temporal products response upon a methanol pulse providing direct and quantitative insights into the MTH reactions. Globally, two consecutive pathways can be discerned: a very fast primary product formation in the presence of methanol in a narrow active MTH reaction zone, followed by a slower formation of light aromatics, which is closely related to the decomposition and release of HCP species and secondary reactions in absence of methanol in the downstream part of the catalyst bed. The time delay between the appearance of inert tracer and primary products represents the time needed to build-up the HCP in the induction period, where methane is observed prior to other products. The primary products (alkanes, olefins, and light aromatics) are nearly instantaneously formed from the pulsed methanol. These results demonstrate the highly dynamic character of the HCP in the MTH process over H-ZSM-5.

The nature of hydrocarbon pool (HCP) intermediates in the methanol-to-hydrocarbons (MTH) process has been thoroughly investigated, especially for BEA- and CHA-type zeolite catalysts like H-β and H-SAPO-34. Herein, we further reveal the dynamic mechanistic details of the MTH process over the H-ZSM-5 catalyst at 400 °C, based on the dual-cycle mechanism and HCP in this medium-pore zeolite. Application of switching sequences of ¹³C-labeled and unlabeled methanol pulses over a model H-ZSM-5 catalyst combined with on-line MS analysis and a recently reported technique called “fast scanning-pulse GC analysis” provides a direct and quantitative insight into the MTH reactions under quasi-steady-state conditions. The transient product responses showed the almost instant formation of hydrocarbons upon a small pulse of methanol, followed by secondary formation of light aromatics via HCP decomposition and olefin alkylation-dealkylation, especially in a long catalyst bed when methanol is quickly consumed in the initial reaction zone in the catalyst bed. The isotopic analysis of typical aliphatic C₃₊ product responses after switching ¹³C-methanol pulses to the unlabeled methanol pulses showed a fast isotope scrambling in the formation of C₃₊ species. MS analysis of the light aromatics indicates a complete consecutive but slower isotope incorporation process of ¹²C into ¹³C-aromatics. Results provide direct experimental confirmation of the kinetically preferred olefin-based cycle over the aromatic-based cycle. The sequential isotopic incorporation strongly suggests that the paring reaction pathway through aromatic ring contraction and re-expansion steps is operative. In the appearance of aromatics upon pulsing methanol over larger catalyst beds, four processes are directly discerned, involving the displacement of adsorbed species by formed water, isotope incorporation yielding directly labeled and unlabeled products through the paring mechanism and direct aromatization, and HCP conversion through secondary reactions.

Cobalt-containing lignin-based fibers were synthesized in one step by electrospinning of Alcell lignin solutions as carbon precursor, a low-cost and renewable co-product of the paper making industry. The lignin fibers were thermostabilized in air to avoid the fusion during the carbonization process between 500 and 800 °C to obtain cobalt-containing porous carbon submicron fibers. These carbon fibers catalysts were studied for the Low-Temperature Fischer-Tropsch synthesis. The lignin-derived fibers containing Co catalyst located on the overall carbon fiber surface (internal and external) heat-treated at 500 °C (Co@CF-500) showed the best catalytic performance after 70 h on stream, with 75% and 60% selectivity to C5+ at 220 °C and H₂/CO ratios of 1 and 2, respectively, attributed to the high Co dispersion, optimal Co-particle size and better Co accessibility. Higher heat-treatment temperatures leaded to Co-containing carbon fibers with larger metallic cobalt nanoparticles encapsulated in graphitic-type carbon, which rendered them inaccessible for FTS.

In a world where capture and separation processes represent above 10% of global energy consumption, novel porous materials, such as Metal-Organic Frameworks (MOFs) used in adsorption-based processes are a promising alternative to dethrone the high-energy-demanding distillation. Shape and size tailor-made pores in combination with Lewis acidic sites can enhance the adsorbate-adsorbent interactions. Understanding the underlying mechanisms of adsorption is essential to designing and optimizing capture and separation processes. Herein, we analyze the adsorption behaviour of light hydrocarbons (methane, ethane, ethylene, propane, and propylene) in two synthesized copper-based MOFs, Cu-MOF-74 and URJC-1. The experimental and computational adsorption curves reveal a limited effect of the exposed metal centers on the olefins. The lower interaction Cu-olefin is also reflected in the calculated enthalpy of adsorption and binding geometries. Moreover, the diamond-shaped pores' deformation upon external stimuli is first reported in URJC-1. This phenomenon is highlighted as the key to understanding the adsorbent's responsive mechanisms and potential in future industrial applications.

Large amounts of carbon monoxide are produced by industrial processes such as biomass gasification and steel manufacturing. The CO present in vent streams is often burnt, this produces a large amount of CO₂, e.g., oxidation of CO from metallurgic flue gasses is solely responsible for 2.7% of manmade CO₂ emissions. The separation of N₂ from CO due to their very similar physical properties is very challenging, meaning that numerous energy-intensive steps are required for CO separation, making the CO separation from many process streams uneconomical in spite of CO being a valuable building block in the production of major chemicals through C1 chemistry and the production of linear hydrocarbons by the Fischer-Tropsch process. The development of suitable processes for the separation of carbon monoxide has both industrial and environmental significance. Especially since CO is a main product of electrocatalytic CO₂ reduction, an emerging sustainable technology to enable carbon neutrality. This technology also requires an energy-efficient separation process. Therefore, there is a great need to develop energy efficient CO separation processes adequate for these different process streams. As such the urgency of separating carbon monoxide is gaining greater recognition, with research in the field becoming more and more crucial. This review details the principles on which CO separation is based and provides an overview of currently commercialised CO separation processes and their limitations. Adsorption is identified as a technology with the potential for CO separation with high selectivity and energy efficiency. We review the research efforts, mainly seen in the last decades, in developing new materials for CO separation via ad/bsorption and membrane technology. We have geared our review to both traditional CO sources and emerging CO sources, including CO production from CO₂ conversion. To that end, a variety of emerging processes as potential CO₂-to-CO technologies are discussed and, specifically, the need for CO capture after electrochemical CO₂ reduction is highlighted, which is still underexposed in the available literature. Altogether, we aim to highlight the knowledge gaps that could guide future research to improve CO separation performance for industrial implementation.

Metal–organic frameworks (MOFs) are superior sorbents for water adsorption-based applications. The unique step-like water isotherm at a MOF-specific relative pressure allows easy loading and regeneration over a small range of temperature and pressure conditions. With good hydrothermal stability and cyclic durability, it stands out over classical sorbents used in applications for humidity control, water harvesting, and adsorption-based heating and cooling. These are easily regenerated at moderate temperatures using “waste” heat or solar heating. The isotherm thermodynamics and adsorption mechanisms are described, and the presence of MOFs in the water–air system is explained. Based on six selection criteria ≈40 reported MOFs and one COF are identified for potential application. Trends and approaches in further synthesis optimization and production scale-up are highlighted. No-MOF-fits-all, each MOF has its own specific step location matching only with a certain application type. Most applications are technically feasible and demonstrated on the bench-scale or small pilot. Their maturity is benchmarked by their technology readiness level. Retrofitting existing applications with MOFs replacing classical desiccants may lead to rapid demonstration. Studies on techno-economic analysis and life cycle analysis are required for a rational evaluation of the feasibility of promising applications.

Zeolite membranes are highly attractive in energy efficient, selective separation technologies. Their high selectivity originates from selective adsorption, diffusion and even molecular sieving. High flux zeolite membranes (> 1 mol s⁻¹m⁻²) with a sub-micrometer thickness are mechanically stabilized by a porous, often multilayer, support. Transport mechanisms in zeolite layer and support, however, are counteracting regarding selectivity, and a support may also act as a flux resistance. Several examples are analyzed quantifying the impact of the support on the observed performance, showing the effect of layer thickness, orientation of the asymmetric membrane and operational conditions, resulting in recommendations for the configuration of zeolite membrane modules.

Identification of the catalyst characteristics correlating with the key performance parameters including selectivity and stability is key to the rational catalyst design. Herein we focused on the identification of property-performance relationships in the methanol-to-olefin (MTO) process by studying in detail the catalytic behaviour of MFI, MEL and their respective intergrowth zeolites. The detailed material characterization reveals that both the high production of propylene and butylenes and the large MeOH conversion capacity correlate with the enrichment of lattice Al sites in the channels of the pentasil structure as identified by ²⁷Al MAS NMR and 3-methylpentane cracking results. The lack of correlation between MTO performance and other catalyst characteristics, such as crystal size, presence of external Brønsted acid sites and Al pairing suggests their less pronounced role in defining the propylene selectivity. Our analysis reveals that catalyst deactivation is rather complex and is strongly affected by the enrichment of lattice Al in the intersections, the overall Al-content, and crystal size. The intergrowth of MFI and MEL phases accelerates the catalyst deactivation rate.

The production of valuable aromatics and the rapid catalyst deactivation due to coking are intimately related in the zeolite-catalyzed aromatization reactions. Here, we demonstrate that these two processes can be decoupled by promoting the Ga/HZSM-5 aromatization catalyst with Ca. The resulting bimetallic catalysts combine high selectivity to light aromatics with extended catalyst lifetime in the methanol-to-aromatics process. Evaluation of the catalytic performance combined with detailed catalyst characterization suggests that the added Ca interacts with the Ga-LAS, with a strong effect on the aromatization processes. A genetic algorithm approach complemented by ab initio thermodynamic analysis is used to elucidate the possible structures of bimetallic extraframework species formed under reaction conditions. The promotion effect of minute amounts of Ca is attributed to the stabilization of the intra-zeolite extraframework gallium oxide clusters with moderated dehydrogenation activity.

In situformation of p-n heterojunctions between TiO₂and Cu_xO in heteroatom-doped carbon nanocomposites and their applications in photocatalytic H₂evolution were demonstrated. One-step pyrolysis of bimetal-organic-frameworks NH₂-MIL-125(Ti/Cu) in steam at 700 °C forms a p-n heterojunction between TiO₂and Cu_xO nanoparticles. Concurrently, a phasejunction between nitrogen/carbon co-doped anatase and rutile TiO₂is formed, accompanied by the formation of Cu_xO heterostructures. These multi-heterostructures are embedded in N-containing and hydrophilic carboxyl functionalized carbon matrix. The optimized TiO₂/Cu_xO/C composite multi-heterostructures offer multiple pathways for photoinduced electrons and holes migration, absorb more visible light, and provide an increased number of active sites for photocatalytic reactions. Without loading expensive noble metals, the TiO₂/Cu_xO/C nanocomposite derived at 700 °C in steam exhibited a superior photocatalytic H₂generation activity of 3298 μmol g_cat⁻¹h⁻¹under UV-Visible light, 40 times higher than that of commercial TiO₂. This work offers a simple approach to fabricate novel photocatalytic nanocomposites for efficient H₂generation.

New membrane materials with excellent water permeability and high ion rejection are needed. Metal-organic frameworks (MOFs) are promising candidates by virtue of their diversity in chemistry and topology. In this work, continuous aluminum MOF-303 membranes were prepared on α-Al2O3 substrates via an in situ hydrothermal synthesis method. The membranes exhibit satisfying rejection of divalent ions (e.g., 93.5% for MgCl2 and 96.0% for Na2SO4) on the basis of a size-sieving and electrostatic-repulsion mechanism and unprecedented permeability (3.0 L·m-2·h-1·bar-1·μm). The water permeability outperforms typical zirconium MOF, zeolite, and commercial polymeric reverse osmosis and nanofiltration membranes. Additionally, the membrane material exhibits good stability and low production costs. These merits recommend MOF-303 as a next-generation membrane material for water softening.

Surface-functionalized nitrogen/carbon co-doped polymorphic TiO₂ phase junction nanoparticles uniformly distributed in porous carbon matrix were synthesized by a simple one-step pyrolysis of titanium based metal–organic framework (MOF), NH₂-MIL-125(Ti) at 700 °C under water vapour atmosphere. Introducing water vapour during the pyrolysis of NH₂-MIL-125(Ti) not only functionalizes the derived porous carbon matrix with carboxyl groups but also forms additional oxygen-rich N like interstitial/intraband states lying above the valence band of TiO₂ along with the self-doped carbon, which further narrows the energy band gaps of polymorphic TiO₂ nanoparticles that enhance photocatalytic charge transfer efficiency. Without co-catalyst, sample N-C-TiO₂/C_ArW demonstrates H₂ evolution activity of 426 µmol g_cat^-1 h⁻¹, which remarkably outperforms commercial TiO₂ (P-25) and N-C-TiO₂/C_Ar with a 5-fold and 3-fold H₂ generation, respectively. This study clearly shows that water vapour atmosphere during the pyrolysis increases the hydrophilicity of the Ti-MOF derived composites by functionalizing porous carbon matrix with carboxylic groups, as well as enhancing the electrical conductivity and charge transfer efficiency due to the formation of additional localized oxygen-rich N like interstitial/intraband states. This work also demonstrates that by optimizing the anatase–rutile phase composition of the TiO₂ polymorphs, tuning the energy band gaps by N/C co-doping and functionalizing the porous carbon matrix in the N-C-TiO₂/C nanocomposites, the photocatalytic H₂ generation activity can be further enhanced.