Commercial Polymeric Membranes Research Articles

In situ hydrolyzed microporous polymer membranes for additional free volume to facilitate CO2 permeation

Advancements in membrane separation technology play a pivotal role in separation processes closely associated with the environment and energy. However, presently available commercial polymeric membranes encounter the challenge of low permeability, impacting both separation efficiency and membrane module costs. Here, we propose a simple and effective in situ acid hydrolysis strategy to significantly enhance membrane permeability. Specifically, a tetrafluorinated monomer with hydrolyzable Schiff base groups (TFNAD) has been meticulously designed, synthesized, and copolymerized with commercial TFTPN and TTSBI, yielding a series of copolymers. Subsequently, in situ hydrolysis removes aniline from the membrane, freeing up the occupied free volume and creating additional channels for gas transport. This process substantially enhances gas permeability while preserving the desired selectivity. PIM-TFAD-30 showed a 68 % improvement in CO2 permeability with virtually no compromise in CO2/N2 selectivity compared to the pre-hydrolysis membrane. Meanwhile, PIM-TFAD-30 also displayed outstanding separation performance and plasticization resistance in simulated flue gas tests, demonstrating its potential for practical application. This facile and straightforward hydrolysis method opens up a new perspective for preparing and modifying polymeric separation membranes beyond gas separation.

Electrospun fibrillary scaffold for electrochemical cell biomarkers detection

A novel scaffold for in situ electrochemical detection of cell biomarkers was developed using electrospun nanofibers and commercial adhesive polymeric membranes. The electrochemical sensing of cell biomarkers requires the cultivation of the cells on/near the (bio)sensor surface in a manner to preserve an appropriate electroactive available surface and to avoid the surface passivation and sensor damage. This can be achieved by employing biocompatible nanofiber meshes that allow the cells to have a normal behavior and do not alter the electrochemical detection. For a better mechanical stability and ease of handling, nylon 6/6 nanofibers were collected on commercial polymeric membranes, at an optimal fiber density, obtaining a double-layered platform. To demonstrate the functionality of the fabricated scaffold, the screening of cellular stress has been achieved integrating melanoma B16-F10 cells and the (bio)sensor components on the transducer whereas the melanin exocytosis was successfully quantified using a commercial electrode. Either directly on the surface of the (bio)sensor or spatially detached from it, the integration of cell cultures in biosensing platforms based on electrospun nanofibers represents a powerful bioanalytical tool able to provide real-time information about the biomarker release, enzyme activity or inhibition, and monitoring of various cellular events.Graphical

Coke oven wastewater treatment using polymeric and ceramic membranes.

This research is aimed to investigate the efficacy of membrane separation technology in treating coke oven wastewater (COW). A comparative study was conducted using three types of membranes: commercial polymeric (CP) membrane, commercial ceramic (CC) membrane, and synthesized ceramic (SC) membrane. The potential of the SC membrane in COW treatment was assessed in comparison to the CC membrane, which had a molecular weight cut-off (MWCO) of 1 Kilo-Dalton. The experiments were conducted under various trans-membrane pressure (TMP) conditions ranging from 1 to 4bar. Additionally, the effect of the CP membrane on COW treatment was examined at TMP levels ranging from 5 to 25bar. The research findings revealed that the SC membrane exhibited promising results in terms of permeability and flux compared to the CC membrane. Also, a significant reduction was observed in various water parameters such as TSS decreased by 89.74%, chlorides by 8.24%, nitrogen by 10%, and hardness by 22%. Moreover, the study was carried out by implementing an anti-fouling mechanism to mitigate fouling effects on membrane performance.

Copolyimide molecular brushes with poly(methacrylic acid) side chains as additive to polyphthalamide membrane: Organization, physical, and transport properties

AbstractMacromolecules of complex architecture find application as modifiers of commercial polymeric membrane materials. In this work, copolyimide molecular brushes (coPI) composed of polyimide backbone and poly(methacrylic acid) side chains were used to modify poly(m‐phenylene iso‐phthalamide) (PPA). Structure, physical, mechanical, and transport properties of dense nonporous PPA/coPI membranes containing up to 10 wt% coPI were studied. The effect of included coPI on the membrane structure was estimated using atomic force microscopy and mechanical tests. The coPI modifier contributes to the additional formation of free volume elements evenly distributed throughout the membrane. Transport properties of PPA/coPI membranes were investigated via sorption tests and pervaporation separation of methanol (MeOH) and methyl tert‐butyl ether (MTBE) mixtures. The inclusion of coPI modifier in the PPA membrane leads to an increase in the total flux of the membrane. The highest separation factor was found for the PPA/coPI membrane containing 10 wt% coPI; transport properties of the best membrane were compared with the literature data on separation of the azeotropic MeOH–MTBE mixture.

Alkadiyne-Pyrene Conjugated Frameworks with Surface Exclusion Effect for Ultrafast Seawater Desalination.

Billions of populations are suffering from the supply-demand imbalance of clean water, resulting in a global sustainability crisis. Membrane desalination is a promising method to produce fresh water from saline waters. However, conventional membranes often encounter challenges related to low water permeation, negatively impacting energy efficiency and water productivity. Herein, we achieve ultrafast desalination over the newly developed alkadiyne-pyrene conjugated frameworks membrane supported on a porous copper hollow fiber. With membrane distillation, the membrane exhibits nearly complete NaCl rejection (>99.9%) and ultrahigh fluxes (∼500 L m-2 h-1) from the seawater salinity-level NaCl solutions, which surpass the commercial polymeric membranes with at least 1 order of magnitude higher permeability. Experimental and theoretical investigations suggest that the large aspect ratio of membrane pores and the high evaporation area contribute to the high flux, and the graphene-like hydrophobic surface of conjugated frameworks exhibits complete salt exclusion. The simulations also confirm that the intraplanar pores of frameworks are impermeable for water and ions.

Electrospun Polysulfone Hybrid Nanocomposite Fibers as Membrane for Separating Oil/Water Emulsion

Commercial polymer membranes are largely utilized to separate oil/water mixtures; however, membrane fouling, flux decline, and short lifetime often inhibit their high performance. In order to resolve these drawbacks of the commercial membranes, we introduce a surface modification strategy following the electrospinning method. Electrospun fibers of polysulfone (PSf)/iron oxide (FeO)/halloysite nanotubes (HNT) nanocomposite are applied to modify the polyether sulfone (PES) standard membrane support surface for developing highly efficient oil/water emulsion separating membranes. This facile and simple spinning process for shorter periods ensures nanocomposite coatings on the standard PES membranes and allows a better oil/water separation. We analyze the structural and morphological characteristics of the modified membrane surface using scanning electron microscopy, Fourier transformation infrared spectroscopy, and X-ray diffraction studies and hydrophilicity from contact angle studies. FeO nanoparticles of 2–5 nm and HNTs of < 50 nm size mixed in PSf produce fibers of 531 ± 162 nm average diameter at a relatively lower applied electrical voltage of 14.5 kV, compared to PSf. Underwater and under-oil contact angle values are used to prove the surface characteristics of the membranes and total organic content (TOC) values for the emulsion separation performance. From PES support to PSf and PSf/HNT-FeO, the TOC values respectively change from 67 to 75 and 79%. We find moderately hydrophilic membranes (PSf/HNT-FeO) resulting in a higher permeate flux (28,447 Lm−2·h−1) and quicker separation performance. We believe this study provides a notable solution to modify the surface of commercial membranes for better emulsion separation performance.

Cross-flow separation characteristics and piloting of graphene oxide nanofiltration membrane sheets and tubes for kraft black liquor concentration

Dewatering of weak black liquor (WBL) in the kraft cycle by evaporation is highly energy intensive. Membranes are an attractive alternative for energy-efficient dewatering, but existing commercial polymeric or ceramic membranes are either degraded in BL or have high capital costs. Our recent works have demonstrated the engineering of graphene oxide (GO) nanofiltration membranes, their stability and promising performance in BL conditions, and preliminary scale-up into sheets and tubes. Here, we describe in detail the separation characteristics of GO membrane sheets and tubes under real BL conditions and crossflow operation. Recycle-mode piloting of a GO tubular membrane showed average “production flux” of 16 L/m2/h (LMH) and high rejections of lignin (98.3%), total solids (66%), and total organic carbon (83%), with no signs of irreversible fouling identified. A corresponding GO sheet membrane produced an average flux of ~25 LMH and maintained high lignin rejection of ~97% during a slipstream pilot at a kraft mill site using WBL with ~16 wt% total solids (TS). Finally, we piloted a Dow/DuPont XUS1808 polyamide composite reverse osmosis (RO) membrane for last-mile processing of the GO nanofiltration membrane permeate. The RO membrane showed a steady state flux of 19 LMH at 65 bar and produced ~0.02 wt% TS water product, which is highly suitable for reuse in pulp washing operations in the kraft process. The results have strong positive implications for the industrial application of GO membranes in BL concentration and other related applications.

Textile dye removal in wastewater by peroxymonosulfate (PMS) activation on a zero-valent iron nanoparticle-modified ultrafiltration catalytic membrane (nZVI@PES).

The use of the nano zero-valent iron (nZVI) nanoparticle-based advanced oxidation systems in conjunction with an activator such as peroxymonosulfate (PMS) to generate hydroxyl and sulfate radicals for the degradation of organic pollutants has been extensively used in recent studies. In this study, a nZVI-modified polyethersulfone (PES) membrane (nZVI@PES) was produced successfully by attaching the nZVI catalytic nanoparticles on the surface of a commercial microporous polymeric membrane material using a simple and easy filter press coating method. The presence of nZVI nanoparticles on the nZVI@PES membrane was confirmed by XRD, SEM, and EDS analyses. The nZVI@PES membrane was applied in the dead-end filtration system in the presence of the PMS activator to treat the reactive black 5 (RB5) dye solution. The effect of catalyst loading, RB5 dye concentration, PMS dosage, and pH level on the nZVI@PES membrane/PMS system was investigated. Quenching experiments were carried out to identify the reactive species responsible, and reusability tests were conducted on the membrane. The highest decolorization efficiency (96.8%) was obtained at 20 mg/L RB5 dye solution, initial pH of 3, the nZVI loading of 5 mg/cm2, and the PMS dosage of 300 mg/L at the end of a reaction time of 30 min. The formation of HO•, [Formula: see text], [Formula: see text] and, 1O2 was confirmed by quenching experiments. The results indicate that the nZVI@PES membrane/PMS system could successfully treat wastewater contaminated with an organic dye.

Energy Application of Graphene Based Membrane: Hydrogen Separation.

Hydrogen gas (H2 ) is a viable energy carrier that has the potential to replace the traditional fossil fuels and contribute to achieving zero net emissions, making it an attractive option for a hydrogen-based society. However, current H2 purification technologies are often limited by high energy consumption, and as a result, there is a growing demand for alternative techniques that offer higher H2 purity and energy efficiency. Membrane separation has emerged as a promising approach for obtaining high-purity H2 gas with low energy consumption. Nevertheless, despite years of development, commercial polymeric membranes have limited performance, prompting researchers to explore alternative materials. In this context, carbon-based membranes, specifically graphene-based nanomaterials, have gained significant attention as potential membrane materials due to their unique properties. In this review, we provide a comprehensive overview of carbon-based membranes for H2 gas separation, fabrication of the membrane, and its characterization, including their advantages and limitations. We also explore the current technological challenges and suggest insights into future research directions, highlighting potential ways to improve graphene-based membranes performance for H2 separations.

Stability of Porous Polymeric Membranes in Amine Solvents for Membrane Contactor Applications.

Membrane gas-liquid contactors have great potential to meet the challenges of amine CO2 capture. In this case, the most effective approach is the use of composite membranes. However, to obtain these, it is necessary to take into account the chemical and morphological resistance of membrane supports to long-term exposure to amine absorbents and their oxidative degradation products. In this work, we studied the chemical and morphological stability of a number of commercial porous polymeric membranes exposed to various types of alkanolamines with the addition of heat-stable salt anions as a model of real industrial CO2 amine solvents. The results of the physicochemical analysis of the chemical and morphological stability of porous polymer membranes after exposure to alkanolamines, their oxidative degradation products, and oxygen scavengers were presented. According to the results of studies by FTIR spectroscopy and AFM, a significant destruction of porous membranes based on polypropylene (PP), polyvinylidenefluoride (PVDF), polyethersulfone (PES) and polyamide (nylon, PA) was revealed. At the same time, the polytetrafluoroethylene (PTFE) membranes had relatively high stability. On the basis of these results, composite membranes with porous supports that are stable in amine solvents can be successfully obtained to create liquid-liquid and gas-liquid membrane contactors for membrane deoxygenation.

Highly tunable structure-by-design polymer brush membranes for organic solvent nanofiltration

Synthetic polymeric nanofiltration membrane processes offer an alternate low-energy option to energy-intensive distillation to fractionate similar size organic solvents for chemical, petroleum, food and biotechnology industries. Here, we synthesize and test a new class of structure-by-design hydrophilic polymeric brush membranes, that address the limitations of commercial polymer membranes, are tunable and exhibit commercially relevant filtration performance. Because these brush membranes are grafted by Single Electron Transfer-Living Radical Polymerization (SET-LRP) and replace statistically random phase inversion or interfacial polymerization used for synthesizing commercial polymer membranes, their porous structure can be remodeled by varying their morphology and chemistry. We graft hydroxyethyl methacrylate (HEMA) brush structures with short and long crosslinkers, demonstrate two competing phenomena - pore stiffening and opening - and obtain high selectivity at reasonable permeability for commercially relevant methanol/toluene separation. This new class of stable, tunable, and scalable membranes offers exciting opportunities to reduce energy for separation of organic solvents.

Modeling and simulation of pervaporation (PV) separation for alcohol dehydration

The separation performance of commercial crosslinked poly (vinyl alcohol) (PVA) membranes (i.e., the new commercial membrane PERVAP™ 4100 H F and standard membrane PERVAP™ 4100) used for the dehydration of two alcohol-water systems (i.e., ethanol-water and isopropanol-water mixtures, with an azeotropic point) were studied based on pervaporation process (PV) experimental data and mathematical modeling. Pervaporation process experiments proved that these two membranes have excellent applicability for the dehydration of alcohol. A semi-empirical solution-diffusion transport model was developed to describe the mass transport in the PVA membranes, which showed a good agreement with the experimental values. The universal quasi-chemical (UNIQUAC) model was utilized to predict the activity coefficient of nonideal alcohol-water systems in PVA membranes. In addition to the UNIQUAC model, the transport of alcohol-water across the commercial polymeric membrane was modeled using the conventional driving force model. The PV process experimental data with the mathematical model were used to develop the diffusivity correlations for water and alcohol (i.e., ethanol and isopropanol) through the PVA membranes. It was found that for swollen membranes (PVA), the developed correlations of water and alcohol diffusivity were strongly influenced by the feed water activity and feed temperature. Based on the mass transport model and developed diffusivity correlations, the permeation flux of water and alcohol through the PVA membranes was predicted, and the results showed a good agreement between the experimental data and the predictive model. The mean relative errors estimated for the permeate mass fluxes of water were 8.4%, and 3.8%, and for the permeate mass fluxes of ethanol were 18%, and 13.6% for the PERVAP™ 4100 and 4100 H F, respectively, as well as for the IPA-water-PVA system are as follows: 5% and 2.8% for the permeate mass fluxes of water and 14.4%, and 12.6% for the permeate mass fluxes of IPA for the PERVAP™ 4100 and 4100 H F, respectively.

Efficiency analysis of commercial polymeric membranes for bone regeneration in rat cranial defects.

To evaluate the in vivo efficiency of commercial polymeric membranes for guided bone regeneration. Rat calvarial critical size defects was treated with LuminaCoat (LC), Surgitime PTFE (SP), GenDerm (GD), Pratix (PR), Techgraft (TG) or control (C-) and histomorphometric analysis determined the percentage of new bone, connective tissue and biomaterial at 1 or 3 months. Statistical analysis used ANOVA with Tukey's post-test for means at same experimental time and the paired Student's t test between the two periods, considering p < 0.05. New bone at 1 month was higher for SP, TG and C-, at 3 months there were no differences, and between 1 and 3 months PR had greater increase growthing. Connective tissue at 1 month was higher for C-, at 3 months for PR, TG and C-, and between 1 and 3 months C- had sharp decline. Biomaterial at 1 month was higher for LC, in 3 months for SP and TG, and between 1 and 3 months, LC, GD and TG had more decreasing mean. SP had greater osteopromotive capacity and limitation of connective ingrowth, but did not exhibit degradation. PR and TG had favorable osteopromotion, LC less connective tissue and GD more accelerated biodegradation.

Self-loading microfluidic platform with ultra-thin nanoporous membrane for organ-on-chip by wafer-level processing

Embedded porous membranes are a key element of various organ-on-chip systems. The widely used commercial polymer membranes impose limits with regard to chip integration and thinness. We report a microfluidic chip platform with the key element of a monolithically integrated, ultra-thin (700 nm) nanoporous membrane made of ultra-low-stress (&lt;35 MPa) SixNy for culturing and testing reconstructed tissue. The membrane is designed to support various in vitro tissues including co-cultures and to allow passage of molecules but not of cells. A digital laser write method was used to produce nanopores with deterministic but highly flexible positioning within the membrane. A thin layer of photoresist was exposed by accumulation of femtosecond pulses for local two-photon polymerization, which allowed nanopores as small as 350 nm in diameter to be generated through the membranes in a subsequent plasma etch process. The fabricated membranes were used to separate a microfluidic chip into two compartments, which are connected to the outside by microchannel structures. With unique side inlets for fluids, all cells are exposed to identical flow velocities and shear stresses. With the hydrophilic nature of chip materials the self-loading seeding is controlled bottom-up by capillary forces, which makes the seeding procedure homogeneous and less dependent on the operator. The chip is designed to allow fabrication by wafer-level MEMS manufacturing technologies without critical assembly steps, thereby promoting reproducibility and scale-up of fabrication. In order to establish a fully functional test system to be used in a lab incubator, a holder for the bare chip was designed and 3D-printed with additional elements for gravity driven pumping. In order to mimic physiological conditions, the holder was designed to provide not only media delivery but also appropriate shear stress to the tissue. To prove usability, murine microvascular endothelial cells (muMEC) were seeded on the membrane within the chip. Cell compatibility was confirmed after 3 days of dynamic cultivation using fluorescence live/dead assays. Cultivation proved to be reproducible and led to confluent layers with cells preferentially grown on nanoporous areas. The system can in future be cost effectively manufactured in larger quantities in MEMS foundries and can be used for a wide variety of in vitro tissues and test scenarios including pumpless operation within cell incubator cabinets.

Network‐Nanostructured ZIF‐8 to Enable Percolation for Enhanced Gas Transport

AbstractMembrane‐based separations offer energy‐efficient solutions for various applications, but commercial polymer membranes show limited performance and stability. Mixed‐matrix membranes (MMMs), incorporating nanoporous inorganic materials in polymer matrices, have been of great interest to circumvent these polymer‐specific issues. However, reaching the percolation threshold is crucial to leverage high‐performing inorganic phases fully, yet the traditional sphere‐like nanofillers require high loadings that easily result in agglomerations and non‐selective defects. Here, a branch‐shaped zeolitic imidazole framework‐8 (ZIF‐8) nanoparticle is synthesized where its unique morphology automatically interconnects, readily forming percolated networks within the polymer matrix at loadings as low as 20 wt.%. Because of the high surface‐area‐to‐volume ratios of branched ZIF‐8 (BZ), strong polymer–particle interactions suppress polymer chain dynamics and the rotation of the ZIF‐8 ligand. This interphase confinement results in enhanced membrane stability and a smaller diffusion cut‐off than traditional ZIF‐8. With pre‐connected diffusion pathways and confined ZIF pores, BZ MMMs significantly outperformed MMMs with sphere‐like ZIF‐8 for H2‐based separations. Overall, the findings provide a novel approach to enhance filler effects in MMMs even at low loadings without any alignment, which can enable the development of advanced membranes in fields where percolation is desired, including separations, sensors, conductors, and batteries.

Supercritical CO2 permeation through dense commercial polymeric membranes: Permeability measurements and influence of pressure.

In the food industry, supercritical CO2 (sc-CO2) is widely used as an extraction solvent, particularly for the extraction of lipids from seeds. After the extraction, the decompression is usually used to recover the products. Afterwards, the recompression for CO2 recycling is highly energy consuming and this handicaps industrial development when medium to low added-value post-extraction products are considered. Recovery of solutes using membrane technology is an interesting alternative for the regeneration of CO2 loaded with oil. The suitable membrane must have a high permeability towards CO2 as reasonable filtration area is needed. In this work, we have studied the CO2 membrane permeability of two different dense polymeric membranes, AG aromatic polyamide reverse osmosis membrane and PuraMem™ silicone nanofiltration membrane. It was considered that the pure sc-CO2 permeation is governed by the solution-diffusion model, which explain the observed permeability changes as a function of CO2 viscosity and fugacity (i.e. pressure) and the polymer properties as chemical composition and structure.Indeed, it was observed that the permeability increased with pressure to reach a maximum value at a permeate pressure of 180 bar (17.3 ± 0.9 kg/(h.m2.bar)), and then decreased in the case of a crosslinked polymer (AG membrane). While, for a slightly crosslinked polymer (PuraMem™ membrane), the permeability was found much higher and it is about 751.6 ± 26.4 kg/(h.m2.bar) at a permeate pressure of 160 bar.

Basement membrane properties and their recapitulation in organ-on-chip applications.

Drug discovery and toxicology is a complex process that involves considerable basic research and preclinical evaluation. These depend highly on animal testing which often fails to predict human trial outcomes due to species differences. Coupled with ethical concerns around animal testing, this leads to a high demand for improved in vitro cell culture platforms. Current research efforts, in this regard, however, are facing a challenge to provide physiologically relevant in vitro human organ models for a reliable assessment of the physiological responses of the body to drug compounds and toxins. The latest development in in vitro cell culture models, organ-on-chips (OOCs), seek to introduce more realistic models of organ function. Current OOCs often use commercial porous polymeric membranes as a barrier membrane for cell culture which is challenging due to the poor replication of the physiological architectures. Better recapitulation of the native basement membrane (BM) characteristics is desirable for modelling physical (e.g. intestine, skin and lung) and metabolic (e.g. liver) barrier models. In this review, the relevance of the physical and mechanical properties of the membrane to cell and system behaviour is elucidated. Key parameters for replicating the BM are also described. This review provides information for future development of barrier organ models focusing on BM-mimicking substrates as a core structure.

Zeolite membrane process for industrial CO2/CH4 separation

Zeolite membrane processes were designed for biogas upgrading for feed pressures ranging from 5 to 20 bar and compared with corresponding polymeric membrane processes. The mass transfer through zeolite membranes was estimated by a model accounting for adsorption and diffusion through the surface barriers and the interior of the pores, while the mass transfer through polymeric membranes was estimated using reported permeances for commercial polymeric membranes. The zeolite membranes displayed approximately three orders of magnitude higher permeance and up to 7 times higher selectivity. To reach a low methane loss, two and three membrane stages were needed for zeolite and polymeric membranes, respectively, because of the differences in selectivity. Due to the higher selectivity, the electricity need for the zeolite membrane process was only 50–60% of that for the corresponding polymeric membrane process. As a result of the much higher permeability, the zeolite membrane processes were much more compact than the equivalent polymeric membrane processes. The estimated cost for zeolite membranes prepared in small scale including modules was much lower than the cost for industrially produced polymeric membranes including modules.

TiO2 Containing Hybrid Composite Polymer Membranes for Vanadium Redox Flow Batteries.

In recent years, vanadium redox flow batteries (VRFB) have captured immense attraction in electrochemical energy storage systems due to their long cycle life, flexibility, high-energy efficiency, time, and reliability. In VRFB, polymer membranes play a significant role in transporting protons for current transmission and act as barriers between positive and negative electrodes/electrolytes. Commercial polymer membranes (such as Nafion) are the widely used IEM in VRFBs due to their outstanding chemical stability and proton conductivity. However, the membrane cost and increased vanadium ions permeability limit its commercial application. Therefore, various modified perfluorinated and non-perfluorinated membranes have been developed. This comprehensive review primarily focuses on recent developments of hybrid polymer composite membranes with inorganic TiO2 nanofillers for VRFB applications. Hence, various fabrications are performed in the membrane with TiO2 to alter their physicochemical properties for attaining perfect IEM. Additionally, embedding the -SO3H groups by sulfonation on the nanofiller surface enhances membrane proton conductivity and mechanical strength. Incorporating TiO2 and modified TiO2 (sTiO2, and organic silica modified TiO2) into Nafion and other non-perfluorinated membranes (sPEEK and sPI) has effectively influenced the polymer membrane properties for better VRFB performances. This review provides an overall spotlight on the impact of TiO2-based nanofillers in polymer matrix for VRFB applications.

Fluorine-free synthesis of all-silica STT zeolite membranes for H2/CH4 separation

Hydrogen (H2) is the most promising alternative to fossil energy for zero-emission of CO2. However, the by-produced H2 from coking process was generally burned as fuel. It is highly desired to recycle the H2 from coke oven gas as the clean energy resource. Herein all-silica STT zeolite membranes were prepared from the fluorine-free precursor for H2/CH4 separation. The crystallization period was shortened by 75% at the elevated temperature. After hydrothermal synthesis of 2 days, the membrane showed H2 permeance up to 2.8 × 10−8 mol·m−2·s−1·Pa−1 and H2/CH4 selectivity up to 49.6 at 0.2 MPa and 298 K. More importantly, STT zeolite membrane was resistant to CO and H2S, which should be prevented from feeding to the commercial polymeric and Pd membranes. The membrane was stable up to 336 h in the simulated coke oven gas of 63 H2: 28 CH4: 7 CO: 2 C2H6 containing 100 ppm H2S. This would pave the way of zeolite membranes to H2 separation in practical applications.