High performance ZIF-8/PBI nano-composite membranes for high temperature hydrogen separation consisting of carbon monoxide and water vapor

Two types of advanced nano-composite materials have been formed by incorporating as-synthesized wet-state zeolitic imidazolate frameworks-8 (ZIF-8) nano-particles into a polybenzimidazole (PBI) polymer. The loadings of ZIF-8 particles in the two membranes (i.e., 30/70 (w/w) ZIF-8/PBI and 60/40 (w/w) ZIF-8/PBI) are 38.2 vol % and 63.6 vol %, respectively. Due to different ZIF-8 loadings, variations in particle dispersion, membrane morphology and gas separation properties are observed. Gas permeation results suggest that intercalation occurs when the ZIF-8 loading reaches 63.6 vol %. The incorporation of ZIF-8 particles significantly enhances both solubility and diffusion coefficients but the enhancement in diffusion coefficient is much greater. Mixed gas tests for H₂/CO₂ separation were conducted from 35 to 230 °C, and both membranes exhibit remarkably high H₂ permeability and H₂/CO₂ selectivity. The 30/70 (w/w) ZIF-8/PBI membrane has an H₂/CO₂ selectivity of 26.3 with an H₂ permeability of 470.5 Barrer, while the 60/40 (w/w) ZIF-8/PBI membrane has an H₂/CO₂ selectivity of 12.3 with an H₂ permeability of 2014.8 Barrer. Mixed gas data show that the presence of CO or water vapor impurity in the feed gas stream does not significantly influence the membrane performance at 230 °C. Thus, the newly developed H₂-selective membranes may have bright prospects for hydrogen purification and CO₂ capture in realistic industrial applications such as syngas processing, integrated gasification combined cycle (IGCC) power plant and hydrogen recovery.     

In situ fabrication of cross-linked PEO/silica reverse-selective membranes for hydrogen purification

Targeting at hydrogen purification, cross-linked organic–inorganic reverse-selective membranes containing poly(ethylene oxide) (PEO) are fabricated in situ by using functional oligomers (O,O′-bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol: Jeffamine^® ED-2003) with a high content of PEO and epoxy-functional silanes (3-glycidyloxypropyltrimethoxysilane: GOTMS). Changes in physicochemical properties due to varying silica content have been characterized; including a great decline in melting temperature; an improvement in glassy and degradation temperature, and the suppression of PEO crystallinity. The strong affinity between quadrupolar CO₂ and polar ethylene oxide (EO) groups enhances the CO₂/H₂ separation performance of hybrid membranes, which can be further tuned by controlling the organic/inorganic ratio. The organic–inorganic hybrid membrane with 90 wt% of ED-2003 demonstrates an appealing CO₂ permeability of 367 Barrer with an attractive CO₂/H₂ selectivity of 8.95 at 3.5 atm and 35 °C. The transport performance trend with composition variations is explained by analyzing the calculated solubility and diffusivity based on the solution-diffusion mechanism. Moreover, CO₂ permeability increases with applied pressure in pure gas tests because of CO₂ plasticization phenomena, which is beneficial for CO₂/H₂ separation. Attributing to CO₂ plasticization and CO₂ dominant sorption, the mixed gas test results of the membrane containing only 25 wt% ED-2003 show greatly improved CO₂/H₂ selectivity of 13.2 with CO₂ permeability of 148 Barrer at 35 °C compared to pure gas results. Interestingly, at a stipulated CO₂ pressure, the inherent tension in cross-linked networks maintains the CO₂ permeability stable with the time. The cross-linked organic–inorganic membranes with enhancements in mechanical and thermal properties are promising for industrial-scale hydrogen purification.     

High performance composite hollow fiber membranes for CO2/H2 and CO2/N2 separation

The search for a clean energy source as well as the reduction of CO₂ emissions to the atmosphere are important strategies to resolve the current energy shortage and global warming issues. We have demonstrated, for the first time, a Pebax/poly(dimethylsiloxane)/polyacrylonitrile (Pebax/PDMS/PAN) composite hollow fiber membrane not only can be used for flue gas treatment but also for hydrogen purification. The composite membranes display attractive gas separation performance with a CO₂ permeance of 481.5 GPU, CO₂/H₂ and CO₂/N₂ selectivity of 8.1 and 42.0, respectively. Minimizing the solution intrusion using the PDMS gutter layer is the key to achieving the high gas permeance while the interaction between poly(ethylene oxide) (PEO) and CO₂ accounts for the high selectivity. Effects of coating solution concentration and coating time on gas separation performance have been investigated and the results have been optimized. To the best of our knowledge, this is the first polymeric composite hollow fiber membrane for hydrogen purification. The attractive gas separation performance of the newly developed membranes may indicate good potential for industrial applications.     

Developing cross-linked poly(ethylene oxide) membrane by the novel reaction system for H2 purification

In this study, a ‘green” method has been discovered by utilizing the amino functional poly(ethylene oxide) (PEO) and epoxy functional PEO with low molecular weights to synthesis cross-linked membranes for enhancing H₂ purification and CO₂ capture performance by retarding the crystallinity of semi-crystalline polymer of PEO. The cross-linking reaction can happen simply by mixing two materials without using any solvent. The reaction has been characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), solid-state ¹³C nuclear magnetic resonance (NMR) and the gel content test. Furthermore, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) confirm the amorphous structure of cross-linked PEO membranes, which should benefit the gas transport. The gas transport properties and the plasticizing phenomenon of CO₂ have been examined in detail. Interestingly, the investigation on CO₂ plasticization phenomenon reveals that the cross-linked PEO membrane should be plasticized immediately after the pressure load. The pressure dependence of CO₂ permeability in the pressure range from 0.25 atm to 30 atm can be separated into two stages based on the permeability increment although the CO₂ permeability continuously increases with the loading pressure. The gas transport results illustrate that CO₂ has much larger permeability than that of any tested gas (including H₂, N₂ and CH₄) attributing to the CO₂-philic characteristic of ethylene oxide (EO) groups in the cross-linked PEO membrane. The good permeability and selectivity make the developed PEO membrane promising for H₂ purification and CO₂ capture applications.     

Molecular-level mixed matrix membranes comprising Pebax and POSS for hydrogen purification via preferential CO2 removal

The molecular-level mixed matrix membranes (MMMs) comprising Pebax^® and POSS have been developed by tuning the membrane preparation process in this work. They exhibit a simultaneous enhancement in CO₂ permeability and CO₂/H₂ selectivity by optimizing the POSS content at extremely low loadings. This is mainly attributed to the large cavity of POSS itself and its effect on the segmental-level polymeric chain packing. More interestingly, the Pebax^®/POSS MMMs reveal a much higher separation performance in the mixed gas test than that in the pure gas test. The highest CO₂/H₂ selectivity reaches 52.3 accompanied by CO₂ permeability of 136 Barrer at 8 atm and 35 °C. This is due to the CO₂-induced plasticization that improves the free volume and polymer chain mobility, hence benefiting the interaction between the polymer matrix and penetrant CO₂. These features may ensure the superiority of Pebax^®/POSS molecular-level MMMs as CO₂-selective membranes in the industrial application of hydrogen purification.     

Hydrogen separation and purification with poly (4-methyl-1-pentyne)/MIL 53 mixed matrix membrane based on reverse selectivity

The effect of MIL 53 (Al) metal organic framework on gas transport properties of poly (4-methyl-1-pentyne) (PMP) was determined based on reverse selectivity. Mixed matrix membranes (MMMs) were fabricated considering various weight percent of MIL 53 particles. The reverse MMMs permselectivities were evaluated through measurement of pure CO₂ and H₂ permeation together with calculation of CO₂/H₂ selectivity. The PMP/MIL 53 (Al) MMMs exhibited privileged CO₂/H₂ permselectivity in comparison with the neat PMP. In addition, CO₂ solubility coefficient was significantly increased with increasing the MIL 53 loading, while the H₂ solubility coefficient was almost remained unchanged. Moreover with increasing the feed pressure the permeability of CO₂ and CO₂/H₂ selectivity were dramatically enhanced, especially at higher filler loadings. Therefore, it was observed that the reverse selectivity of MMMs was enhanced so that the Robeson upper bound was overcome. The best yielding membranes (PMP/30 wt.% MIL 53) represented the CO₂ permeability and CO₂/H₂ selectivity of 377.24 barrer and 24.91 for pure gas experiments respectively.     

Enhancing hydrogen gas separation performance of thin film composite membrane through facilely blended polyvinyl alcohol and PEBAX

Polymeric membranes offer economic separation processes but are less explored for H₂ separation application. This work aims to unveil the H₂ separation potential of polymeric membrane by developing PVA-based reverse selective composite membrane. CO₂-selective PEBAX was blended at different PVA:PEBAX ratio. The effect of PEBAX blending on membrane morphology, crystallinity and gas separation behavior was studied. Incorporation of PEBAX at <50 wt% resulted in composite with improved CO₂ permeability but selectivity loss. Blending of >60 wt% PEBAX enhanced both permeance and selectivity of the resulted composite as the host matrix was dominated by this PEO containing material thus greatly enhancing polymer chain mobility and promoting CO₂-solubility. The best composite which contains 60 wt% PEBAX exhibited CO₂ permeability of 20.0 Barrer and CO₂/H₂ selectivity of 7.6. This performance surpasses the Robeson's boundary and unleashes the potential of tailoring the properties of polymeric nanocomposite membrane for H₂ separation application through facile PVA/PEBAX blending.     

Enhanced hydrogen purification by graphene - Poly(Dimethyl siloxane) membrane

In this study, a nanocomposite graphene oxide (GO) incorporated poly (dimethyl siloxane) (PDMS) membrane was produced and used for the purification of hydrogen (H₂₎ by separating the (CO₂). The produced membrane was characterized and the single-gas permeability test was performed. Effects of GO addition, trans-membrane pressure and membrane thickness on the gas separation performance of membrane were evaluated as a function of permeability and CO₂/H₂ selectivity. GO addition increased the CO₂/H₂ selectivity and H₂ purification performance. The highest CO2 permeability of 3670 Barrer and CO₂/H₂ selectivity of 11.7 were obtained when the GO loading was 0.5 wt% when the trans-membrane pressure was 0.2 Mpa.     

Palladium nanoparticle binding in functionalized track etched PET membrane for hydrogen gas separation

In this work, track-etched poly (ethylene terephthalate) (PET) membranes having different pore sizes were functionalized by the carboxylic groups and the amino groups. Palladium (Pd) nanoparticles of average diameter 5 nm were synthesized chemically and deposited onto pore walls as well as on the surface of these pristine and functionalized membranes. Effect of Pd nanoparticles binding on these membranes were explored and aminated membrane were found to bind more Pd nanoparticles due to its affinity. The morphology of these composite membranes is characterized by Scanning Electron Microscope (SEM) for confirmation of Pd nanoparticle deposition on pore wall as well as on the surface. Gas permeability of functionalized and non-functionalized membranes for hydrogen and carbon dioxide has been examined. From the gas permeability data of hydrogen (H₂) and carbon dioxide (CO₂) gases, it was observed that these membranes have higher permeability for H₂ as compared with CO₂. Due to absorption of hydrogen by Pd nanoparticles selectivity of H₂ over CO₂ was found higher as compared to without Pd embedded membranes. Such type of membranes can be used to develop hydrogen selective nanofilters for purification/separation technology.     

PVDF/ionic liquid polymer blends with superior separation performance for removing CO2 from hydrogen and flue gas

We have demonstrated, for the first time, a polymer blend comprising poly(vinylidene fluoride) (PVDF) and a room-temperature ionic liquid (RTIL) that shows a high CO₂ permeability of 1778 Barrer with CO₂/H₂ and CO₂/N₂ selectivity of 12.9 and 41.1, respectively. The low viscosity RTIL, 1-ethyl-3-methylimidazolium tetracyanoborate ([emim][B(CN)₄]) possesses a high CO₂ solubility, and plays a significant role in CO₂ separation, whereas PVDF provides the mechanical strength to the blend membranes. A series of PVDF/[emim][B(CN)₄] polymer blends with different compositions were tested for their gas separation performance involving H₂, N₂ and CO₂ in both pure gas and mixed gas conditions. Both optical observation and Maxwell predictions confirm the heterogeneous nature of the PVDF/[emim][B(CN)₄] system. However, compared to miscible ionic liquid based blends, where molecular level interactions may restrain chain flexibility and reduce gas permeability, heterogeneous PVDF/RTIL blend systems show far superior gas transport properties. Most of these blend membranes outperform most reported materials and their gas transport and separation capabilities fall within the attractive region bound by the “2008 Robeson Upper Limit” for CO₂/H₂ and CO₂/N₂ gas pairs, and are also very stable at trans-membrane pressure up to 5 atm. Therefore, they are potential materials for H₂ purification and CO₂ capture from hydrogen production and flue gas.     

Thermally rearranged (TR) HAB-6FDA nanocomposite membranes for hydrogen separation

Thermally rearranged (TR) polymers exhibited a good balance of high permeability and high selectivity. For this purpose HAB-6FDA polyimide was synthesized from 3,3 dihydroxy-4,4-diamino-biphenyl (HAB) and 2,2-bis-(3,4-dicarboxyphenyl) hexafluoro propane dianhydride (6FDA) by chemical imidization. Initially, the sample was modified from pure polymer to silica nanofiller doped polymer membrane. Further the modification was done by thermal rearrangement reaction at 350 °C temperature. This modification causes a mass loss in polymer structure and therefore enhances the fractional free volume (FFV). The gases used for the permeation test were H₂, CO₂, N₂ and CH₄. Selectivity was calculated for H₂/CO₂, H₂/N₂ and H₂/CH₄ gas pairs and plotted in the Robeson's 2008 upper bound and compared with reported data. The transport properties of these gases have been compared with the unmodified membrane. Permeability of all the gases has increased to that of unmodified polymer membrane. Thermally rearranged polymer nanocomposite exhibits higher gas permeability than that of silica doped and pure polymer. Also the selectivity for H₂/CO₂ and H₂/N₂ gas pairs exceeds towards Robeson's upper bound limit. It crosses this limit dramatically for H₂/CH₄ gas pair. Polymer nanocomposite can be utilized to obtain high purity hydrogen gas for refinery and petrochemical applications.     

Fabrication and characterization of poly(phenylene oxide)/SBA-15/carbon molecule sieve multilayer mixed matrix membrane for gas separation

A novel multilayer mixed matrix membrane (MMM), consisting of poly(phenylene oxide) (PPO), large-pore mesoporous silica molecular sieve zeolite SBA-15, and a carbon molecular sieve (CMS)/Al₂O₃ substrate, was successfully fabricated using the procedure outlined in this paper. The membranes were cast by spin coating and exposed to different gases for the purpose of determining and comparing the permeability and selectivity of PPO/SBA-15 membranes to H₂, CO₂, N₂, and CH₄. PPO/SBA-15/CMS/Al₂O₃ MMMs with different loading weights of zeolite SBA-15 were also studied. This new class of PPO/SBA-15/CMS/Al₂O₃ multilayer MMMs showed higher levels of gas permeability compared to PPO/SBA-15 membranes. The permselectivity of H₂/N₂ and H₂/CH₄ combinations increased remarkably, with values at 38.9 and 50.9, respectively, at 10 wt% zeolite loading. Field emission scanning electron microscopy results showed that the interface between the polymer and the zeolite in MMMs was better at a 10 wt% loading than other loading levels. The increments of the glass transition temperature of MMMs with zeolite confirm that zeolite causes polymer chains to become rigid.     

Theoretical investigations of permeability and selectivity of Pd–Cu and Pd–Ni membranes for hydrogen separation

Hydrogen is one of the most prospective energy resources with zero polluted emission and high energy utilization, an improved separation and purification performance of hydrogen is critical for application of hydrogen energy. In this work, hydrogen separating performance of Pd–Cu and Pd–Ni alloy membranes are theoretically explored through density functional theory and molecular dynamics calculations. The results demonstrate that both Pd–Cu and Pd–Ni membranes exhibit excellent selectivity to H₂ over N₂, CO, CO₂, CH₄, H₂S at varied temperatures, and are superior to industrial production limit based on predicting permeance of H₂. The outstanding selectivity of Pd–Cu alloy toward H₂ is in accordance with experimental conclusion. Moreover, the DFT calculations are further supported by molecular dynamics simulations, which visually demonstrate the H₂ separation performance of the Pd-based alloys in a dynamic way. This work provides an effective and efficient approach to evaluate the permeability and selectivity of metal alloys membranes for gas separation.     

Hydrogen separation and purification using crosslinkable PDMS/zeolite A nanoparticles mixed matrix membranes

The transport properties of gases in polydimethylsiloxane (PDMS)/zeolite A mixed matrix membranes (MMMs) were determined based on pure gas permeation experiments. MMMs were prepared by incorporating zeolite 4A nanoparticles into a PDMS matrix using a new procedure. The permeation rates of C₃H₈, CH₄, CO₂, and H₂ were evaluated through a dense homogeneous pure PDMS membrane and PDMS/4A MMMs to assess the viability of these membranes for natural gas sweetening and hydrogen purification. SEM investigations showed good adhesion of the polymer to the zeolite in MMMs. Permeation performance of the membranes was also investigated using a laboratory-scale gas separation apparatus and effects of feed pressure, zeolite loading and pore size of zeolite on the gas separation performance of the MMMs were evaluated. The MMMs exhibited both higher selectivity of H₂/CH₄ and H₂ permeability as compared with the neat PDMS membrane, suggesting that these membranes are very promising for gas separations such as H₂/CH₄ separation.     

Polyurethane-based membranes for CO2 separation: A comprehensive review

The membrane process has been considered a promising technology for effective CO₂ capture due to its outstanding features, including a small environmental footprint, reduced energy consumption, simplicity of operation, compact design, ease of scalability and maintenance, and low capital cost. Among the developed polymeric materials for membrane fabrication, polyurethane (PU) and poly(urethane-urea) (PUU) as multi-block copolymers have exhibited great potential for CO₂ capture because of their excellent mechanical properties, high thermal stability, good film formation ability, favorable permeation properties, and a large diversity of monomers (i.e., polyol, diisocyanate, and chain extender) for the synthesis of desired polymers with prescribed properties. However, PU- and PUU-based membranes' gas selectivity is relatively low and thus not attractive for practical gas separation (GS) applications. Therefore, the present review scrutinizes the main influential factors on the gas transport properties and GS performance of these membranes. In this regard, we summarize the recent progress in the PU-based membranes in view of (I) design and synthesis of new PUs, (II) blending with other polymeric matrices, (III) cross-linking PU membranes, and (IV) fabricating PU-based mixed-matrix membranes (MMMs) with deep insight into an increase in CO₂ permeability, as well as CO₂/other gases selectivity. Finally, the challenges and future direction of PU-based membranes will be presented.     

Experimental investigation of natural polysaccharide-based mixed matrix membrane modified with graphene oxide and Pd-nanoparticles for enhanced gas separation performance

In this work, we proposed a mixed matrix membrane prepared by using a glycerol modified guar gum (GGP) polymer matrix incorporated with graphene oxide (GO). The influence of varying GO concentration on the gas separation performance was investigated and 2 wt% was found to be the optimum concentration for high performance. The 2 wt% GO mixed matrix membranes were further modified with Pd nanoparticles. When GO, and Pd nanoparticles were mixed, CO₂ permeability increased by 49.94%, while the permeability of H₂ gas molecules decreased by 98.11%, respectively, compared to the pristine GGP membrane. The selectivity of CO₂/H₂ was obtained as 18.27. The glass transition temperature of the membrane increased from 85 to 95.2 °C, tensile strength and elongation of the break were significantly improved by 29.09% and 84.37% through the addition of Pd and GO into the membrane. The scanning electron microscopy revealed a dense top surface after GO nanosheets incorporation. Further, the thermogravimetric analysis proposes that the modified membrane is thermally stable than GGP. Henceforth, the study suggests GO incorporation and Pd nanoparticles modification of guar gum membrane is a promising gas separation membrane with potentially high selectivity for CO₂ gas.     

H2 permeation and its influence on gases through a SAPO-34 zeolite membrane

This work analysed the permeation of binary and ternary H₂-containing mixtures through a SAPO-34 membrane, aiming at investigating how hydrogen influences and its permeation is influenced by the presence of the other gaseous species, such as CO₂ and CH₄. We considered the behaviour of various gas mixtures in terms of permeability and selectivity at various temperatures (25–300 °C), feed pressures (400–1000 kPa) and compositions by means of an already validated mass transport model, which is based on surface and gas translation diffusion. We found that the presence of CO₂ and CH₄ in the H₂-containing mixtures influences in a similar way the H₂ permeation, reducing its permeability of about 80% compared to the single-gas value because of their stronger adsorption. On the other hand, H₂ promotes the permeation of CO₂ and CH₄, causing an increment of their permeability with respect to those as single gases. These combined effects reflected in interesting selectivity values in binary mixture (e.g., CO₂/H₂ about 11 at 25 °C, H₂/CH₄ about 9 at 180 °C), which showed the potential of SAPO-34 membranes in treating of H₂-containing mixtures.     

Active block copolymer layer on carboxyl-functionalized PET film for hydrogen separation

To rationalize the energy requirements and environmental complications of the world, supply of pure hydrogen is the most promising as well best possible approach of such issues. Purified hydrogen gas is the necessity factor for the hydrogen-based economy. Hydrogen perm-selective membrane plays a crucial role for producing a large amount of hydrogen. Palladium is one of the best materials because of its excellent affinity to absorb hydrogen. In present work, our aim to improve selectivity as well permeability of the H₂ gas compare to N₂ and CO₂ gases of the block copolymer coated functionalized porous PET membrane. Porous polyethylene terephthalate (PET) membranes having pore size 0.2 μm, functionalized with a carboxyl group. The supramolecular assembly was prepared from PS (35500)-b- P4VP (4400) and 2-(4- Hydroxyphenylazo) benzoic acid (HABA) in 1, 4-dioxane. Chemically synthesized palladium nanoparticles were deposited on carboxylated block copolymer (BC) coated porous PET membrane. It is an appropriate way to use H₂ sensitive materials with block copolymer coated functionalized membranes to enhance the selectivity of H₂. It has been found that such membranes gain better permeability and selectivity towards H₂ as compared with N₂ and CO₂. Increment with the dipping time of these membranes in the palladium nanoparticle solution, permeability as well selectivity of H₂ over N₂, CO₂ increases as the more attachment of Palladium nanoparticles. A fine active layer of block copolymer on the carboxyl functionalized PET membrane play a crucial role for hydrogen based gas separation. The magnitude of the permeability of such membranes for different gases shows dependency on the pore size of the upper layer (BC coated) of the membrane in addition to the molecule size of the permeating gas. Block copolymer coating of the membranes established an effective responsibility for the selectivity of H₂ over CO₂ gas as well over N₂ gas.     

Surface segregation of Pd–Cu alloy in various gas atmospheres

Pd–Cu alloys have been investigated as promising candidates for hydrogen separation membranes. Surface segregation influences the long-term performance of these membranes since their catalytic effect is mainly controlled by the surface composition. In the present research, surface segregation of Pd-40 at.% Cu alloy in vacuum and various gas atmospheres (H₂, CO and CO₂) was investigated with both XPS and LEISS probing different depths below the surface. Adsorption of H₂ and CO on the surface has a significant impact and the surface segregation trend can be reversed as compared to segregation in vacuum, however, CO₂ has almost no influence on the segregation behaviour. A thermodynamic model is also presented to explain these phenomena and to understand surface segregation behaviour of binary alloys in various gas atmospheres. The results can be considered as basic guidelines to design novel alloys for hydrogen separation membranes and predict their long-term performance under actual working conditions.     

Permeation characteristics of hydrogen through palladium membranes in binary and ternary gas mixtures

The permeances of two palladium (Pd) membranes in pure H₂, binary and ternary gas mixtures are investigated experimentally. With 10% of gas impurities (N₂, CO₂, or CO) in H₂, the profiles of dimensionless permeance suggest that H₂ permeation rate is lessened by approximately 50% to 90%, and the permeance reduced by the gas impurities is ranked as CO > CO₂ > N₂. By introducing a parameter of permeance resistance, which is the reciprocal of permeance, the permeance resistance in a ternary gas mixture can be predicted from the summation of individual permeance resistances in binary gas mixtures, revealing no synergistic effect exhibited from the interaction of contaminants. At least 75% and up to 100% of H₂ in the gas mixtures can be recovered in the membrane system, and the maximum H₂ recovery develops at the H₂ partial pressure difference of 2 or 3 atm. In the Arrhenius‐type equation describing the relationship between the permeance and temperature, the activation energy is between approximately 2 and 18 kJ mole^?1. In general, the permeances of the membranes in gas mixtures, especially in ternary gas mixtures, are more sensitive to temperature when compared with those in pure H₂, stemming from lower activation energy exhibited. Copyright © 2017 John Wiley & Sons, Ltd.