Natural Gas Upgrading Research Articles

Highly Selective Benzimidazole-Based Polyimide/Ionic Polyimide Membranes for Pure- and Mixed-Gas CO2/CH4 Separation

This paper reports two new series of benzimidazole functionalized polyimides and ionic polyimides for highly selective membranes with great potential for natural gas sweetening. It has been demonstrated that both the –NH groups in the benzimidazole moieties and the corresponding ionic groups after N-quaternization tighten the microporous structure and restrict polymer chain mobility through hydrogen bonding and electrostatic interaction. The BET surface areas and d-spacing values decrease with benzimidazole molar content or the degree of ionization. Consequently, a linear correlation between CO2 permeability coefficients with benzimidazole molar content or degree of ionization was observed due to the decrease of CO2 diffusivity, and the monotonic increase of CO2/CH4 selectivities is ascribed to the increase of both diffusivity selectivity and solubility selectivity. The benzimidazole-based copolyimide and the ionic copolyimide membranes exhibited high CO2/CH4 selectivity under high-pressure mixed-gas conditions. In particular, the copolyimide PI-0.75 membrane displayed a mixed-gas CO2 permeability of 27 Barrer and CO2/CH4 selectivity of 47 at 20 bar total pressure. The performance was much higher than those of the state-of-the-art commercial cellulose triacetate membranes for natural gas upgrading. The facile polymer synthesis and microporosity tunability, as well as the excellent mixed-gas separation performance, render the copolyimide membranes in this study promising towards economic membrane-mediated natural gas upgrading.

A Review of the Recent Progress in the Development of Nanocomposites Based on Poly(ether-block-amide) Copolymers as Membranes for CO2 Separation.

An inspiring challenge for membrane scientists is to exceed the current materials’ performance while keeping the intrinsic processability of the polymers. Nanocomposites, as mixed-matrix membranes, represent a practicable response to this strongly felt need, since they combine the superior properties of inorganic fillers with the easy handling of the polymers. In the global strategy of containing the greenhouse effect by pursuing a model of sustainable growth, separations involving CO2 are some of the most pressing topics due to their implications in flue gas emission and natural gas upgrading. For this purpose, Pebax copolymers are being actively studied by virtue of a macromolecular structure that comprises specific groups that are capable of interacting with CO2, facilitating its transport with respect to other gas species. Interestingly, these copolymers show a high versatility in the incorporation of nanofillers, as proved by the large number of papers describing nanocomposite membranes based on Pebax for the separation of CO2. Since the field is advancing fast, this review will focus on the most recent progress (from the last 5 years), in order to provide the most up-to-date overview in this area. The most recent approaches for developing Pebax-based mixed-matrix membranes will be discussed, evidencing the most promising filler materials and analyzing the key-factors and the main aspects that are relevant in terms of achieving the best effectiveness of these multifaceted membranes for the development of innovative devices.

A metal-doped flexible porous carbon cloth for enhanced CO2/CH4 separation

• Smart porous flexible magnetic carbon sieves were developed. • Flexible carbon sieve decorated with carbon nanoparticles rich with N was developed. • Ni nanorodes were decorated on flexible porous carbons inducing magnetic features. • Outstanding CO 2 /CH 4 selectivity of 369.5 was achieved for natural gas upgrading. From a practical perspective, carbon adsorbents are mostly prepared to form functional components from carbon powder by using binders or hot pressing, which results in the degradation of its textural properties. Thus, the flexible activated porous carbon cloths have attracted increasing interest in recent years because these are easier to handle than powder and granular materials when constructing more conformable and efficient membrane device designs. In this work, a metal-doped flexible porous carbon cloth with outstanding CO 2 /CH 4 selectivity was developed. Carbon cloth deposited with spherical porous carbon nanoparticles and doped with nitrogen was prepared from viscose rayon cloth decorated with polypyrrole nanoparticles. Then, this flexible carbon cloth was doped with nickel. Two samples with moderate Ni content (7 and 10 wt%) were used to investigate the fundamental magnetic properties and CO 2 /CH 4 separation performance. These two samples have both antiferromagnetic and ferromagnetic properties, and it is originated from the different ratios of NiO and pure Ni. The Ni(O) contents in the flexible carbon cloth influenced the CO 2 and CH 4 sorption properties and separation performance as well. Based on the ideal adsorbed solution theory (IAST) model, the developed metal-decorated flexible activated carbon cloth shows 13 times better separation performance than Ni-free sample and achieved CO 2 /CH 4 (1:1) selectivity of 369.5 and 70.7 at 20 and 1 bar, respectively, at 298 K, which is among the highest selectivity values reported for porous carbon materials so far.

Room-temperature catalyst-free methane chlorination

The chlorination of methane presents a route for the upgrading of natural gas to value-added products. However, due to the low reactivity of methane, existing chlorination processes require the use of elevated temperatures and catalysts. Here, we report a simple process for the chlorination of methane at near-ambient temperatures using minimal reagents and no catalysts or external sources of energy. The reaction is carried out in an aqueous medium with trichloroisocyanuric acid as a chlorinating agent. The dissolution of trichloroisocyanuric acid in water leads to the sustained and buffered release of hypochlorous acid, which triggers the chlorination of methane by a free-radical mechanism. The process is also general to other alkanes, as shown by a similar chlorination of ethane. Further developments are required for this process to be deployed as a practical method of chloromethane production. • Methane is chlorinated at room temperature with no catalysts or energy sources • Trichloroisocyanuric acid in water serves as a source of chlorinating species • Further development may enable natural gas upgrading and methanol production Large reserves of natural gas either remain untapped or are flared. Chlorination of methane, the primary component of natural gas, would allow its upgrading to higher hydrocarbons, olefins, and polymers. Mohan et al. describe a room-temperature process for the chlorination of methane without catalysts or additional sources of energy.

Formation of a N/O/F-Rich and Rooflike Cluster-Based Highly Stable Cu(I/II)-MOF for Promising Pipeline Natural Gas Upgrading by the Recovery of Individual C3H8 and C2H6 Gases.

Due to the ultralow amounts of C3H8 and C2H6 gases, to design and synthesize water-stable MOFs that are promising for real-world efficient pipeline natural gas (NG) upgrading by the recovery of individual C3H8 and C2H6 gases is still a great challenge. Here, a N/O/F heteroatom-rich and rooflike [Cu(II)4Cu(I)2(COO)4(tetrazolyl)6] cluster-based ultra-microporous tsi-MOF (SNNU-Bai68) was afforded as a multiple heteroatom-rich and curved-surface-shaped cluster-based ultra-microporous MOF and the first porous MOF based upon such rooflike [Cu(II)xCu(I)y(tetrazolyl)z](2x+y-z)+ cluster. In SNNU-Bai68, the rooflike cluster was further assembled into a 1D chain secondary building block (SBB), which led to a high density of accessible potential adsorptive sites. Very interestingly, it exhibited the most promising balance of high gas adsorption uptakes at 0.01, 0.03, and 0.05 bar, high C3H8/CH4, C3H8/C2H6, and C2H6/CH4 adsorption selectivities, moderate adsorption enthalpies, and high water and chemical stability for pipeline natural gas upgrading by the recovery of individual C3H8 and C2H6 gases, which was further confirmed by the breakthrough experiments of the gas mixtures with/without 74% RH. Furthermore, the SC-XRD and GCMC studies revealed that the successful separation of C3H8, C2H6, and CH4 gases in SNNU-Bai68 is due to different synergistic effects of H-bonds between the frameworks at three adsorptive sites around each rooflike cluster and those different gas molecules, which were initially described systematically by the number of H atoms from the gas molecules, the total number of H-bonds within the synergistic H-bonds, and the binding energy of the framework at an adsorption site toward the gas molecules. In addition, this work may provide a method for the construction of a multiple heteroatom-rich and curved-surface-shaped cluster-based ultra-microporous MOF as a novel approach to build MOFs with polar pore surfaces, suitable pore sizes, and unique pore shapes to maximize the synergistic H-bonds between the framework and guests.

In Memoriam Prof. Dr.‐Ing. Jens Weitkamp

AbstractNo abstract.

Economic assessment of a natural gas upgrading process using pressure vacuum swing adsorption for nitrogen removal

Economic assessment of a natural gas upgrading process using pressure vacuum swing adsorption for nitrogen removal

Low viscosity superbase protic ionic liquids for the highly efficient simultaneous removal of H2S and CO2 from CH4

CO2 and H2S are considered impurities in natural gas that moderate the pace of environmental health. Developing highly efficient and cost-effective absorbents is of significance for sweetening natural gas. Herein, four superbase protic ionic liquids (SPILs) were prepared in this study. Typical physical properties (density, viscosity, and decomposition temperature) were also examined at ambient pressure. These SPILs show low viscosity values at ranging from 5.1 cP to 18.3 cP at 313.2 K. The solubility of H2S (0–1.0 bar), CO2 (0–1.0 bar), and CH4 (0–5.0 bar) was systematically measured at temperatures in the range of 298.2 K to 333.2 K. Impressively, the absolute solubility of H2S under 0.1 bar was found to be located at 4.31–5.15 mol/kg at 313.2 K, which is the highest value obtained among the reported results in the literature. The ideal selectivity of H2S/CH4 and CO2/CH4 (H2S or CO2 solubility at 0.1 bar vs CH4 solubility at 1 bar) at 313.2 K are in the ranges of 367–653 and 92.4–240, respectively. The interaction mechanism we explored was characterized by NMR and FT-IR spectroscopy. Thermodynamic parameters, such as enthalpy, Gibbs free energy, and entropy of dissolution were calculated from the temperature dependent solubility using the “deactivated model”. These SPILs are promising alternative candidates for the simultaneous removal of H2S and CO2 in natural gas upgrading.

Process Analysis of Ionic Liquid-Based Blends as H2S Absorbents: Search for Thermodynamic/Kinetic Synergies

Acid gas absorption by ionic liquids (ILs) has arisen as a promising alternative technique for biogas or natural gas upgrading. In the present work, IL-based blends are evaluated for potential thermodynamic/kinetic synergistic effects on hydrogen sulfide (H2S) capture through physical and/or chemical absorption. First, a molecular simulation analysis by means of COSMO-RS was used to select IL-based blends with enhanced H2S absorbent thermodynamic properties. Physical absorption parameters of reference (KHenry) for H2S in several IL-based blends were calculated at 298 K, involving both IL mixtures and conventional industrial absorbents (tetraglyme (TGM)) with ILs at different compositions. A Henry’s constant deviation parameter (ΔHKHenryH2S) was employed to analyze the nonideal effects of the mixture on H2S gas solubility in IL-based blends. In addition, the viscosities and diffusivities of the IL-based blends were estimated as key parameters controlling H2S diffusion and absorbent uptake rates. From this analysis, a sample of IL-based blends with promising thermodynamic and kinetic properties was selected for H2S physical absorption. A process simulation analysis using the COSMO-based/Aspen Plus methodology was then carried out and the selected absorbents were evaluated by modeling H2S capture in an industrial-scale commercial packed column. One IL, 1-butyl-3-methylimidazoium acetate ([Bmim][OAc]), presenting high H2S chemical absorption and a low viscous industrial solvent (TGM) were also included. The strong kinetic control of H2S capture by physical absorption indicated the limited potential performance of IL-based blends or neat ILs in industrial equipment. In contrast, the COSMO/Aspen analysis revealed that adequate formulations based on [Bmim][OAc] and TGM present enhanced H2S absorbent properties compared to the neat compounds. These computational results may be used to guide future experimental research to design new H2S absorbents, reducing the highly demanding experimental input.

Elucidating the origin of selective dehydrogenation of propane on γ-alumina under H2S treatment and co-feed

A bulk γ-Al2O3 catalyst shows high selectivity for propane dehydrogenation upon pretreatment and co-feeding with H2S. The reaction kinetics, deactivation rates, and active sites for propane dehydrogenation on this catalyst were characterized using fixed bed conversion studies, NH3-TPD, O2-TPO, XPS, and density functional theory (DFT). Specifically, we observe that the selectivity to propylene was 94% at ca. 16% propane conversion at 560 °C for a C3H8:H2:H2S ratio of 1.1:1:0.1 on γ-Al2O3. Our results indicate that H2S can irreversibly modify the active sites of γ-Al2O3, postulated to be defect sites on the 110 facet comprised of a tri-coordinated Al atom, such that the modified site was more active and selective towards propylene and less inhibited by co-fed H2S. Along with XPS and O2-TPO, the dehydrogenation-regeneration experiments suggest the formation of sulfurous coke and strong adsorption of reaction products result in a less active catalyst. This study shows the potential of alumina/metal-sulfide as an earth-abundant and relatively benign class of catalysts for alkane activation, especially in the context of sour natural gas upgrading.

Computer simulations for the adsorption and separation of CH4/H2/CO2/N2 gases by hybrid ultramicroporous materials

The adsorption isotherms of two types of hybrid ultra-microporous materials SIFSIX-3-M (M = Fe, Cu, Zn) and M′FSIX-2-Cu-i (M′ = Si, Ti, Ge) for H2, CH4, CO2 and N2 are comparatively studied by grand canonical Monte Carlo simulation (GCMC), and their differences are explained from pore structure and isosteric heat of adsorption. Natural gas and biogas upgrading (CO2/CH4), synthesis gas separation (CO2/H2), flue gas separation (CO2/N2), and steam methane reforming hydrogen production (CH4/H2) are simulated equimolar binary mixture system. The related separation factors are elucidated from the adsorption selectivity and the difference of isosteric heat of adsorption. The microscopic adsorption mechanism of the material is further analyzed by the preferential adsorption sites of the gas on the framework. Our works provide new insights into the adsorption and separation mechanism of HUMs for the energy-related gas, as well as in industrial application.

Understanding CO2/CH4 Separation in Pristine and Defective 2D MOF CuBDC Nanosheets via Nonequilibrium Molecular Dynamics.

The separation of CO2/CH4 gas mixtures is a key challenge for the energy sector and is essential for the efficient upgrading of natural gas and biogas. A new emerging field, that of metal–organic framework nanosheets (MONs), has shown the potential to outperform conventional separation methods and bulk metal–organic frameworks (MOFs). In this work, we model the CO2/CH4 separation in both defect-free and defective 2D CuBDC nanosheets and compare their performance with the bulk CuBDC MOF and experimental data. We report the results of external force nonequilibrium molecular dynamics (EF-NEMD) for pure components and binary mixtures. The EF-NEMD simulations reveal a pore blocking separation mechanism, in which the CO2 molecules occupy adsorption sites and significantly restrict the diffusion of CH4. The MON structure achieves a better selectivity of CO2 over CH4 compared to the bulk CuBDC MOF which is due to the mass transfer resistance of the methane molecules on the surface of the nanosheet. Our results show that it is essential to consider the real mixture in these systems rather than relying solely on pure component data and ideal selectivity. Furthermore, the separation is shown to be sensitive to the presence of missing linker defects in the nanosheets. Only 10% of missing linkers result in nonselective nanosheets. Hence, the importance of a defect-free synthetic method for CuBDC nanosheets is underlined.

An integrated methane dehydroaromatization and chemical looping process

Most of the natural gas co-produced in oil wells is flared due to the high transportation costs of bringing it to market. Onsite upgrading of natural gas to liquid products could address this issue but there are few processes for effective direct conversion of natural gas to liquid products. Methane dehydroaromatization (DHA) over Mo/H-ZSM-5 offers a potential route to a value-added liquid product, however, DHA conversion is severely limited by thermodynamics at most industrially relevant temperatures. Here we propose an integrated process coupling methane DHA, chemical looping for selective hydrogen oxidation, and subsequent water removal to achieve higher yields of aromatic products limited by the thermodynamics in one-pass systems. We validate this process via the construction and operation of a one-of-a-kind multibed recirculating reactor, and achieve a combined aromatics yield of 42%. Detailed technoeconomic analysis of the process for mobile applications show that such a process could be economically viable under certain circumstances.

Selective Adsorption of CO2 on Zeolites NaK-ZK-4 with Si/Al of 1.8-2.8.

Zeolites with appropriately narrow pore apertures can kinetically enhance the selective adsorption of CO2 over N2. Here, we showed that the exchangeable cations (e.g., Na+ or K+) on zeolite ZK-4 play an important role in the CO2 selectivity. Zeolites NaK ZK-4 with Si/Al = 1.8–2.8 had very high CO2 selectivity when an intermediate number of the exchangeable cations were K+ (the rest being Na+). Zeolites NaK ZK-4 with Si/Al = 1.8 had high CO2 uptake capacity and very high CO2-over-N2 selectivity (1190). Zeolite NaK ZK-4 with Si/Al = 2.3 and 2.8 also had enhanced CO2 selectivity with an intermediate number of K+ cations. The high CO2 selectivity was related to the K+ cation in the 8-rings of the α-cage, together with Na+ cations in the 6-ring, obstructing the diffusion of N2 throughout the zeolite. The positions of the K+ cation in the 8-ring moved slightly (max 0.2 Å) toward the center of the α-cage upon the adsorption of CO2, as revealed by in situ X-ray diffraction. The CO2-over-N2 selectivity was somewhat reduced when the number of K+ cations approached 100%. This was possibly due to the shift in the K+ cation positions in the 8-ring when the number of Na+ was going toward 0%, allowing N2 diffusion through the 8-ring. According to in situ infrared spectroscopy, the amount of chemisorbed CO2 was reduced on zeolite ZK-4s with increasing Si/Al ratio. In the context of potential applications, a kinetically enhanced selection of CO2 could be relevant for applications in carbon capture and bio- and natural gas upgrading.

Computational study of the effect of functionalization on natural gas components separation and adsorption in NUM-3a MOF

The upgrading of natural gas on the pristine and functionalized NUM-3a -X (X = -Cl, –NH2, –F) were studied using Monte Carlo simulations in the grand canonical ensemble (GCMC). The equilibrium structures of the functionalized NUM-3a-X were found and confirmed by the quantum mechanical DFT methods. At first, the adsorptions of the components of the natural gas, CH4, CO2, H2S and N2 as pure gases in the pristine MOF were calculated, utilizing the common force fields for the MOFs and compared with the available experimental data to find out the best performing ones for the simulation of adsorption of the studied gases. Based on the obtained results, NUM-3a -Cl showed the highest uptake for the pure gases. Also, we found that the adsorption of CO2 on NUM-3a -X (X = -Cl, –NH2, –F) is higher than that of other gases. Furthermore, our GCMC simulations revealed that the inclusion of functional groups increases the CO2 selectivity in binary mixtures. In addition, the selectivity of NUM-3a-Cl for CO2 was found to be higher than that the other studied MOFs. The simulated CO2 selectivity were in the order of CO2/N2 > CO2/CH4. Our results indicated that the inclusion of electron withdrawing functional groups can enhance the performance of a MOF for CO2 separation applications. In addition, the isosteric heats of adsorption and Henry’s law coefficients were studied.

Highly microporous nitrogen-doped carbons from anthracite for effective CO2 capture and CO2/CH4 separation

The goal of this study is to develop a cost-efficient carbon adsorbent for effective CO2 capture and CO2/CH4 separation. Using anthracite as the precursor, highly microporous nitrogen-doped (N-doped) carbons are fabricated through a combination of KOH activation and urea treatment. The as-prepared carbon samples possess developed microporosity and large nitrogen content. The sample synthesized under mild KOH/anthracite ratio (KOH/anthracite = 2), following with urea treatment shows a remarkable CO2 uptake of 4.46 mmol g−1, among the highest achieved for N-doped porous carbons. This high CO2 capture capability should be attributed to the synergistic effect of large amount of narrow micropores (pore with＜1 nm) and nitrogen doping in the carbon adsorbent. Experiment evidence suggests that nitrogen doping contributes much on CO2/CH4 selectivity than that on CO2 capture. According to ideal adsorption solution theory (IAST), assuming different binary mixture proportions of 50/50, 30/70 and 15/85, the sample possessing the largest nitrogen content (6.48 wt %) exhibits CO2/CH4 IAST selectivities of 8.83, 7.02 and 8.09, respectively. Combining excellent CO2 capture capacity and desirable CO2/CH4 separation property, the microporous N-doped carbons prepared in this work appear to be a very promising candidate for greenhouse gas treatment and natural gas upgrading.

Highly selective absorption separation of H2S and CO2 from CH4 by novel azole‐based protic ionic liquids

AbstractRecently, the selective removal of H2S and CO2 has been highly desired in natural gas sweetening. Herein, four novel azole‐based protic ionic liquids (PILs) were designed and prepared through one‐step neutralization reaction. The solubility of H2S (0–1.0 bar), CO2 (0–1.0 bar), and CH4 (0–5.0 bar) was systematically measured at temperatures from 298.2 to 333.2 K. NMR and theoretical calculation were used to investigate the reaction mechanism between these PILs and H2S. Reaction equilibrium thermodynamic model (RETM) was screened to correlate the H2S solubility. Impressively, 1,5‐diazabicyclo[4,3,0] non‐5‐ene 1,2,4‐1H‐imidazolide ([DBNH][1,2,4‐triaz]) shows the highest H2S solubility (1.4 mol/mol or 7.3 mol/kg at 298.2 K and 1.0 bar) and superior H2S/CH4 (831) and CO2/CH4 (199) selectivities compared with literature results. Considering the excellent absorption capacity of H2S, high H2S/CH4, and CO2/CH4 selectivity, acceptable reversibility, as well as facile preparation process, it is believed that azole‐based PILs provide an attractive alternative in natural gas upgrading process.

Molecular sieving mixed matrix membranes embodying nano-fillers with extremely narrow pore-openings

Polysulfone-based mixed matrix membranes (MMMs) embodying metal-organic framework ZIF-11 with extremely narrow pore-openings (~3.0 Å of aperture windows) as the nano-fillers were fabricated and applied in CO2/CH4 separation for natural gas upgrading. The proper dispersion of ZIF-11 nano-fillers, below a threshold loading, led to defect-free free-standing membranes. The CO2/CH4 separation factor and CO2 permeability of MMMs with filler loading of 24 wt% showed a 43.5% and 99.5% of increment compared with the pure polysulfone (PSF) membrane, respectively. Adsorption/diffusion coefficients and the corresponding selectivities of gases for ZIF-11/PSF MMMs were quantitatively determined. Importantly, the diffusion coefficient of CO2 of MMMs with 24 wt% of ZIF-11 nanoparticles increased by 48.8% compared with that of the pure polymer membrane, but the diffusion coefficient of CH4 decreased by 42.7%. Accordingly, the CO2/CH4 diffusion selectivity increased by 160%, indicating that the restricted aperture windows of ZIF-11 permit CO2 to pass through but imped CH4. A clear molecular sieving process was realized in MMMs with ZIF-11 nano-fillers.

Effect of swing on removing CO2 from offshore natural gas by adsorption

Removing CO2 from CH4/CO2 mixture gas is significantly important in natural gas upgrading and greenhouse gas emission control. In order to improve the separation effect, the influence of swing on removing CO2 from offshore natural gas by the adsorption was studied systematically by experiment and simulation. Firstly, the adsorption experiment was carried out under the quiescent condition, single direction swing with a frequency of 0.12 Hz, bidirectional coupling swing with a frequency of 0.12 Hz and quiescent condition with a tilting angle of 20° by the swing experiment platform. The results indicated that the swing of the adsorber can reduce the adsorption purification effect, and which is not caused by the decrease of the adsorbent performance. Then, the adsorption purification model was established and the validity of the model was verified by experiments. Finally, the effects of tilting angle and L/D ratio of the porous zone, inlet flow rate of the mixture gas, particle diameter of adsorbent, and gas inlet distribution of the adsorber on adsorption purification under the quiescent and swing conditions were studied in detail. The results showed that decreasing the tilting angle of the porous zone and inlet flow rate of the mixture gas, or increasing the L/D ratio of the porous zone, the particle diameter of the adsorbent and the inlet amounts of the adsorber can reduce the adverse effect of swing on purification of natural gas. It is of great significance to improve the effect of adsorption purification of natural gas under swing condition by changing the adsorption conditions and structure of the adsorber. The research will provide a certain guidance for removing CO2 from offshore natural gas by adsorption.

Surprising plasticization benefits in natural gas upgrading using polyimide membranes

Hydrogen sulfide (H2S) and carbon dioxide (CO2) are acid gases that must be removed from natural gas prior to transmission and use. Here, we report the H2S/CH4 and CO2/CH4 separation performance of two polyimide membranes, i.e. 6FDA-DAM and 6FDA-DAM/DABA (3:2) for various realistic gas compositions and conditions. So-called plasticization effects of the polyimides are generally viewed as negative features when using such membranes, but we report important applications where H2S is present in the feed and the polyimide membrane plasticization is actually a tool for performance optimization. In fact, we identify cases where polyimide plasticization can provide large performance benefits for H2S/CH4 separations. We further analyze the transport mechanisms in terms of sorption and diffusion factors to understand this surprising discovery for various important feeds and conditions. The 6FDA-DAM membrane showed H2S permeability of 495 barrer and H2S/CH4 selectivity of ~31 with CO2 permeability of 301 barrer and CO2/CH4 selectivity of ~19 for a 20% H2S, 20% CO2 and 60% CH4 feed at 35 °C and 46 bar. Such CO2/CH4 performance and higher H2S/CH4 separation performance for aggressive high pressure feeds exceeds that of rubbery polymers, making the glassy materials ideal for processing natural gas feeds containing H2S and CO2.