Thin-film composite membranes incorporating a polyphenylene ionomer and separation processes therewith

Abstract

A thin-film composite membrane incorporating a gas separation layer from a polyphenylene ionomer, a nonporous high-diffusion rate layer, and a porous layer support is disclosed. The thin-film composite membrane may be used in a process to separate carbon dioxide, sulfur dioxide, hydrogen sulfide, or an alkene from a mixture with a less permeable component in a gaseous feed stream.

Description

THIN-FILM COMPOSITE MEMBRANES INCORPORATING A POLYPHENYLENE IONOMER AND SEPARATION PROCESSES THEREWITHCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. provisional application No. 63 / 520,291 filed August 17, 2023, the entire contents of which are incorporated herein by reference.BACKGROUND

[0002] Membranes may be used for separation of gas mixtures that are produced in industrial processes, such as energy production. These separations can include separation of carbon dioxide from nitrogen in effluent streams from the combustion of hydrocarbons ( / .e., flue gases), separation of alkenes from alkanes such as propylene from propane in hydrocarbon refinery operations, and separation of carbon dioxide from less permeable gases such as hydrocarbons including methane ( / .e., biogas). The separations can also include separation of sulfur dioxide or hydrogen sulfide from a less permeable gas such as methane in natural gas. Useful membranes have included thin-film composite membranes that incorporate a gas-separation layer that is necessarily thin and contacted to a nonporous high-diffusion rate layer (i.e. , a gutter layer), and a porous layer support for overall strength and durability.

[0003] Ionomers are polymer materials that have been used in the gas separation layer and contain ionic functionality such as carboxylic acid, phosphonic acid, sulfonic acid, or salts therefrom. The ionomers are hydrophilic and can absorb and hold liquid water, which can help to impart a high gas permeability and separation selectivity to the composite membrane. For example, fluorinated ionomers absorb liquid water, have been shown to have high gas permeance and separation selectivity, and durability under high water content operating (swelling) conditions. However, societal preference in general is to move away from fluorinated materials where possible, and there is an unmet need for thin-film composite membranes with gas separation layers incorporating ionomers that are hydrocarbon-based. While many hydrocarbon-based ionomers are known in the prior art, few have a good balance of properties. Such desirable properties include the ability to form stable films and composite membranes that retain adequate performance, tensile strength, and adherence — such as with a nonporous high- diffusion rate layer under high water content (swelling) conditions, and resistance to damage from hydration / dehydration cycling during long-term operation.SUMMARY

[0004] Polyphenylenes are polymers incorporating sterically encumbered aryl-aryl linkages in their repeating unit structure. Unexpectedly, a polyphenylene ionomer was discovered that forms stable films and gas-separation layers therefrom, which display excellent gas separationperformance and can remain adhered to a nonporous high-diffusion rate layer even under high water content conditions. In the first aspect herein, a thin-film composite membrane comprising the gas separation layer incorporating the polyphenylene ionomer, a nonporous high-diffusion rate layer comprising a highly permeable polymer material, and a porous layer support is disclosed. The polyphenylene ionomer may be a homopolymer or a copolymer and comprises a repeating unit of formula (P):in which each RIA is independently aryl or heteroaryl, each optionally substituted with 1 , 2 ,3, 4, or 5 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, SC>3'X+, PC>32'X+2, or CC>2'X+, wherein X+is H+or a cation, and provided that at least two of the RIA are substituted with 1 , 2, 3, 4, or 5 substituents selected from SC>3'X+, PC>32'X+2, or CC>2'X+;

[0005] each RIB is independently H, aryl, or heteroaryl, wherein each R2is optionally substituted with 1 , 2, 3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SO3_X+, PC>32'X+2, or CC>2'X+, wherein X+is H+or a cation;

[0006] A1 is arylene, heteroarylene, aralkylene, or heteroaralkylene, each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;

[0007] A2 is absent, arylene or heteroarylene, wherein said arylene and heteroarylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;

[0008] L1 is an optionally substituted linking heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, wherein said arylene, heteroarylene, aralkylene, and heteroaralkylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl;

[0009] L2is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl; and

[0010] l_3 is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl.

[0011] In embodiments, the thickness of the gas separation layer may be less than 2 microns and the polyphenylene ionomer may have an ion exchange capacity of about 2.49 meq g-1to about 3.7 meq g-1.

[0012] In embodiments, the repeating unit of formula (P) may have the structure (1) and X+may be selected from: H+, Li+, Ag+, ammonium, or alkyl ammonium:

[0013] In embodiments, the polyphenylene ionomer may be a random copolymer or a block copolymer and may comprise an additional repeating unit having the structure (2):

[0014] In embodiments, the nonporous high-diffusion rate layer may comprise a polymer material selected from polydimethylsiloxane, a substituted polyacetylene such poly(1- trimethylsilyl-1-propyne) (PTMSP), an addition-polymerized and substituted polynorbornene such as poly(5-trimethylsilyl norborn-2-ene), or an addition-polymerized and substituted polytricyclononene such as poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene). The porous layer support can comprise a material such as porous polyvinylidine fluoride, expanded polytetrafluoroethylene, polyacrylonitrile, polysulfone, or polyethersulfone.

[0015] In another aspect disclosed herein, the thin-film composite membrane having a feed side and a permeate side may be used in a process to separate carbon dioxide from a mixture comprising a less permeable component in a gaseous feed stream. The process comprises exposing the feed side to the gaseous feed stream, selectively permeating carbon dioxide across the thin-film composite membrane and producing a gaseous permeate stream at the permeate side having a higher concentration of carbon dioxide with respect to the mixture with the less permeable component in the gaseous feed stream.

[0016] In another aspect disclosed herein, the thin-film composite membrane having a feed side and a permeate side may be used in a process to separate sulfur dioxide (SO2) or hydrogen sulfide (H2S) from a mixture comprising a less permeable component such as methane in a gaseous feed stream. The process comprises exposing the feed side to the gaseous feed stream, selectively permeating carbon dioxide across the thin-film composite membrane and producing a gaseous permeate stream at the permeate side having a higher concentration of sulfur dioxide or hydrogen sulfide with respect to the mixture with the less permeable component in the gaseous feed stream.

[0017] In yet another aspect disclosed herein, the thin-film composite membrane having a feed side and a permeate side and wherein X+is Ag+may be used in a process to separate an alkene from a mixture comprising an alkane in a gaseous feed-stream. The process comprises exposing the feed side to the gaseous feed-stream, selectively permeating the alkene across the thin-film composite membrane and producing a gaseous permeate stream at the permeate side having a higher concentration of the alkene with respect to the mixture with the alkane in the gaseous feed-stream.

[0018] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. In addition, use of "a" or "an" are employed to describe elements and components described herein. This is done merely for convenience and for a general sense of the scope of the invention. This description should be read to include one or at least one; the singular also includes the plural unless it is obvious that it is meant otherwise.

[0019] This summary of the invention has introduced aspects and some of the embodiments of the invention and is not intended to be limiting. As used herein, an aspect is a defining characteristic of the invention as may be recited in an independent claim and further disclosed in the detailed description. An embodiment may be viewed as a variation, or one implementation of an aspect as may be recited in a dependent claim and further disclosed in the detailed description. Certain exemplary embodiments are described herein and are only forpurposes of illustrating the invention and should not be interpreted as limiting the scope of the invention. Alternate embodiments, including certain modifications, combinations, and improvements of the described embodiments will occur to those skilled in the art and all such alternate embodiments are within the scope of the invention.DESCRIPTION OF THE DRAWING

[0020] Figure 1 shows a flow diagram for a membrane gas separation performance evaluation; P: pressure gauge; PR: pressure regulator; MFC: mass flow controller; BPR: back pressure regulator.DETAILED DESCRIPTION

[0021] Polyphenylenes are polymer materials incorporating sterically encumbered aryl-aryl linkages in their repeating unit structure and can have inherent chemical stability and good mechanical strength in certain applications. For example, US Patent No. 7,301 ,002 B1 disclosed polyphenylene ionomers and a membrane therefrom for use in a proton exchange membrane (PEM) fuel cell, wherein the membrane partitions an anode side of the PEM fuel cell from a cathode side and prevents hydrogen gas in the anode side from mixing with the air or oxygen in the cathode side. US 2020 / 0362129 A 1 and US 2023 / 0159716 A1 , which are hereby incorporated by reference in their entirety, disclosed processes for the precise control of a polyphenylene ionomer structure and accurate placement of the ionic functionality along the polyphenylene backbone. PEM fuel cell membranes therefrom showed enhanced ionic conductivity, a higher tensile strength, and a higher Young’s modulus compared to a commercially available fluorinated ionomer. Herein, it was discovered that a thin-film composite membrane incorporating the polyphenylene ionomer can be used to permeate and selectively separate components from a mixture in a gaseous feed stream.Definitions

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Certain definitions are used herein and defined as follows.

[0023] As used herein, the term “repeating unit” corresponds to the smallest structural unit, the repetition of which constitutes a regular polymer molecule. A “homopolymer” consists essentially of one repeating unit structure while a “copolymer” refers to polymer molecule having at least two structurally different repeating units. The repeating units can be disposed in a purely random, an alternating random, a regular alternating, a regular block, or a random block configuration. For a block copolymer, a regular block configuration can have the following repeating unit order: ... x-x-x-y-y-y-x-x-x-y-y-y... , while a random block copolymer configurationmay have the following repeating unit order: ...x-x-x-y-y-x-x-y-y-y-y-x-x-x-y-y-x-x-x... , or for example, ... x-x-x-y-y-y-y-x-x-y-y-y-x-x-x-y-y ... .

[0024] As used herein, the term “alkyl” refers to a straight chain, branched chain, or a cyclic hydrocarbon group. In some embodiments, a hydrocarbon group can have 1 to 14 carbon atoms. Representative alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, n-butyl, secbutyl, tert-butyl, pentyl and pentyl isomers, hexyl and hexyl isomers including cyclohexyl. Cycloalkyl groups can include mono or polycyclic groups that have 2, 3, or 4 fused rings.

[0025] As used herein, the term “alkoxy” refers to an alkyl or cycloalkyl group as defined herein bonded to an oxygen atom. Representative alkoxy groups include methoxy, ethoxy, propoxy, and isopropoxy groups.

[0026] As used herein, the term “alkylsilyl” group refers to a tetravalent silicon atom bonded to 3 alkyl groups and to a carbon atom of at least one repeating unit in a polymer material. Representative alkylsilyl groups include trimethylsilyl, triethylsilyl, and triisopropylsilyl.

[0027] As used herein, the term “alkoxysilyl” group refers to a tetravalent silicon atom bonded to 3 alkoxy groups and to a carbon atom of at least one repeating unit in a polymer material. Representative alkoxysilyl groups include trimethoxysilyl, triethoxysilyl, and triisopropoxysilyl.

[0028] As used herein, the term “aryl” refers to an aromatic hydrocarbon group having 6, 10, 14, or more atoms. Representative aryl groups include phenyl groups. In some embodiments “aryl” includes monocyclic or polycyclic (e.g., having 2,3 or 4 fused rings) aromatic hydrocarbons such as for example, phenyl, naphthyl, anthracenyl, phenanthrenyl, indanyl, and indenyl.

[0029] As used herein, the term “heteroaryl” refers to a 5 to 10-menbered aromatic monocyclic or bicyclic ring containing 1 to 4 heteroatoms selected from O, S, and N. Representative 5- or 6-membered aromatic monocyclic ring groups include pyridine, pyrimidine, pyridazine, furan, thiophene, thiazole, oxazole, and isoxazole. Representative 9- or 10-membered aromatic bicyclic ring groups include benzofuran, benzothiophene, indole, pyranopyrrole, benzopyran, quinoline, benzocyclohexyl, and naphthyridine.

[0030] As used herein, the term “aralkyl” refers to an aryl group substituted with an alkyl or cycloalkyl group for one of the aryl hydrogen atoms. A representative aralkyl group is a benzyl group. “Heteroaralkyl” refers to a heteroaryl group as defined above substituted with an alkyl or cycloalkyl group for one of the heteroaryl hydrogen atoms. For example, a representative heteroaralkyl group is 2-methylpyridine.

[0031] As used herein, the term “optionally substituted” can refer to, for example, functional groups that may be substituted by additional functional that may be substituted or unsubstituted by additional functional groups. For example, when a group is unsubstituted, it can be referred to as the group name, for example alkyl or aryl. When a group is substituted with additionalfunctional groups, it may more generically be referred to as substituted alkyl or substituted aryl. The term “substituted” refers to the replacement of a hydrogen atom with a substituent other than H. For example, an “N-substituted piperidinyl” refers to replacement of the H atom from the NH of the piperidinyl with a non-hydrogen substituent such as, for example, alkyl. The term “optionally substituted with 1 , 2, 3, 4, or 5” is intended to individually disclose optionally substituted with 1 , 2, 3, or 4; 1 , 2, or 3; 1 or 2; or 1 substituent(s).

[0032] As used herein, the terms “alkylene”, “arylene”, “heteroarylene”, “aralkylene”, and heteroaralkylene” refer to divalent alkyl, aryl, heteroaryl, aralky, and hetereoaralkyl groups, respectively, that form a link between a first and a second moiety.Thin-film composite membrane

[0033] Although methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the present disclosure, suitable methods and materials are described herein. The thin-film composite membrane comprises a gas separation layer incorporating a polyphenylene ionomer, a nonporous high-diffusion rate layer comprising a highly permeable polymer material, and a porous layer support. The polyphenylene ionomer may be a homopolymer or a copolymer and comprises a repeating unit of formula (P):in which each RIAis independently aryl or heteroaryl, each optionally substituted with 1 , 2 ,3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SC>3'X+, PO32'X+2, or CO2'X+, wherein X+is H+or a cation, and provided that at least two of the RIAare substituted with 1 , 2, 3, 4, or 5 substituents selected from SC>3'X+, PO32'X+2, or CO2'X+;

[0034] each RIB is independently H, aryl, or heteroaryl, wherein each R2is optionally substituted with 1 , 2, 3, 4, or 5 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, SOs" X+, PC>32'X+2, or CO2'X+, wherein X+is H+or a cation;

[0035] A1 is arylene, heteroarylene, aralkylene, or heteroaralkylene, each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;

[0036] A2 is absent, arylene or heteroarylene, wherein said arylene and heteroarylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;

[0037] L1 is an optionally substituted linking heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, wherein said arylene, heteroarylene, aralkylene, and heteroaralkylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl;

[0038] L2 is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl; and

[0039] L3is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl.

[0040] The polyphenylene ionomer can have an ion exchange capacity (I EC) of about 2.49 meq g-1to about 3.7 meq g-1, wherein the I EC is a measure of the molar quantity of ionic groups within a given mass of the polyphenylene ionomer. The ionic groups include sulfonic acid or sulfonate groups (SC>3'X+), phosphonic acid of phosphonate groups (PC>32'X+2), and carboxylic acid or carboxylate groups (CC>2'X+), wherein X+is a proton (H+) or a cation that includes Li+, Ag+, ammonium, or alkyl ammonium. The ionic groups, H+, or the choice of cation, can facilitate absorption of liquid water within the polyphenylene ionomer in the gas separation layer and can help to impart a high gas permeability and separation selectivity to the thin-film composite membrane.

[0041] The polyphenylene ionomer can comprise a repeating unit having the structure (1) and may be homopolymer, a random copolymer, or block copolymer. The copolymer may comprise an additional repeating unit having the structure (2). The polyphenylene ionomer as a copolymer comprising repeating unit structures (1) and (2) and having an ion exchange capacity of about 2.49 meq g-1to about 3.7 meq g-1is commercially available from lonomr Innovations, Inc., Vancouver, Canada and marketed as Pemion®. Pemion® is soluble in lower alcohols such as ethanol and isopropanol, and mixtures therefrom.

[0042] The thin-film composite membrane comprises a nonporous high-diffusion rate layer incorporating a polymer material that is sandwiched (layered) between the gas separation layer incorporating the polyphenylene ionomer and a porous layer support. The polymer material is highly gas permeable and can enhance overall permeability of the composite but is not necessarily highly gas selective. The polymer material for the nonporous high-diffusion rate layer may be selected from polydimethylsiloxane, a substituted polyacetylene such as poly(1 - trimethylsilyl propyne) (PTMSP), an addition-polymerized and substituted polynorbornene such as poly(5-trimethylsilyl norborn-2-ene) (PTMSN), or an addition-polymerized and substituted polytricyclononene such as poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene) (PTCNSi2g). The polymer materials are substituted in that they can incorporate functional groups such alkyl groups, aryl groups, or silyl groups including alkylsilyl groups or alkoxysilyl groups in their repeating unit structure.

[0043] PTMSP is commercially available from Gelest (Morrisville, PA) and is soluble in organic solvents that include toluene, cyclohexane, heptane, and chloroform. PTMSN may be synthesized by addition polymerization of 5-trimethylsilyl-2-norbornene as disclosed by Finkelshtein et al. in “Addition-Type Polynorbornenes with Si(CH3)3 Side Groups: Synthesis, Gas Permeability, and Free Volume” Macromolecules 2006, 39, 7022-7029. PTMSN is soluble in organic solvents that include toluene and chloroform. PTCNSi2g may be synthesize byaddition polymerization of 3,3-bis(trimethylsilyl)tricyclonon-7-ene as disclosed by Gringolts et al. in Russian Patent 2,410,397 or by Chapala et al. in “A Novel, Highly Gas-Permeable Polymer Representing a New Class of Silicon-Containing Polynorbornenes as Efficient Membrane Materials” Macromolecules 2015, 48, 8055-8061. PTCNSi2g is soluble in organic solvents that include toluene and chloroform.

[0044] A general structure for a substituted polyacetylene is shown in (3), wherein R1comprises an alkyl or an aryl group, and R2comprises an aryl group or an alkylsilyl group. A general structure for an addition-polymerized and substituted polynorbornene is shown in (4), wherein R3is H, an alkyl group, an alkylsilyl group, or an alkoxysilyl group, and R4comprises an alkylsilyl group or an alkoxy silyl group. A general structure for an addition-polymerized and substituted polytricyclononene is shown in (5), wherein R5is H, an alkylsilyl group or an alkoxysilyl group; R6comprises an alkylsilyl group or an alkoxysilyl group; R7is H, or when R5is H, R7comprises an alkylsilyl group or an alkoxysilyl group; and n is an integer that defines the degree of polymerization of the repeating unit structure in the polymer material.substituted polyacetylene(3)addition-polymerized and substituted polynorbornene(4)addition-polymerized and substituted polytricyclononene(5)

[0045] Other substituted polyacetylenes may include certain indan-containing poly(diphenylacetylene) derivatives that were disclosed by Hu et al. in “Synthesis and Propertiesof Indan-Based Polyacetylenes That Feature the Highest Gas Permeability among All the Existing Polymers” Macromolecules 2008, 41, 8525-8532. Other addition-polymerized substituted polynorbornenes may include alkoxysilyl-substituted polynorbornenes such as disclosed by Maroon et al. in “Addition-type alkoxysilyl-substituted polynorbornenes for postcombustion carbon dioxide separations” Journal of Membrane Science, 595, February 2020, 117532.

[0046] A supported film that will subsequently become the nonporous high-diffusion rate layer may be prepared by coating (i.e., solution casting) a dilute solution of the polymer material onto the surface of a porous layer support. The porous layer support may be in the form of a flat sheet, hollow fiber, or other tube-like and porous structure. For a hollow fiber or other tube-like and porous structure, the dilute solution of the polymer material may be cast on the outer surface (shell) or the inner surface (lumen). A dilute solution of polydimethylsiloxane (PDMS), PTMSP, PTMSN, or PTCNSi2g is prepared in an organic solvent at concentrations that may be less than 2%, or between 0.1% and 1%. Preferred coating methods include but are not limited to ring casting, dip-coating, spin-coating, slot-die coating, roll coating, Mayer rod coating, and injection coating. The organic solvent is evaporated to form the supported film of the polymer material that will subsequently become the nonporous high-diffusion rate layer. Residual or trace organic solvent remaining in the supported film should not interfere with subsequent fabrication steps.

[0047] The supported film that will subsequently become the high diffusion rate layer is thin and can have a thickness that is between 0.05pm to 5-pm, or between 0.1 m to 2pm. Permeance, which is pressure normalized flux, is typically reported as a gas permeance unit (GPU) coefficient that has units of GPU*106xcm3(STP) / (cm2s cmHg). Permeability is permeance normalized for thickness and is typically reported in Barrer, in which the Barrer permeability coefficient has units of Barrer* 101°xcm3(STP) cm / (cm2s cmHg). Together, the supported film and porous layer support can have a helium or carbon dioxide permeance of at least 5000 GPU, or greater than 10,000 GPU when measured at 25°C.

[0048] The porous layer support reinforces the high-diffusion rate layer and the gas separation layer that are necessarily thin for high permeance and helps to strengthen the composite such that the thin-film composite membrane may be fabricated into complex geometries that include spiral-wound or hollow-fiber membrane modules. The porous layer support may be in the form of a flat sheet, hollow fiber, or other tube-like and porous structure. Suitable materials for a porous layer support include but are not limited to polyvinylidine fluoride, expanded polytetrafluoroethylene, polyacrylonitrile, polyetheretherketone (PEEK), polysulfone, and polyethersulfone. The porous layer support may also comprise a porous and even stronger backing material such as a non-woven polyester or polypropylene sheet. Inorganic substratessuch as porous silica or alumina sheets or tubes may also be suitable materials for a porous layer support. The porous layer support can have a helium or carbon dioxide permeance that is higher than the high diffusion rate layer, such as at least 2 times higher or at least 5 times higher. Permeate gases can therefore flow relatively unobstructed through the porous layer support having a porosity that may be at least 40%. The average pore size may be less 0.1-pm or between 0.01-pm and 0.03-pm, corresponding to molecular weight cut-offs of approximately 50,000 Daltons to 200,000 Daltons, respectively.

[0049] The thin-film composite membrane may be subjected to a thermal treatment step “annealed” to improve mechanical durability and longer-term performance stability. The polyphenylene ionomer in the gas separation layer can be annealed by heating the thin-film composite membrane. The appropriate temperature will be dependent on the stability of the polyphenylene ionomer composition. For example, a polyphenylene ionomer that is a copolymer comprising repeating units from structures (1) and (2) may be annealed at temperatures of at least 120°C. The thin-film composite membrane may be heated for 0.1 minute to 10 minutes, or for 1 minute to 5 minutes. An appropriate annealing temperature and time should not degrade the other components of the thin-film composite membrane.

[0050] The polyphenylene ionomer in the gas separation layer and comprising H+ or cations other than silver (Ag+) is initially inactive for a separation of an alkene from an alkane. That is, the thin-film composite membrane may not be significantly perm-selective (selectivity <5) and the alkene permeance can be low (<25-GPU). The thin-film composite membrane may be activated by exchange of H+or cations other than silver for silver in the gas-separation layer. For example, the exchange may be carried out by contacting the exposed surface of the gas separation layer with a solution comprising water and a soluble and ionizable silver compound such as silver nitrate. It was shown that a sufficient level of exchange quickly occurred for the H+form of a thin (<2pm) gas separation layer as evidenced by a high permeance (>100-GPU) and selectivity (>25) for propylene over propane after less than 1 minute of contact with aqueous silver nitrate at ambient (~23°C) temperature.

[0051] The thin-film composite membrane is useful for the separation of carbon dioxide, sulfur dixodie, or hydrogen sulfide from a mixture comprising a less permeable component in a gaseous feed stream. A less permeable component can include nitrogen or an alkane, such as methane. The thin-film composite membrane when X+= Ag+may also be used for the separation of an alkene from a mixture comprising an alkane in a gaseous feed stream. The alkene and alkane can include propylene and propane or ethylene and ethane. In an example of a separation process using carbon dioxide, the thin-film composite membrane having a feed side and a permeate side is exposed at the feed side to the gaseous feed stream. Carbon dioxide selectively permeates across the thin-film composite membrane. A gaseous permeatestream is produced at the permeate side having a higher concentration of carbon dioxide with respect to the mixture with the less permeable component in the gaseous feed stream. The performance of the gas separation layer in the thin-film composite membrane may be enhanced by the presence or the addition of water vapor to the gaseous feed stream or the permeate stream.EXAMPLESExample 1

[0052] General procedure for thin-film composite membrane fabrication from Pemion® ionomer: The sulfonic-acid form of Pemion® ionomer (part # PP1-HNN8-00-X) and having an ion exchange capacity of 2.8 meq g-1to 3.1 meq g-1was purchased from lonomr Innovations, Inc., Vancouver, Canada. Substrates comprising a nonporous high-diffusion rate layer on a porous layer support were first prepared by ring or immersion casting a 0.5 wt% solution of poly(1 - trimethylsilyl-1-propyne) (PTMSP) in heptane onto asymmetrically porous sheets of polyvinylidene fluoride (PVDF), or polyacrylonitrile (PAN) microfiltration membrane respectively. All substrates were dried at ambient temperature. The Pemion® ionomer was dissolved at 60°C in 95% purity ethanol to make a 1.0 wt.% solution. Fractions from the solution were then diluted with additional ethanol to make 0.5 wt.%, 0.25 wt.%, 0.1 wt.%, 0.05 wt.%, and 0.025 wt.% solutions. The solutions were filtered through 1-pm glass microfiber and then separately ring or immersion cast onto the surface of the high-diffusion rate layer for the substrates on porous sheets or the hollow fiber, respectively. The wet films were dried at ambient (20-25°C) temperatures to dry for 30 minutes and form the gas separation layer. Once dry, the membranes were further annealed for 3 minutes at 120°C in a forced-air oven.Example 2

[0053] Membrane fabrication for separation of an alkene from an alkane: Thin-film composite membranes from the 0.5 wt.% solution of the sulfonic-acid form of Pemion® ionomer and a porous layer support from PVDF in Example 1 were converted to a silver-sulfonate form by applying a 0.15 molar aqueous silver nitrate solution to the surface of the gas separation layer. The solution was removed after 1 minute and the membranes were dried in a 60°C oven for 20 minutes and cooled to room temperature. The membranes were stored under dark and dry conditions until needed for testing.Example 3

[0054] General procedure for membrane gas-separation measurement: Membrane gas separation measurements were carried out in an experimental setup shown schematically in Figure 1. Appropriate feed gas mixtures were generated by blending two pure gases from gas cylinders. The individual gas stream pressure and flow rate were controlled using a pressureregulator and a mass flow controller, respectively. The feed gas mixture was humidified before it entered a stainless-steel crossflow permeation cell. The thin-film composite membranes each having a 13.85 cm2active area were separately tested in this cell. The feed side pressure was maintained by a back pressure regulator, and it was always higher than the permeate side pressure. After allowing sufficient time for the system to reach a steady state, the retentate and permeate stream flows were measured and compositions analyzed.Example 4

[0055] CO2-N2 gas separation performance of thin-film composite membranes prepared in Example 1: Feed-gas mixtures were prepared by blending pure CO2 and N2 gases to generate 20 mol % CO2180 mol % N2. The feed-gas mixture at flow rates between 0.2-0.4 standard liters per min was humidified using an inline water bubbler or Nation® tube in shell humidifier that was purchased from Perma Pure®. The permeate flow rate was measured using a bubble flow meter, and concentrations of carbon dioxide in the permeate were measured using a Landtech Biogas 5000 meter. Feed-gas flow rates were adjusted such that the stage cut ( / .e., flow of permeate stream relative to the feed-gas flow) was maintained below 10.0%. CO2-N2 mixed gas separation tests were carried out at 60°C at a feed pressure of 21 psia, and a permeate pressure of 3 psia. The thin-film composite membranes from Example 1 were tested and permeance was calculated for each component independently using the log mean partial pressure difference across the membrane. Selectivity was calculated as the ratio of carbon dioxide permeance to nitrogen permeance. Table 1 shows a high CO2 permeance and selectivity over nitrogen for all tested membranes.Table 1Example 5

[0056] Alkene-alkane separation performance of thin-film composite membranes prepared inExample 2: A feed mixture was prepared by blending pure propylene and propane gases to generate a 50 mol % propylene / 50 mol % propane mixture. The feed-gas mixture washumidified in a bubbler at a flow rate of 200 seem before entering the permeation cell at 60 psig pressure and 20°C. The permeate pressure was maintained at 1 atm (-14.7 psig). The performance of thin-film composite membranes fabricated in Example 2 were measured after stabilizing for 30 min. Propylene and propane compositions in the permeate and retentate were analyzed with a gas chromatograph equipped with a flame ionization detector. The permeate and retentate flow rates were measured with a bubble flowmeter. Permeance was calculated for each component independently using the log mean partial pressure difference across the membrane. Selectivity was calculated as the ratio of propylene permeance to propane permeance. Table 2 shows the excellent separation results of feed side humidification tests.Table 2Example 6

[0057] Alkene-alkane separation performance of thin-film composite membranes prepared in Example 2 using backside humidification: The thin-film composite membranes of Example 2 and tested in Example 5 were further evaluated using an enhanced humidification method where water was injected (H2O injection) into the permeate channel as shown in Figure 1 and thus humidifying the membrane from the backside. These additional tests used the same procedure and operating conditions as in Example 5. The separation performance results are summarized in Table 3.Table 3Example 7

[0058] Fabrication of a gas separation layer on a nonporous high-diffusion rate layer from poly(5-trimethylsilyl norborn-2-ene) and CO2-N2 separation performance: Poly(5-trimethylsilyl norborn-2-ene) (PTMSN) is synthesized by addition polymerization of 5-trimethylsilyl-2- norbornene as disclosed by Finkelshtein et al. in “Addition-Type Polynorbornenes with Si(CH3)3Side Groups: Synthesis, Gas Permeability, and Free Volume” Macromolecules 2006, 39, 7022- 7029. A 0.5 wt% solution of PTMSN is prepared in toluene and ring cast onto an asymmetrically porous sheet of polyacrylonitrile (PAN) microfiltration membrane and dried at ambient temperature. A 0.05% solution of the Pemion® ionomer in ethanol is ring cast onto the surface of the high-diffusion rate layer from PTMSN. The wet film is set horizontally at ambient (20- 25°C) temperatures and is dried for 30 minutes to form the gas separation layer. The thin-film membrane is annealed for 3 minutes at 120°C in a forced-air oven. The CO2-N2 separation performance is tested as described in Examples 3 and 4 and the CO2 permeance is at least 1100 and the selectivity over nitrogen is at least 20.Example 8

[0059] Fabrication of a gas separation layer on a nonporous high-diffusion rate layer from poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene) (PTCNSi2g) and CO2-N2 separation performance: Poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene) (PTCNSi2g) is prepared as described by Chapala et al. in “A Novel, Highly Gas-Permeable Polymer Representing a New Class of Silicon- Containing Polynorbornenes as Efficient Membrane Materials” Macromolecules 2015, 48, 8055- 8061. A 0.5 wt% solution of PTCNSi2g is prepared in toluene and ring cast onto an asymmetrically porous sheet of polyacrylonitrile (PAN) microfiltration membrane and dried at ambient temperature. A 0.05% solution of the Pemion® ionomer in ethanol is ring cast onto the surface of the high-diffusion rate layer from PTCNSi2g. The wet film is set horizontally at ambient (20-25°C) temperatures and is dried for 30 minutes to form the gas separation layer. The thin-film membrane is annealed for 3 minutes at 120°C in a forced-air oven. The CO2-N2 separation performance is tested as described in Examples 3 and 4 and the CO2 permeance is at least 1300 and the selectivity over nitrogen is at least 25.Example 9

[0060] Sulfur dioxide or hydrogen sulfide gas separation performance of a thin-film composite membrane prepared in Example 1: Feed-gas mixtures are prepared by blending sulfur dioxide or hydrogen sulfide with methane to generate a 20 mol % sulfur dioxide or hydrogen sulfide mixture in methane. A feed-gas mixture at flow rates between 0.2-0.4 standard liters per min is humidified using an inline water bubbler or Nation® tube in shell humidifier that may be purchased from Perma Pure®. The permeate flow rate is measured using a bubble flow meter, and concentrations of sulfur dioxide or hydrogen sulfide in the permeate are measured using a Landtech Biogas 5000 meter. Feed-gas flow rates are adjusted such that the stage cut ( / .e., flow of permeate stream relative to the feed-gas flow) is maintained below 10.0%. Separation tests are carried out at 60°C at a feed pressure of 21 psia, and a permeate pressure of 3 psia. A thin-film composite membrane from example 1 having a gas separation layer from a 0.25% (w / w) Pemion® solution is tested and permeance is calculated for each componentindependently using the log mean partial pressure difference across the membrane. Selectivity is calculated as the ratio of sulfur dioxide or hydrogen sulfide permeance to methane permeance.

[0061] These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure. The present application claims priority to U.S. Provisional Application No. 63 / 520,291 filed on August 17, 2023 in the United States Patent Office, the entire contents and disclosure of which are incorporated herein by reference.

Claims

CLAIMS1. A thin-film composite membrane comprising: a) a gas separation layer comprising a polyphenylene ionomer; b) a nonporous high-diffusion rate layer; and c) a porous layer support, wherein the polyphenylene ionomer is a homopolymer or a copolymer and comprises a repeating unit of formula (P):(P), in which, each RIA is independently aryl or heteroaryl, each optionally substituted with 1 , 2 ,3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SC>3'X+, PC>32'X+2, or CC>2'X+, wherein X+is H+or a cation, and provided that at least two of the RIA are substituted with 1 , 2, 3, 4, or 5 substituents selected from SC>3'X+, PC>32'X+2, or CO2’X+; each RIB is independently H, aryl, or heteroaryl, wherein each R2 is optionally substituted with 1 , 2, 3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SC>3'X+, PC>32'X+2, or CC>2'X+, wherein X+is H+or a cation;A1 is arylene, heteroarylene, aralkylene, or heteroaralkylene, each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;A2 is absent, arylene or heteroarylene, wherein said arylene and heteroarylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;Li is an optionally substituted linking heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, wherein said arylene, heteroarylene, aralkylene, and heteroaralkylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl;L2 is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl; andL3 is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl.

2. The thin-film composite membrane of claim 1 , wherein the thickness of the gas separation layer is less than 2 microns.

3. The thin-film composite membrane of claim 2, wherein the polyphenylene ionomer has an ion exchange capacity of about 2.49 meq g-1to about 3.7 meq g-1.

4. The thin-film composite membrane of claim 3, wherein the repeating unit of formula (P) has the structure (1):(1).

5. The thin-film composite membrane of claim 4. wherein X+is selected from: H+, Li+, Ag+, ammonium, or alkyl ammonium.

6. The thin-film composite membrane of claim 5, wherein the polyphenylene ionomer is a copolymer and comprises an additional repeating unit having the structure (2):(2).

7. The thin-film composite membrane of claim 6, wherein the polyphenylene ionomer is a random copolymer or a block copolymer.

8. The thin-film composite membrane of claim 6, wherein the nonporous high- diffusion rate layer comprises a polymer material selected from polydimethylsiloxane, poly(1 - trimethylsilyl propyne), poly(5-trimethylsilyl norborn-2-ene), or poly(3,3- bis(trimethylsilyl)tricyclonon-7-ene).

9. The thin-film composite membrane of claim 6, wherein the nonporous high- diffusion rate layer comprises a polymer material selected from poly(1 -trimethylsilyl propyne), poly(5-trimethylsilyl norborn-2-ene), or poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene).

10. The thin-film composite membrane of claim 1 , in which the nonporous high- diffusion rate layer comprises a polymer material selected from a substituted polyacetylene having the general structure (3), an addition-polymerized and substituted polynorbornene having the general structure (4), or an addition-polymerized and substituted polytricyclononene having the general structure (5):substituted polyacetylene(3)addition-polymerized and substituted polynorbornene(4)addition-polymerized and substituted polytricyclononene(5) whereinR1comprises an alkyl or an aryl group;R2comprises an aryl group or an alkylsilyl group;R3is H, an alkyl group, an alkylsilyl group, or an alkoxysilyl group;R4comprises an alkylsilyl group or an alkoxysilyl group;R5is H, an alkylsilyl group or an alkoxysilyl group;R6comprises an alkylsilyl group or an alkoxysilyl group;R7is H; or when R5is H, R7comprises an alkylsilyl group or an alkoxysilyl group; and n is an integer that defines the degree of polymerization of the repeating unit structure of the polymer material.

11. The thin-film composite membrane of claim 1 , wherein the porous layer support comprises a material selected from polyvinylidine fluoride, expanded polytetrafluoroethylene, polyacrylonitrile, polyetheretherketone, polysulfone, or polyethersulfone.

12. The thin-film composite membrane of claim 1 , wherein the porous layer support comprises a material selected from polyvinylidine fluoride, expanded polytetrafluoroethylene, polyacrylonitrile, polysulfone, or polyethersulfone.

13. A process to separate carbon dioxide from a mixture comprising a less permeable component in a gaseous feed stream and comprising: a) providing a thin-film composite membrane having a feed side and a permeate side and comprising: i) a gas separation layer comprising a polyphenylene ionomer; ii) a nonporous high-diffusion rate layer; and iii) a porous layer support, wherein the polyphenylene ionomer is a homopolymer or a copolymer and comprises a repeating unit of formula (P):in which, each RIA is independently aryl or heteroaryl, each optionally substituted with 1 , 2, 3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SC>3'X+, PC>32'X+2, or CC>2'X+, wherein X+is H+or a cation, and provided that at least two of theRIA are substituted with 1, 2, 3, 4, or 5 substituents selected from SC>3'X+, PC>32'X+2, or CO2’X+; each RIB is independently H, aryl, or heteroaryl, wherein each R2is optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SC>3'X+, PC>32'X+2, or CO2'X+, wherein X+is H+or a cation;Ai is arylene, heteroarylene, aralkylene, or heteroaralkylene, each optionally substituted with 1, 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;A2is absent, arylene or heteroarylene, wherein said arylene and heteroarylene are each optionally substituted with 1, 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;Li is an optionally substituted linking heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, wherein said arylene, heteroarylene, aralkylene, and heteroaralkylene are each optionally substituted with 1, 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl;L2is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1, 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl; andL3 is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1, 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl; b) exposing the feed side to the gaseous feed stream; c) selectively permeating carbon dioxide across the thin-film composite membrane; and d) producing a gaseous permeate stream at the permeate side having a higher concentration of carbon dioxide with respect to the mixture with a less permeable component in the gaseous feed stream.

14. The process of claim 13, wherein the thickness of the gas separation layer is less than 2 microns.

15. The process of claim 13, wherein the polyphenylene ionomer has an ion exchange capacity of about 2.49 meq g-1to about 3.7 meq g-1.

16. The process of claim 13, wherein the repeating unit of formula (P) has the structure (1):(1).

17. The process of claim 16, wherein X+is H+, Li+, Ag+, ammonium, or alkyl ammonium.

18. The process of claim 16, wherein the polyphenylene ionomer as a copolymer comprises an additional repeating unit having the structure (2):

19. The process of claim 13, wherein the polyphenylene ionomer is a random copolymer or a block copolymer.

20. The process of claim 13, wherein the nonporous high-diffusion rate layer comprises a polymer material selected from polydimethylsiloxane, poly(1 -trimethylsilyl propyne), poly(5-trimethylsilyl norborn-2-ene), or poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene).21 . The process of claim 13, wherein the nonporous high-diffusion rate layer comprises a polymer material selected from poly(1 -trimethylsilyl propyne), poly(5-trimethylsilyl norborn-2-ene), or poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene).

22. The process of claim 13, wherein the porous layer support comprises a material selected from, polyvinylidine fluoride, expanded polytetrafluoroethylene, polyacrylonitrile, polyetheretherketone, polysulfone, or polyethersulfone.

23. The process of claim 13, wherein the porous layer support comprises a material selected from polyvinylidine fluoride, expanded polytetrafluoroethylene, polyacrylonitrile, polysulfone, or polyethersulfone.

24. A process to separate an alkene from a mixture comprising an alkane in a gaseous feed stream and comprising: a) providing a thin-film composite membrane having a feed side and a permeate side and comprising: i) a gas separation layer comprising a polyphenylene ionomer; ii) a nonporous high-diffusion rate layer; and iii) a porous layer support, wherein the polyphenylene ionomer is a homopolymer or copolymer and comprises a repeating unit of formula (P):in which, each RIA is independently aryl or heteroaryl, each optionally substituted with 1 , 2 ,3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SC>3'Ag+, PC>32'Ag+2, or CC>2'Ag+, and provided that at least two of the RIA are substituted with 1 , 2, 3, 4, or 5 substituents selected from SC>3'Ag+, PC>32'Ag+2, or CC>2'Ag+; each RIB is independently H, aryl, or heteroaryl, wherein each R2 is optionally substituted with 1 , 2, 3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SC>3'Ag+, PC>32'Ag+2, or CC>2'Ag+;A1 is arylene, heteroarylene, aralkylene, or heteroaralkylene, each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;A2 is absent, arylene or heteroarylene, wherein said arylene and heteroarylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;Li is an optionally substituted linking heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, wherein said arylene, heteroarylene, aralkylene, and heteroaralkylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl;I_2 is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1, 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl; andL3 is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1, 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl; b) exposing the feed side to the gaseous feed stream; c) selectively permeating the alkene across the thin-film composite membrane; and d) producing a gaseous permeate stream at the permeate side having a higher concentration of the alkene with respect to the alkane in the mixture.

25. The process of claim 24, wherein the thickness of the gas separation layer is less than 2 microns.

26. The process of claim 24, wherein the polyphenylene ionomer has an ion exchange capacity of about 2.49 meq g-1to about 3.7 meq g-1.

27. The process of claim 24, wherein the repeating unit of formula (P) has the structure (1b):

28. The process of claim 27, wherein the polyphenylene ionomer as a copolymer comprises an additional repeating unit having the structure (2):

29. The process of claim 24, wherein the polyphenylene ionomer is a random copolymer or a block copolymer.

30. The process of claim 24, wherein the nonporous high-diffusion rate layer comprises a polymer material selected from polydimethylsiloxane, poly(1 -trimethylsilyl propyne), poly(5-trimethylsilyl norborn-2-ene), or poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene).31 . The process of claim 24, wherein the nonporous high-diffusion rate layer comprises a polymer material selected from poly(1 -trimethylsilyl propyne), poly(5-trimethylsilyl norborn-2-ene), or poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene).

32. The process of claim 24, wherein the porous layer support comprises a material selected from polyvinylidine fluoride, expanded polytetrafluoroethylene, polyacrylonitrile, polyetheretherketone, polysulfone, or polyethersulfone.

33. The process of claim 24, wherein the porous layer support comprises a material selected from polyvinylidine fluoride, expanded polytetrafluoroethylene, polyacrylonitrile, polysulfone, or polyethersulfone.

34. A process to separate sulfur dioxide or hydrogen sulfide from a mixture comprising a less permeable component in a gaseous feed stream and comprising: a) providing a thin-film composite membrane having a feed side and a permeate side and comprising: i) a gas separation layer comprising a polyphenylene ionomer; ii) a nonporous high-diffusion rate layer; and iii) a porous layer support, wherein the polyphenylene ionomer is a homopolymer or a copolymer and comprises a repeating unit of formula (P):in which, each RIA is independently aryl or heteroaryl, each optionally substituted with 1 , 2 ,3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SC>3'X+, PC>32'X+2, or CC>2'X+, wherein X+is H+or a cation, and provided that at least two of the RIA are substituted with 1 , 2, 3, 4, or 5 substituents selected from SC>3'X+, PO32-X+2, or CO2-X+; each RIB is independently H, aryl, or heteroaryl, wherein each R2 is optionally substituted with 1 , 2, 3, 4, or 5 substituents independently selected from C1-6 alkyl halo, nitro, cyano, SC>3'X+, PC>32'X+2, or CC>2'X+, wherein X+is H+or a cation;A1 is arylene, heteroarylene, aralkylene, or heteroaralkylene, each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;A2is absent, arylene or heteroarylene, wherein said arylene and heteroarylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl;Li is an optionally substituted linking heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, wherein said arylene, heteroarylene, aralkylene, and heteroaralkylene are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl;L2 is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl; andL3 is absent, arylene, or heteroarylene, wherein said arylene and heteroarylene, are each optionally substituted with 1 , 2, 3, or 4 substituents independently selected from C1-6 alkyl, halo, nitro, cyano, aryl, and heteroaryl; b) exposing the feed side to the gaseous feed stream; c) selectively permeating sulfur dioxide or hydrogen sulfide across the thin-film composite membrane; and d) producing a gaseous permeate stream at the permeate side having a higher concentration of sulfur dioxide or hydrogen sulfide with respect to the mixture with a less permeable component in the gaseous feed stream.

35. The process of claim 34, wherein the thickness of the gas separation layer is less than 2 microns.

36. The process of claim 34, wherein the polyphenylene ionomer has an ion exchange capacity of about 2.49 meq g-1to about 3.7 meq g-1.

37. The process of claim 34, wherein the repeating unit of formula (P) has the structure (1):(1).

38. The process of claim 37, wherein X+is H+, Li+, Ag+, ammonium, or alkyl ammonium.

39. The process of claim 37, wherein the polyphenylene ionomer as a copolymer comprises an additional repeating unit having the structure (2):

40. The process of claim 34, wherein the polyphenylene ionomer is a random copolymer or a block copolymer.41 . The process of claim 34, wherein the nonporous high-diffusion rate layer comprises a polymer material selected from polydimethylsiloxane, poly(1 -trimethylsilyl propyne), poly(5-trimethylsilyl norborn-2-ene), or poly(3,3-bis(trimethylsilyl)tricyclonon-7-ene).

42. The process of claim 34, wherein the porous layer support comprises a material selected from polyvinylidine fluoride, expanded polytetrafluoroethylene, polyacrylonitrile, polyetheretherketone, polysulfone, or polyethersulfone.

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