Abstract: A device useful for separating the components of gas mixtures includes a selectively gas permeable mixed matrix membrane of a dispersed phase of chabazite type molecular sieve particles uniformly distributed throughout a continuous phase of a polymer. The membrane can be fabricated by dispersing the chabazite type molecular sieve particles in a solution of the polymer dissolved in a suitable solvent, and then forming the suspension into a membrane structure by conventional polymer membrane fabrication techniques. Mixed matrix membranes with chabazite type molecular sieves are well suited to separations of oxygen, carbon dioxide or helium from nitrogen or methane.

Abstract: The invention is a process to recover a high pressure hydrogen rich gas stream from synthesis gas. The synthesis gas is separated into a hydrogen-enriched permeate and a hydrogen-depleted non-permeate by use of a membrane. The permeate experiences a substantial pressure drop of between about 500 psi (23.9 KPa) to 700 psi (33.5 kPa) as it passes through the membrane. The pressure of the non-permeate gas is unchanged by the membrane. The non-permeate gas pressure is reduced to between about 200 and about 500 psi for use in a combustion turbine. The hydrogen-rich permeate is compressed to between about 800 and 3000 psi (143.6 kPa) for use in subsequent operations, i.e., for use in hydrotreating of crude oil. The non-permeate gas is expanded in a manner to provide energy which is used to compress the permeate gas.

Abstract: A gas-liquid separation membrane is provided with high reliability and performance while having gas-permeable pores formed independently of each other in even pore size and in uniform distribution. The gas-liquid separation membrane has a plurality of gas-permeable pores that permit permeation of gas and that prevent permeation of liquid by capillary force, and the plurality of gas-permeable pores are formed independently of each other and in even pore size by laser machining.

Abstract: A fully perfluorinated thermoplastic hollow fiber membrane fluid-fluid contactor and a process for manufacturing the contactor is described. The contactor has a unitary end structure produced by a single step potting and bonding process. The contactor can be operated with low surface tension liquids and in harsh chemical environments.

Abstract: The present invention provides a CO2-selective membrane process that is useful for the purification and/or water gas shift reaction of a reformed gas, generated from on-board reforming of a fuel, e.g., hydrocarbon, gasoline, diesel, methanol or natural gas, to hydrogen for fuel cell vehicles. Another embodiment of the present invention is directed toward a composition comprising a hydrophylic polymer and at least one ammonium halide salt, the ammonium halide salt being present in an amount ranging from about 10 to 80 wt % based on the total weight of the composition. The composition is suitable in formation of a membrane useful for separating CO2 from a CO2-containing gas, particularly from an on-board reformed gas for the CO2-selective membrane process.

Abstract: Oleophobic and hydrophobic filters for filter venting applications are made by forming a fluorosulfone coating on the surface of a filtration substrate. The filters have high water penetration pressures and high air permeabilities. The coatings are formed by grafting a fluorosulfone oligomer to a polymeric substrate.

Abstract: A high carbon content membrane and method for making the same are disclosed. The carbon membrane includes an asymmetric hollow filamentary carbon membrane, including a partial carbonization product of an asymmetric hollow filament including an aromatic imide polymer material. The carbon membrane is at least 95 weight percent carbon, and has a dense layer located in the outside surface portion of the hollow filamentary membrane and a porous base layer continued from the dense layer and located in the inside portion of the hollow filamentary membrane. A process for separating CO2 from natural gas is described including: contacting a mixture of CO2 and natural gas with a first side of a carbon membrane in a manner to cause a portion of the mixture to pass through the carbon membrane to a permeate side. The resulting mixture on the permeate side becomes enriched in CO2 over that of the mixture on the first side. The contacting step occurs at a pressure of at least about 200 psia.

Abstract: A process for separating hydrogen from a multicomponent gas mixture containing hydrogen and a hydrocarbon, using gas-separation membranes selective for hydrogen over the hydrocarbon. The membranes use a selective layer made from a polymer having repeating units of a fluorinated polymer, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment, and good recovery after exposure to liquid aromatic hydrocarbons.

Abstract: A method for fabricating a composite membrane includes coating a substrate, such as, for example, an asymmetrical porous hollow fiber substrate, with a solution which includes a perfluorinated polymer and a perfluorinated solvent. Prior to coating, the substrate is impregnated with an impregnation fluid which is immiscible with the perfluorinated solvent. The method of the invention further includes removing the perfluorinated solvent and the impregnation fluid. A composite membrane includes a porous asymmetric hollow fiber substrate having an outer surface coated with a perfluoropolymer coating. Separation devices which include composite membranes and methods of separating a fluid mixture into a fraction enriched in a first component and a fraction depleted in that component also are described.

Abstract: To prevent a pressure container of a battery, a condenser or the like from exploding due to an abnormal increase of a pressure within the pressure container without having a rubber breaking plate with which it is hard to control the breaking pressure, there is provided a breaking plate integrally formed with a resin seal plate main body for closing an opening portion of a pressure container, a thin portion integrally formed between the seal plate main body and the breaking plate and being thinner than the breaking plate, and an inclined surface portion formed to be gradually thicker from a thickness of the thin portion and provided in a peripheral edge portion of the breaking plate.

Abstract: Liquid crystalline polymer blended gas separation membranes are obtained by melting and processing 50˜99 wt % of a thermoplastic resin, 1˜50 wt % of a thermotropic liquid crystalline polymer and 0.1˜10 wt % of a compatibilizer based on the weight of the thermotropic liquid crystalline polymer. A method for fabricating liquid crystalline polymer blended gas separation membrane includes the steps of: mixing 50˜99 wt % of thermoplastic resin, 1˜50 wt % of thermotropic liquid crystalline polymer and 0.1˜10 wt % of compatibilizer based on the weight of the thermotropic liquid crystalline polymer; and biaxially extruding the resulting blend melt from an extrusion die of a film blowing apparatus to fabricate a film. The gas separation membrane exhibits high permeability exceeding the limit value which has been hardly overcome by the existing separation membranes.

Abstract: A mixed matrix membrane for gas separations is provided with a nonporous continuous phase of a polymer and a dispersed phase of molecular sieve particles reacted with a monofunctional organosilicon compound. The monofunctional organosilicon compound is characterized by (a) at least one silicon substituent group which reacts or is compatible with the polymer, and (b) at most one displaceable radical that can react with the molecular sieve. A process for making a selectively gas permeable mixed matrix membrane involves reacting a molecular sieve with the monofunctional organosilicon compound, uniformly dispersing the reacted sieve with a polymer, and forming the resulting mixed matrix composition into a membrane structure. These mixed matrix membranes provide an improved combination of permeability and selectivity as compared to polymer-only membranes and mixed matrix membranes in which the molecular sieve is not reacted with a monofunctional organosilicon compound.

Abstract: Composite membranes capable of separating p-xylene from mixtures including p-xylene and m-xylene, and processes for purifying p-xylene using the membranes, are disclosed. The membranes are polymer membranes with a thickness of between about 10 and 1000 microns that include non-interconnected zeolite particles less than 5 microns. In one embodiment, a relatively thin polymer layer (0.5-3 microns) that includes zeolite particles is adjacent to a relatively thick polymer layer which may or may not include zeolite particles, where the thickness of the two layers is between about 10 and 1000 microns. The preferred ratio of zeolite/polymer is about 0.2 by weight. A preferred method for preparing the composite is by dispersing the zeolite in a polymer solution, casting a film of the polymer solution, and evaporating the solvent to form a polymeric film. The polymer permits passage of p-xylene and m-xylene in the vapor state, such that p-xylene diffuses at the same or a faster rate through the polymer.

Abstract: A process for preparing polyimide gas separation membranes is disclosed. The process involves preparing polyamic acid salt membrane precursors that are converted into polyimide membranes by mild thermal or chemical treatments. The gas separation processes that utilize these polyimide membranes are further disclosed.

Abstract: Process for producing integrally asymmetrical hydrophobic polyolefinic membranes with a separation layer, in particular for gas exchange, via thermally induced liquid-liquid phase separation. A solution of at least one polyolefin in a solvent system containing a compound A and a compound B is extruded to form a shaped object. Compound A is a strong solvent and compound B a weak non-solvent for the polymer. After leaving the die, the shaped object is cooled using a solid or liquid cooling medium, which does not dissolve the polymer and does not react chemically with it, until the phase separation and solidification of the high-polymer-content phase take place.

Abstract: Apparatus for removing non-condensible gas from a working fluid utilized in a thermodynamic system comprises a membrane having an upstream side operatively connected to the thermodynamic system so that the upstream side of the membrane receives a portion of the working fluid. The first membrane separates the non-condensible gas from the working fluid. A pump operatively associated with the membrane causes the portion of the working fluid to contact the membrane and to be returned to the thermodynamic system.

Abstract: An asymmetric membrane is formed using a mixture of two or more different polymers including at least one type of polyimide. It is thereby possible to produce a gas separation membrane with low permeation resistance (a high permeation rate) for permeate gases passing through the porous layer of the membrane, which also maintains a practical level of mechanical strength of the membrane and has excellent water resistance and hot water resistance.

Abstract: A downhole preferential hydrocarbon gas recovery system and method employ preferentially selective materials to separate the hydrocarbon gas from contaminants. According to one aspect of the invention, the preferentially selective materials are arranged in tubes with the hydrocarbon gas flowing through the tubes and the contaminants permeating out through the preferentially selective material.

Abstract: The invention relates to sulphonated polyimides, notably of formula (I) The invention also relates to an ion exchange membrane that includes such a polyimide and a fuel cell that includes such a membrane. The membranes of the invention have excellent durability and low cost and the fuel cells can be used, in particular, in electric vehicles.

Abstract: The process is characterised by sulfonating a partially brominated poly(phenylene oxide). The gas separation material so formed may be made into a membrane and is useful in separating component gases from a gas mixture.

Abstract: Water- and ion-conducting membranes composed of sulfonated statistical arylvinyl polymers, the arylvinyl polymer comprising at least one arylvinyl monomer and at least one olefin monomer and wherein aromatic moieties derived from the arylvinyl monomer are at least partially sulfonated, are used as proton-conducting membranes for production of electricity, as water-conducting membranes for humidification of fuel gases in fuel cells and heat and moisture exchange in heating/ventilation/air conditioning systems. Water-conducting membranes composed of sulfonated arylvinyl polymers, the arylvinyl polymer comprising at least one arylvinyl monomer and wherein aromatic moieties derived from the arylvinyl monomer are at least partially sulfonated are used for desalination of seawater.

Abstract: The separation factor with respect to a gas binary of a selectively gas permeable membrane of a fluoropolymer can be increased by fabricating the membrane from a composition of a blend of the fluoropolymer with a nonfugitive, nonpolymeric fluorinated adjuvant. The composition can be made by dissolving the adjuvant and the polymer in a suitably compatible solvent then forming the membrane from the solution for example by casting, dipping, or spraying the solution on a substrate and devolatilizing the solvent. The extent of the selectivity increase varies widely with the combination of fluoropolymer and adjuvant and largely increases in direct relation with the proportion of adjuvant in the membrane composition.

Abstract: A membrane contactor degasses a liquid. A liquid having a dissolved gas is introduced into a contactor which is connected to a vacuum source. The contactor has a perforated core, a plurality of hollow fiber membranes, a tube sheet affixing each end of the fibers, and a shell having a liquid egress. The shell encloses the fibers, the tube sheet, and the core. The hollow fiber lumens are in fluid communication with the vacuum source. Liquid enters the contactor via the core's open end radially exits the core, crosses over the membranes within the shell, and exits the contactor by the liquid egress. The dissolved gas thereby diffuses from the liquid across the membrane into the lumen. The liquid exiting may have a dissolved gas content to less than 1 ppb.

Abstract: Improved polymer blends, and polymer blend membranes having improved mechanical properties are provided by alteration of the critical solution temperature of the polymer blend spinning solution through the incorporation of organic or inorganic complexing agents.

Abstract: A gas separation membrane is formed from a copolyimide produced by copolymerization of monomers which include o-tolidine sulfone, at least one other hydrophilic diamine and 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride. One or more additional aromatic dianhydrides can optionally be included. The novel membrane exhibits an excellent combination of high selectivity of gases to be separated from a gas mixture, high permeability and strong solvent resistance to hydrocarbon chemicals. The membrane is therefore useful in separating gases from gas mixtures in which vapor or liquid hydrocarbon contaminants are present, for example in the separation of carbon dioxide from methane and/or nitrogen in the purification of natural gas.

Abstract: The invention relates to a method of making an epoxysilicone coated membrane by coating a porous asymmetric membrane layer with a UV-curable controlled release epoxysilicone coating. A mixture of the epoxysilicone resin and an onium photocatalyst are applied to the porous asymmetric membrane layer in a dilute non-polar solution and cured by UV or electron beam radiation to produce a dry epoxysilicone coated membrane. The porous asymmetric membrane layer is comprised of an asymmetric cellulosic membrane or an asymmetric polymer membrane with a low selectivity. The epoxysilicone coating was found to provide the asymmetric membrane layer with improved selectivity which extends to separation temperatures below 70° C. and provides stable flux rates. Membranes produced in this manner are useful for the separation of gases such as carbon dioxide from natural gas.

Abstract: The present invention provides a compact and inexpensive air-permeable cap and an outdoor lamp, automobile lamp and automobile electrical component including such an air-permeable cap. A novel air-permeable cap is provided including a closed-end cylindrical cover member, a substantially cylindrical body fitted in the closed-end cylindrical cover member, and an air passage formed between the inner wall of the closed-end cylindrical cover member and the outer wall of the substantially cylindrical body and between the bottom surface of the closed-end cylindrical cover member and the lower end of the substantially cylindrical body, wherein the mounting portion at which the air-permeable cap is mounted on the mounting opening of the housing is formed at the top of the substantially cylindrical body.

Abstract: A property transfer assembly for transferring properties from a first flowing fluid to a second flowing fluid comprising a plurality of spacer components in a stacked relationship including at least one first spacer component defining a first path of travel for the first flow and at least one second spacer component defining a second path of travel for the second flow, the first and second spacer components being separated in a spaced relationship; and a transfer sheet located between the spacer components and adapted to transfer heat therethrough from the warmer to the cooler flow and to transfer moisture therethrough from the moister to the drier fluid.

Abstract: Improved polymer blends, and polymer blend membranes having improved mechanical properties are provided by alteration of the critical solution temperature of the polymer blend spinning solution through the incorporation of organic or inorganic completing agents.

Abstract: A gas recovery device utilizes membranes of a gas permeable, liquid impermeable substance to strip gas from gas-containing liquids, such as brine in subterranean geological formations. The device includes a shell defined by perforated outer walls and a plurality of elongated permeation tubes. Only one end of the tubes is attached to a plenum with the tube lumina in fluid communication with the plenum. The remainder of the tubes is not anchored and therefore is free to move. Substantially liquid-free gas is removed from the plenum through a pipe to a remote facility for storage and use. The gas recovery device can be deployed within the casing of a well suspended by the product discharge pipe and immersed in gas-containing brine flowing from a natural geological formation. The brine seeps into the well casing and flows through the perforations to surround the permeation tubes.

Abstract: A multi-phase solid electrolyte ion transport membrane comprising at least two phases wherein one of the phases comprises an oxygen ion single conductive material, or a mixed conductor. The other phase comprises an electronically-conductive metal or metal oxide that is incorporated into the membrane by deposition of the metal or metal oxide from a polymer made by polymerizing a chelated metal dispersion in a polymerizable organic monomer or prepolymer. The multi-phase composition advantageously comprises a first phase of a ceramic material and a second phase of a metal or metal oxide bound to a surface of the ceramic material. The multi-phase composition is advantageously prepared in an in-situ fashion before fabricating the membrane matrix. As another alternative, a preformed ceramic matrix is surface-coated with a metal or metal oxide.

Abstract: Watertight sealed type electric motor 10, with a clearance between a core wire and a cover 24 of a lead wire 20, which is a vent path between the interior of the motor 10 and the outside, which clearance is covered a vent filter 28, which permits only gas to pass therethrough, and is attached to the lead wire 20 so as to cover an opening end portion of the cover 24.

Abstract: Separation membranes excellent in strength, durability, heat resistance and solvent resistance as well as in balance between substance separation properties and substance permeability are disclosed, which are formed from polyhydrazidoimide resins, and preferably comprises a non-porous dense layer formed from a polyhydrazidoimide resin obtained from the reaction of an aromatic tetracarboxylic dianhydride such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and an aromatic dihydrazide such as isophthalic dihydrazide as essential components.

Abstract: A novel polyimide having a repeating structure unit expressed by the following general formula (1), a method for manufacturing the same, a gas separation membrane using the novel polyimide and the method for manufacturing the same. The gas separation membrane using this polyimide is excellent in gas permeable performance and separation selectivity for gas, for example, carbon dioxide, methane, etc.General Formula (1) ##STR1## where R denotes a quadrivalent organic group.

Abstract: Gas separation membranes are prepared from sulfonated polyimides exhibiting desirable gas separation characteristics, combined with good film-forming properties and desirable solubility characteristics.

Abstract: A supported gas separation membrane for separating a particular component from a mixture of gases, a process for its manufacture and the use of the membrane in the separation of gases are provided in which the supported gas separation membrane comprises (a) a porous polymeric support layer and (b) an asymmetric gas separation membrane layer formed from a polyimide having repeating units of the general formula: ##STR1## wherein R is: ##STR2## and x is an integer.

Abstract: This invention provides a polyamide separation membrane, prepared from high molecular weight polyamide having a repeating unit represented by the formula (I) and a process for separating gaseous mixtures using them. ##STR1## wherein, R is an aliphatic or aromatic organic group derived from dicarboxylic acid or halide. The polyamide separation membrane according to the present invention has a large free volume and good permeation properties such as permeability and permeation selectivity.

Abstract: Processes and systems to recover at least one perfluorocompound gas from a gas mixture are provided. In one embodiment the inventive process comprises the steps of a) providing a gas mixture comprising at least one perfluorocompound gas and at least one carrier gas, the gas mixture being at a predetermined pressure; b) providing at least one glassy polymer membrane having a feed side and a permeate side; c) contacting the feed side of the at least one membrane with the gas mixture; d) withdrawing from the feed side of the membrane as a non-permeate stream at a pressure which is substantially equal to the predetermined pressure a concentrated gas mixture comprising essentially the at least one perfluorocompound gas; and e) withdrawing from the permeate side of the membrane as a permeate stream a depleted gas mixture comprising essentially the at least one carrier gas.

Abstract: The invention provides for gas separation membranes with superior gas transport properties made from certain two- and three-component blends of polyethersulfone with aromatic polyimides, to provide a gas separation membrane with superior productivity and good selectivity.

Abstract: Disclosed are a first vent filter member which includes: an elastomer member made of a thermoplastic elastomer to which a water-repellent film can be fixed by fusion and having a cylindrical form whose one end part serves as an opening for insertion of a mounting part of a base; a water-repellent film thermally fusion-bonded to the other end part of the elastomer member; and a covering cap which protects the water-repellent film and has been fitted and fixed to the elastomer member in such a manner that a vent passageway is formed between the elastomer member and the covering cap, and a second vent filter member which includes: an elastomer member made of a thermoplastic elastomer to which a water-repellent film can be fixed by fusion and having a disk form which has on one side thereof a tapered insertional part to be inserted into a mounting part, is blocked on the other side with a mist barrier cover, and has a sealing/fixing part on the outer periphery thereof and a vent passageway extending from said one

Abstract: A polyimide resin semipermeable membrane has a continuous structure of a homogeneous skin layer part having an average thickness of 5-1000 nm and a porous layer that is made of the same materials and has the same thickness as the skin layer. The porous layer is formed by the void structure having the average hole diameter of less than 3 .mu.m so that a gas separation membrane can be provided, having high permeability and satisfying cost efficiency requirements can be provided. The above-mentioned membrane is formed by the following steps: a solution is made by adding diethylene glycol dimethyl ether into polyimide; the obtained solution is left for deaeration and adjusted; the film-forming solution is cast on a polyester nonwoven cloth, which serves as a supporting layer, with an applicator; the solution is soaked in water as a solidifying solution for 5 minutes and in a water. Thus semipermeable membrane comprising the homogeneous skin layer part and the porous layer.

Abstract: This invention relates to a method of an apparatus and method for separating component gases in a gas mixture employing a glassy polymer membrane at temperatures at or slightly above the freezing point of any liquid present so as to achieve superior separator of gas components. The composition of certain monomers and polymers are claimed.

Abstract: Gas separation membranes having enhanced selectivity for a mixture of gases is disclosed. The membranes may be asymmetric or multicomponent. The membranes surprisingly provide selectivity for gases in a mixture that approaches the relative selectivity of the single gas components. Preferably the membrane provides selectivity for a mixture of gases which is at least 65%, preferably 80%, of the relative selectivity of the corresponding single gases. A process for making improved gas separation membranes is also disclosed.

Abstract: The present invention provides a process for preparing membranes using novel silicon containing polyarylates of Formula I ##STR1## where R.sub.1 to R.sub.8 represent hydrogen, alkyl groups containing 1 to 5 methylene group or halogen atoms, R.sub.9 and R.sub.10 represents alkyl groups containing 1 to 5 carbon atoms or CF.sub.3 group and R.sub.11 and R.sub.12 represent alkyl groups with 1 to 5 carbon atoms or phenyl groups.

Abstract: A fluorine-containing polyimide gas separation membrane which is pinhole-free, uniform over a large area, and has a high permeability and a high separation factor .alpha. is provided. A polyimide resin is dissolved in at least one solvent selected from the group consisting of an organic solvent (A) or (B). The organic solvent (A) has a dielectric constant of 30 or less and a dipole moment of 3.0 D or less. The organic solvent (B) mainly contains an organic solvent having at least one ether bonding in the molecular unit. In the next step, the polyimide resin is dipped in a solvent (C) in order for desolvation. The solvent (C) does not dissolve the fluorine-containing polyimide resin while it is miscible with the organic solvent (A) or (B). As a result, an asymmetric gas separation membrane is formed. The fluorine-containing polyimide resin layer comprises a skin layer the thickness L.sub.1 thereof is about 40 nm and a sponge like layer the thickness L.sub.2 thereof is about 30 .mu.m.

Abstract: Processes and systems to recover at least one perfluorocompound gas from a gas mixture are provided. In one embodiment the inventive process comprises the steps of a) providing a gas mixture comprising at least one perfluorocompound gas and at least one carrier gas, the gas mixture being at a predetermined pressure; b) providing at least one glassy polymer membrane having a feed side and a permeate side; c) contacting the feed side of the at least one membrane with the gas mixture; d) withdrawing from the feed side of the membrane as a non-permeate stream at a pressure which is substantially equal to the predetermined pressure a concentrated gas mixture comprising essentially the at least one perfluorocompound gas; and e) withdrawing from the permeate side of the membrane as a permeate stream a depleted gas mixture comprising essentially the at least one carrier gas.

Abstract: A device and method for selectively removing one or more components from a multicomponent gas/vapor mixture by membrane fractionation. The membrane fractionation gas removal system preferably comprises: a feed chamber which contains the gas/vapor mixture; at least one porous membrane having a first side which contacts the gas/vapor mixture in the feed chamber, and a second side; at least one nonporous membrane having a first side which contacts the second side of the at least one porous membrane, and a second side, the nonporous membrane having a permeability selective to one or more components; an exit chamber connected to the second side of the at least one nonporous membrane such that the component exiting the nonporous gas enters the exit chamber; and an evacuation member connected to the exit chamber for evacuating one or more components from within the exit chamber.

Abstract: A homogeneous membrane or an asymmetric membrane which is made of polyimide resin containing fluorine as a main component and has high separation and permeation properties, is used in a method of separating unsaturated hydrocarbon from a mixture of unsaturated and saturated hydrocarbon. The method includes the steps of contacting the mixture onto the membrane made of the polyimide resin having a repeating unit shown in the following formula as a main component, selectively permeating unsaturated hydrocarbon through the membrane, and separating unsaturated hydrocarbon from the mixture. The membrane satisfies the condition of a solubility coefficient ratio between unsaturated and saturated hydrocarbon.gtoreq.1.2 at 25.degree. C. and more than 50 Torr when the absorption of hydrocarbon to the polyimide resin is in equilibrium.

Abstract: An apparatus (10) and a method are described for extracting gas from a liquid containing dissolved gas. The liquid is pumped from an external reservoir (40) of the liquid into a separation cell (14) by a liquid-pumping chamber (11). In separation cell (14) a permselective membrane (17) effects extraction of the dissolved gas from the liquid. A gas-pumping chamber (23) pumps the extracted gas from the permeate chamber (16) of the separation cell (14) to a collection station (27), where the extracted gas can be analyzed, separated into its individual components, or stored, as desired.

Abstract: Novel polyimide gas separation membranes and the process of using such membranes to separate gases are disclosed. The polyimides are formed from rigid aromatic dianhydrides and aromatic diamines that contain sulfonic acid, salified sulfonic acid, or sulfonic ester groups. Methods of preparing improved composite gas separation membranes from the sulfonated polyimides of this invention are disclosed.