Abstract: This invention relates to a polymeric membrane composition comprising an associating polymer. The polymer coating is characterized as having hard and soft segments where the hard segment comprises TMPA, combined with HDPA. The membrane may utilize a porous substrate.

Abstract: The present invention discloses blend polymer membranes comprising thermally rearranged polymers derived from aromatic polyimides containing ortho-positioned functional groups and methods for making and using these blend polymer membranes. The blend polymer membranes described in the current invention are prepared by heat treatment of blend polymer membranes comprising aromatic polyimides containing ortho-positioned functional groups such as —OH or —SH groups. In some instances, an additional crosslinking step is performed to improve the selectivity of the membrane. These blend polymer membranes have improved flexibility, reduced cost, improved processability, and enhanced selectivity and/or permeability compared to the comparable polymer membranes that comprise a single polymer.

Abstract: The present invention is for high performance UV-cross-linked membranes from polymers of intrinsic microporosity (PIMs) and the use of such membranes for separations. More specifically, the invention involves the methods of making UV-cross-linked membranes from PIMs. These membranes were prepared by cross-linking the UV-cross-linkable membranes from PIMs by exposure to UV-radiation. Pure gas permeation test results demonstrate that the UV-cross-linked membranes from PIMs exhibit CO2/CH4 performance well above the Robeson's polymer upper bound trade-off curve for CO2/CH4 separation. They have more than doubled selectivity for CO2/CH4 and extremely high permeability of CO2 compared to the original UV-cross-linkable membranes from PIMs. These membranes also show excellent separation performance for CO2/N2, H2/CH4, O2/N2, and propylene/propane separations.

Abstract: The present invention discloses a new type of high performance polymer membranes prepared from aromatic polyimide membranes by thermal treating and crosslinking and methods for making and using these membranes. The polymer membranes were prepared from aromatic polyimide membranes by thermal treating under inert atmosphere followed by crosslinking preferably by using a UV radiation source. The aromatic polyimide membranes were made from aromatic polyimide polymers comprising both pendent hydroxy functional groups ortho to the heterocyclic imide nitrogen and cross-linkable functional groups in the polymer backbone. The membranes showed significantly improved selectivity and permeability for gas separations compared to the aromatic polyimide membranes without any treatment. The membranes can be fabricated into any convenient geometry and are not only suitable for a variety of liquid, gas, and vapor separations, but also can be used for other applications such as for catalysis and fuel cell applications.

Abstract: In the present invention high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes and methods for making and using these membranes have been developed. The cross-linked polybenzoxazole and polybenzothiazole polymer membranes are prepared by: 1) first synthesizing polyimide polymers comprising pendent functional groups (e.g., —OH or —SH) ortho to the heterocyclic imide nitrogen and cross-linkable functional groups in the polymer backbone; 2) fabricating polyimide membranes from these polymers; 3) converting the polyimide membranes to polybenzoxazole or polybenzothiazole membranes by heating under inert atmosphere such as nitrogen or vacuum; and 4) finally converting the membranes to high performance cross-linked polybenzoxazole or polybenzothiazole membranes by a crosslinking treatment, preferably UV radiation. The membranes can be fabricated into any convenient geometry.

Abstract: The present invention discloses mixed matrix membranes (MMMs) comprising ion-exchanged molecular sieves such as UZM-5 zeolite ion-exchanged with Li+ cation (Li-UZM-5) and a continuous polymer matrix and methods for making and using these membranes. These MMMs, comprising ion-exchanged molecular sieves, in the form of symmetric dense films, asymmetric flat sheets, asymmetric hollow fibers, or thin-film composites, have exhibited simultaneously increased selectivity and permeability (or permeance) over polymer-only membranes and the mixed matrix membranes made from molecular sieves that have not been ion exchanged for gas separations. These MMMs are suitable for a variety of liquid, gas, and vapor separations such as desalination of water by reverse osmosis, deep desulfurization of gasoline and diesel fuels, ethanol/water separations, pervaporation dehydration of aqueous/organic mixtures, CO2/CH4, CO2/N2, H2/CH4, O2/N2, olefin/paraffin, iso/normal paraffins separations, and other light gas mixture separations.

Abstract: A nonporous metal carbonate membrane for selective separation of CO2 from a CO2-containing fluid having a porous substrate having a feed side and a permeate side. The membrane is also suitable for removal of H2S that may be present in the fluid.

Abstract: A method for contacting a liquid with a gas in which the gas is introduced into a vessel containing at least one hollow fiber membrane having a plurality of porous hollow fibers. The liquid is introduced into a lumen of at least a portion of the plurality of porous hollow fibers at a liquid pressure sufficient to overcome a resistance to wetting of the porous hollow fibers, thereby covering at least a portion of an outer surface of the plurality of porous hollow fibers with the liquid and providing intimate contact between the gas and the liquid.

Abstract: The invention relates to an improved membrane pervaporation and vapor permeation system in which the vacuum is produced by a fluid passing through a Venturi-type nozzle. The fluid is chosen from solvents that have little or no affinity for the permeate molecules. It is applicable over process feed rates, and can be used for the separation of aromatic species from hydrocarbon.

Abstract: A reverse osmosis membrane, and methods for making and using the membrane. The membrane has a continuous, defect-free, non-porous, hydrophilic coating that reduces the susceptibility to fouling.

Abstract: A process and system for separating a fuel stream containing a low concentration of sulfur compounds from a primary fuel stream is disclosed. The process includes isolating a stage-one permeate stream and a stage-one retentate stream from the primary fuel stream, evaporating the stage-one permeate stream at a vacuum, and isolating a stage-two permeate stream and a stage-two retentate stream from the stage-one permeate stream. The stage-two retentate stream is a fuel stream containing low concentrations of sulfur compounds. The system includes a fuel supply, a stage-one separator for separating a fuel stream into a stage-one permeate stream and a stage-one retentate stream, a stage-two separator, a first supply line connecting a portion of the fuel supply to the stage-one separator, and a second supply line connecting the stage-one separator permeate stream to the stage-two separator.

Abstract: A system for producing an auxiliary fuel stream containing a low concentration of sulfur compounds from a primary fuel stream includes a first separation stage to separate a portion of a primary fuel stream into a first vapor permeate stream and a first retentate stream, a first separation stage partial condenser connected to the first vapor permeate stream condensing a portion of the first vapor permeate stream into a first liquid stage stream and a first vapor stage stream, and a second separation stage partial condenser condensing a portion of the first vapor stage stream into a second liquid stage. The first vapor permeate stream is preferable sent through a vapor phase reactive desulfurization catalyst reactor to condition any sulfur compounds present into species that can be easily separated from the fuel stream.

Abstract: Disclosed are a method and system for sweetening a raw natural gas feed stream using a multi-stage membrane separation process, and in embodiments a two-stage membrane separation process. The method and system also include use of a gas turbine which operates with an impure fuel gas stream (such as in the sense of having a relatively high CO2 and H2S acid gas contaminant content) as derived from a permeate gas stream obtained in at least the second stage of a membrane separation process, or later stages if more than two stages are employed. In embodiments, the gas turbine is coupled with an electrical generator, which generates electrical power that drives a compressor for the second stage (or higher) of the membrane separation process, as well as other process equipment associated therewith, such as air coolers and process pumps. Alternatively, the gas turbine can be coupled mechanically to the compressor employed.

Abstract: Membrane, methods of making membranes, and methods of separating gases using membranes are provided. The membranes can include at least one hydrophilic polymer, at least one cross-linking agent, at least one base, and at least one amino compound. The methods of separating gases using membranes can include contacting a gas stream containing at least one of CO2, H2S, and HCl with one side of a nonporous and at least one of CO2, H2S, and HCl selectively permeable membrane such that at least one of CO2, H2S, and HCl is selectively transported through the membrane.

Abstract: Provided is a novel system and apparatus for producing primary standard gas mixtures. The system includes providing a gas permeation device having a constant diffusion rate into a temperature controlled enclosure; connecting a supply source of a component to the permeation device; routing the component from the gas permeation device to a product container until a desired amount of said component in the product container is reached; and supplying a balance of purified gas to the product container to obtain a known concentration of component in the primary standard gas mixture.

Abstract: A method for separating aromatic hydrocarbons from a feed stream. The method includes flowing the feed stream through a first channel within a first wafer assembly that may contain an underflow distribution weir. Next, the feed stream is exposed to a first thin film polymer membrane. A stream permeates through the first thin film polymer membrane, and the permeate is produced from the first wafer assembly. The retentate is directed via a redistribution tube to a second wafer assembly that may contain an underflow distribution weir. This retentate is exposed to a second thin film polymer membrane. A second permeate stream is created that permeates through the second thin film polymer membrane. The second permeate stream is flown into the permeate zone and ultimately produced from the second wafer assembly. An apparatus for separating aromatic components from a feed stream is also disclosed. In the preferred embodiment, the apparatus includes a series of tandem wafer assemblies.

Abstract: A polyphosphazene having a glass transition temperature (“Tg”) of approximately ?20° C. or less. The polyphosphazene has at least one pendant group attached to a backbone of the polyphosphazene, wherein the pendant group has no halogen atoms. In addition, no aromatic groups are attached to an oxygen atom that is bound to a phosphorus atom of the backbone. The polyphosphazene may have a Tg ranging from approximately ?100° C. to approximately ?20° C. The polyphosphazene may be selected from the group consisting of poly[bis-3-phenyl-1-propoxy)phosphazene], poly[bis-(2-phenyl-1-ethoxy)phosphazene], poly[bis-(dodecanoxypolyethoxy)-phosphazene], and poly[bis-(2-(2-(2-?-undecylenyloxyethoxy)ethoxy)ethoxy)phosphazene]. The polyphosphazene may be used in a separation membrane to selectively separate individual gases from a gas mixture, such as to separate polar gases from nonpolar gases in the gas mixture.

Abstract: Gas separation membranes formed from polyester-polyether block copolymers which are useful for separating gases from gas mixtures. The membranes and processes are especially suited for separating polar gases from mixtures that contain polar and non-polar species. The novel membranes exhibit good permeability and permselectivity as well as durability, making them well suited for industrial applications such as removal of acid gases from natural gas and removal of carbon dioxide from synthesis gas.

Abstract: Gas separation membranes formed from polyether-urethane or polyether-urea block copolymers are useful for separating gases from gas mixtures. The membranes and processes are especially suited for separating polar gases from mixtures that contain polar and non-polar species. The novel membranes exhibit good permeability and permselectivity, as well as durability, making them well suited for industrial applications such as removal of acid gases from natural gas and removal of carbon dioxide from synthesis gas.

Abstract: Methods and apparatus for reducing moisture content of fluids comprising moisture and a sulfur-containing compound are disclosed. The methods use an acid gas resistant molecular sieve, and the sulfur-containing compounds are preferably selected from the group consisting of carbondisulfide, carbonylsulfide, and compounds within the formula Y—S—X , wherein S is sulfur, and X and Y are the same or different and are independently selected from the group consisting of hydrogen, alkyl, aryl, oxygen, and alcohol. Compositions comprising the reduced moisture fluids are also described.

Abstract: A method for the recovery or separation of sulfur oxyfluorides from gas mixtures, in which the gas mixture passes through at least one adsorption stage or membrane stage containing or consisting of zeolites with a modulus >10. The sulfur oxyfluorides fixed to the adsorbent may be made available for use after desorption. The sulfur oxyfluorides enriched through the membrane can be re-used directly.

Abstract: The invention relates to a method of separating one or more components from a multi-component gas stream comprising at least one non-acid gas component and at least one acid gas component. A multi-component gas stream at a pressure above 1,200 psia (82.8 bar) and a temperature above 120° F. (48.9° C.) with the concentration of at least one acid gas component in the gas stream being at least 20 mole percent is passed to a membrane system that selectively separates at least one acid gas component from the multi-component gas stream as a permeate stream. The permeate stream has a pressure at least 20% of the pressure of the feed pressure.

Abstract: The invention relates to a method of separating one or more components from a multi-component gas stream comprising at least one non-acid gas component and at least one acid gas component. A multi-component gas stream at a pressure above 1,200 psia (82.8 bar) and a temperature above 120° F. (48.9° C.) with the concentration of at least one acid gas component in the gas stream being at least 20 mole percent is passed to a membrane system that selectively separates at least one acid gas component from the multi-component gas stream as a permeate stream. The permeate stream has a pressure of at least 20% of the pressure of the feed pressure.

Abstract: The operating system of a gas engine accommodating to sour gas comprises a sour gas compressing and feeding part including a compressor 11 and a gas engine 12, a pre-membrane-treatment 13 for obtaining a compressed gas of proper temperature 13a removed of oil, solid mixture, etc. from the high pressure, high temperature sour gas 11a discharged from the compressor, a preceding step filter 18 for removing a minute amount of oil and water contained in the branched off gas 13b of the compressed gas of proper temperature 13a, a membrane separator for separating the gas from the filter 18 into sweet gas 21 and the hydrogen sulfide gas, and an adsorptive separator 20 through which sweet gas is obtained only at the time of starting of the compressor 11.

Abstract: A process for separating nitrogen from a multicomponent gas mixture containing nitrogen and a hydrocarbon, such as natural gas or associated gas, using gas-separation membranes selective for nitrogen 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 process for treating natural gas or other methane-rich gas to remove excess nitrogen and optionally excess carbon dioxide, water vapor or hydrogen sulfide. The invention relies on gas separation by membranes, using nitrogen/methane selective membranes. The membranes are characterized by having the capability to exhibit a nitrogen/methane selectivity between about 2 and 5 at a temperature higher than about −25° C. The gas may be brought to pipeline specification for nitrogen, and acid gases if present, without requiring the use of amine scrubbing or other acid gas removal technique.

Abstract: A process and a plant for removing the gaseous fluorocompounds or fluorosulphur compounds, such as CF4, C2F6, and SF6, present in a stream of xenon and/or krypton, by permeation via one or more membranes, such as polymer membranes. The xenon and/or krypton thus produced may then be further purified or separated by cryogenic distillation. Prior to the permeation step, the other impurities, particularly the hydrocarbons, may be removed by oxidative catalysis and subsequent adsorption of the carbon dioxides and of the water produced. The xenon, the krypton and the xenon/krypton mixtures free of gaseous fluorocompounds or fluorosulphur compounds and purified by such process can be used as plasma propulsion gas, especially for satellites, or as inter-pane insulation gas for a sealed unit, particularly for double-glazing windows.

Abstract: A process for treating natural gas or other methane-rich gas to remove excess nitrogen and carbon dioxide simultaneously. The invention relies on membrane separation using nitrogen/methane and carbon dioxide/methane selective membranes. The gas can typically be brought to pipeline specification for both components, without requiring the use of amine scrubbing or other acid gas removal technique. Where water vapor or hydrogen sulfide is present in the raw gas, these contaminants may also be removed to meet pipeline specification in a single operation.

Abstract: The present invention provides an operating method of a gas engine accommodating to sour gas containing hydrogen sulfide and the system thereof, which enables the continuous and automatic operation of the system without causing environmental pollution by creating a high grade sweet gas through removing hydrogen and water from the sour gas to be supplied to a gas engine to drive a compressor for pressure feeding natural gas.

Abstract: A method for the recovery or separation of sulfur oxyfluorides from gas mixtures, in which the gas mixture passes through at least one adsorption stage or membrane stage containing or consisting of zeolites with a modulus >10. The sulfur oxyfluorides fixed to the adsorbent may be made available for use after desorption. The sulfur oxyfluorides enriched through the membrane can be re-used directly.

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: Porous titanium silicate molecular sieves are produced in the form of a membrane capable of separating fluid molecular mixtures.

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 invention relates to an apparatus for performing membrane gas/liquid absorption at elevated pressure, comprising a pressure vessel in which a membrane unit is provided for separate feed-through of the gas phase and the liquid phase, in such a way that exchange of components to be absorbed can take place between the gas phase and the liquid phase, the flow direction of the gas phase through the absorber being essentially perpendicular to the flow direction of the liquid phase through the absorber. The invention further relates to a method for performing gas/liquid membrane absorption employing this absorber, in particular for the absorption of CO2, H2S, mercury (vapor) and/or water (vapor) from a gas phase at elevated pressure. The invention finally relates to a method for refining natural gas using the absorber and method according to the invention.

Abstract: Membrane gas adsorption is conducted wherein the gas phase contains mercury in the gaseous state and the liquid phase containing at least one oxidizing agent for mercury such that the mercury in the gaseous state is absorbed into the liquid phase, and an oxidation/reduction reaction between the mercury and the oxidizing agent takes place in one step.

Abstract: The speed of coal gas desulfurization is improved and the total size of the apparatus can be made compact. The apparatus comprises a sulfide-ion-producing portion (54), which reacts with a sulfur compound being supplied by the coal gas and produces sulfide ion S2− in molten carbonate. A sulfur compound discharge portion (53) discharges a sulfur compound produced by a reaction with sulfur discharge gas (56).

Abstract: A vaporizable solute transfer system for transferring a vaporizable solute from a gas feed mixture to an absorbent liquid comprises an absorption module, a porous membrane which divides the absorption module into a gas-feed chamber and an absorbent chamber, a regeneration module, and a nonporous material which divides the regeneration module into an absorbent chamber and a vacuum atmosphere chamber. The absorption module has gas feed mixture inlet and outlet ports which communicate with the gas feed chamber, and absorbent liquid inlet and outlet ports which communicate with the absorbent chamber. The regeneration module has a liquid absorbent inlet and outlet port which communicate with the liquid absorbent chamber, and a vacuum outlet port which communicates with the vacuum chamber.

Abstract: A process for conditioning natural gas containing C.sub.3+ hydrocarbons and/or acid gas, so that it can be used as combustion fuel to run gas-powered equipment, including compressors, in the gas field or the gas processing plant. Compared with prior art processes, the invention creates lesser quantities of low-pressure gas per unit volume of fuel gas produced. Optionally, the process can also produce an NGL product.

Abstract: A process for separating a feed gas stream containing elemental oxygen and nitrogen to produce a purified nitrogen gas stream by removing oxygen from the feed gas stream using an ion transport membrane to produce a retentate gas stream and a permeate gas stream, wherein the feed gas stream or the retentate gas stream is purified to remove impurities either before or after the separation step to produce the purified nitrogen gas stream.

Abstract: A staged adsorbent membrane system is operated to separate a gas mixture wherein more strongly adsorbed secondary components preferentially adsorb and permeate through the adsorbent membrane in the first stage. Less strongly adsorbed primary components are recovered therefrom in a nonpermeate gas product stream. Preferably two stages are utilized wherein the permeate gas from the first stage is introduced into the second stage and the nonpermeate gas from the second stage is recycled to the first stage as additional feed gas to increase the overall recovery and/or purity of the nonpermeate gas product. The two-stage membrane system is operated such that the ratio of the recovery of the primary component in the first stage to the recovery of the primary component in the second stage is less than about 1.0. The method is particularly useful for the recovery of hydrogen from hydrogen-containing gas mixtures.

Abstract: The invention relates to a method for the absorption of one or more gaseous components from a gas phase, in that the gas phase with the component(s) to be absorbed present therein is brought into contact with a liquid phase, wherein the gas phase and the liquid phase are separated by a hydrophobic membrane of a material other than polytetrafluoroethene, wherein the liquid phase comprises water and a water-miscible and/or water-soluble absorbent, and wherein the liquid phase does not give rise to any leakage from the membrane or is effective in preventing or counteracting leakage from the membrane. According to a first preferred aspect, the liquid phase comprises waterand a water-miscible and/or water-soluble organic absorbent, wherein the surface tension at 20.degree. C. has been brought to at least 60.times.10.sup.-3 N/m by adding a water-soluble salt.

Abstract: The process comprises a cold absorption step 2 for removing acid gas from natural gas using a solvent phase at a pressure P.sub.2 which delivers a purified gas 5; a step for depressurizing and separating resultant acidic solvent phase containing hydrocarbons (lines 4, 11), at a pressure P.sub.12 which is lower than pressure P.sub.2 in a column-heat exchanger 12 which delivers a purified gaseous effluent 13 overhead and a further solvent phase at the bottom (line 17) which is enriched in hydrogen sulphide; and a solvent phase regeneration step carried out in a distillation column 18 at a pressure P.sub.18 and no higher than pressure P.sub.12. A gas 29 containing essentially hydrogen sulphide which is depleted in hydrocarbons is recovered from column 18 and is a suitable feed for a Claus plant for eliminating H.sub.2 S. The regenerated hot solvent phase 20 indirectly exchanges heat with the cold acidic solvent phase from absorber 2 or separator 6. It is then recycled to the absorbent after cooling.

Abstract: A process for the removal of at least one non-water vapor component of a vaporous mixture, the basic process comprising directing a vaporous mixture against the feed side of a membrane, directing a condensable vapor sweep stream past the permeate side of the membrane in a manner such that the flow of the condensable vapor sweep is substantially countercurrent to the flow of the vaporous mixture, thereby transporting at least a portion of at least one non-water vapor component of the vaporous mixture from the feed side to the permeate side of the membrane to form a combined permeate side mixture of condensable vapor and at least one non-water vapor transported component.

Abstract: Improved processes for treating gas streams containing hydrogen sulfide and carbon dioxide, particularly natural gas streams. The processes rely on the availability of a membrane that maintains high hydrogen sulfide/methane selectivity and adequate hydrogen sulfide/carbon dioxide selectivity when measured with multicomponent gas mixtures at high pressure. The processes have three steps: an acid gas removal step, to remove both hydrogen sulfide and carbon dioxide from the primary gas stream; a membrane fractionation step, to separate hydrogen sulfide from carbon dioxide and create a highly hydrogen-sulfide-concentrated fraction; and a sulfur-fixing step.

Abstract: Improved processes for treating gas streams containing hydrogen sulfide and carbon dioxide, particularly gas streams from fossil fuel gasification processes. The processes rely on the availability of a membrane that maintains high hydrogen sulfide/methane selectivity and adequate hydrogen sulfide/carbon dioxide selectivity when measured with multicomponent gas mixtures at high pressure. The processes have three steps: an acid gas removal step, to remove both hydrogen sulfide and carbon dioxide from the primary gas stream; a membrane fractionation step, to separate hydrogen sulfide from carbon dioxide and create a highly hydrogen-sulfide-concentrated fraction; and a sulfur-fixing step.

Abstract: A process for removing inorganic components from water is disclosed. The process involves gas stripping followed by membrane separation treatment of the stripping gas. The stripping step can be carried out using one or multiple gas strippers and using air or any other gas as stripping gas. The membrane separation step can be carried out using a single-stage membrane unit or a multistage unit. Apparatus for carrying out the process is also disclosed. The process is particularly suited for treatment of contaminated groundwater or industrial wastewater.

Abstract: Improved membranes and improved membrane processes for treating gas streams containing hydrogen sulfide, carbon dioxide, water vapor and methane, particularly natural gas streams. The processes rely on the availability of two membrane types, one of which has a hydrogen sulfide/methane selectivity of at least about 40 when measured with multicomponent gas mixtures at high pressure. Based on the different permeation properties of the two membrane types, optimized separation processes can be designed.

Abstract: Improved processes for treating gas streams containing hydrogen sulfide, carbon dioxide, water vapor and methane, particularly natural gas streams. The processes rely on the availability of two membrane types, one of which has a hydrogen sulfide/methane selectivity of at least about 40 when measured with multicomponent gas mixtures at high pressure. Based on the different permeation properties of the two membrane types, optimized separation processes can be designed. The membrane separation is combined with non-membrane treatment of the residue and/or permeate streams.

Abstract: Improved membranes and improved membrane processes for treating gas streams containing hydrogen sulfide and methane, plus water vapor, carbon dioxide or both. The processes rely on the availability of two membrane types, one of which has a high hydrogen sulfide/methane selectivity and a high water vapor/methane selectivity, when measured with multicomponent gas mixtures at high pressures. Based on the different permeation properties of the two membrane types, optimized separation processes can be designed. In favorable cases, the processes can simultaneously dehydrate the gas stream and remove the hydrogen sulfide to very low levels.

Abstract: Acid gases are separated from a gas stream by bringing the gas stream into contact with a multilayer composite membrane comprising a nonselective polymeric support layer and an active separating layer comprising a polyelectrolyte polymer which contains cationic groups which are electrostatically associated with anions for which the pK.sub.a of the conjugate acid is greater than 3.