Abstract: A process of producing an asymmetric membrane of multicomponent polyimide. The process includes the steps of (1) preparing a multicomponent polyimide blend solution by mixing a polyimide component A having a number-averaged polymerization index NA and a polyimide component B having a number-averaged polymerization index NB, wherein NA and NB satisfies equation 1: 2.35×NA?2.09<NB<450×NA?1.12??1 (2) subjecting the multicomponent polyimide blend solution to further polymerization and imidation reaction, and (3) causing a phase inversion in the resulting multicomponent polyimide blend solution to form an asymmetric membrane. The polyimide component A is raw materials of polyimide A containing a fluorine atom in the chemical structure thereof and/or a polymerization and imidation reaction product of the raw materials. The polyimide component B is raw materials of polyimide B and/or a polymerization and imidation reaction product of the raw materials.

Abstract: The present invention discloses a new type of high performance polymer membranes derived from aromatic polyimide membranes and methods for making and using these membranes. The polymer membranes described in the present invention were derived from aromatic polyimide membranes by crosslinking followed by thermal treating. 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 high performance polymer membranes showed significantly improved permeability for gas separations compared to the aromatic polyimide membranes without any treatment. The high performance polymer membranes also showed significantly improved selectivity for gas separations compared to the thermal-treated but non-UV-crosslinked aromatic polyimide membranes.

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: 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 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: The subject of the invention is method and envelope structure for handling gas diffusion of airships and other balloons to significantly decrease, respectively fully eliminate envelope diffusion of gases through envelopes of airships and other balloons. During the method according to the invention the gases diffused through the envelope (8, 9) of airships and other balloons are collected into a separator space (2). These gases are separated from the mixture of this separator space by physical and/or chemical action and forwarded back to their sources. The invention is further an envelope structure for handling gas diffusion of airships and other balloons for applying methods according to the invention.

Abstract: Helium is recovered from gas streams containing high concentrations of hydrogen gas and low concentrations of helium gas, such as from the recycle stream from the production of ammonia. The inventive process provides for an integrated process for the recovery of both an enriched helium gas stream product and a high purity hydrogen gas stream product.

Abstract: The processing of gas mixtures, in particular, of respiration gases for ventilated patients. The processing according to the invention relates, in particular, to the use of selective gas separation membranes for the retention of noble gases in the exhaled air of ventilated patients. The gas separation membrane is an active separator which is integrated in a ventilator. The separation membrane separates the noble gases from the remainder of the residual of the exhaled air by selectively retaining the noble gases. Thus, it is possible to provide a ventilator which enables the application of noble gases, in particular xenon, as an anesthetic preferably with low loss and as simple as possible.

Abstract: A process of producing an asymmetric membrane of multicomponent polyimide. The process includes the steps of (1) preparing a multicomponent polyimide blend solution by mixing a polyimide component A having a number-averaged polymerization index NA and a polyimide component B having a number-averaged polymerization index NB, wherein NA and NB satisfies equation 1: 2.35×NA?2.09<NB<450×NA?1.12??1 (2) subjecting the multicomponent polyimide blend solution to further polymerization and imidation reaction, and (3) causing a phase inversion in the resulting multicomponent polyimide blend solution to form an asymmetric membrane. The polyimide component A is raw materials of polyimide A containing a fluorine atom in the chemical structure thereof and/or a polymerization and imidation reaction product of the raw materials. The polyimide component B is raw materials of polyimide B and/or a polymerization and imidation reaction product of the raw materials.

Abstract: A polyimide MMC membrane useful for the production of oxygen-enriched air or nitrogen-enriched-air, for the separation of carbon dioxide from hydrocarbons or nitrogen, and the separation of helium or hydrogen from various streams. Membranes of polyimide polymers, such as polyimide polymers sold under the tradename P-84, are mixed with molecular sieve materials, such as SSZ-13, to make MMC membranes. The MMC membranes of the invention provide improved membrane performance compared to polymer only membranes, particularly when used to form asymmetric film membranes or hollow fiber membranes. The MMC films exhibit consistent permeation performance as dense film or asymmetric membranes, and do not interact with components of the process streams, such as organic solvents. The membranes of the invention exhibit particularly surprisingly good selectivity for the fluids of interest.

Abstract: The subject of the present invention is a method for producing a gas separation membrane, comprising the deposition of a film from a silica sol onto a porous support followed by heat treatment of the film thus deposited, in which the silica sol deposited is prepared by hydrolysing a silicon alkoxide in the presence of a doping amount of a precursor of an oxide of a trivalent element, especially boron or aluminium. The invention also relates to the membranes as obtained by this method, and also to their uses, especially for the separation of helium or hydrogen at high temperature, and in particular for removing impurities in helium streams.

Abstract: A gas transmitter having selective gas permeable surfaces includes a support disc that is provided with a plurality of through openings. The support disc is made from a semiconductor material. The transmitter further includes a membrane covering the openings in the support disc thereby forming the selective gas permeable surfaces and further controls the temperature of the membrane.

Abstract: The present invention relates to composite structured adsorbents and methods of use therefor. The invention more particularly relates to composite structured adsorbents that can include a multi-channel framework (e.g., monoliths), the channels of the multi-channel framework containing adsorbent beads particles therein, with a channel-to-particle diameter ratio in the range of 1 to 10, more preferably 1 to 7 and even more preferably 1 to 5. In the case of non-spherical particles, the hydraulic diameter is used in the calculation of the channel-to-particle diameter. The composite structured adsorbents of the present invention can be used in various industrial applications, for example in pressure swing adsorption (PSA) or vacuum pressure swing adsorption (VPSA) processes to produce O2 from air.

Abstract: A gas recovery system comprising a source of gas having a preselected concentration of a desired component (9), at least one application (1) that adds impurities to said gas, and at least one an adsorption system (6) that purifies said gas to produce a purified gas for re-use in application (1), wherein said at least one adsorption system includes at least one adsorbent bed (A) having at least three layers of adsorbents. A recovery process is also disclosed.

Abstract: Methods for recovering and recycling helium and unreacted chlorine from a process for manufacturing optical fiber are disclosed. Helium-rich and chlorine-rich gas streams are recovered from the consolidation furnace and separated. The helium-rich stream is dried and blended with make-up helium and the chlorine-rich stream is purified and blended with make-up chlorine so that each may be reused in the optical fiber production process.

Abstract: Gas supplying method and system in which effective component gas in exhaust gas can be separated and purified efficiently to be resupplied regardless of variation in the flow rate or composition of the exhaust gas and consumed gas can be replenished efficiently. In a method for collecting exhaust gas discharged from a gas using facility, separating/purifying effective component gas contained in the exhaust gas and supplying the effective component gas thus obtained to the gas using facility, the exhaust gas discharged from the gas using facility is added with a replenishing gas of the same components as the effective component gas before the effective component gas is separated and purified.

Abstract: The present invention relates to a gas recycling system that includes a) a source of gas having a predetermined purity; b) an application system that uses the gas and adds contaminants to the gas; c) an adsorption system for removing the contaminants from the gas to produce a purified gas and a waste gas; d) a gas purity analyzer for measuring the amount of the contaminants in the waste gas; and e) conduits connecting the gas source to the application system, and the application system to the adsorption system.

Abstract: A gas-selective permeable membrane (1) utilisable in a leak detector for a gas, more particularly helium, comprising a sheet-like body (11) on which at least one reduced thickness area (15) is defined by removing a material from the sheet-like body. This at least one reduced thickness area (15) being permeable to at least one gas and formed so as that it is partly surrounded by a thicker and substantially gas-impermeable area (16) ensuring the structural strength of the membrane.

Abstract: A method and apparatus is disclosed for producing fluorine by providing a contained fluorine precursor source located proximate to or remotely from an adsorbent bed, optionally in a replaceable unit that may be a replaceable module comprising both the fluorine source and the adsorbent bed. Fluorine derived preferably from a nitrogen trifluoride source and used to remove deposited silicon-containing impurities in reaction chambers is reclaimed from an adsorbent bed, and made available to the reaction chamber as a supplemental fluorine source to reduce the total required amount of nitrogen trifluoride source gas. The separation column adsorbent is regenerated in cyclical intervals using a reverse flow of inert gas.

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: The invention relates to preparation and uses of novel polymeric materials, polyimide amic acid salts (PIAAS). The use of these materials for the fabrication of fluid separation membranes is further disclosed.

Abstract: The invention concerns a method and an installation for purifying impure helium. Said method consists in subjecting the helium to at least two successive steps: (a) cryogenic refrigeration of impure helium so as to eliminate by condensation at least part of the main impurities it contains and recuperating helium with intermediate purity containing residual impurities; and (b) permeation of at least part of the helium with intermediate purity derived form step (a) so as to eliminate at least part of said residual impurities and recuperating helium with final purity higher than said intermediate purity. Said method and said installation are useful for purifying impure helium recuperated at the output of an optical fibre cooling chamber, prior to the reintroduction of the resulting purified helium into said chamber so as to recycle the helium.

Abstract: The feed gas contains essentially hydrocarbons, particularly methane, and impurities including helium. The process includes the conversion of the hydrocarbons into hydrogen and CO2, and the purification by adsorption of the hydrogen contained in the resulting gaseous mixture. Prior to the conversion of the hydrocarbons, the feed gas is processed in a unit for separation by permeation producing a retentate gas impoverished in helium, containing essentially hydrocarbons, and a permeate gas enriched in helium, the retentate gas being then treated by the conversion of the hydrocarbons, particularly of the methane.

Abstract: A method of producing high-purity helium, which contains the step of: producing high-purity helium of 99.99 mol % or higher, by a process in which crude helium having a helium concentration of 40 to 90 mol % is, at least, permeated through a separation membrane module composed of a plurality of glass hollow fiber membrane.

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 polysulfone-zeolite composite membrane can be used to separate gas pairs such as hydrogen/carbon dioxide. Zeolite, preferably zeolite 3A particles are covalently bonded to the polymer using an aminofunctional methoxysilane as a coupling agent to bind the zeolite particles to an aldehyde modified polysulfone matrix.

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: 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: 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: An apparatus for extracting a gas, in particular hydrogen, from a fluid stream utilizing a plate membrane flattened with a wave spring on the low pressure side of the membrane and a turbulence generator on the high pressure side. Alternately, the membrane is folded and wrapped against a central conduit within the membrane fold. Extraction membranes have a substrate layer of Ta—W, V—Co, V—Pd, V—Au, V—Cu, V—Al, Nb—Ag, Nb—Au, Nb—Pt, Nb—Pd, V—Ni—Co, V—Ni—Pd, V—Nb—Pt or V—Pd—Au alloy or combination thereof and a first layer affixed to the outer surface of the substrate towards a mixed gas flow which is composed of palladium, platinum, rhodium, or palladium alloys.

Abstract: Disclosed are a method for supplying a liquid raw material wherein the liquid raw material is deaerated and supplied from a liquid raw material container to a liquid flow control section, the method comprising passing the liquid raw material, supplied from a liquid raw material container by the pressure of a first inert gas, inside of a gas permeable synthetic resin tube, passing a second inert gas having a lower permeability into the synthetic resin tube than the first inert gas along the external surface of the synthetic resin tube whereby the first inert gas dissolved in the liquid raw material is allowed to penetrate into the outside of the synthetic resin tube and then supplying the liquid raw material to the liquid flow control section and an apparatus for supplying a liquid raw material which apparatus is used in the method. The invention ensures that inert gas dissolved in a liquid raw material can be removed easily and efficiently in a semiconductor manufacturing process using a liquid raw material.

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: 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 once 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 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: 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: 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 once 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: 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 glass structure for controlled permeability of gases includes a glass vessel. The glass vessel has walls and a hollow center for receiving a gas. The glass vessel contains a metal oxide dopant formed with at least one metal selected from the group consisting of transition metals and rare earth metals for controlling diffusion of the gas through the walls of the glass vessel. The vessel releases the gas through its walls upon exposure to a radiation source.

Abstract: A CVD device A is provided which is equipped with a gas introduction part A3 having an inert gas supply part G1 for supplying a diluting inert gas and a cleaning gas supply path G2 for supplying a cleaning gas, each connected therewith, and equipped with an exhaust gas discharge part A4 for releasing an exhaust gas; an exhaust gas circulation part D1 for circulating an exhaust gas from the CVD device, a cooling part D4 for cooling down and liquefying the cleaning gas in the exhaust gas, and a recovery part 4 for recovering the cleaning gas liquefied in said cooling part D4; the diluting inert gas is composed of a gas having a boiling point lower than that of the cleaning gas; a supply part 6 for supplying a cooling inert gas having the same composition as the diluting inert gas in a liquid state, an inert gas circulation part D3 which is cooled down by heat of evaporation of the cooling inert gas, and an inert gas discharge part 7 for discharging the cooling inert gas evaporated in the inert gas circulation p

Abstract: A process for separating and/or recovering gases from gas and/or gas vapor mixtures includes a membrane separating device to which a gas and/or gas vapor mixture is supplied, the latter being separated in the membrane separating device into a permeate, which is enriched with gas, and a retentate, which is depleted of gas. A first membrane separating device and a downstream second membrane separating device are provided, to which is supplied (at its inlet end) the retentate from the first membrane separating device, the first membrane separating device having a membrane which is selective for higher hydrocarbons in the gas and/or gas vapor mixture to be separated and in that the second membrane separating device has a membrane which is selected for gases of small molecular diameter.

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 process for the separation/recovery of gases is described where the desired component to be separated from the gaseous mixture is present in low/very low molar amount and/or low/moderate pressure, the process comprising contacting the gaseous mixture with a separation membrane unit containing high permeability/medium selectivity membranes which separate the feed stream into a permeate stream, enriched in the desired component and at a lower pressure and a retentate stream lean in the desired component and at a higher pressure. The retentate stream is made to convey its pressure to the permeate stream which then is directed to an adsorption PSA unit for further purification of the permeate stream so that the effluent stream from the PSA unit which contains the purified component has a purity of up to 99.90%.

Abstract: A method of enriching chlorine gas is described, which method comprises: (a) providing a supported ceramic membrane having a feed side and a permeate side; (b) bringing a feed gas comprising chlorine gas and contaminant gas into contact with the feed side of the ceramic membrane; (c) removing a gaseous permeate depleted in chlorine from the permeate side of the ceramic membrane; and (d) recovering a gas enriched in chlorine from the feed side of the ceramic membrane. The supported ceramic membrane has pore diameters in the range of from 3 angstroms to 12 angstroms. Preferably, the supported ceramic membrane is a substantially cylindrical supported ceramic membrane having a substantially cylindrical internal coaxial passage.

Abstract: An apparatus (5) and methods for extracting a gas, especially hydrogen, from a fluid stream includes a pressure vessel (12) having an inlet (22) and at least one outlet (26) for allowing fluid flow therethrough. A plurality of extraction membranes (14) are axially disposed in pressure vessel (12). Extraction membranes (14) are selected from cylindrical or approximately cylindrical tubular metal substrate membranes and ceramic or polymeric substrate membranes. Enhanced mass transfer during the extracting is achieved by reducing the diameter and separation barrier thickness of extraction membranes (14) by adding bumps (18), curves, or packing (19). Extraction membranes (14) have inner and/or outer layers of palladium, platinum, rhodium or palladium alloys having greater hydrogen separation surface properties than a core membrane.

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 present invention provides a process for recovering sulfur hexafluoride ("SF.sub.6 ") from a gas stream using membrane separation.

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 process for separating perfluoro compound gas or vapor from another gas, typically nitrogen, in a gas mixture. The process involves a combination of membrane separation and condensation, and is particularly useful in the semiconductor industry, for treating exhaust gases from cleaning of chemical vapor deposition chambers. Operation of the condensation step at temperatures no lower than about -30.degree. C. reduces the need for refrigeration equipment and controls the amount of gas dissolved in the recovered perfluoro compound.

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.