Abstract: A process for removing oxygen from a feed gas stream to produce an oxygen-depleted retentate gas stream by supplying the feed gas stream to a bulk oxygen separation system for removing oxygen to produce an oxygen-depleted crude product gas stream and a first oxygen-containing permeate effluent stream, and supplying the oxygen-depleted crude product gas stream to a separator having a primary ion transport membrane to produce a second permeate effluent stream and the oxygen-depleted retentate gas stream. A reactive purge gas is added to react with a portion of the oxygen permeating through the primary ion transport membrane and purge the permeate side of the primary ion transport membrane, and/or a recycle gas stream comprising at least a portion of one gas stream produced during the process is added to at least one other of the gas streams.

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 recovering at least one of CF.sub.4 and C.sub.2 F.sub.6 from a vent gas from an aluminum electrolysis cell. The process includes the steps of:(a) removing inorganic fluorides from a vent gas comprising inorganic fluorides and at least one of CF.sub.4 and C.sub.2 F.sub.6 to obtain a purified vent gas; and(b) contacting the purified vent gas with a membrane at conditions effective to obtain a retentate stream rich in at least one of CF.sub.4 and C.sub.2 F.sub.6, and a permeate stream depleted in at least one of CF.sub.4 and C.sub.2 F.sub.6.

Abstract: A method for increasing product recovery or reducing the size of steam methane reformer and pressure swing adsorption systems utilized for hydrogen production. A significant portion of the hydrogen in the PSA depressurization and purge effluent gas, which is otherwise burned as fuel in the reformer, is recovered and recycled to the PSA system to provide additional high purity hydrogen product. This is accomplished by processing selected portions of the depressurization and purge effluent gas in adsorbent membrane separators to increase hydrogen content for recycle to the PSA system. Remaining portions of the depressurization and purge effluent gas which contain lower concentrations of hydrogen are utilized for fuel value in the reformer.

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: This invention comprises an improved process for generating Nitrogen from air in which a vacuum is placed on the permeate side of a gas separation membrane, usually of the polysulfone type, resulting in highly enhanced flow rates and nitrogen purity sufficient for oil and gas pipeline repair use and for use in grain silos.

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.

Abstract: A spiral-wound, gas-separation membrane module and a gas-separation process. The module and process provide at least partial counter-current flow between the feed and permeate gas streams without requiring a permeate sweep. The counter-current flow pattern can be achieved by appropriate placement of barriers or baffles in the feed channel. Similar modules and processes may also be used for pervaporation.

Abstract: A method of separating a gas, especially carbon dioxide, from a gas mixture of the gas and nitrogen at a low temperature of -20.degree. C. to 50.degree. C. using a gas separation membrane permeable to the gas, including the step of cooling the gas mixture using at least one cooling medium selected from the group consisting of liquefied petroleum gas and liquefied natural gas. The liquefied petroleum gas comprises at least one selected from the group consisting of propane gas and butane gas in an amount of more than 50 vol. %. The gas separation membrane has a CO.sub.2 permeation rate of 1.times.10.sup.-4 to 5.times.10.sup.-2 N cm.sup.3 /(cm.sup.2 cm Hg sec) at 25.degree. C. and a CO.sub.2 /N.sub.2 separation factor of 10 to 200 at 25.degree. C.

Abstract: A composite membrane made of an asymmetric porous support and an ultrathin layer having a thickness of less than 100 nm is provided. A method of making the membrane and method for carrying out gas separations using the membrane are also provided.

Abstract: A semi-permeable gas membrane process is described for the separation of very high purity nitrogen from a process feed gas mixture that is predominantly nitrogen, and one or more other permeable gases, which process comprises providing a feed gas mixture under pressure to a membrane separator unit comprising a semi-permeable separation membrane with respect to which the largest fraction of the other permeable gases is at least 20 times more permeable than nitrogen, to provide a very high purity raffinate nitrogen gas product.

Abstract: The invention produces essentially pure nitrogen from air by an intermittent, automatic, and unattended process. Air is filtered, compressed and enters a nitrogen module containing a permeable membrane that selectively separates nitrogen from the air and discharges oxygen and other gases. Automated temperature and pressure controls allow the permeable membrane to separate air components. A discharge hose allows use of the nitrogen product for a variety of intermittent applications including vending for inflation of tires, filling portable nitrogen vessels, and use in manufacturing processes.

Abstract: The process for introducing a filling gas into an enclosure initially containing a holding gas includes a step of introducing the filling gas into the enclosure as well as a step of extracting a specific gas initially contained in the filling gas or the holding gas from a mixture collected at the outlet of the enclosure, and possibly a step of recycling this extracted specific gas. Before the step of introducing the filling gas, the enclosure is purged using a purging gas which differs from the fill and holding gases.

Abstract: A process is disclosed for the shut-down of a membrane separation zone comprising a non-permeate side and a permeate side and processing a feed stream comprising a non-permeable component, a less-readily permeable, condensible component, and a readily permeable component. When the feed stream is not passed to the membrane separation zone, a purge stream is passed to the non-permeate side of the membrane separation zone to remove a residual gas stream and thereby prevent condensation of the less-readily permeable, condensible component upon depressurization and/or cooling of the membrane separation zone. The invention reduces the need for oversizing membrane system which reduces treating costs and prevents permeate damage to membrane surfaces caused by condensation of less-readily permeable, condensible components such as C.sub.6.sup.+ hydrocarbons.

Abstract: A process for purifying water including removing cations, anions and carbon dioxide and/or ammonia from water feed stream to produce high purity water having a resistivity of greater than 1 megohm-era comprising the steps of providing a water feed stream to be purified, the stream containing cations, anions and carbon dioxide and/or ammonia; introducing the water feed stream to a high pressure side of a first reverse osmosis membrane module; passing water through the first reverse osmosis membrane to provide a first retentate having cations and anions concentrated therein and a first permeate depleted in cations and anions and containing carbon dioxide and/or ammonia; adding the first permeate to a high pressure side, of a gas permeable hydrophobic membrane module; passing carbon dioxide and/or ammonia through the gas-permeable membrane from the first permeate in the high pressure side of the gas-permeable hydrophobic membrane to provide a carbon dioxide and/or ammonia permeate on a low pressure side of the h

Abstract: A filter material from active carbon compacts is prepared by the following steps:(a) mixing active carbon powder with polyvinyl alcohol powder in the ratio of 9:1 to 3:1,(b) mixing the powder from step (a) with distilled water or a mixture of distilled water and ethyl alcohol,(c) shaping tablets and similar articles in a mold under pressure, and(d) successively heating the tablets at1) 40.degree. to 80.degree. C. for 3 to 6 hours,2) 80.degree. to 120.degree. C. for 10 to 14 hours.A filter material according to the invention for the selective separation of organic material from an organic phase consists of active carbon compacts thus prepared and is used for the selective separation of organic and inorganic phases.

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 is directed toward a composition suitable for use in separating CO.sub.2 from gas streams containing CO.sub.2 especially H.sub.2 rich gas streams containing CO.sub.2 and CO. The composition comprises a hydrophylic polymer and at least one salt of an aminoacid, the salt of the aminoacid being present in an amount ranging from about 10 to about 80 wt % based on the total weight of the composition.

Abstract: A process for separating a first gas from a second gas, having the steps of: (1) contacting one side of a semi-permeable gas separation membrane with a feed gas mixture containing at least the first gas and the second gas, wherein the membrane divides a separation chamber into a high-pressure side into which the feed gas mixture is fed and a low-pressure side; (2) maintaining a pressure differential across the membrane under conditions such that the first gas in the feed gas mixture selectively permeates through the membrane from the high-pressure side to the low-pressure side of the membrane; (3) removing from the low-pressure side of the membrane permeated gas mixture which is enriched in the first gas and depleted in the second gas; and (4) removing from the high-pressure side of the membrane a gas mixture which is enriched in the second gas and depleted in the first gas.

Abstract: Essentially pure nitrogen gas is produced from air and stored by an intermittent, automatic, and unattended process that is compact and self contained. Air is first filtered, compressed and enters a nitrogen module containing a permeable membrane that selectively separates nitrogen from the air and discharges oxygen and other gases. The nitrogen gas then flows into a vessel for storage. The apparatus is enclosed in a housing where automated temperature and pressure controls allows the permeable membrane to separate air components. A discharge hose allows use of the nitrogen product for a variety of intermittent applications including vending for inflation of tires, filling portable nitrogen vessels, and use in other processes needing intermittent and automatic manufacture of nitrogen gas.

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: Process and apparatus for the separation of at least one gas from an entering gaseous mixture (1), of the type in which a membrane separation is conducted with at least two successive membrane separators in the following manner: the entering mixture is passed through a first membrane separator (2) operating at a first operating temperature and all or a portion of the residual mixture (5) from this first membrane separator is passed through a second membrane separator (3) operating at a second operating temperature. A mixture enriched in the gas is obtained from the permeate outlet (6, 4) of each of these two separators. Two separators are used whose selectivities for the gas are different. These may be membranes of different type, or membranes of the same type, if the first operating temperature is different from the second operating temperature.

Abstract: A membrane process and apparatus are described for the production of a desired very high purity permeate gas by use of a multiple stage membrane process wherein in a primary stage a process feed gas mixture is provided to a primary membrane separator unit comprising a membrane having a relatively high intrinsic permeability to provide an intermediate permeate gas and a retentate gas, and providing the intermediate permeate gas in a secondary stage to a secondary membrane separator unit comprising a membrane having a relatively low intrinsic permeability, to produce therefrom a very high purity permeate gas product.

Abstract: A membrane for the separation of carbon dioxide is disclosed which includes a hydrogel film of a cross-linked, vinyl alcohol/acrylic acid salt copolymer impregnated with an aqueous carrier solution containing a carbon dioxide carrier dissolved therein. A composition containing a solvent, an alkali metal carbonate or bicarbonates, and a polydentate ligand capable of forming a complex with an alkali metal ion is suitably used as the carrier solution. This composition may also be used for the preparation of a liquid film of a carbon dioxide separation membrane.

Abstract: Recovery of hydrogen from hydrogen-containing gas mixtures by pressure swing adsorption is increased by utilizing an adsorbent membrane to concentrate hydrogen in the pressure swing adsorption reject gas and recycling the resulting hydrogen-enriched stream to the feed of the pressure swing adsorption system. Lower compression requirements are realized compared with the use of polymeric membranes for the same service because the hydrogen-enriched stream is recovered from the adsorbent membrane as nonpermeate at essentially the membrane feed pressure. Simultaneous permeation of carbon dioxide and methane occur in the adsorbent membrane, which can be operated at feed pressures as low as 5 psig when hydrogen is used as a sweep gas.

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: A process for the rejection of carbon dioxide from a natural gas feedstream comprising a gas permeable membrane and a multiple bed pressure swing adsorption system to produce a fixed gas product having a desired concentration of carbon dioxide. The permeate stream from the gas permeable membrane system is fed to the PSA unit and a stream essentially free of carbon dioxide gas from the PSA unit is compressed and blended with the non-permeate stream to form the mixed gas product.

Abstract: This invention relates to hydrous gel membranes for gas separation which comprise support membranes formed by solvent-soluble polymeric materials containing in their repeating unit a bulky structural part and hydrophilic functional groups represented by the following general formula (1) ##STR1## (R.sub.1, R.sub.2, R.sub.3, and R.sub.4 designate hydrogen, alkyl group, and halogen and R.sub.5 and R.sub.6 designate any one of --H, --SO.sub.3 H, --COOH, and --OH) and water or an aqueous solution of substances with affinity for CO.sub.2 substantially uniformly retained in the support membranes. The membranes show not only high CO.sub.2 permeation and CO.sub.2 selectivity but also long-term stable membrane performance and ease of fabricability into membranes and are capable of recovering a large volume of CO.sub.2 generated at stationary sites efficiently at low cost.

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, 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 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: A composite or asymmetric membrane for separating and concentrating a particular component from a mixture of gases. The asymmetric membrane is of a fluorine-containing aromatic polyimide resin of the 6FDA type. The composite membrane has a thin film of an elastomeric polymer formed on a supporting film of a fluorine-containing aromatic polyimide resin of the 6FDA type.

Abstract: Dopable, fully dense polymer membranes are used to form membranes having selective permeabilities. To improve selectivity, the membranes may be subjected to chemical or electrochemical treatment with electron donors or acceptors to alter the doping level of the polymer membrane, generally in a reversible fashion. This leads to significant changes in gas permeation rates relative to what is observed for the non-doped, fully dense polymers. This change in doping level of the polymer films can be precisely controlled by varying the concentration and nature of chemical dopants used. Desirable changes in permeation rates are achieved by a treatment which comprises a reversal doping of the polymeric material, followed by removal of the dopants (to provide an "undoped" polymer).

Abstract: The present invention relates to composite membranes and membranes which are formed from modified poly(phenylene oxide) polymers having improved film forming properties and separation characteristics. The present invention further relates to poly(phenylene oxide) polymer and modified poly(phenylene oxide) polymer, having improved membrane forming characteristics and processes for producing the same.

Abstract: Composite membrane, process for its production and its useA composite membrane for gas separation having a three-layer structure, constructed fromA) a supporting membrane layer made of porous polymer,B) a nonporous, gas-permeable intermediate layer,C) a permselective layer of regularly arranged organic molecules having a layer thickness of 3 to 100 nm,the layers (A) and (C) enclosing the intermediate layer (B), wherein the permselective layer (C) is constructed from regularly arranged amphiphilic molecules which contain one or two alkyl chains each having 7 to 25 carbon atoms per polar hydrophilic group.

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.

Abstract: A method is disclosed for separating a multicomponent gas mixture comprising at least three components into three product streams by use of adsorbent membrane zones operating in series. Each product is enriched in a different component based upon the relative strength of adsorption of each component on the adsorbent material. A non-permeate primary component product is obtained by the selective adsorption and permeation through the adsorbent membranes of secondary components which are more strongly adsorbed than the primary components in the gas mixture. Two or more permeate streams enriched in the more strongly adsorbed components are withdrawn from the membrane zones as individual secondary products, each of which contains a different component distribution determined by the relative strength of adsorption of the secondary components on the adsorbent material.

Abstract: This invention provides a composite gas separation membrane comprising: (a) a porous polyacrylonitrile structural support material having a polyacrylonitrile surface; (b) a gutter layer coating comprising a crosslinked polar phenyl-containing-organopolysiloxane material on the polyacrylonitrile surface of the structural support material, leaving an uncoated gutter layer surface; and (c) an ultrathin 6FDA type polyimide selective membrane layer coating on the uncoated gutter layer surface. In preferred embodiments, the phenyl-containing-organopolysiloxane material additionally comprises a silica-sol. Processes for making the composite gas separation membrane and for using the membrane to carry out gas separations are also provided.

Abstract: Carbon dioxide and water vapor are continuously removed by a venting membrane system which employs porous membranes and a liquid amine based sorbent, and which has a partial pressure gradient across the porous membranes. The partial pressure gradient induces absorption of carbon dioxide and water vapor from a gaseous stream, transport of the absorbed carbon dioxide through the pores of the membrane or to a second membrane, and desorption of the absorbed carbon dioxide.

Abstract: Aromatic polyimide membranes have superior flux at low temperature for carbon dioxide and other condensable gases. Superior flux is achieved without reduction in selectivity or other valuable properties of prior art membranes.