Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G61/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
  • C08G61/02—Macromolecular compounds containing only carbon atoms in the main chain of the macromolecule, e.g. polyxylylenes
  • C08G61/04—Macromolecular compounds containing only carbon atoms in the main chain of the macromolecule, e.g. polyxylylenes only aliphatic carbon atoms
  • C08G61/06—Macromolecular compounds containing only carbon atoms in the main chain of the macromolecule, e.g. polyxylylenes only aliphatic carbon atoms prepared by ring-opening of carbocyclic compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
  • B01D53/228—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion characterised by specific membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0002—Organic membrane manufacture
  • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
  • B01D67/00091—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching by evaporation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/12—Composite membranes; Ultra-thin membranes
  • B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
  • B01D71/06—Organic material
  • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
  • B01D71/60—Polyamines
  • B01D71/601—Polyethylenimine
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/30—Sulfur compounds
  • B01D2257/304—Hydrogen sulfide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/50—Carbon oxides
  • B01D2257/504—Carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2323/00—Details relating to membrane preparation
  • B01D2323/30—Cross-linking
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
  • Y02C20/00—Capture or disposal of greenhouse gases
  • Y02C20/40—Capture or disposal of greenhouse gases of CO2
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers

Definitions

• compositions comprise at least one hydrophilic polymer, at least one cross-linking agent, at least one base, and at least one amino compound.
• the amino compound comprises at least one of a polyamine and a salt of aminoacid.
• the aminoacid salt is selected from salts having the formula:
• R 1 , R 2 , R 3 , and R 4 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms, n is an integer ranging from 0 to 4, A m+ is a cation having a valence of 1 to 3 and an amine cation having the formula:
• R 5 and R 6 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms
• R 7 is hydrogen or a hydrocarbon group having from 1 to 4 carbon atoms or an alkyl amine of from 2 to 6 carbon atoms and 1 to 4 nitrogen atoms
• y is an integer ranging from 1 to 4
• m is an integer equal to the valence of the cation.
• the base is selected from potassium hydroxide, sodium hydroxide, lithium hydroxide, triethylamine, N,N-dimethylaminopyridine, hexamethyltriethylenetetraamine, potassium carbonate, sodium carbonate, lithium carbonate, and combinations thereof.
• processes for separating at least one of CO 2 , H 2 S, and HCl from a gas stream containing at least one of CO 2 , H 2 S, and HCl comprise contacting a gas stream containing at least one of CO 2 , H 2 S, and HCl with one side of a nonporous and at least one of CO 2 , H 2 S, and HCl selectively permeable membrane and withdrawing from the obverse side of the membrane a permeate containing of at least one of CO 2 , H 2 S, and HCl, wherein at least one of CO 2 , H 2 S, and HCl is selectively removed from the gaseous stream.
• the membrane comprises at least one hydrophilic polymer, at least one cross-linking agent, at least one base, and at least one amino compound.
• the amino compound comprises at least one of a polyamine and a salt of aminoacid, and the aminoacid salt is selected from salts having the formula:
• R 1 , R 2 , R 3 , and R 4 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms, n is an integer ranging from 0 to 4, A m+ is a cation having a valence of 1 to 3 and an amine cation having the formula:
• R 5 and R 6 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms
• R 7 is hydrogen or a hydrocarbon group having from 1 to 4 carbon atoms or an alkyl amine of from 2 to 6 carbon atoms and 1 to 4 nitrogen atoms
• y is an integer ranging from 1 to 4
• m is an integer equal to the valence of the cation.
• the base is selected from potassium hydroxide, sodium hydroxide, lithium hydroxide, triethylamine, N,N-dimethylaminopyridine, hexamethyltriethylenetetraamine, potassium carbonate, sodium carbonate, lithium carbonate, and combinations thereof.
• the at least one of CO 2 , H 2 S, and HCl is selectively transported through the membrane.
• a nonporous membrane for separating at least one of CO 2 , H 2 S, and HCl from a gaseous stream containing at least one of CO 2 , H 2 S, and HCl.
• the method comprises: forming a casting solution of a solvent, at least one hydrophilic polymer, at least one cross-linking agent, at least one base, and at least one amino compound; casting the solution on a substrate; and evaporating the solvent such that a nonporous membrane is formed.
• the amino compound comprises at least one of a polyamine and a salt of aminoacid.
• the aminoacid salt is selected from salts having the formula:
• R 1 , R 2 , R 3 , and R 4 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms, n is an integer ranging from 0 to 4, A m+ is a cation having a valence of 1 to 3 and an amine cation having the formula:
• R 5 and R 6 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms
• R 7 is hydrogen or a hydrocarbon group having from 1 to 4 carbon atoms or an alkyl amine of from 2 to 6 carbon atoms and 1 to 4 nitrogen atoms
• y is an integer ranging from 1 to 4
• m is an integer equal to the valence of the cation.
• the base is selected from potassium hydroxide, sodium hydroxide, lithium hydroxide, triethylamine, N,N-dimethylaminopyridine, hexamethyltriethylenetetraamine, potassium carbonate, sodium carbonate, lithium carbonate, and combinations thereof.
• methods for producing a nonporous membrane for separating at least one of CO 2 , H 2 S, and HCl from a gaseous stream containing at least one of CO 2 , H 2 S, and HCl comprise: forming a casting solution of a solvent, at least one hydrophilic polymer, at least one cross-linking agent, and at least one base, and at least one amino compound; heating the solution; casting the solution on a substrate; and evaporating the solvent such that a nonporous membrane is formed.
• the amino compound comprises at least one of a polyamine and a salt of aminoacid.
• the aminoacid salt is selected from salts having the formula:
• R 1 , R 2 , R 3 , and R 4 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms, n is an integer ranging from 0 to 4, A m+ is a cation having a valence of 1 to 3 and an amine cation having the formula:
• R 5 and R 6 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms
• R 7 is hydrogen or a hydrocarbon group having from 1 to 4 carbon atoms or are alkyl amine of from 2 to 6 carbon atoms and 1 to 4 nitrogen atoms
• y is an integer ranging from 1 to 4
• m is an integer equal to the valence of the cation.
• the base is selected from potassium hydroxide, sodium hydroxide, lithium hydroxide, triethylamine, N,N-dimethylaminopyridine, hexamethyltriethylenetetraamine, potassium carbonate, sodium carbonate, lithium carbonate, and combinations thereof;
• compositions are provided.
• the compositions comprise at least one of at least one hydrophilic polymer and at least one amino compound, at least one cross-linking agent, and at least one base.
• the amino compound comprises at least one of a polyamine and a salt of aminoacid.
• the compositions can be used to form nonporous membranes as discussed herein.
• the compositions can comprise any suitable amount of the hydrophilic polymers.
• the compositions can comprise from about 10 to about 90 percent hydrophilic polymers by weight of the composition.
• the compositions can comprise any suitable amount of cross-linking agents.
• the compositions can comprise about 1 to about 40 percent cross-linking agents by weight of the composition.
• the compositions can comprise any suitable amount of bases.
• compositions can comprise about 1 to about 40 percent bases by weight of the composition.
• the compositions can comprise any suitable amount of the amino compounds.
• the compositions can comprise from about 10 to about 90 percent polyamines by weight of the composition and/or about 10 to about 90 percent aminoacid salts by weight of the composition.
• hydrophilic polymers suitable for use in the present invention include, but are not limited to, polyvinylalcohol, polyvinylacetate, polyethylene oxide, polyvinylpyrrolidone, polyacrylamine, and blends, and copolymers thereof.
• the hydrophilic polymer comprises polyvinylalcohol.
• the polyamines suitable for use in the present invention include, but are not limited to, polyallylamine, polyethylenimine, poly-N-1,2-dimethylpropylallylamine, poly-N-methylallylamine, poly-N,N-dimethylallylamine, poly-2-vinylpiperidine, and poly-4-vinylpiperidine, and blends and copolymers thereof.
• the hydrophilic polymer comprises polyallylamine.
• the hydrophilic polymer comprises of polyethylenimine.
• compositions of the present invention can include either hydrophilic polymers, polyamines, or combinations thereof.
• hydrophilic polymers and polyamines may have any suitable weight average molecular weights.
• the hydrophilic polymers and polyamines can have weight average molecular weights in the range of from about 15,000 to about 2,000,000 and from about 50,000 to about 200,000.
• the polyamines can comprise polyethylenimines with molecular weights in the range of from about 50,000 to about 100,000.
• the hydrophilic polymers can comprise polyvinylalcohols with molecular weights in the range of from about 50,000 to about 150,000.
• aminoacid salts in the compositions of the present invention are selected from salts having the formula:
• R 1 , R 2 , R 3 , and R 4 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms, n is an integer ranging from 0 to 4, A m+ is a cation having a valence of 1 to 3 and an amine cation having the formula:
• R 5 and R 6 are hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms
• R 7 is hydrogen or hydrocarbon groups having from 1 to 4 carbon atoms or an alkyl amine of from 2 to 6 carbon atoms and 1 to 4 nitrogen atoms
• y is an integer ranging from 1 to 4
• m is an integer equal to the valence of the cation.
• the hydrocarbon can be saturated or unsaturated, branched or unbranched, and substituted or unsubstituted hydrocarbon, which may be substituted with heteroatoms in the hydrocarbon chain or at the end of the hydrocarbon chain.
• a m+ is a metal cation, and it can be selected from Groups Ia, Ia, IIa, and VIII of the Periodic Table of Elements.
• a m+ can comprise lithium, aluminum, or iron.
• the aminoacid salt can comprise aminoisobutyric acid-K salt, dimethylglycine-K salt, or dimethylglycine-Li salt.
• cross-linking agents suitable for use in the present invention include, but are not limited to, formaldehyde, glutaraldehyde, maleic anhydride, glyoxal, divinylsulfone, toluenediisocyanate, trimethylol melamine, terephthalatealdehyde, epichlorohydrin, vinyl acrylate, and combinations thereof.
• the cross-linking agent comprises formaldehyde, glutaraldehyde, or maleic anhydride.
• the bases suitable for use in the present invention include, but are not limited to, potassium hydroxide, sodium hydroxide, lithium hydroxide, triethylamine, N,N-dimethylaminopyridine, hexamethyltriethylenetetraamine, potassium carbonate, sodium carbonate, lithium carbonate, and combinations thereof.
• the base comprises potassium hydroxide. It is believed, without intending to be limiting, that the base acts as a catalyst to catalyze the cross-linking of hydrophilic polymers and polyamines in the compositions during formation of the membranes. The base or bases remain in the membranes and constitute part of the membranes.
• the compositions can be used to form nonporous membranes.
• nonporous membrane refers to a membrane having a at least a portion that is substantially nonporous such that a gas moves through the nonporous portion via diffusion rather than separation from a larger gas by pores.
• the membranes of the present invention are permeable to at least one of CO 2 , H 2 S, or HCl.
• the membranes of the present invention are CO 2 selective versus hydrogen, nitrogen, or combinations thereof.
• the membranes of the present invention are H 2 S selective versus hydrogen, nitrogen, or combinations thereof.
• the membranes of the present invention are HCl selective versus hydrogen, nitrogen, or combinations thereof. In a further example, the membranes of the present invention are CO 2 , H 2 S, and HCl selective versus hydrogen, nitrogen, or combinations thereof. In another example, the membranes of the present invention may be used at temperatures of about 100° C. and greater than about 100° C. In yet another example, the membranes of the present invention may be used at temperatures of from about 100° C., about 110° C., about 120° C., about 130° C. about 140° C., about 150° C., about 160° C., about 170° C., and about 180° C. In another example, the membranes of the present invention may be used at temperatures of less than about 100° C. The membranes can be free standing membranes or composite membranes.
• Formulations for forming the membranes are prepared using the compositions of the present invention.
• the formulations can be prepared by first forming a casting solution of at least one of the hydrophilic polymer, the cross-linking agent, the base, and the amino compound in a suitable solvent.
• a suitable solvent is water.
• the amount of water employed will be in the range of from about 50% to about 99%.
• the membrane composition can then be recovered from the casting solution by removing the solvent, for example, by allowing the solvent to evaporate.
• the casting solution can be used in forming a nonporous membrane.
• the resulting casting solution or membrane composition is formed into a nonporous membrane by using any suitable techniques.
• the casting solution can be cast onto a substrate using any suitable techniques, and the solvent may be evaporated such that a nonporous membrane is formed on the substrate.
• suitable techniques include, but are not limited to, “knife casting” or “dip casting”. Knife casting is a process in which a knife is used to draw a polymer solution across a flat substrate to form a thin film of a polymer solution of uniform thickness after which the solvent of the polymer solution is evaporated, at ambient temperatures or temperatures up to about 100° C. or higher, to yield a fabricated membrane.
• the membrane can then be removed from the substrate providing a free standing polymer membrane.
• the flat substrate used is a non-selective porous support such as porous polytetrafluoroethylene
• the resulting membrane is a composite membrane comprising the selective membrane polymer and the support.
• Dip casting is a process in which a polymer solution is contacted with a non-selective porous support. Then excess solution is permitted to drain from the support, and the solvent of the polymer solution is evaporated at ambient or elevated temperatures as discussed above.
• the membrane comprises both the membrane polymer and the porous support.
• the membranes of the present invention also may be shaped in the form of hollow fibers, tubes, films, sheets, etc.
• membranes formed from compositions containing a cross-linking agent can be formed in any suitable manner.
• the compositions of the present invention, including any solvent can be heated at a temperature and for a time sufficient for cross-linking to occur.
• cross-linking temperatures in the range from about 80° C. to about 100° C. are employed.
• cross-linking occurs in from about 1 to about 72 hours.
• the resulting solution can be cast onto a substrate and the solvent evaporated, as discussed above.
• a higher degree of cross-linking for the cast membrane after solvent removal takes place at about 100° C. to about 180° C., and the cross-linking occurs in from about 1 to about 72 hours.
• an additive may be included in the composition before forming a membrane to increase the water retention ability of the membrane.
• Suitable additives include, but are not limited to, polystyrenesulfonic acid-K salt, polystyrenesulfonic acid-Na salt, polystyrenesulfonic acid-Li salt, sulfonated polyphenyleneoxides, alum, and combinations thereof.
• the additive comprises polystyrenesulfonic acid-K salt.
• processes for separating acid gases from a gas stream containing at least one acid gas include contacting a gas stream containing at least one acid gas with one side of a nonporous acid gas selectively permeable membrane of the present invention, and withdrawing from the obverse side of the membrane a permeate containing at least one acid gas, wherein the acid gas is selectively removed from the gaseous stream.
• the permeate comprises the at least one acid gas in increased concentration relative to the feed stream.
• permeate is meant that portion of the feed stream which is withdrawn at the obverse or second side of the membrane, exclusive of other fluids such as a sweep gas or liquid which may be present at the second side of the membrane.
• the acid gas is at least one of CO 2 , H 2 S, or HCl.
• the membranes of the present invention may be used for the removal of at least one of CO 2 , H 2 S, or HCl from gases including synthesis gases derived from fossil fuels that require hydrogen purification for fuel cell, electricity generation, and hydrogenation applications, biogas for renewable energy, and natural gas for commercial uses.
• gases including synthesis gases derived from fossil fuels that require hydrogen purification for fuel cell, electricity generation, and hydrogenation applications, biogas for renewable energy, and natural gas for commercial uses.
• the membranes can be used for removal of CO 2 from flue gas containing nitrogen. It will be understood that the membranes of the present invention can be used for any other suitable gases.
• the retentate refers to the mixture on the feed side of the membrane that is rejected/retained by the membrane under the operating conditions.
• the separation factor for acid gas vs. nitrogen is expressed as follows:
• the flux expressed in units of cm 3 (STP)/(cm 2 ⁇ s)
• p 1 and p 2 are the acid gas (carbon dioxide, hydrogen sulfide, or hydrogen chloride) partial pressures in the retentate and permeate streams, respectively, and l is the membrane thickness.
• the partial pressures are determined based on concentration measurements by gas chromatography and total pressure measurements by using pressure gauges.
• the flux is determined based on permeate concentration measurements by gas chromatography and permeate stream flow rate measurements by using a flow meter.
• PVA polyvinylalcohol
• the KOH concentration was 1.74 wt %.
• an aqueous polyethylenimine solution containing 7.38 g polyethylenimine and 44.90 g water under stirring at 80-85° C.
• an N,N-dimethylglycine-Li salt solution was prepared by adding 6.75 g (0.066 mole) of N,N-dimethylglycine and 2.77 g (0.066 mole) of LiOH ⁇ H 2 O slowly to 9.10 g of water with stirring. This solution was added to the above PVA/formaldehyde/KOH solution under stirring at 80-85° C. for about 30 minutes to obtain a clear, homogeneous solution.
• the solution was then centrifuged at 5000 rpm while cooling for 30 minutes. Following centrifugation, the membrane was knife-cast (with a gap setting of 16 mils) onto a support of microporous polytetrafluoroethylene. Water was allowed to evaporate from the membrane in a hood at ambient conditions overnight. The membrane was then heated in an oven at 120° C. for about 6 hours.
• the resulting membrane comprised about 23.6 wt % dimethylglycine-Li salt, 23.6 wt % polyethylenimine, 46.4 wt % (polyvinylalcohol/formaldehyde at 44/3.9 by weight), and 6.4 wt % KOH.
• the membrane had a thickness of about 35 microns (exclusive of the support).
• Polyvinylalcohol (PVA) in an amount of 8.76 g was added to 58.82 g of water with stirring and heating at about 80° C. until a clear solution of the polymer was obtained.
• PVA solution was added an aqueous 37 wt % formaldehyde solution of 2.04 g (0.76 g of formaldehyde) under stirring.
• the resulting solution was heated at about 95° C. and maintained at this temperature with stirring for about 4 hours to thermally enhance the cross-linking of PVA with formaldehyde.
• an aqueous polyethylenimine solution containing 4.58 g polyethylenimine and 30.05 g water under stirring at 80-85° C.
• an N,N-dimethylglycine-Li salt solution was prepared by adding 4.50 g (0.044 mole) of N,N-dimethylglycine and 1.83 g (0.044 mole) of LiOH ⁇ H 2 O slowly to 6.91 g of water with stirring. This solution was added to the above PVA/formaldehyde solution under stirring at 80-85° C. for about 30 minutes to obtain a clear, homogeneous solution.
• the solution was then centrifuged while cooling for about 30 minutes. Following centrifugation, the membrane was knife-cast (with a gap setting of 18 mils) onto a support of microporous polytetrafluoroethylene. Water was allowed to evaporate from the membrane in a hood at ambient conditions overnight. The membrane was then heated in an oven at 120° C. to give the resulting membrane.
• This resulting membrane comprised about 25 wt % dimethylglycine-Li salt, 25 wt % polyethylenimine, and 50 wt % (polyvinylalcohol/formaldehyde at 44/3.9 by weight).
• the membrane had a thickness of about 39 microns (exclusive of the support).
• This membrane has the same ratios of dimethylglycine-Li salt/polyethylenimine/polyvinylalcohol (PVA)/formaldehyde as those of the membrane of Example 1.
• PVA polyvinylalcohol
• the membrane of Example 2 did not contain KOH whereas the membrane of Example 1 included KOH.
• the membrane of Example 2 was synthesized in the similar procedure taught in U.S. Pat. Nos. 5,611,843 and 6,099,621, and this membrane served as the comparative example.
• the membrane was placed in a permeation cell comprising the first compartment for contacting a feed stream on the upstream side of the membrane and the second compartment for withdrawing the permeate from the downstream side of the membrane.
• the active membrane area in the cell was 45.6 cm 2 .
• a feed gas comprising 40% hydrogen, 20% carbon dioxide, and 40% nitrogen (on the dry basis) under a total pressure of about 2 atm was contacted against the membrane at a flow rate of about 60 cm 3 /min (at ambient condition) in the gas permeation apparatus.
• the permeate was swept by nitrogen under a pressure of about 1 atm and a total flow rate of about 30 cm 3 /min for the permeate/nitrogen stream. Both the feed and sweep streams were humidified by injecting 0.03 ml/min of deionized water into each of the two streams prior to contacting the membrane. Each permeation measurement was carried out at an operating temperature.
• Example 1 For the membrane of Example 1 comprising about 23.6 wt % dimethylglycine-Li salt, 23.6 wt % polyethylenimine, 46.4 wt % (polyvinylalcohol/formaldehyde at 44/3.9 by weight), and 6.4 wt % KOH (with a thickness of 35 microns), the carbon dioxide/hydrogen selectivity results obtained were 1782, 277, and 285 at 80° C., 100° C., and 110° C., respectively. The carbon dioxide permeability results obtained were 338, 49, and 50 Barrers at 80° C., 100° C., and 110° C., respectively.
• the membrane of Comparative Example A comprising about 25 wt % dimethylglycine-Li salt, 25 wt % polyethylenimine, and 50 wt % (polyvinylalcohol/formaldehyde at 44/3.9 by weight) was evaluated in the same way as the membrane of Example 1 as described earlier in Permeation Measurement of Membrane of Example 1.
• the carbon dioxide/hydrogen selectivity results obtained were 602, 453, 11 and 7 at 80° C., 90° C., 100° C., and 110° C., respectively.
• the selectivity result dropped drastically at 100° C., indicating excessive membrane swelling and insufficient thermal stability at the temperatures greater than 100° C.
• the membrane of Example 1 had better results than the membrane of Comparative Example A, particularly for temperatures greater than 100° C. At temperatures greater than 100° C., the membrane of Comparative Example A had a carbon dioxide/hydrogen selectivity of 11 or lower. However, the membrane of Examples 1 of the present invention still had a carbon dioxide/hydrogen selectivity of 277 or higher at 100-110° C. Thus, this membrane of the present invention that was synthesized with the base (KOH) outperformed the membrane that was synthesized without this base.
• KOH base
• polystyrenesulfonic acid-K salt solution was prepared by adding 2.563 g of 30% polystyrenesulfonic acid and 0.232 g of KOH slowly to 1.293 g of water with stirring. This solution was adjusted using KOH to have a pH of 7 and contained 0.927 g of polystyrenesulfonic acid-K salt. This solution was added to the PVA solution with stirring at about 80° C.
• an N,N-dimethylglycine-K salt solution was prepared by adding 3.369 g (0.033 mole) of N,N-dimethylglycine and 1.898 g (0.033 mole) of KOH slowly to 3.015 g of water with stirring. This solution was added to the above PVA/formaldehyde/KOH/polystyrenesulfonic acid-K salt solution under stirring at about 80° C. for about 30 minutes to obtain a clear, homogeneous solution.
• the solution was then centrifuged at 8000 rpm while cooling for 12 minutes. Following centrifugation, the membrane was knife-cast (with a gap setting of 11 mils) onto a support of microporous polytetrafluoroethylene. Water was allowed to evaporate from the membrane in a hood at ambient conditions overnight. The membrane was then heated in an oven at 120° C. for about 6 hours.
• the resulting membrane comprised about 23.7 wt % dimethylglycine-K Salt, 4.7 wt % polystyrenesulfonic acid-K salt, 54.0 wt % (polyvinylalcohol/formaldehyde at 44/9 by weight), and 17.6 wt % KOH.
• the membrane had a thickness of about 33 microns (exclusive of the support).
• the membrane of Example 2 comprising about 23.7 wt % dimethylglycine-K Salt, 4.7 wt % polystyrenesulfonic acid-K salt, 54.0 wt % (polyvinylalcohol/formaldehyde at 44/9 by weight), and 17.6 wt % KOH (with a thickness of about 33 microns) was evaluated in the same way described in Permeation Measurement of Membrane of Example 1.
• the carbon dioxide/hydrogen selectivity and carbon dioxide permeability results obtained at 120-170° C. are shown in Table 1.
• this membrane possessed a high selectivity of carbon dioxide vs. hydrogen as well as high carbon dioxide permeability.
• this membrane is useful for the removal of carbon dioxide from the hydrogen-containing synthesis gas comprising this impurity to increase the concentration of hydrogen for hydrogen purification and enhancement.
• an aminoisobutyric acid-K salt solution was prepared by adding 4.480 g (0.044 mole) of aminoisobutyric acid and 2.580 g (0.046 mole) of KOH slowly to 5.284 g of water with stirring.
• a polyallylamine solution was prepared by adding 2.327 g polyallylamine in 15.234 g water. To the above PVA/formaldehyde/KOH solution were added the aminoisobutyric acid-K salt solution and the polyallylamine solution under stirring at about 80° C. for about 30 minutes to obtain a clear, homogeneous solution.
• the solution was then centrifuged at 8000 rpm while cooling for 10 minutes. Following centrifugation, the membrane was knife-cast (with a gap setting of 11 mils) onto a support of microporous polytetrafluoroethylene. Water was allowed to evaporate from the membrane in a hood at ambient conditions overnight. The membrane was then heated in an oven at 120° C. for about 6 hours.
• the resulting membrane comprised about 27.2 wt % aminoisobutyric acid-K salt, 10.1 wt % polyallylamine, 45.9 wt % (polyvinylalcohol/formaldehyde at 44/9 by weight), and 16.8 wt % KOH.
• the membrane had a thickness of about 26 microns (exclusive of the support).
• the membrane of Example 3 comprising about 27.2 wt % aminoisobutyric acid-K salt, 10.1 wt % polyallylamine, 45.9 wt % (polyvinylalcohol/formaldehyde at 44/9 by weight), and 16.8 wt % KOH (with a thickness of about 26 microns) was evaluated in the similar way described in Permeation Measurement of Membrane of Example 1 except for the water injection rate to the feed gas.
• the water injection rate to the feed gas was 0.03 ml/min at 120-130° C., 0.06 ml/min at 140° C., 0.09 ml/min at 150° C., and 0.12 ml/min at 160-180° C.
• the carbon dioxide/hydrogen selectivity and carbon dioxide permeability results obtained at 120-180° C. are shown in Table 2.
• this membrane exhibited a very high selectivity of carbon dioxide vs. hydrogen as well as very high carbon dioxide permeability.
• this membrane is very useful for the removal of carbon dioxide from the hydrogen-containing synthesis gas comprising this impurity to increase the concentration of hydrogen for hydrogen purification and enhancement.
• PVA polyvinylalcohol
• aqueous 37 wt % formaldehyde solution 8.123 g (3.006 g of formaldehyde)
• an aqueous KOH solution containing 4.072 g KOH and 4.331 g water under stirring.
• the resulting solution was heated at about 80° C. and maintained at this temperature with stirring for 23.5 hours to enhance the cross-linking of PVA with formaldehyde, catalyzed by KOH.
• the KOH concentration was about 5.5 wt %.
• an aminoisobutyric acid-K salt solution was prepared by adding 3.123 g of aminoisobutyric acid and 1.833 g of KOH slowly to 4.432 g of water with stirring.
• a polyallylamine solution was prepared by adding 2.206 g polyallylamine in 10.325 g water. To the above PVA/formaldehyde/KOH solution were added the aminoisobutyric acid-K salt solution and the polyallylamine solution under stirring at about 80° C. for about 10 minutes to obtain a clear, homogeneous solution.
• the solution was then centrifuged at 8000 rpm while cooling for 8 minutes. Following centrifugation, the membrane was knife-cast onto a support of microporous polytetrafluoroethylene. Water was allowed to evaporate from the membrane in a hood at ambient conditions overnight. The membrane was then heated in an oven at 120° C. for about 6 hours.
• the resulting membrane comprised about 19.6 wt % aminoisobutyric acid-K salt, 9.8 wt % polyallylamine, 52.5 wt % (polyvinylalcohol/formaldehyde at 44/15 by weight), and 18.1 wt % KOH.
• the membrane had a thickness of about 51 microns (exclusive of the support).
• the membrane of Example 4 comprising about 19.6 wt % aminoisobutyric acid-K salt, 9.8 wt % polyallylamine, 52.5 wt % (polyvinylalcohol/formaldehyde at 44/15 by weight), and 18.1 wt % KOH (with a thickness of about 51 microns) was evaluated in the similar way described in the Permeation Measurement of Membrane of Example 1, except for the feed gas and the water injection rates.
• the feed gas contained 50 ppm hydrogen sulfide in 17% carbon dioxide, 1% carbon monoxide, 45% hydrogen, and 37% nitrogen (on the dry basis).
• the water injection rate to sweep gas was maintained constant at 0.27 ml/min.
• the water injection rate to the feed gas was 0.075 ml/min at 110° C., 0.09 ml/min at 120-130° C., and 0.12 ml/min at 140° C.
• Table 3 shows the carbon dioxide/hydrogen, hydrogen sulfide/hydrogen and carbon dioxide/nitrogen selectivities, and carbon dioxide and hydrogen sulfide permeabilities obtained at 110-140° C.
• this membrane had very high selectivities of carbon dioxide and hydrogen sulfide vs. hydrogen as well as very high carbon dioxide and hydrogen sulfide permeabilities. In other words, this membrane is very useful for the removal of both carbon dioxide and hydrogen sulfide from the hydrogen-containing synthesis gas comprising these impurities. Also shown in this table, this membrane had very high selectivity of carbon dioxide vs. nitrogen. Thus, this membrane is also useful for the removal of the greenhouse gas, carbon dioxide, from the nitrogen-containing flue gas.

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