Multicomponent membranes for gas separations

• US 4,230,463 A
• Filed: 09/13/1977
• Issued: 10/28/1980
• Est. Priority Date: 09/13/1977
• Status: Expired due to Term

• Current Assignee: Permea Incorporated
• Original Assignee: Monsanto Company (Bayer AG)
• Inventors: Henis, Jay M. S., Tripodi, Mary K.
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US05/832,481
• Time in Patent Office: 1,141 Days
• Field of Search: 55/16, 55/158, 55/68-73, 210/22, 210/23 F, 210/23 H, 210/321 R, 210/490, 210/491, 210/500 M, 427/245, 428/304-306, 428/326, 428/327
• US Class Current: 95/47
• CPC Class Codes: B01D 2323/30 Cross-linking
• CPC Class Codes: B01D 53/22 by diffusion manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 67/0011 Casting solutions therefor
• CPC Class Codes: B01D 67/0088 Physical treatment with compounds, e.g. swelling, coating or impregnation
• CPC Class Codes: B01D 67/0093 Chemical modification
• CPC Class Codes: B01D 67/00931 by introduction of specific groups after membrane formation, e.g. by grafting
• CPC Class Codes: B01D 69/08 Hollow fibre membranes manufacture of hollow fibres D01D5/24, D01F1/08
• CPC Class Codes: B01D 69/12 Composite membranes; Ultra-thin membranes
• CPC Class Codes: B01D 69/1214 Chemically bonded layers, e.g. cross-linking
• CPC Class Codes: B01D 71/16 Cellulose acetate
• CPC Class Codes: B01D 71/42 Polymers of nitriles, e.g. polyacrylonitrile
• CPC Class Codes: B01D 71/421 Polyacrylonitrile
• CPC Class Codes: B01D 71/68 Polysulfones; Polyethersulfones
• CPC Class Codes: B01D 71/80 Block polymers

Abstract

Multicomponent membranes for gas separation are disclosed which are effective for separating at least one gas from gaseous mixtures by permeation wherein the multicomponent membranes are comprised of a coating in occluding contact with a porous separation membrane. The multicomponent membranes advantageously exhibit less resistance to permeate gas flow for the at least one gas than for at least one remaining gas in the gaseous mixture. For at least one pair of gases the separation factor of the multicomponent membrane is significantly greater than the determined intrinsic separation factor of the material of the coating. Processes and apparatus for gas separation utilizing the multicomponent membranes are also disclosed.

Claims

1. A multicomponent membrane for gas separation comprising a coating in occluding contact with a porous separation membrane of material, which material exhibits selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, said porous separation membrane having a substantial void volume, wherein, with respect to at least one pair of gases, the material of the porous separation membrane exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor significantly greater than the determined intrinsic separation factor of the material of said coating and greater than the separation factor exhibited by the porous separation membrane.

47. In an apparatus for selectively separating at least one gas in a gaseous mixture from at least one remaining gas comprising an enclosure and a membrane within said enclosure for selectively separating said at least one gas in the gaseous mixture and providing a permeated product, said membrane having a feed surface and an opposing exit surface, and said enclosure having means to enable said gaseous mixture to be supplied said feed surface, means to enable removal of gases from the vicinity of the feed surface, and means to enable said permeated product to be removed from the vicinity of the exit surface, the improvement wherein the membrane comprises a multicomponent membrane of claim 1.

48. The apparatus of claim 47 in which said separation factor exhibited by the multicomponent membrane is at least about 35 percent greater than said predetermined intrinsic separation factor, and in which the void volume of the porous separation membrane is about 10 to 80 percent.

2. A multicomponent membrane for gas separation comprising a coating and a porous separation membrane of material, which material exhibits selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, said porous separation membrane being anisotropic having a substantial void volume and at least one relatively dense region within its thickness in barrier flow relationship to gas flow across the porous separation membrane, wherein the coating is in occluding contact with at least one relatively dense region, wherein with respect to at least one pair of gases consisting of one of hydrogen, helium, ammonia and carbon dioxide and one of carbon monoxide, nitrogen, argon, sulfur hexafluoride, methane and ethane, the material of the porous separation membrane exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor significantly greater than the determined intrinsic separation factor of the material of the coating and greater than the separation factor exhibited by the porous separation membrane.

3. The multicomponent membrane of claim 2 in which said separation factor exhibited by the multicomponent membrane is at least about 35 percent greater than said determined intrinsic separation factor of the material of the coating and in which the void volume of the porous separation membrane is about 10 to 80 percent.

4. The multicomponent membrane of claim 3 in which, with respect to at least one gas of said pair of gases, the material of the coating has a higher permeability constant than does the material of the porous separation membrane.

5. The multicomponent membrane of claim 3 in which, with respect to at least one gas, which gas is selected from the group consisting of carbon monoxide, nitrogen, argon, sulfur hexafluoride, methane, ethane and carbon dioxide, the effective separating thickness of the multicomponent membrane is less than about 15,000 angstroms based on the permeability constant of the material of the porous separation membrane for said gas, and the ratio of total surface area to total pore cross-sectional area of the porous separation membrane is at least about 10³ :

1.

6. The multicomponent membrane of claim 3 in which the multicomponent membrane is a film.

7. The multicomponent membrane of claim 3 in which the multicomponent membrane is a hollow fiber.

8. The multicomponent membrane of claim 3 in which the coating is in contact with at least one surface of the porous separation membrane, and the coating has an average thickness up to about 50 microns.

9. The multicomponent membrane of claim 8 in which the coating is in contact with both surfaces of the porous separation membrane, and the coating in contact with each surface has an average thickness up to about 50 microns.

10. The multicomponent membrane of claim 8 in which an essentially liquid substance comprising polymerizable material is applied to the porous separation membrane, and the polymerizable material is polymerized after application to the porous separation membrane to provide the coating.

11. The multicomponent membrane of claim 3 in which the coating comprises at least two layers.

12. The multicomponent membrane of claim 3 in which the porous separation membrane comprises at least one of polysulfone, copolymer of styrene and acrylonitrile poly(arylene oxide), polycarbonate, and cellulose acetate.

13. The multicomponent membrane of claim 12 in which the coating comprises at least one of poly(siloxane), poly(isoprene), copolymer of α

-methylstyrene and poly(siloxane), poly(styrene) having a degree of polymerization of about 2 to 20, and aliphatic hydrocarbyl-containing organic compounds having about 14 to 30 carbon atoms.

14. The multicomponent membrane of claim 13 in which the coating comprises at least one of aliphatic and aromatic poly(siloxane) having repeating units containing 1 to about 20 carbon atoms, and the coating is substantially non-interrupted.

15. The multicomponent membrane of claim 14 in which the poly(siloxane) is cross-linked to provide silicone rubber and has a molecular weight of about 1000 to 100,000 prior to cross-linking.

16. The multicomponent membrane of claim 12 in which the material of the porous separation membrane comprises a polysulfone, and the multicomponent membrane is a hollow fiber.

17. The multicomponent membrane of claim 16 in which the polysulfone has a repeating unit represented by ##STR10## wherein each of R and R'"'"' are aliphatic or aromatic hydrocarbyl-containing moieties of 1 to about 40 carbon atoms, and the polysulfone has a molecular weight of at least about 10,000.

18. The multicomponent membrane of claim 17 in which the polysulfone has a repeating unit represented by ##STR11## wherein n is about 50 to 80.

19. The multicomponent membrane of claim 18 in which, with respect to at least one gas, which gas is selected from the group consisting of carbon monoxide, nitrogen, argon, sulfur hexafluoride, methane, ethane and carbon dioxide, the effective separating thickness of the multicomponent membrane is less than about 5000 angstroms based on the permeability constant of the polysulfone for said gas;

the porous separation membrane has a total surface area to total pore cross-sectional area of at least about 10³ ;

1; and

the porous separation membrane has an average pore diameter less than about 20,000 angstroms.

20. The multicomponent membrane of claim 19 in which the coating contacts at least the feed surface of the porous separation membrane.

21. The multicomponent membrane of claim 19 in which the coating contacts at least the outside surface of the hollow fiber.

22. The multicomponent membrane of claim 19 in which the coating comprises at least one of poly(siloxane), poly(isoprene), copolymer of α

-methylstyrene and poly(siloxane), poly(styrene) having a degree of polymerization of about 2 to 20, and aliphatic hydrocarbyl-containing organic compounds having about 14 to 30 carbon atoms.

23. The multicomponent membrane of claim 22 in which the coating comprises at least one of aliphatic and aromatic poly(siloxane) having repeating units containing 1 to about 20 carbon atoms, and the coating is substantially non-interrupted.

24. The multicomponent membrane of claim 23 in which the poly(siloxane) is cross-linked to provide silicone rubber and has a molecular weight of about 1000 to 100,000 prior to cross-linking.

25. The multicomponent membrane of claim 24 in which the poly(siloxane) is cross-linked after being applied to the porous separation membrane.

26. Multicomponent membranes of claim 3 in which both the separation factor and the permeability of the multicomponent membrane are influenced by the ratio of total surface area to total pore cross-sectional area and by the average pore cross-sectional diameter of said porous separation membrane.

27. Multicomponent membranes of claim 3 in which both the separation factor and the permeability of the multicomponent membrane are influenced by the relative resistances to gas flow through the pores of said porous separation membrane and through the solid portions of said porous separation membrane.

28. The multicomponent membrane of claim 3 in which the multicomponent membrane exhibits a greater permeability than an annealed membrane, said annealed membrane consisting of a membrane substantially the same as the porous separation membrane of the multicomponent membrane but which membrane has been sufficiently annealed that said annealed membrane exhibits, with respect to said at least one pair of gases, a separation factor equal to or greater than the separation factor exhibited by the multicomponent membrane.

29. The multicomponent membrane of claim 3 in which the multicomponent membrane exhibits a greater permeability than a densified membrane, said densified membrane consisting of a membrane substantially the same as the porous separation membrane of the multicomponent membrane but which membrane has been treated to sufficiently densify the membrane such that said densified membrane exhibits, with respect to said at least one pair of gases, a separation factor equal to or greater than the separation factor exhibited by the multicomponent membrane.

30. The multicomponent membrane of claim 3 in which the porous separation membrane is an anisotropic hollow fiber which is capable of maintaining the configuration of the hollow fiber under gas separation conditions and in which the multicomponent membrane exhibits a greater permeability than an anisotropic hollow fiber membrane, said anisotropic hollow fiber membrane consisting of the material of the porous separation membrane and being capable of maintaining the configuration of the hollow fiber under gas separation conditions, and said anisotropic hollow fiber membrane exhibits, with respect to said at least one pair of gases, a separation factor equal to or greater than the separation factor exhibited by the multicomponent membrane.

31. In an apparatus for selectively separating at least one gas in a gaseous mixture from at least one remaining gas comprising an enclosure and a membrane within said enclosure for selectively separating said at least one gas in the gaseous mixture and providing a permeated product, said membrane having a feed surface and an opposing exit surface, and said enclosure having means to enable said gaseous mixture to be supplied said feed surface, means to enable removal of gases from the vicinity of the feed surface, and means to enable said permeated product to be removed from the vicinity of the exit surface, the improvement wherein the membrane comprises a multicomponent membrane of claim 2.

32. In an apparatus for selectively separating at least one gas in a gaseous mixture from at least one remaining gas comprising an enclosure and a membrane within said enclosure for selectively separating said at least one gas in the gaseous mixture and providing a permeated product, said membrane having a feed surface and an opposing exit surface, and said enclosure having means to enable said gaseous mixture to be supplied said feed surface, means to enable removal of gases from the vicinity of the feed surface, and means to enable said permeated product to be removed from the vicinity of the exit surface, the improvement wherein the membrane comprises a multicomponent membrane of claim 24.

33. A multicomponent membrane for gas separation comprising a coating in occluding contact with a porous separation membrane of a material, which material exhibits selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, said coating being applied using an essentially liquid substance suitable for forming the coating, wherein, with respect to at least one pair of gases, the material of the porous separation membrane exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor significantly greater than the determined intrinsic separation factor of the material of said coating and greater than the separation factor exhibited by the porous separation membrane.

34. The multicomponent membrane of claim 33 in which said separation factor exhibited by the multicomponent membrane is at least about 35 percent greater than said determined intrinsic separation factor of the material of the coating.

35. The multicomponent membrane of claim 34 in which the coating comprises at least one of poly(isoprene), poly(siloxane), poly(styrene) having a degree of polymerization of about 2 to 20, and aliphatic hydrocarbyl-containing organic compounds having about 14 to 30 carbon atoms.

36. The multicomponent membrane of claim 35 in which the coating comprises at least one of aliphatic and aromatic poly(siloxane) having repeating units containing 1 to about 20 carbon atoms, and the coating is substantially non-interrupted.

37. The multicomponent membrane of claim 36 in which the poly(siloxane) is cross-linked to provide silicone rubber and has a molecular weight of about 1000 to 100,000 prior to cross-linking.

38. The multicomponent membrane of claim 34 in which the essentially liquid substance comprises polymerizable material, and the polymerizable material is polymerized after application to the porous separation membrane to provide the coating.

39. In an apparatus for selectively separating at least one gas in a gaseous mixture from at least one remaining gas comprising an enclosure and a membrane within said enclosure for selectively separating said at least one gas in the gaseous mixture and providing a permeated product, said membrane having a feed surface and an opposing exit surface, and said enclosure having means to enable said gaseous mixture to be supplied said feed surface, means to enable removal of gases from the vicinity of the feed surface, and means to enable said permeated product to be removed from the vicinity of the exit surface, the improvement wherein the membrane comprises a multicomponent membrane of claim 33.

40. A multicomponent membrane for gas separation comprising a coating in occluding contact with a porous separation membrane comprising polysulfone wherein, with respect to at least one pair of gases, the polysulfone exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor significantly greater than the determined intrinsic separation factor of the material of said coating and greater than the separation factor exhibited by the porous separation membrane.

41. The multicomponent membrane of claim 40 in which said separation factor exhibited by the multicomponent membrane is at least about 35 percent greater than said determined intrinsic separation factor of the material of the coating and the polysulfone has a repeating unit represented by ##STR12## wherein each of R and R'"'"' are aliphatic or aromatic hydrocarbyl-containing moieties of 1 to about 40 carbon atoms and the polysulfone has a molecular weight of at least about 10,000.

42. The multicomponent membrane of claim 41 in which the porous separation membrane is anisotropic with a relatively dense region, and the multicomponent membrane is a hollow fiber.

43. The multicomponent membrane of claim 42 in which the polysulfone has a repeating unit represented by ##STR13## wherein n is about 50 to 80.

44. The multicomponent membrane of claim 41 in which the polysulfone comprises a poly(arylene ether)sulfone.

45. A multicomponent membrane for gas separation comprising a coating and a hollow fiber porous separation membrane of material, which material exhibits selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, said porous separation membrane being anisotropic having a substantial void volume and at least one relatively dense region within its thickness in barrier flow relationship to gas flow across the porous separation membrane, wherein the coating is in occluding contact with at least one relatively dense region, wherein, with respect to at least one pair of gases, the material of the porous separation membrane exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor at least about 35 percent greater than the determined intrinsic separation factor of the material of said coating and greater than the separation factor exhibited by the porous separation membrane.

46. A multicomponent membrane for a gas separation comprising a coating in occluding contact with a porous separation membrane of a material, which material exhibits selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, in which the porous separation membrane has a substantial void volume, wherein, with respect to at least one pair of gases, the material of the porous separation membrane exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor at least about 35 percent greater than the determined intrinsic separation factor of the material of said coating and at least about 10 percent greater than the separation factor exhibited by the porous separation membrane.

49. A process for separating at least one gas in a gaseous mixture from at least one other gas in said gaseous mixture by selective permeation and providing a permeated product containing at least one permeating gas, comprising:

contacting the gaseous mixture with one surface of a multicomponent membrane, which, with respect to at least one pair of gases of said gaseous mixture, multicomponent membrane exhibits selective permeation of one gas of said pair of gases over that of the remaining gas of said pair of gases, and which multicomponent membrane comprises a coating in occluding contact with a porous separation membrane having a substantial void volume, wherein, with respect to said pair of gases, the material of the porous separation membrane exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor significantly greater than the determined intrinsic separation factor of the material of the coating and greater than the separation factor exhibited by the porous separation membrane;

maintaining the opposite surface of the multicomponent membrane at a lower chemical potential for said at least one permeating gas than the chemical potential at the said surface;

permeating said at least one permeating gas into and through the multicomponent membrane; and

removing from the vicinity of said opposite surface a permeated product having a different proportion of said at least one gas of said gaseous mixture to said at least one other gas of said gaseous mixture than the proportion in the gaseous mixture of said at least one gas to said at least one other gas.

50. A process for separating at least one gas in a gaseous mixture from at least one other gas in said gaseous mixture by selective permeation and providing a permeated product containing at least one permeating gas, comprising:

contacting the gaseous mixture with one surface of a multicomponent membrane, which, with respect to at least one pair of gases of said gaseous mixture multicomponent membrane exhibits selective permeation of one gas of said pair of gases over that of the remaining gas of said pair of gases, and which multicomponent membrane comprises a coating and a porous separation membrane being anisotropic having a substantial void volume and at least one relatively dense region within its thickness in barrier flow relationship to gas flow across the porous separation membrane, wherein the coating is in occluding contact with at least one relatively dense region, wherein, with respect to said pair of gases, the material of the porous separation membrane exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor significantly greater than the determined intrinsic separation factor of the material of the coating and greater than the separation factor exhibited by the porous separation membrane;

maintaining the opposite surface of the multicomponent membrane at a lower chemical potential for said at least one permeating gas than the chemical potential at the said surface;

permeating said at least one permeating gas into and through the multicomponent membrane; and

removing from the vicinity of said opposite surface a permeated product having a different proportion of said at least one gas of said gaseous mixture to said at least one other gas of said gaseous mixture than the proportion in the gaseous mixture of said at least one gas to said at least one other gas.

51. The process of claim 50 wherein said separation factor exhibited by the multicomponent membrane is at least about 35 percent greater than said determined intrinsic separation factor of the material of the coating, and the void volume of the porous separation membrane is about 10 to 80 percent.

52. The process of claim 51 wherein the said at least one gas comprises oxygen and the gaseous mixture comprises air.

53. The process of claim 52 wherein the porous separation membrane comprises at least one of polysulfone, copolymer of styrene and acrylonitrile, poly(arylene oxide), polycarbonate, and cellulose acetate.

54. The process of claim 53 wherein the porous separation membrane comprises a polysulfone and the coating comprises at least one of poly(isoprene), poly(siloxane), poly(styrene) having a degree of polymerization of about 2 to 20, and aliphatic hydrocarbyl-containing organic compound of about 14 to 30 carbon atoms.

55. The process of claim 54 wherein the coating comprises a poly(siloxane), the multicomponent membrane is a hollow fiber, and the coating is substantially non-interrupted.

56. The process of claim 53 wherein the polysulfone has a repeating unit represented by ##STR14## wherein each of R and R'"'"' are aliphatic or aromatic hydrocarbyl-containing moieties of 1 to about 40 carbon atoms;

the polysulfone has a molecular weight of at least about 10,000 and the poly(siloxane) comprises aliphatic or aromatic poly(siloxane) having 1 to about 20 carbon atoms.

57. The process of claim 56 wherein the poly(siloxane) is cross-linked and has a molecular weight of about 1000 to 100,000 prior to cross-linking.

58. The process of claim 51 wherein said at least one gas comprises hydrogen and said at least one other gas comprises at least one of the group consisting of carbon monoxide, carbon dioxide, helium, nitrogen, oxygen, argon, hydrogen sulfide, nitrous oxide, ammonia, and hydrocarbon of 1 to about 5 carbon atoms.

59. The process of claim 58 wherein the porous separation membrane comprises at least one of polysulfone, copolymer of styrene and acrylonitrile, poly(arylene oxide), polycarbonate, and cellulose acetate.

60. The process of claim 59 wherein the porous separation membrane comprises polysulfone and the coating comprises at least one of poly(isoprene), poly(siloxane), copolymer of α

-methylstyrene and poly(siloxane), poly(styrene) having a degree of polymerization of about 2 to 20, and aliphatic hydrocarbyl-containing organic compound of about 14 to 30 carbon atoms.

61. The process of claim 60 wherein the multicomponent membrane is a hollow fiber.

62. The process of claim 61 wherein the polysulfone has a repeating unit represented by ##STR15## wherein each of R and R'"'"' are aliphatic or aromatic hydrocarbyl-containing moieties of 1 to about 40 carbon atoms, and the polysulfone has a molecular weight of at least about 10,000;

and wherein the coating comprises aliphatic or aromatic poly(siloxane) having 1 to about 20 carbon atoms.

63. The process of claim 62 wherein the poly(siloxane) is cross-linked to provide a silicone rubber and has a molecular weight of about 1000 to 100,000 prior to cross-linking.

64. The process of claim 59 wherein the porous separation membrane comprises a poly(arylene oxide).

65. The process of claim 64 wherein the porous separation membrane comprises a brominated poly(xylylene oxide).

66. The process of claim 59 wherein the porous separation membrane comprises a copolymer of styrene and acrylonitrile containing about 20 to 70 weight percent styrene and about 30 to 80 weight percent acrylonitrile.

67. The process of claim 51 wherein said at least one gas comprises ammonia and the gaseous mixture comprises ammonia and at least one of hydrogen, nitrogen, methane, and argon.

68. The process of claim 51 wherein said at least one gas comprises carbon dioxide and the gaseous mixture comprises carbon dioxide and at least one of carbon monoxide, hydrocarbon of 1 to about 5 carbon atoms, and nitrogen.

69. The process of claim 51 wherein said at least one gas comprises helium and the gaseous mixture comprises helium and at least one hydrocarbon of 1 to about 5 carbon atoms.

70. The process of claim 51 wherein said at least one gas comprises hydrogen sulfide and the gaseous mixture comprises hydrogen sulfide and at least one hydrocarbon of 1 to about 5 carbon atoms.

71. The process of claim 51 wherein said at least one gas comprises carbon monoxide and the gaseous mixture comprises carbon monoxide and at least one of hydrogen, helium, nitrogen, and hydrocarbon of 1 to about 5 carbon atoms.

72. The process of claim 51 wherein, with respect to a gas of the gaseous mixture, the effective separating thickness of the multicomponent membrane is less than about 15,000 angstroms based on the permeability constant of the material of the porous separation membrane for said gas, and the ratio of total surface area to total pore cross-sectional area of the porous separation membrane is at least about 10³ :

1.

73. The process of claim 51 wherein the multicomponent membrane exhibits a greater permeability than an annealed membrane, said annealed membrane consisting of a membrane substantially the same as the porous separation membrane of the multicomponent membrane but which membrane has been sufficiently annealed that said annealed membrane exhibits a separation factor equal to or greater than the separation factor exhibited by the multicomponent membrane.

74. The process of claim 51 wherein the multicomponent membrane exhibits a greater permeability than a densified membrane, said densified membrane consisting of a membrane substantially the same as the porous separation membrane of the multicomponent membrane but which membrane has been treated to density the membrane such that said densified membrane exhibits a separation factor equal to or greater than the separation factor exhibited by the multicomponent membrane.

75. The process of claim 51 wherein the porous separation membrane is an anisotropic hollow fiber which is capable of maintaining the configuration of the hollow fiber under gas separation conditions and in which the multicomponent membrane exhibits a greater permeability than an anisotropic hollow fiber membrane, said anisotropic hollow fiber membrane consisting of the material of the porous separation membrane and being capable of maintaining the configuration of the hollow fiber under gas separation conditions, and said anisotropic hollow fiber membrane exhibits a separation factor equal to or greater than the separation factor exhibited by the multicomponent membrane.

76. A process for separating at least one gas in a gaseous mixture from at least one other gas in said gaseous mixture by selective permeation and providing a permeated product containing at least one permeating gas comprising:

contacting the gaseous mixture with one surface of a multicomponent membrane, which, with respect to at least one pair of gases of said gaseous mixture, multicomponent membrane exhibits selective permeation of one gas of said pair of gases over that of the remaining gas of said pair of gases, and which multicomponent membrane comprises a coating in occluding contact with a porous separation membrane having a substantial void volume, wherein, with respect to said pair of gases, the material of the porous separation membrane exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor at least about 35 percent greater than the determined intrinsic separation factor of the material of the coating and at least about 10 percent greater than the separation factor exhibited by the porous separation membrane;

maintaining the opposite surface of the multicomponent membrane at a lower chemical potential for said at least one permeating gas than the chemical potential at the said one surface;

permeating said at least one permeating gas into and through the multicomponent membrane; and

removing from the vicinity of said opposite surface a permeated product having a different proportion of said at least one gas of said gaseous mixture to said at least one other gas of said gaseous mixture than that proportion in the gaseous mixture of said at least one gas to said at least one other gas.

77. A process for separating at least one gas comprising hydrogen in a gaseous mixture from at least one other gas comprising at least one of carbon monoxide, carbon dioxide, helium, nitrogen, oxygen, argon, hydrogen sulfide, nitrous oxide, ammonia and hydrocarbon of 1 to about 5 carbon atoms, in said gaseous mixture by selective permeation and providing a permeated product containing at least one permeating gas comprising:

contacting the gaseous mixture with one surface of a multicomponent membrane which, with respect to at least one pair of gases of said gaseous mixture, multicomponent membrane exhibits selective permeation of one gas of said pair of gases over that of the remaining gas of said pair of gases, in which said multicomponent membrane comprises a coating in occluding contact with a porous separation membrane, wherein, with respect to said pair of gases, the material of the porous separation membrane exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor significantly greater than the determined intrinsic separation factor of the material of the coating and greater than the separation factor exhibited by the porous separation membrane;

maintaining the opposite surface of the multicomponent membrane at a lower chemical potential for said at least one permeating gas than the chemical potential at the said one surface;

permeating said at least one permeating gas into and through the multicomponent membrane; and

removing from the vicinity of said opposite surface a permeated product having a different proportion of said at least one gas to said at least one other gas than that proportion in said gaseous mixture of said at least one gas to said at least one other gas.

78. A process for separating at least one gas in a gaseous mixture from at least one other gas in said gaseous mixture by selective permeation and providing a permeated product containing at least one permeating gas comprising:

contacting the gaseous mixture with one surface of a multicomponent membrane which, with respect to at least one pair of gases of said gaseous mixture, multicomponent membrane exhibits selective permeation of one gas of said pair of gases over that of the remaining gas of said pair of gases, and which membrane comprises a coating in occluding contact with a porous separation membrane comprising polysulfone, wherein, with respect to said pair of gases, the polysulfone exhibits a determined intrinsic separation factor greater than the determined intrinsic separation factor of the material of said coating, and the multicomponent membrane exhibits a separation factor at least about 35 percent greater than the determined intrinsic separation factor of the material of the coating and greater than the separation factor exhibited by the porous separation membrane;

maintaining the opposite surface of the multicomponent membrane at a lower chemical potential for said at least one permeating gas than the chemical potential at the said one surface;

permeating said at least one permeating gas into and through the multicomponent membrane; and

removing from the vicinity of said opposite surface a permeated product having a different proportion of said at least one gas to said at least one other gas than that proportion in said gaseous mixture of said at least one gas to said at least one other gas.