Gas separation using organic-vapor-resistant membranes

• US 6,361,583 B1
• Filed: 05/19/2000
• Issued: 03/26/2002
• Est. Priority Date: 05/19/2000
• Status: Expired due to Term

• Current Assignee: Membrane Technology and Research, Inc.
• Original Assignee: Membrane Technology and Research, Inc.
• Inventors: Da Costa, Andre R., Pinnau, Ingo, Daniels, Ramin, He, Zhenjie, Amo, Karl D.
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US09/574,420
• Time in Patent Office: 676 Days
• Field of Search: 95/45, 95/47--55, 95/96--06
• US Class Current: 95/45
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 71/06 Organic material
• CPC Class Codes: B01D 71/32 containing fluorine atoms
• CPC Class Codes: B01D 71/643 Polyether-imides
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A process for separating a gas from a gas mixture containing an organic compound gas or vapor, using gas-separation membranes selective for the gas over the organic compound. The membranes use a selective layer made from a polymer having repeating units of a fluorinated cyclic structure of an at least 5-member ring, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment.

Claims

1. A process for separating a desired gas from a gas mixture comprising the desired gas and a C₃₊ hydrocarbon vapor, the process comprising the steps of:

(a) bringing the gas mixture into contact with the feed side of a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising;

a polymer comprising repeat units of a fluorinated cyclic structure of an at least 5-member ring, the polymer having a fractional free volume no greater than about 0.3;

(b) providing a driving force for transmembrane permeation;

(c) withdrawing from the permeate side a permeate stream enriched in the desired gas compared to the gas mixture;

(d) withdrawing from the feed side a residue stream depleted in the desired gas compared to the gas mixture.

2. The process of claim 1, wherein the desired gas is chosen from the group consisting of hydrogen, nitrogen, oxygen, argon, carbon dioxide and organic compounds.

3. The process of claim 1, wherein the desired gas is hydrogen.

4. The process of claim 1, wherein the desired gas is nitrogen.

5. The process of claim 1, wherein the desired gas is methane.

6. The process of claim 1, wherein the desired gas is carbon dioxide.

7. The process of claim 1, wherein the desired gas is propylene.

8. The process of claim 1, wherein the C₃₊ hydrocarbon vapor comprises a paraffin.

9. The process of claim 1, wherein the C₃₊ hydrocarbon vapor comprises an olefin.

10. The process of claim 1, wherein the C₃₊ hydrocarbon vapor comprises an aromatic compound.

11. The process of claim 1, wherein the C₃₊ hydrocarbon vapor is chosen from the group consisting of halogenated compounds, amines, ketones and alcohols.

12. The process of claim 1, wherein the gas mixture further comprises methane.

13. The process of claim 1, wherein the gas mixture further comprises methane, and wherein the desired gas is not methane.

14. The process of claim 1, wherein the desired gas is hydrogen and the gas mixture further comprises methane.

15. The process of claim 1, wherein the desired gas is carbon dioxide and the gas mixture further comprises methane.

16. The process of claim 1, wherein the desired gas is nitrogen and the gas mixture further comprises methane.

17. The process of claim 1, wherein the desired gas is propylene and the C₃₊ hydrocarbon is propane.

18. The process of claim 1, wherein the gas mixture is a refinery gas stream.

19. The process of claim 1, wherein the gas mixture is a petrochemical plant gas stream.

20. The process of claim 1, wherein the gas mixture is natural gas.

21. The process of claim 1, wherein the polymer comprises a perfluorinated polymer.

22. The process of claim 1, wherein the polymer is formed from a fluorinated dioxole monomer.

23. The process of claim 1, wherein the polymer is formed from a fluorinated dioxolane monomer.

24. The process of claim 1, wherein the polymer is formed from a fluorinated cyclically polymerizable alkyl ether.

25. The process of claim 1, wherein the polymer is formed from a perfluorinated polyimide.

26. The process of claim 1, wherein the repeat unit is 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole.

27. The process of claim 1, wherein the polymer is a polyperfluoro (alkenyl vinyl ether).

28. The process of claim 1, wherein the polymer comprises a copolymer.

29. The process of claim 1, wherein the polymer comprises a copolymer having repeat units as recited in claim 1 copolymerized with repeat units of a second fluorinated monomer.

30. The process of claim 1, wherein the polymer comprises a copolymer having repeat units as recited in claim 1 copolymerized with repeat units of tetrafluoroethylene.

31. The process of claim 1, wherein the polymer has the formula:

where x and y represent the relative proportions of the dioxole and the tetrafluoroethylene blocks, such that x+y=1.

32. The process of claim 1, wherein the polymer has the formula:

where n is a positive integer.

33. The process of claim 1, wherein the separation membrane comprises a composite membrane that comprises a support membrane, a gutter layer and the selective layer, the gutter layer forming a layer between the support membrane and the selective layer.

34. The process of claim 33, wherein the gutter layer comprises a polymer formed from a fluorinated dioxole monomer, the polymer having a fractional free volume of at least about 0.3.

35. The process of claim 33, wherein the gutter layer comprises a copolymer of perfluoro-2,2-dimethyl-1,3-dioxole and tetrafluoroethylene.

36. The process of claim 1, wherein the gas mixture, as brought into contact with the feed side, has a total C₃₊ hydrocarbons partial pressure of at least about 25 psia.

37. The process of claim 1, wherein the gas mixture contains at least about 5% C₃₊ hydrocarbons.

38. The process of claim 1, wherein the gas mixture, as brought into contact with the feed side, has a pressure of at least about 30% of the saturation vapor pressure of the gas mixture.

39. The process of claim 1, wherein the separation membrane provides a pressure-normalized hydrogen flux as measured with pure gas at 25°

C. of at least about 200 GPU.

40. The process of claim 1, further comprising passing the permeate stream to additional separation treatment.

41. The process of claim 1, further comprising passing the residue stream to additional separation treatment.

42. A process for separating hydrogen from a gas mixture comprising hydrogen and a C₃₊ hydrocarbon vapor, the process comprising the steps of:

(a) bringing the gas mixture into contact with the feed side of a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising;

a polymer comprising repeat units of a fluorinated cyclic structure of an at least 5-member ring, the polymer having a fractional free volume no greater than about 0.3;

(b) providing a driving force for transmembrane permeation;

(c) withdrawing from the permeate side a permeate stream enriched in hydrogen compared to the gas mixture;

(d) withdrawing from the feed side a residue stream depleted in hydrogen compared to the gas mixture.

43. The process of claim 42, wherein the polymer is formed from a fluorinated monomer chosen from the group consisting of dioxoles, dioxolanes, alkyl ethers and perfluorinated polyimides.

44. The process of claim 42, wherein the polymer comprises a copolymer having repeat units as recited in claim 42 copolymerized with repeat units of tetrafluoroethylene.

45. The process of claim 42, wherein the polymer has the formula:

where x and y represent the relative proportions of the dioxole and the tetrafluoroethylene blocks, such that x+y=1.

46. The process of claim 42, wherein the gas mixture further comprises methane.

47. The process of claim 42, wherein the separation membrane exhibits a mixed-gas selectivity for hydrogen over methane as measured at the operating conditions of the process of at least about 10.

48. The process of claim 42, wherein the separation membrane exhibits a mixed-gas selectivity for hydrogen over propane as measured at the operating conditions of the process of at least about 50.

49. The process of claim 42, wherein the gas mixture is a refinery off-gas stream.

50. The process of claim 42, further comprising passing the residue stream to a fuel gas supply.

51. The process of claim 42, further comprising passing the permeate stream to a pressure swing adsorption unit to produce a high-purity hydrogen stream.

52. The process of claim 42, wherein the gas mixture comprises tail gas from a pressure swing adsorption unit.

53. The process of claim 42, wherein the gas mixture, as brought into contact with the feed side, has a total C₃₊ hydrocarbons partial pressure of at least about 25 psia.

54. A process for separating propylene from a gas mixture comprising propylene and propane, the process comprising the steps of:

(a) bringing the gas mixture into contact with the feed side of a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising;

a polymer comprising repeat units of a fluorinated cyclic structure of an at least 5-member ring, the polymer having a fractional free volume no greater than about 0.3;

(b) providing a driving force for transmembrane permeation;

(c) withdrawing from the permeate side a permeate stream enriched in propylene compared to the gas mixture;

(d) withdrawing from the feed side a residue stream depleted in propylene compared to the gas mixture.

55. The process of claim 54, wherein the polymer is formed from a fluorinated monomer chosen from the group consisting of dioxoles, dioxolanes, alkyl ethers and perfluorinated polyimides.

56. The process of claim 54, wherein the polymer comprises a copolymer having repeat units as recited in claim 54 copolymerized with repeat units of tetrafluoroethylene.

57. The process of claim 54, wherein the polymer has the formula:

where x and y represent the relative proportions of the dioxole and the tetrafluoroethylene blocks, such that x+y=1.

58. The process of claim 54, wherein the separation membrane exhibits a mixed-gas selectivity for propylene over propane as measured at the operating conditions of the process of at least about 2.5.

59. A process for separating nitrogen from a gas mixture comprising nitrogen and a C₂₊ hydrocarbon vapor, the process comprising the steps of:

(a) bringing the gas mixture into contact with the feed side of a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising;

a polymer comprising repeat units of a fluorinated cyclic structure of an at least 5-member ring, the polymer having a fractional free volume no greater than about 0.3;

(b) providing a driving force for transmembrane permeation;

(c) withdrawing from the permeate side a permeate stream enriched in nitrogen compared to the gas mixture;

(d) withdrawing from the feed side a residue stream depleted in nitrogen compared to the gas mixture.

60. The process of claim 59, wherein the polymer is formed from a fluorinated monomer chosen from the group consisting of dioxoles, dioxolanes, alkyl ethers and perfluorinated polyimides.

61. The process of claim 59, wherein the polymer comprises a copolymer having repeat units as recited in claim 59 copolymerized with repeat units of tetrafluoroethylene.

62. The process of claim 59, wherein the polymer has the formula:

where x and y represent the relative proportions of the dioxole and the tetrafluoroethylene blocks, such that x+y=1.

63. The process of claim 59, wherein the gas mixture further comprises methane.

64. The process of claim 59, wherein the C₂₊ hydrocarbon vapor comprises ethylene.

65. The process of claim 59, wherein the separation membrane exhibits a mixed-gas selectivity for nitrogen over methane as measured at the operating conditions of the process of at least about 2.

66. The process of claim 59, wherein the separation membrane exhibits a mixed-gas selectivity for nitrogen over ethylene as measured at the operating conditions of the process of at least about 4.

67. The process of claim 59, wherein the gas mixture is natural gas.

68. A process for separating carbon dioxide from a gas mixture comprising carbon dioxide, methane and a C₃₊ hydrocarbon vapor, the process comprising the steps of:

(a) bringing the gas mixture into contact with the feed side of a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising;

a polymer comprising repeat units of a fluorinated cyclic structure of an at least 5-member ring, the polymer having a fractional free volume no greater than about 0.3;

(b) providing a driving force for transmembrane permeation;

(c) withdrawing from the permeate side a permeate stream enriched in carbon dioxide compared to the gas mixture;

(d) withdrawing from the feed side a residue stream depleted in carbon dioxide compared to the gas mixture.

69. The process of claim 68, wherein the polymer is formed from a fluorinated monomer chosen from the group consisting of dioxoles, dioxolanes, alkyl ethers and perfluorinated polyimides.

70. The process of claim 68, wherein the polymer comprises a copolymer having repeat units as recited in claim 68 copolymerized with repeat units of tetrafluoroethylene.

71. The process of claim 68, wherein the polymer has the formula:

where x and y represent the relative proportions of the dioxole and the tetrafluoroethylene blocks, such that x+y=1.

72. The process of claim 68, wherein the separation membrane exhibits a mixed-gas selectivity for carbon dioxide over methane as measured at the operating conditions of the process of at least about 5.

73. The process of claim 68, wherein the gas mixture is natural gas.

74. The process of claim 68, wherein the gas mixture, as brought into contact with the feed side, has a total C₃₊ hydrocarbons partial pressure of at least about 25 psia.

75. A process for separating methane from a gas mixture comprising methane and C₃₊ hydrocarbon vapors, the process comprising the steps of:

(a) bringing the gas mixture into contact with the feed side of a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising;

a polymer comprising repeat units of a fluorinated cyclic structure of an at least 5-member ring, the polymer having a fractional free volume no greater than about 0.3;

(b) providing a driving force for transmembrane permeation;

(c) withdrawing from the permeate side a permeate stream enriched in methane compared to the gas mixture;

(d) withdrawing from the feed side a residue stream depleted in methane compared to the gas mixture.

76. The process of claim 75, wherein the polymer is formed from a fluorinated monomer chosen from the group consisting of dioxoles, dioxolane, alkyl ethers and perfluorinated polyimides.

77. The process of claim 75, wherein the polymer comprises a copolymer having repeat units as recited in claim 75 copolymerized with repeat units of tetrafluoroethylene.

78. The process of claim 75, wherein the polymer has the formula:

wherein x and y represent the relative proportions of the dioxole and the tetrafluoroethylene blocks, such that x+y=1.

79. The process of claim 75, wherein the separation membrane exhibits a mixed-gas selectivity for methane over propane as measured at the operating conditions of the process of at least about 5.

80. The process of claim 75, wherein the gas mixture is natural gas.

81. The process of claim 75, wherein the gas mixture, as brought into contact with the feed side, has a total C₃₊ hydrocarbons partial pressure of at least about 25 psia.

82. A process for separating argon from a gas mixture comprising argon and ethylene, the process comprising the steps of:

(a) bringing the gas mixture into contact with the feed side of a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising;

a polymer comprising repeat units of a fluorinated cyclic structure of an at least 5-member ring, the polymer having a fractional free volume no greater than about 0.3;

(b) providing a driving force for transmembrane permeation;

(c) withdrawing from the permeate side a permeate stream enriched in argon compared to the gas mixture;

(d) withdrawing from the feed side a residue stream depleted in argon compared to the gas mixture.

83. The process of claim 82, wherein the polymer is formed from a fluorinated monomer chosen from the group consisting of dioxoles, dioxolanes, alkyl ethers and perfluorinated polyimides.

84. The process of claim 82, wherein the polymer comprises a copolymer having repeat units as recited in claim 82 copolymerized with repeat units of tetrafluoroethylene.

85. The process of claim 82, wherein the polymer has the formula:

wherein x and y represent the relative proportions of the dioxole and the tetrafluoroethylene blocks, such that x+y=1.