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Gas separation membranes formed from polyether-urethane or polyether-urea block copolymers are useful for separating gases from gas mixtures. The membranes and processes are especially suited for separating polar gases from mixtures that contain polar and non-polar species. The novel membranes exhib

Gas separation membranes formed from polyether-urethane or polyether-urea block copolymers are useful for separating gases from gas mixtures. The membranes and processes are especially suited for separating polar gases from mixtures that contain polar and non-polar species. The novel membranes exhibit good permeability and permselectivity, as well as durability, making them well suited for industrial applications such as removal of acid gases from natural gas and removal of carbon dioxide from synthesis gas.

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1. A process for separating component gases of a gas mixture comprising the steps of:a) providing a permeable membrane comprising a polyurethane-polyether or polyurea-polyether block copolymer comprising repeating units of a polymer soft segment of formula (Is) and a polymer hard segment of formula

1. A process for separating component gases of a gas mixture comprising the steps of:a) providing a permeable membrane comprising a polyurethane-polyether or polyurea-polyether block copolymer comprising repeating units of a polymer soft segment of formula (Is) and a polymer hard segment of formula (Ih): wherein Ri of formulae (Is) and (Ih) is an aliphatic or aromatic radical; s denotes soft; h denotes hard; (PE) of formula (Is) is a polyether segment; Ra of formula (Ih) is a linear or branched aliphatic radical; and X of formula (Ih) is an oxygen atom or ?NH?; b) contacting a first side of the membrane with a feed gas mixture; and c) causing a component of said feed gas mixture to selectively permeate through said permeable membrane, thereby forming on a second side of the membrane a permeate composition which has a greater concentration of said component than that of said feed gas mixture. 2. The process of claim 1, further comprising the step of removing from said second side of the membrane said permeate composition.3. The process of claim 2, further comprising the step of withdrawing from said first side of the membrane a gas composition depleted in said component.4. The process of claim 1, wherein Ri is an aliphatic or aromatic radical comprising about 2-18 carbon atoms.5. The process of claim 4, wherein Ri is linear ?(CH2)6?, or is selected from the group of molecular structures consisting of the formulas: and mixtures thereof.6. The process of claim 1, wherein said polyether segment has a number average molecular weight, Mn, ranging from at least about 600 to 8000.7. The process of claim 1, wherein Ra is an linear or branched aliphatic radical of at least about 2-18 carbon atoms, and wherein X is an oxygen atom.8. The process of claim 1, wherein Ra is a linear or branched aliphatic radical comprising at least about 2-18 carbon atoms, and wherein X is ?NH?.9. The process of claim 1, wherein the number average molecular weight of said polymer hard segment (Ih) is in the range of about 200 to 3000.10. The process of claim 1, wherein said polyurethane-polyether or polyurea-polyether block copolymer exhibits a number average molecular weight in the range from about 23,000 to 400,000.11. The process of claim 1, wherein an oxygen to carbon ratio of said polyether segment is about 0.2-0.5.12. The process of claim 11, wherein said polyether segment is derived from a polyether glycol selected from a group consisting of hydroxyl terminated polyethylene glycol, hydroxyl terminated 1,2-polypropylene glycol, hydroxyl terminated 1,4-polybutylene glycol, and mixtures thereof.13. The process of claim 1, wherein Ra is derived from a linear or branched aliphatic diol comprising at least about 2-18 carbon atoms.14. The process of claim 13, wherein said branched aliphatic diol is selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, and mixtures thereof.15. The process of claim 1, wherein Ra is derived from a linear or branched aliphatic diamine comprising at least about 2-18 carbon atoms.16. The process of claim 15, wherein said linear or branched aliphatic diamine is selected from the group consisting of 1,2-diaminoethane, 1,4-diaminobutane, 1,5-diaminopentane, 1,5-diaminohexane, 1,6-diaminohexane, and mixtures thereof.17. The process of claim 15, wherein said membrane comprises flat-sheet membranes stacked in plate-and-frame modules or wound in spiral-wound modules.18. The process of claim 1, wherein said linear or branched aliphatic radical is derived from a mixture comprising an aliphatic diol and an aliphatic diamine.19. The process of claim 1, wherein Ra is derived from dl-seine (3-amino-2-hydroxypropionic acid).20. The process of claim 1, wherein said polymer soft segment (Is) comprises about 50-90 weight % of said polyurethane-polyether or polyurea-polyether block copolymer.21. The process of claim 1, wherein said component comprises a polar gas.22. The process of claim 21, wherein said polar gas is selected from the group consisting of carbon dioxide, hydrogen sulfide, sulfur dioxide, water, and mixtures thereof.23. The process of claim 21, wherein the solubility of said component in said polyester-polyether block copolymer is controlled by the relative affinity of a molecule of said component to said polyurethane-polyether or polyurea-polyether block copolymer.24. The process of claim 21, wherein said polar gas is separated at temperatures of about 0° C. to about 120° C.25. The process of claim 21, wherein a pressure gradient across said permeable membrane is about 0.7 to about 11 Mpa during gas separation.26. The process of claim 1, wherein said membrane has a thickness of about 0.00005 mm to about 0.30 mm.27. The process of claim 26, wherein said permeable membrane further comprises a non-selective microporous support.28. The process of claim 26, further comprising a membrane module.29. The process of claim 28, wherein said module is housed individually in a separate pressure vessel or wherein multiple said membrane modules are mounted together in a common housing.30. A permeable membrane for separating and/or concentrating gases comprising:a permeable membrane comprising a polyurethane-polyether or polyurea-polyether block copolymer, wherein said polyurethane-polyether or polyurea-polyether block copolymer comprises repeating units of a polymer soft segment of formula (Is) and a polymer hard segment of formula (Ih): wherein Ri of formula (Is) and (Ih) is an aliphatic or aromatic radical; s denotes soft; h denotes hard; (PE) is a polyether segment; Ra of formula (Ih) is a linear or branched aliphatic radical; and X of formula (Ih) is an oxygen atom or ?NH?. 31. The membrane of claim 30, wherein Ri is an aliphatic or aromatic radical comprising at least about 2-18 carbon atoms.32. The membrane of claim 31, wherein Ri is linear ?(CH2)6?, or selected from the group of molecular structures consisting of the formulas: and mixtures therof.33. The membrane of claim 30, wherein said polyether segment has a number average molecular weight, Mn, ranging from about 600 to 8000.34. The membrane of claim 30, wherein Ra is a linear or branched aliphatic radical comprising at least about 2-18 carbon atoms, and wherein X is an oxygen atom.35. The membrane of claim 30, wherein Ra is a linear or branched aliphatic radical comprising at least about 2-18 carbon atoms, and wherein X is ?NH?.36. The membrane of claim 30, wherein the number average molecular weight of said polymer hard segment (Ih) is in the range of about 200 to 3000.37. The membrane of claim 30, wherein said polyurethane-polyether or polyurea-polyether block copolymers exhibit a number average molecular weight in the range from about 23,000 to 400,000.38. The membrane of claim 30, wherein an oxygen to carbon ratio of said polyether segment is about 0.2-0.5.39. The membrane of claim 30, wherein said polyether segment is derived from a polyether glycol selected from the group consisting of hydroxyl terminated polyethylene glycol, hydroxyl terminated 1,2-polypropylene glycol, hydroxyl terminated 1,4-polybutylene glycol, and mixtures thereof.40. The membrane of claim 30, wherein Ra is derived from a linear or branched aliphatic diol containing about 2-18 carbon atoms.41. The membrane of claim 40, wherein said linear or branched aliphatic diol is selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, and mixtures thereof.42. The membrane of claim 30, wherein Ra derived from a linear or branched aliphatic diamine comprising at least about 2-18 carbon atoms.43. The membrane of claim 42, wherein said linear or branched aliphatic diamine is selected from the group consisting of 1,2-diaminoethane, 1,4-diaminobutane, 1,5-diaminopentane, 1,5-diaminohexane, 1,6-diaminohexane, and mixtures thereof.44. The membrane of claim 30, wherein Ra is derived from a mixture of an aliphatic diol and an aliphatic diamine.45. The membrane of claim 30, wherein Ra is derived from dl-serine (3-amino-2-hydroxypropionic acid).46. The membrane of claim 30, wherein said polymer soft segment (Is) comprises about 50-90 weight % of said polyurethane-polyether or polyurea-polyether block copolymer.47. The membrane of claim 30, having a thickness of about 0.00005 mm to about 0.30 mm.48. The membrane of claim 47, further comprising a non-selective microporous support.49. The membrane of claim 30, wherein Ri comprises an aliphatic or aromatic radical comprising at least about 2-18 carbon atoms and wherein Ra comprises a linear or branched aliphatic radical comprising at least about 2-18 carbon atoms.50. The membrane of claim 30, wherein said polyether segment is derived from a polyether glycol selected from the group consisting of hydroxyl terminated polyethylene glycol, hydroxyl terminated 1,2-polypropylene glycol, hydroxyl terminated 1,4-polybutylene glycol, and mixtures thereof, and wherein said polyether segment has a number average molecular weight, Mn, ranging from about 600 to 8000.51. The membrane of claim 30, wherein the number average molecular weight of said polymer hard segment (Ih) is in the range of about 200 to 3000 and wherein said polymer soft segment (Is) comprises about 50-90 weight % of said polyurethane-polyether or polyurea-polyether block copolymer.52. The membrane of claim 30, wherein Ra is derived from a mixture consisting of an aliphatic diol and an aliphatic diamine and wherein Ra is derived from dl-serine (3-amino-2-hydroxypropionic acid).