Designed selectivity gas permeable membranes
First Claim
1. A process for separating gases present in a gas mixture comprising contacting the gas mixture with one side of a selectively gas permeable membrane having a membrane separation factor with respect to two gases in the mixture, the membrane comprising a blend of a major fraction of a fluoropolymer of which a nonporous membrane exhibits a fluoropolymer separation factor with respect to the two gases, and an amount of a nonfugitive, nonpolymeric fluorinated adjuvant having an atmospheric boiling point at least about 200°
- C., the amount being effective to make the membrane separation factor greater than the fluoropolymer separation factor.
2 Assignments
0 Petitions
Accused Products
Abstract
The separation factor with respect to a gas binary of a selectively gas permeable membrane of a fluoropolymer can be increased by fabricating the membrane from a composition of a blend of the fluoropolymer with a nonfugitive, nonpolymeric fluorinated adjuvant. The composition can be made by dissolving the adjuvant and the polymer in a suitably compatible solvent then forming the membrane from the solution for example by casting, dipping, or spraying the solution on a substrate and devolatilizing the solvent. The extent of the selectivity increase varies widely with the combination of fluoropolymer and adjuvant and largely increases in direct relation with the proportion of adjuvant in the membrane composition. Novel membranes of fluoropolymers adapted for separation of chemically aggressive gases can be made to have higher selectivity than previously available from the adjuvant free fluoropolymers
46 Citations
19 Claims
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1. A process for separating gases present in a gas mixture comprising contacting the gas mixture with one side of a selectively gas permeable membrane having a membrane separation factor with respect to two gases in the mixture, the membrane comprising a blend of a major fraction of a fluoropolymer of which a nonporous membrane exhibits a fluoropolymer separation factor with respect to the two gases, and an amount of a nonfugitive, nonpolymeric fluorinated adjuvant having an atmospheric boiling point at least about 200°
- C., the amount being effective to make the membrane separation factor greater than the fluoropolymer separation factor.
- View Dependent Claims (2, 3)
- 4. A membrane composition for separation of components of a mixture including a more preferentially permeable gas and a less preferentially permeable gas of a binary gas combination comprising a nonporous gas permeable membrane of a blend comprising about 50-99 wt % of a fluoropolymer and an amount of a nonfugitive, nonpolymeric fluorinated adjuvant effective to produce a separation factor of the membrane with respect to the two gases of the binary gas combination greater than the separation factor of a membrane consisting essentially of the fluoropolymer.
- 12. A gas separation device comprising a selectively gas permeable membrane having a membrane separation factor with respect to two gases, the membrane comprising a blend of a major fraction of a fluoropolymer of which a nonporous membrane exhibits a fluoropolymer separation factor with respect to the two gases, and an amount of a nonfugitive, nonpolymeric fluorinated adjuvant effective to make the membrane separation factor greater than the fluoropolymer separation factor.
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15. A process for making a gas separation membrane comprising the steps of mixing a fluoropolymer comprising a monomer selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, perfluoro-2,2-dimethyl-1,3-dioxole, 2,2,4-trifluoro-5-trifluoromethyl- 1,3-dioxole hexafluoropropylene, vinylidene fluoride and a perfluoroalkylvinyl ether, and a nonfugitive, nonpolymeric fluorinated adjuvant to obtain a uniform composition of which the fluoropolymer comprises a major fraction, and fabricating a nonporous gas permeable membrane of about 0.05-50 μ
- m thickness from the composition.
- View Dependent Claims (16, 17, 18, 19)
Specification