High performance facilitated transport membranes for olefin/paraffin separations
AssigneeUop LLC
InventorsChunqing Liu, Nicole K. Karns
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Abstract
A high performance facilitated transport membrane comprising a metal cation exchanged/chelated carboxylic acid functional group containing functional polyimide, a method of making this a membrane, and the use of this membrane for olefin/paraffin separations, particularly for propylene/propane and ethylene/ethane separations. The facilitated transport membrane has either an asymmetric integrally skinned membrane structure or a thin film composite membrane structure, wherein the top selective layer of the membrane comprises a metal cation exchanged/chelated carboxylic acid functional group containing functional polyimide.
Claims15
A facilitated transport membrane comprising a carboxylic acid functional group containing polyimide wherein the carboxylic acid functional groups are ion-exchanged or chelated with silver (I) or copper (I) cations wherein the silver (I) or copper (I) cation ion-exchanged or chelated carboxylic acid functional group containing polyimide comprises a plurality of repeating units of formula (I)
- wherein X1 and X2 are selected from the group consisting of
- and mixtures thereof, wherein X1 and X2 may be the same or different from each other;
- wherein Y1—COOM is selected from the group consisting of
- and mixtures thereof and wherein M is selected from a silver (I) cation or a copper (I) cation;
- wherein Y2 is selected from the group consisting of
- and mixtures thereof, —R′— is selected from the group consisting of
- and mixtures thereof, —R″— is selected from the group consisting of —H, COCH3, and mixtures thereof, M is selected from a silver (I) cation or a copper (I) cation;
- wherein n and m are independent integers from 2 to 500;
- and wherein n/m is in a range of 1:0 to 1:10.
A method of making a high performance facilitated transport membrane comprising a carboxylic acid functional group containing polyimide wherein the carboxylic acid functional groups are ion-exchanged or chelated with metal cations such as silver (I) or copper (I) cations, said method comprising:
- (a) preparing an asymmetric carboxylic acid functional group containing polyimide flat sheet or hollow fiber membrane with either an asymmetric integrally skinned or a thin film composite membrane structure, wherein at least the top selective layer of said membrane comprises a carboxylic acid functional group containing polyimide;
- and
- (b) preparation the facilitated transport membrane by ion-exchanging or chelating the carboxylic acid functional groups on the polyimide polymer of said asymmetric carboxylic acid functional group containing polyimide flat sheet or hollow fiber membrane prepared in step a) with silver (I) or copper (I) cations.
An olefin/paraffin separation process comprising:
- (a) contacting a first surface of a membrane with an olefin/paraffin feed, wherein said membrane comprises a carboxylic acid functional group containing polyimide wherein the carboxylic acid functional groups are ion-exchanged or chelated with silver (I) or copper (I) cations;
- (b) causing a permeate to flow through said membrane and from a second surface of said membrane wherein the permeate has a higher concentration of olefin than said olefin/paraffin feed;
- and
- (c) removing a retentate from said first surface of said membrane wherein the retentate has a lower concentration of olefin than the permeate and wherein the retentate has a higher concentration of paraffin than the permeate.
Dependencies are inferred from the claim text.