Crosslinked and crosslinkable hollow fiber membrane and method of making same
AssigneesChevron U.S.A. Inc., The University of Texas System
InventorsWilliam J. Koros, David Wallace, John D. Wind, Stephen J. Miller, Claudia Staudt-Bickel
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Abstract
A composition of and a method of making high performance hollow fiber membranes is described. The membranes have a high resistance to plasticization by use of a predetermined amount of crosslinking. The preferred polymer material for the membrane is a polyimide polymer comprising covalently bonded ester crosslinks. The resultant hollow fiber membrane exhibits a high permeability of CO2 in combination with a high CO2/CH4 selectivity. Another embodiment provides a method of making the hollow fiber membrane from a monesterified polymer followed by final crosslinking after hollow fiber formation.
Claims23
A hollow fiber polymer membrane, comprising:
- a crosslinked polyimide polymer having covalent ester crosslinks;
- and having
- a CO2 permeance of at least 20 GPU and a CO2/CH4 selectivity of greater than 20, at 35 degrees C. and a pressure of 100 psia.
A hollow fiber polymer membrane, comprising:
- a crosslinked polyimide polymer having at least some covalent ester crosslinks and having a ratio of crosslinkable sites to imide groups of between 3:8 and 1:16.
A hollow fiber polymer membrane, comprising:
- a polyimide polymer made from the monomers A+B+C;
- where A is a dianhydride of the formula;
- where X1 and X2 are the same or different halogenated alkyl group, phenyl or halogen;
- where R1, R2, R3, R4, R5, and R6 are H, alkyl, or halogen;
- where B is a diamino cyclic compound without a carboxylic acid functionality;
- where C is a diamino cyclic compound with a carboxylic acid functionality;
- and
- wherein the ratio of B to C is between 1:4 and 8:1, and wherein said hollow fiber polymer membrane further comprises at least some covalent ester crosslinks.
A method of making a crosslinked hollow fiber membrane, comprising:
- preparing a polyimide polymer comprising a predetermined quantity of crosslinkable sites;
- treating the polyimide polymer with a diol selected from the group consisting of ethylene glycol, propylene glycol, 1,3 propanediol, 1,4 butanediol, 1,2 butanediol, and 1,3 butanediol, at esterification conditions, to form a monoesterified polymer;
- forming a monoesterified hollow fiber from the monoesterified polymer;
- and subjecting the monoesterified hollow fiber to transesterification conditions to form a covalently crosslinked hollow fiber membrane.
A method of making a crosslinked hollow fiber membrane, comprising:
- preparing a polyimide polymer comprising a predetermined quantity of crosslinkable sites;
- forming a hollow fiber from said polyimide polymer;
- treating the hollow fiber with a diol selected from the group consisting of ethylene glycol, propylene glycol, 1,3 propanediol, 1,4 butanediol, 1,2 butanediol, and 1,3 butanediol, at esterification conditions, to form a monoesterified hollow fiber;
- and
- subjecting the monoesterified hollow fiber to transesterification conditions to form a crosslinked hollow fiber membrane.
Dependencies are inferred from the claim text.