Crosslinked and crosslinkable hollow fiber membrane and method of making same
First Claim
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1. 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.
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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.
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Citations
23 Claims
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1. A hollow fiber polymer membrane, comprising:
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a crosslinked polyimide polymer having covalent ester crosslinks; and
havinga 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. - View Dependent Claims (2, 3, 4)
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5. 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.
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6. A hollow fiber polymer membrane, comprising:
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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. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. 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.- View Dependent Claims (22)
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23. A method of making a crosslinked hollow fiber membrane, comprising:
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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.
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Specification