Crosslinked and crosslinkable hollow fiber membrane and method of making same

• US 20030221559A1
• Filed: 12/18/2002
• Published: 12/04/2003
• Est. Priority Date: 12/20/2001
• Status: Active Grant

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Wallace, David, Miller, Stephen J., Koros, William J., Wind, John D., Staudt-Bickel, Claudia
• Granted Patent: US 6,932,859 B2
• Time in Patent Office: Days
• US Class Current: 96/10
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2323/30 Cross-linking
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 65/10 Testing of membranes or membrane apparatus; Detecting or repairing leaks
• CPC Class Codes: B01D 65/109 Testing of membrane fouling or clogging, e.g. amount or affinity
• CPC Class Codes: B01D 67/0093 Chemical modification
• CPC Class Codes: B01D 67/00931 by introduction of specific groups after membrane formation, e.g. by grafting
• CPC Class Codes: B01D 67/00933 by addition of a layer chemically bonded to the membrane
• CPC Class Codes: B01D 69/08 Hollow fibre membranes manufacture of hollow fibres D01D5/24, D01F1/08
• CPC Class Codes: B01D 71/64 Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
• CPC Class Codes: B01D 71/643 Polyether-imides
• CPC Class Codes: B01D 71/82 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y10S 55/05 Methods of making filter

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.

Claims

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.

15. The hollow fiber polymer membrane of claim 1 wherein the polyimide is 6FDA.

16. The hollow fiber polymer membrane of claim 1 wherein the ester crosslinks are formed by the monoesterification of a polyimide polymer having carboxylic acid sites incorporated therein, with a diol.

17. The hollow fiber polymer membrane of claim 16 wherein the diol is selected from the group consisting of ethylene glycol, propylene glycol, 1,3 propanediol, 1,4 butanediol, 1,2 butanediol, benzenedimethanol, and 1,3 butanediol.

2. 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.

3. 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 material further comprises at least some covalent ester crosslinks.

5. The hollow fiber polymer membrane of claim 3 where X₁ and X₂ are CF₃.

6. The hollow fiber polymer membrane of claim 3 where R₁, R₂, R₃, R₄, R₅, and R₆ are H.

7. The hollow fiber polymer membrane of claim 3 wherein the dianhydride is 6FDA.

8. The hollow fiber polymer membrane of claim 3 wherein C is DABA.

9. The hollow fiber polymer membrane of claim 3 wherein B is a diamino aromatic compound.

10. The hollow fiber polymer membrane of claim 3 wherein B is a methyl substituted diamino benzene.

11. The hollow fiber polymer membrane of claim 3 wherein the ratio of B to C is between 17:

3 and 3;

2.

12. The hollow fiber polymer membrane of claim 3 wherein the ratio of B to C is between 17:

3 and 3;

1.

13. The hollow fiber polymer membrane of claim 3 wherein said ester crosslinks are made using a diol selected from the group consisting of ethylene glycol, propylene glycol, 1,3 propanediol, 1,4 butanediol, 1,2 butanediol, benzenedimethanol, and 1,3 butanediol.

14. The hollow fiber polymer membrane material of claim 13 wherein the hollow fiber membrane monoester is subjected to transesterification conditions to form a crosslinked hollow fiber polymer membrane.

18. The hollow fiber polymer membrane material of claim 3 wherein the ratio of B to C is between 4:

1 and 3;

2.

19. The hollow fiber polymer membrane of claim 3 wherein the polyimide polymer has an average molecular weight of between 20,000 and 200,000.

20. The hollow fiber polymer membrane material of claim 3 wherein the membrane material has an average molecular weight greater than the entanglement MW of the polymer.

21. The hollow fiber polymer membrane material of claim 3 wherein the membrane material has an average molecular weight of between 40,000 and 140,000.

4. 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.

23. The method of making a crosslinked hollow fiber membrane of claim 4 wherein the polyimide polymer is treated with a diol in the presence of a esterification catalyst.

22. 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.