Methods of Making Crosslinked Membranes Utilizing an Inert Gas Atmosphere

Patent metadata

Field	Value
Publication number	US-2016339397-A1
Application number	US-201514720397-A
Country	US
Kind code	A1
Filing date	May 22, 2015
Priority date	May 22, 2015
Publication date	Nov 24, 2016
Grant date	—

Abstract

Disclosed herein is a method of making a crosslinked membrane such as a crosslinked hollow fiber membrane. The method comprises (a) preparing a polyimide polymer comprising carboxylic acid functional groups from a reaction solution comprising monomers and at least one solvent; (b) treating the polyimide polymer with a diol at esterification conditions to form a monoesterified polyimide polymer; (c) forming a monoesterified polyimide membrane or dense film from the monoesterified polyimide polymer; and (d) subjecting the monoesterified polyimide membrane or dense film to transesterification conditions under a CO 2 atmosphere to form a crosslinked polyimide membrane or dense film.

First claim

What is claimed is:

1 . A method of making a crosslinked polyimide membrane or dense film:
(a) preparing a polyimide polymer comprising carboxylic acid functional groups from a reaction solution comprising monomers and at least one solvent; (b) treating the polyimide polymer with a diol at esterification conditions to form a monoesterified polyimide polymer; (c) forming a monoesterified polyimide membrane or dense film from the monoesterified polyimide polymer; and (d) subjecting the monoesterified polyimide membrane or dense film to transesterification conditions under a CO 2 atmosphere to form a crosslinked polyimide membrane or dense film.

2 . The method of claim 1 , wherein the crosslinked membrane is a crosslinked hollow fiber membrane.

3 . The method of claim 1 , wherein the CO 2 atmosphere is a pure CO 2 atmosphere.

4 . The method of claim 1 , wherein the CO 2 atmosphere contains majority CO 2 and one or more additional nonreactive gases.

5 . The method of claim 1 , wherein the CO 2 atmosphere has a CO 2 pressure or a CO 2 partial pressure from about 14.6 psig to about 200 psig.

6 . The method of claim 5 , wherein the CO 2 pressure or the CO 2 partial pressure is from about 50 psig to about 75 psig.

7 . The method of claim 1 , wherein the transesterification conditions comprise heating at a temperature from about 175° C. to about 350° C.

8 . The method of claim 7 , wherein the temperature is from about 200° C. to about 300° C.

9 . The method of claim 7 , wherein the transesterification conditions comprise heating for a time from about 2 to about 24 hours.

10 . The method of claim 9 , wherein the time is from about 2 to about 12 hours.

11 . The method of claim 1 , wherein the monomers comprise:
(i) dianhydride monomers; (ii) diamino monomers without carboxylic acid functional groups; and (iii) diamino monomers with carboxylic acid functional groups.

12 . The method of claim 11 , wherein the dianhydride monomers are of a formula (I):

wherein
X 1 and X 2 are independently halogenated alkyl, phenyl or halogen;
R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are independently H, alkyl, or halogen.

13 . The method of claim 11 , wherein the diamino monomers without carboxylic acid functional groups are selected from the group consisting of 4,4′ isopropylidene dianiline; 3,3′ hexafluoroisopropylidene dianiline; 4,4′ hexafluoroisopropyliene dianiline; 4,4′ oxydianiline; 3,3′ oxydianiline; 4,4′ diaminodiphenyl; diaminotoluene; diaminobenzotrifluoride; dimethyldiaminobenzene; trimethyldiaminobenezene; tetramethyldiaminobenzene; 2,4,6-trimethyl-m-phenylenediamine (DAM); and combinations thereof.

14 . The method of claim 11 , wherein the diamino monomers with carboxylic acid functional groups are of a formula (II):

15 . The method of claim 11 , wherein the dianhydride monomers are 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), the diamino monomers without carboxylic acid functional groups are 2,4,6-trimethyl-m-phenylenediamine (DAM), and the diamino monomers with carboxylic acid functional groups are 3,5-diaminobenzoic acid (DABA).

16 . The method of claim 1 , wherein less than 25% loss in CO 2 permeance is observed after subjecting the monoesterified polyimide membrane to transesterification conditions under the CO 2 atmosphere to form the crosslinked polyimide membrane.

17 . The method of claim 1 , wherein the CO 2 permeance of the crosslinked polyimide membrane is about 10 to about 30% greater than a comparative CO 2 permeance of a comparative crosslinked hollow fiber membrane made identically but where transesterification occurs under a vacuum atmosphere instead of under the CO 2 atmosphere.

18 . The method of claim 2 , wherein the CO 2 permeance of the crosslinked hollow fiber membrane at about 35° C. and from about 100 psig to about 500 psig is from about 80 GPU to about 130 GPU.

19 . The method of claim 2 , wherein the CO 2 permeance of the crosslinked hollow fiber membrane at about 35° C. and from about 100 psig to about 500 psig is from about 100 GPU to about 130 GPU.

20 . The method of claim 2 , wherein the CO 2 /CH 4 selectivity of the crosslinked hollow fiber membrane at about 35° C. and from about 100 psig to about 500 psig is from about 20 to about 40.

21 . The method of claim 2 , wherein the CO 2 /CH 4 selectivity of the crosslinked hollow fiber membrane at about 35° C. and from about 100 psig to about 500 psig is from about 30 to about 40.

Assignees

• Bhuwania Nitesh
• Hussain Shabbir
• Chinn Daniel
• Wind John
• Miller Stephen
• Chevron Usa Inc

Inventors

• Bhuwania Nitesh
• Hussain Shabbir
• Chinn Daniel
• Wind John
• Miller Stephen

Classifications

• B01D2323/08

  Specific temperatures applied · CPC title

• B01D69/125

  In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction · CPC title

• B01D2323/30

  Cross-linking · CPC title

• B01D2325/20

  Specific permeability or cut-off range · CPC title

• B01D2323/10

  Specific pressure applied · CPC title