Methods of preparing a crosslinked fiber membrane

• US 8,734,567 B2
• Filed: 04/29/2013
• Issued: 05/27/2014
• Est. Priority Date: 08/25/2010
• Status: Expired due to Fees

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Husain, Shabbir
• Primary Examiner(s): Greene, Jason M
• Application Number:
  US13/872,523
• Publication Number:
  US 20130239805A1
• Time in Patent Office: 393 Days
• Field of Search: 95/45, 95/47, 95/50, 95/51, 95/54, 96/4, 96/8, 96/10, 96/11, 96/12, 96/13, 96/14, 264/178.R, 264/203, 264/209.6, 521/27
• US Class Current: 95/45
• CPC Class Codes: B01D 2323/30 Cross-linking
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• 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 69/087 Details relating to the spinning process
• CPC Class Codes: B01D 71/64 Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
• CPC Class Codes: D01D 5/06 Wet spinning methods D01D5/0046 takes precedence
• CPC Class Codes: D01D 5/24 with a hollow structure; Spinnerette packs therefor D01D5/38 takes precedence; producing tubes of plastic material B29D; addition of agents forming hollow filaments D01F1/08
• CPC Class Codes: D01F 6/74 from polycondensates of cyclic compounds, e.g. polyimides, polybenzimidazoles

Abstract

Disclosed herein is a method for preparing a crosslinked hollow fiber membrane. The method involves spinning a one phase solution comprising a monoesterified polyimide polymer, acetone as a volatile solvent, a spinning solvent, a spinning non-solvent, and optionally an organic and/or inorganic additive, wherein the volatile solvent is present in an amount of greater than 25 wt. % to about 50 wt. %, based on the total weight of the solution.

Claims

1. A method for preparing a crosslinked hollow fiber membrane, the method comprising spinning into a monoesterifed fiber a one phase solution comprising a monoesterified polyimide polymer, acetone as a volatile solvent, a spinning solvent, and a spinning non-solvent, wherein the volatile solvent is present in an amount of greater than 25 wt. % to about 50 wt. %, based on the total weight of the solution;

and

subjecting the monoesterified fiber to crosslinking [one of esterfication and transesterification] conditions to prepare a crosslinked hollow fiber membrane.

2. The method of claim 1, wherein the monoesterifed fiber is subjected to esterification conditions.

3. The method of claim 1, wherein the monoesterified polyimide polymer is present in the spinning solution in an amount between about 20 and about 50 weight percent.

4. The method of claim 1, wherein the monoesterified, polyimide polymer has an average molecular weight between about 50,000 and about 300,000.

5. The method of claim 1, wherein the monoesterified, polyimide polymer has a polydispersity index between about 2 and about 5.

6. The method of claim 1, wherein the volatile solvent is present in an amount of greater than 25 wt. % to about 35 wt. %, based on the total weight of the solution.

7. The method of claim 1, wherein the volatile solvent is present in an amount of about 35 wt. % to about 50 wt. %, based on the total weight of the solution.

8. The method of claim 1, wherein the spinning solvent is an organic solvent selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), and diglyme.

9. The method of claim 1, wherein the one phase solution further comprises one or more inorganic additives.

10. The method of claim 9, wherein the inorganic additive is an antilyotropic salt.

11. The method of claim 1, wherein the spinning non-solvent is selected from the group consisting of a C₂ to C₁₀ aliphatic alcohol, water, and mixtures thereof.

12. The method of claim 1, wherein the spinning non-solvent is ethanol.

13. The method of claim 1, wherein the monoesterified hollow fiber is spun from the spinning dope by a dry-jet/wet-quench spinning process comprising:

(a) extruding the monoesterified polyimide polymer through orifices of a spinneret to provide a monoesterified hollow fiber;

(b) conveying the monoesterified hollow fiber through an air gap and through a coagulating bath of de-ionized water; and

(c) winding the monoesterified hollow fiber around a take-up drum at a take-up rate between about 10 m/min and about 150 m/min, wherein the dry-jet/wet-quench spinning process has a draw ratio of less than 150.

14. The method of claim 13, wherein the temperature of the spinning solution is greater than about 40°

C.

15. The method of claim 13, wherein the temperature of the coagulating bath is between about 10°

C. and about 70°

C.

16. The method of claim 13, wherein the dry-jet/wet-quench spinning process has an air gap height that is greater than 0.1 centimeter.

17. The method of claim 13, wherein the dry-jet/wet-quench spinning process has a face velocity of air surrounding the spinneret that is greater than 15 m per minute.

18. The method of claim 1, wherein the resulting crosslinked membrane comprises a porous substructure and a relatively defect free dense skin of uniform density.

19. A method of using a hollow fibers membrane made according to the method of claim 1, comprising:

(a) providing a feed stream selected from the group consisting of air, a mixture of methane and nitrogen, a mixture of methane and hydrogen, a mixture of methane and hydrogen sulfide, a refinery stream, a mixture of carbon dioxide and methane, and syngas,

the feed stream including a gaseous component selected from the group consisting of nitrogen, oxygen, hydrogen, hydrogen sulfide and carbon dioxide;

(b) maintaining a pressure differential between an upstream side of the membrane and a downstream side of the membrane;

(c) contacting the upstream side of the membrane with the feed stream at a pressure between about 20 psia and about 4000 psia;

(d) isolating a permeate stream on the downstream side of the membrane having a larger mole fraction of the faster permeating component of the feed stream; and

(e) isolating a retentate stream having a smaller mole fraction of the faster permeating component of the feed stream.