Carbon molecular sieve membrane produced from a carbon forming polymer-polyvinylidene chloride copolymer blend

Patent metadata

Field	Value
Publication number	US-12036518-B2
Application number	US-202017424703-A
Country	US
Kind code	B2
Filing date	Jan 15, 2020
Priority date	Jan 25, 2019
Publication date	Jul 16, 2024
Grant date	Jul 16, 2024

Abstract

A carbon molecular sieve (CMS) membrane may advantageously be made by pyrolyzing a membrane precursor composition comprised of a carbon forming polymer (e.g., polyimide) blended with a polyvinylidene chloride copolymer (PVDC), the polyvinylidene chloride copolymer being the reaction product of at least 60% to 97% by weight of vinylidene chloride and at least one other comonomer and the carbon forming polymer to polyvinylidene chloride copolymer has a weight ratio of greater than 1 to 99. The membrane precursor composition may be formed by dissolving the carbon forming polymer and PVDC in a solvent to form a dope solution. The dope solution may be shaped, for example, into an asymmetric hollow fiber. The asymmetric hollow fiber may be heated to a temperature to dehydrochorinate the PVDC and then subsequently heated in a non-oxidizing atmosphere to carbonize the polymers of the shaped membrane to form the CMS membrane.

First claim

The invention claimed is:

1. A membrane precursor composition comprised of a carbon forming polymer blended with a polyvinylidene chloride copolymer, the polyvinylidene chloride copolymer being the reaction product of at least 60% to 97% by weight of vinylidene chloride and at least one other comonomer and the carbon forming polymer to polyvinylidene chloride copolymer has a weight ratio of greater than 1 to 99.

2. The membrane precursor of claim 1 , wherein the carbon forming polymer is a polyimide, polyetherimide, polyamide, polyvinyl chloride, polyvinylidene fluoride, cellulose acetate, polyacrylonitrile, polyphenylene, or combination thereof.

3. The membrane of claim 1 , wherein the carbon forming polymer is polyimide.

4. The membrane precursor of claim 1 , wherein the comonomer is vinyl monomer, vinyl chloride monomer, an acrylate monomer, a methacrylate monomer, a styrenic monomer, acrylonitrile, methacrylonitrile, itaconic acid, chlorotrifluoroethylene, or a combination thereof.

5. The membrane precursor of claim 1 , wherein the vinylidene chloride is at least 70% by weight of the polyvinylidene chloride copolymer.

6. The membrane precursor of claim 1 , wherein the weight ratio of the carbon forming polymer to polyvinylidene chloride copolymer is from 2 to 10.

7. The membrane precursor of claim 3 , wherein the polyimide is an aromatic polyimide that is a reaction product of a diamine and dianhydride.

8. The membrane precursor of claim 7 , wherein the aromatic polyimide is the reaction product of at least one of the following diamines: 2,4,6-trimethyl-1,3-phenylenediamine (DAM), 3,5-diaminobenzoic acid (DABA), 2,3,5,6-tetramethyl-1,4-phenylenediamine (durene), or tetramethylmethylenedianiline (TMMDA) and at least one of the following dianhydride 5,5′-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]-1,3-isobenzofurandion (6FDA), 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTDA), and benzophenone tetracarboxylic dianhydride (BTDA).

9. A method of forming a carbon forming polymer-polyvinylidene chloride copolymer carbon molecular sieve membrane precursor, the method comprising:
(i) dissolving a carbon forming polymer and a polyvinylidene chloride copolymer, polyvinylidine chloride copolymer being the reaction product of at least 60% by weight of vinylidene chloride and at least one other comonomer and the carbon forming copolymer and polyvinylidene chloride copolymer are present in a weight ratio of greater than 1 to 99 carbon forming copolymer/polyvinlylidine chloride copolymer to form a dope of the polyimide and polyvinylidene chloride copolymer in the solvent;
(ii) shaping the dope solution to form a shape; and
(iii) removing the solvent to form the carbon forming polymer-polyvinylidene chloride copolymer carbon molecular sieve membrane precursor.

10. The method of claim 9 , wherein the shape is an asymmetric hollow fiber.

11. The method of claim 9 , wherein carbon forming polymer-polyvinylidene chloride copolymer carbon molecular sieve membrane precursor is heated to a dehydrochlorination temperature from 100° ° C. to 180° C. to form a dehydrochlorinated precursor carbon molecular sieve membrane.

12. The method of claim 11 , further comprising heating the dehydrochlorinated precursor carbon molecular sieve membrane to a pyrolysis temperature of 450° C. to 1200° ° C. for a time or at least 15 minutes to 72 hours under a nonoxidizing atmosphere.

13. The method of claim 9 , wherein the carbon forming polymer is a polyimide, polyetherimide, polyamide, polyvinyl chloride, polyvinylidene fluoride, cellulose acetate, polyacrylonitrile, polyphenylene oxide, or combination thereof.

14. The method of claim 13 , wherein carbon forming polymer is the polyimide.

Assignees

• Dow Global Technologies Llc

Inventors

• Liu Junqiang
• Xu Liren
• Goss Janet M
• Wolford Troy D

Classifications

• B01D2325/0233

  with clearly distinguishable layers · CPC title

• B01D71/643

  Polyether-imides · CPC title

• B29K2105/0085

  Copolymers · CPC title

• B29D99/005

  Producing membranes · CPC title

• B01D71/76

  Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74 (rubbers in general B01D71/24) · CPC title