Composite carbon molecular sieve membranes having anti-substructure collapse particles loaded in a core thereof

Patent metadata

Field	Value
Publication number	US-2016151746-A1
Application number	US-201514827064-A
Country	US
Kind code	A1
Filing date	Aug 14, 2015
Priority date	Nov 30, 2014
Publication date	Jun 2, 2016
Grant date	—

Abstract

A carbon molecular sieve (CMS) membrane is made by pyrolyzing, to a peak pyrolysis temperature T P , a hollow fiber membrane having a polymeric sheath surrounding a polymeric core, anti-substructure collapse particles present in pores formed in the polymeric core help prevent collapse of pores formed in the hollow fiber membrane before pyrolysis. The anti-substructure collapse particles are made of a material or materials that either: i) have a glass transition temperature T G higher than T P , ii) have a melting point higher than T P , or ii) are completely thermally decomposed during said pyrolysis step at a temperature less than T P . The anti-substructure collapse particles are not soluble in a solvent used for dissolution of the polymeric material of the core.

First claim

What is claimed is:

1 . A method for producing a CMS membrane fiber, comprising the steps of:
forming a composite precursor polymeric hollow fiber having a sheath covering a hollow core, the core being solidified from a core composition comprising a polymeric core material dissolved in a core solvent and anti-substructure collapse particles insoluble in the core solvent, the anti-substructure collapse particles being disposed within pores formed in the polymeric core material, the sheath being solidified from a sheath composition comprising a polymeric sheath material dissolved in a sheath solvent, the anti-substructure collapse particles having an average size of less than one micron; and pyrolyzing the composite precursor polymeric hollow fiber up to a peak pyrolysis temperature T P , wherein the anti-substructure collapse particles are made of a material or materials that either:
i) have a glass transition temperature T G higher than T P ,
ii) have a melting point higher than T P , or
ii) are completely thermally decomposed during said pyrolysis step at a temperature less than T P .

2 . The method of claim 1 , wherein the material or materials of the anti-substructure collapse particles are selected from the group consisting of: polymer, glasses, ceramics, graphite, silica and mixtures of two or more thereof.

3 . The method of claim 2 , wherein the material of the anti-substructure collapse particles is polybenzimidazole.

4 . The method of claim 2 , wherein the material of the anti-substructure collapse particles is silica.

5 . The method of claim 1 , wherein the material or materials of the anti-substructure collapse particles are selected from cellulosic materials and polyethylene.

6 . The method of claim 1 , wherein the polymeric sheath material and the polymeric core material are a same polymer or copolymer.

7 . The method of claim 6 , wherein a wt % of the polymer or copolymer in the core composition is lower than a wt % of the polymer or copolymer in the sheath composition.

8 . The method of claim 1 , wherein the polymeric sheath material is different from the polymeric core material.

9 . The method of claim 8 , wherein the polymeric sheath material comprises a major amount of a first polymer or copolymer and a minor amount of second polymer or copolymer and the polymeric core material comprises a minor amount of the first polymer or copolymer and a major amount of the second polymer or copolymer.

10 . The method of claim 8 , wherein the polymeric sheath material is a first polymer having a first coefficient of thermal expansion, the polymeric core material is a second polymer having a second coefficient of thermal expansion, and the first and second coefficients of thermal expansion differ from one another by no more than 15%.

11 . The method of claim 10 , wherein first coefficient of thermal expansion is greater than the second coefficient of thermal expansion.

12 . The method of claim 10 , wherein a wt % of the anti-substructure collapse particles in the core composition is selected such that the polymeric sheath material shrinks along a length of the fiber no more than +/−15% than that of the polymeric core material, but in any case is at least 5 wt %.

13 . The method of claim 8 , wherein the polymeric sheath material is a first polymer exhibiting a first coefficient of thermal shrinkage above a temperature at which the first polymer starts to thermally degrade, the polymeric core material is a second polymer having a second coefficient of thermal shrinkage above a temperature at which the second polymer starts to thermally degrade, and the first and second coefficients of thermal shrinkage differ from one another by no more than 15%.

14 . The method of claim 8 , wherein the polymeric sheath material is a first polymer, the polymeric core material is a second polymer, and the second polymer has a glass transition temperature equal to or greater than 200° C.

15 . The method of claim 14 , wherein the second polymer has a glass transition temperature equal to or greater than 280° C.

16 . The method of claim 1 , wherein the polymeric core material is a polyaramide consisting of repeating units of diamino mesitylene isophthalic acid.

17 . The method of claim 1 , wherein the polymeric core material is the condensation product of 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride and m-phenylenediamine or p-phenylenediamine.

18 . The method of claim 1 , wherein the polymeric core material is polybenzimidazole

19 . The method of claim 1 , wherein each of the polymeric core and sheath materials is made of a polymer or copolymer independently selected from the group consisting of polyimides, polyether imides, polyamide imides, cellulose acetate, polyphenylene oxide, polyacrylonitrile, and combinations of two or more thereof.

20 . The method of claim 19 , wherein the polymeric sheath material is made of a polyimide.

21 . The method of claim 20 , wherein the polyimide consists of the repeating units of formula I:

22 . The method of claim 20 , wherein the polyimide is 6FDA:BPDA/DAM.

23 . The method of claim 20 , wherein the polyimide is selected from the group consisting of: 6FDA:mPDA/DABA and 6FDA:DETDA/DABA.

24 . The method of claim 19 , wherein the polymeric sheath material is poly (4,4′-oxydiphenylene-pyromellitimide).

25 . The method of claim 19 , wherein the polymeric sheath material consists of the repeating units of formulae II and III:

26 . The method of claim 20 , wherein the polyimide consists of repeating units of formula IV:

27 . A CMS membrane fiber produced according to the method of claim 1 .

28 . A CMS membrane module including a plurality of the CMS membrane fibers of claim 27 .

29 . A method for separating a gas mixture, comprising the steps of feeding a gas mixture to the CMS membrane module of claim 28 , withdrawing a permeate gas from the CMS membrane module that is enriched in at least one gas relative to the gas mixture, and withdrawing a non-permeate gas from the CMS membrane module that is deficient in said at least one gas relative to the gas mixture.

Assignees

• Air Liquide

Inventors

• Kratzer Dean W
• Kosuri Madhava R
• Ma Canghai

Classifications

• Y02C20/40

  of CO2 · CPC title

• B01D2323/18

  Pore-control agents or pore formers · CPC title

• B01D69/088

  Co-extrusion; Co-spinning · CPC title

• B01D67/0067 Primary

  by carbonisation or pyrolysis · CPC title

• B01D53/228

  characterised by specific membranes · CPC title