High carbon content filamentary membrane and method of making the same

• US 6,565,631 B2
• Filed: 10/03/2001
• Issued: 05/20/2003
• Est. Priority Date: 11/10/1999
• Status: Expired due to Term

• Current Assignee: University of Texas System
• Original Assignee: University of Texas System
• Inventors: Koros, William John, Vu, De Quang
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US09/970,541
• Publication Number:
  US 20020033096A1
• Time in Patent Office: 594 Days
• Field of Search: 95/45, 95/51, 96/8, 96/10, 96/14, 555/22, 555/27, 555/28, 55D/IG.5
• US Class Current: 96/8
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2323/081 Heating
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 69/08 Hollow fibre membranes manufacture of hollow fibres D01D5/24, D01F1/08
• CPC Class Codes: B01D 71/021 Carbon
• 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
• CPC Class Codes: D01F 9/24 from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02P 70/62 related technologies for production or treatment of textile or flexible materials or products thereof, including footwear
• CPC Class Codes: Y10S 55/05 Methods of making filter

Abstract

A high carbon content membrane and method for making the same are disclosed. The carbon membrane includes an asymmetric hollow filamentary carbon membrane, including a partial carbonization product of an asymmetric hollow filament including an aromatic imide polymer material. The carbon membrane is at least 95 weight percent carbon, and has a dense layer located in the outside surface portion of the hollow filamentary membrane and a porous base layer continued from the dense layer and located in the inside portion of the hollow filamentary membrane. A process for separating CO₂ from natural gas is described including: contacting a mixture of CO₂ and natural gas with a first side of a carbon membrane in a manner to cause a portion of the mixture to pass through the carbon membrane to a permeate side. The resulting mixture on the permeate side becomes enriched in CO₂ over that of the mixture on the first side. The contacting step occurs at a pressure of at least about 200 psia.

Claims

1. A carbon membrane for separating first and second gases from a feed mixture of gases, the membrane comprising:

an asymmetric hollow filamentary carbon membrane, comprising a partial carbonization product of an asymmetric hollow filament comprising an aromatic imide polymer material, comprising at least 95 weight percent carbon, and having a dense layer located in the outside surface portion of the hollow filamentary membrane and a porous base layer continued from the dense layer and located in the inside portion of the hollow filamentary membrane;

wherein the carbon membrane is selectively permeable in favor of the first gas such that when a feed mixture containing the first and second gases contacts the carbon membrane, the first gas preferably passes through the membrane thereby forming a permeate enriched in the first gas and a retentate depleted in the first gas.

2. The membrane of claim 1 wherein:

the membrane is capable of withstanding contacting the feed mixture of first and second gases at pressures in excess of 200 psia when forming the enriched permeate and the depleted retentate.

3. The membrane of claim 2 wherein:

said membrane can withstand a pressure of at least about 500 psia.

4. The membrane of claim 2 wherein:

said membrane can withstand a pressure of at least about 1000 psia.

5. The membrane of claim 1 wherein:

the thickness of the carbon membrane is at least 20 micrometers.

6. The membrane of claim 1 wherein:

the thickness of the carbon membrane is between 20 and 40 micrometers.

7. The membrane of claim 1 wherein:

said carbon membrane comprises at least 98 weight percent carbon.

8. The membrane of claim 1 wherein:

the mixture of gases includes natural gas and CO₂ and said membrane is capable of withstanding contacting the natural gas and CO₂ mixture at pressures in excess of 200 psia and wherein at least a portion of CO₂ in said mixture preferentially passes through said carbon membrane when so contacted thereby forming a CO₂-enriched permeate and a CO₂-depleted retentate.

9. The membrane of claim 8 wherein:

said carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 30;

1.

10. The membrane of claim 8 wherein:

said carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 40;

1.

11. The membrane of claim 8 wherein:

said carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 50;

1.

12. A carbon membrane for separating first and second gases from a mixture of gases, the membrane comprising:

a hollow filamentary carbon membrane, comprising a partial carbonization product of a hollow filament comprising a polymer material, comprising at least 95 weight percent carbon;

wherein the carbon membrane is selectively permeable in favor of the first gas such that when a feed mixture containing the first and second gases contacts the carbon membrane, the first gas preferably passes through the membrane thereby forming a permeate enriched in the first gas and a retentate depleted in the first gas.

13. The carbon membrane of claim 12 wherein:

the hollow filamentary membrane is asymmetric.

14. The carbon membrane of claim 13 wherein:

the asymmetric membrane has a dense layer and a porous base layer.

15. The carbon membrane of claim 14 wherein:

the dense layer is located on the outside surface portion of the hollow filamentary membrane and the porous base layer continues from the dense layer and is located in the inside portion of the hollow filamentary membrane.

16. The carbon membrane of claim 12 wherein:

the partial carbonization product is made from an imide polymer.

17. The carbon membrane of claim 16 wherein:

the imide polymer is aromatic.

18. The membrane of claim 12 wherein:

the carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 30;

1.

19. A separation module for separating a first gas and a second gas from a feed mixture, the module comprising:

a shell and tube separation module including a plurality of asymmetric hollow filamentary carbon membranes, each membrane comprising a partial carbonization product of an asymmetric hollow filament comprising an aromatic imide polymer material, comprising at least 95 weight percent carbon, and having a dense layer located in the outside surface portion of the hollow filamentary membrane and a porous base layer continued from the dense layer and located in the inside portion of the hollow filamentary membrane;

the module having an upstream end and a downstream end wherein when the feed mixture is introduced into the upstream end, a first gas enriched permeate and a first gas depleted retentate is formed.

20. The module of claim 19 wherein:

the first gas is CO₂ and the second gas is natural gas; and

the carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 30;

1.

21. The module of claim 19 wherein:

the carbon membranes are capable of withstanding contacting the feed mixture of first and second gases at pressures in excess of 200 psia when forming the enriched permeate and the depleted retentate.

22. A process for making an asymmetric hollow filamentary carbon membrane, the process comprising:

forming an asymmetric hollow filament comprising an aromatic imide polymer material and having a dense layer located on the outside surface portion thereof and a porous base layer continued from the dense layer located on the inside of the dense layer; and

pyrolyizing the asymmetric hollow filament to produce a membrane including a partial carbonization product of the asymmetric hollow filament;

wherein the membrane comprises at least 95 weight percent carbon.

23. The process of claim 22 wherein:

the membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 30;

1.

24. The process of claim 22 wherein:

the membrane has a ratio of CO₂ permeability to natural gas permeability of at least 40;

1.

25. The process of claim 22 wherein:

the membrane has a ratio of CO₂ permeability to natural gas permeability of at least 50;

1.