Process for CO2/natural gas separation

• US 6,299,669 B1
• Filed: 11/10/1999
• Issued: 10/09/2001
• 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:
  US09/437,993
• Time in Patent Office: 699 Days
• Field of Search: 95/45, 95/51, 96/8, 96/10, 96/14
• US Class Current: 95/51
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2323/08 Specific temperatures applied
• 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

The invention includes a process for separating CO₂ from natural gas 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 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. The contacting step occurs at a pressure of at least about 200 psia.

Claims

1. A process for separation of CO₂ from natural gas comprising:

(a) contacting a CO₂-containing natural gas with a carbon membrane;

(b) wherein said carbon membrane comprises 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;

(c) wherein said contacting in step (a) occurs at a pressure of at least about 200 psia; and

(d) wherein at least a portion of CO₂ in said CO₂-containing natural gas preferentially passes through said carbon membrane, thereby forming a CO₂-enriched permeate and a CO₂-depleted retentate.

2. The process of claim 1, wherein said contacting in step (a) occurs at a pressure of at least about 500 psia.

3. The process of claim 1, wherein said contacting in step (a) occurs at a pressure of at least about 1000 psia.

4. The process of claim 1, wherein said carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 30:

1.

5. The process of claim 1, wherein said carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 40:

1.

6. The process of claim 1, wherein said carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 50:

1.

7. The process of claim 1, wherein said carbon membrane comprises at least 98 weight percent carbon.

8. The process of claim 1, further comprising a shell and tube separation module comprising a plurality of said carbon membranes, wherein said CO₂-containing natural gas is fed to an upstream end of said separation module and said CO₂-enriched permeate and a CO₂-depleted retentate are recovered from a downstream end.

9. A process for separating CO₂ from natural gas comprising:

(a) 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 being enriched in CO₂ over that of the mixture on the first side;

(b) wherein said carbon membrane comprises 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; and

(c) wherein said contacting in step (a) occurs at a pressure of at least about 200 psia.

10. The process of claim 9, wherein said contacting in step (a) occurs at a pressure of at least about 500 psia.

11. The process of claim 9, wherein said contacting in step (a) occurs at a pressure of at least about 1000 psia.

12. The process of claim 9, wherein said carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 30:

1.

13. The process of claim 9, wherein said carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 40:

1.

14. The process of claim 9, wherein said carbon membrane has a ratio of CO₂ permeability to natural gas permeability of at least about 50:

1.

15. The process of claim 9, wherein said carbon membrane comprises at least 98 weight percent carbon.

16. The process of claim 9, further comprising a shell and tube separation module comprising a plurality of said carbon membranes, wherein said CO₂-containing natural gas is fed to an upstream end of said separation module and said CO₂-enriched permeate and a CO₂-depleted retentate are recovered from a downstream end.