Process and system for separation and recovery of perfluorocompound gases

• US 6,605,133 B1
• Filed: 04/23/1999
• Issued: 08/12/2003
• Est. Priority Date: 07/17/1995
• Status: Expired due to Fees

• Current Assignee: American Air Liquide Incorporated (L'Air Liquide SA), L'Air Liquide SA
• Original Assignee: American Air Liquide Incorporated (L'Air Liquide SA), L'Air Liquide SA
• Inventors: Li, Yao-En, Vassallo, David, Fleming, Gregory K., Paganessi, Joseph E.
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US09/296,652
• Time in Patent Office: 1,572 Days
• Field of Search: 95/45, 95/47--49, 95/51--54, 95/90, 95/92, 951/49, 952/30, 952/37, 96/4, 96/7--14, 961/08, 961/34, 963/61
• US Class Current: 95/45
• CPC Class Codes: B01D 2257/204 Inorganic halogen compounds
• CPC Class Codes: B01D 2257/2066 Fluorine
• CPC Class Codes: B01D 53/22 by diffusion manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00
• CPC Class Codes: B01D 53/225 Multiple stage diffusion
• CPC Class Codes: B01D 53/226 in serial connexion
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 53/229 Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption)
• CPC Class Codes: C07C 17/38 Separation; Purification; Stabilisation; Use of additives
• CPC Class Codes: C07C 19/08 containing fluorine
• CPC Class Codes: Y02C 20/30 of perfluorocarbons [PFC], hydrofluorocarbons [HFC] or sulfur hexafluoride [SF6]
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2
• CPC Class Codes: Y02P 20/155 Perfluorocarbons [PFC]; Hydrofluorocarbons [HFC]; Hydrochlorofluorocarbons [HCFC]; Chlorofluorocarbons [CFC]

Abstract

Processes and systems to recover at least one perfluorocompound gas from a gas mixture are provided. In one embodiment the inventive process comprises the steps of a) providing a gas mixture comprising at least one perfluorocompound gas and at least one carrier gas, the gas mixture being at a predetermined pressure; b) providing at least one glassy polymer membrane having a feed side and a permeate side; c) contacting the feed side of the at least one membrane with the gas mixture; d) withdrawing from the feed side of the membrane as a non-permeate stream at a pressure which is substantially equal to the predetermined pressure a concentrated gas mixture comprising essentially the at least one perfluorocompound gas; and e) withdrawing from the permeate side of the membrane as a permeate stream a depleted gas mixture comprising essentially the at least one carrier gas.

Claims

1. A process for the separation and recovery of SF₆, which comprises contacting a gas mixture comprising a low concentration of SF₆ and at least one carrier gas with a membrane selected from the group consisting of polyimides and cellulose acetates at conditions effective to obtain a permeate stream depleted in SF₆ and a non-permeate stream rich in SF₆.

2. The process according to claim 1, wherein [the gas mixture comprises 0.01% volume of SF₆] said low concentration of SF₆ is 0.01% volume.

3. A process for the on and recovery of SF₆, which comprises contacting a gas mixture comprising a low concentration of SF₆ and at least one carrier gas with a membrane at conditions effective to obtain a permeate stream depleted in SF₆ and a non-permeate stream rich in SF₆.

4. The process according to claim 3, wherein said low concentration of SF₆ is 0.01% volume.

5. The process according to claim 3, wherein the carrier gas is air, nitrogen, oxygen, argon, or helium.

6. The process according to claim 3, wherein the membrane is made from polyimides, polyamides, polyamide-imides, polyesters, polycarbonates, polysulfones, polyethersulfones, polyetherketone, alkyl substituted aromatic polyesters, blends of polyethersulfones, aromatic polyimides, aromatic polyamides, aromatic polyamide-imides, fluorinated aromatic polyimides, fluorinated aromatic polyamides, fluorinated aromatic polyamide-imides, or cellulose acetates.

7. The process according to claim 3, wherein the conditions comprise a pressure drop across the membrane ranging from about 3 to about 200 psig.

8. The process according to claim 7, wherein the pressure drop is from about 20 to about 60 psig.

9. The process according to claim 3, wherein the conditions include a gas mixture temperature ranging from about 10°

C. to about 80°

C.

10. The process according to claim 9, wherein the temperature is from about 20°

C. to about 60°

C.

11. A process for the separation and recovery of SF₆, which comprises contacting a gas mixture comprising SF₆ and at least one carrier gas with a membrane selected from the group consisting of polyimides and cellulose acetates at conditions effective to obtain a permeate stream depleted in SF₆ and a non-permeate stream rich in SF₆.

12. The process according to claim 11, wherein the carrier gas is air, nitrogen, oxygen, argon, or helium.

13. The process according to claim 11, wherein the conditions comprise a pressure drop across the membrane ranging from about 3 to about 200 psig.

14. The process according to claim 13, wherein the pressure drop is from about 20 to about 60 psig.

15. The process according to claim 11, wherein the conditions include a gas mixture temperature ranging from about 10°

C. to about 80°

C.

16. The process according to claim 15, wherein the temperature is from about 20°

C. to about 60°

C.