Claims
- 1. A process for producing vinyl acetate, comprising the following steps:
- (a) reacting ethylene, acetic acid and oxygen in a reactor to form vinyl acetate;
- (b) withdrawing from said reactor a crude product stream comprising vinyl acetate, ethylene and argon;
- (c) removing at least a portion of said vinyl acetate from said crude product stream to form a non-product stream;
- (d) providing a membrane having a feed side and a permeate side, and being selectively permeable to ethylene over argon;
- (e) passing at least a portion of said non-product stream across said feed side under conditions in which there is a pressure drop from said feed side to said permeate side;
- (f) withdrawing from said feed side an argon-rich purge stream enriched in argon and depleted in ethylene compared with said non-product stream;
- (g) withdrawing from said permeate side an ethylene-rich permeate stream enriched in ethylene and depleted in argon compared with said non-product stream;
- (h) recirculating at least a portion of said ethylene-rich permeate stream to said reactor.
- 2. The process of claim 1, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 30%.
- 3. The process of claim 1, wherein said membrane comprises a rubbery polymer.
- 4. The process of claim 1, wherein said membrane comprises silicone rubber.
- 5. The process of claim 1, wherein said membrane has an ethylene/argon selectivity of at least about 4.
- 6. The process of claim 1, wherein said ethylene-rich permeate stream contains at least 50% of the ethylene that was present in said portion of said non-product stream.
- 7. The process of claim 1, wherein said ethylene-rich permeate stream contains at least 70% of the ethylene that was present in said portion of said non-product stream.
- 8. The process of claim 1, wherein said ethylene-rich permeate stream contains at least 90% of the ethylene that was present in said portion of said non-product stream.
- 9. The process of claim 1, wherein said non-product stream further comprises carbon dioxide and wherein at least a portion of said non-product stream is treated to remove carbon dioxide and then recirculated to said reactor.
- 10. The process of claim 1, wherein said non-product stream further comprises carbon dioxide and wherein said portion of said non-product stream is treated to at least partially remove carbon dioxide prior to carrying out said step (e).
- 11. A process for treating a purge stream from an vinyl acetate manufacturing process, said purge stream comprising ethylene and argon, said process comprising the following steps:
- (a) providing a membrane having a feed side and a permeate side, and being selectively permeable to ethylene over argon;
- (b) passing at least a portion of said purge stream across said feed side under conditions in which there is a pressure drop from said feed side to said permeate side;
- (c) withdrawing from said feed side an argon-rich stream enriched in argon and depleted in ethylene compared with said purge stream;
- (d) withdrawing from said permeate side an ethylene-rich permeate stream enriched in ethylene and depleted in argon compared with said purge stream;
- (e) recirculating at least a portion of said ethylene-rich permeate stream to said vinyl acetate manufacturing process.
- 12. The process of claim 11, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said purge stream of at least about 30%.
- 13. The process of claim 11, wherein said membrane comprises a rubbery polymer.
- 14. The process of claim 11, wherein said membrane comprises silicone rubber.
- 15. The process of claim 11, wherein said membrane has an ethylene/argon selectivity of at least about 4.
- 16. The process of claim 11, wherein said ethylene-rich permeate stream contains at least 50% of the ethylene that was present in said portion of said purge stream.
- 17. The process of claim 11, wherein said ethylene-rich permeate stream contains at least 70% of the ethylene that was present in said portion of said purge stream.
- 18. The process of claim 11, wherein said ethylene-rich permeate stream contains at least 90% of the ethylene that was present in said portion of said purge stream.
- 19. A process for producing vinyl acetate, comprising the following steps:
- (a) reacting ethylene, acetic acid and oxygen in a reactor to form vinyl acetate;
- (b) withdrawing from said reactor a crude product stream comprising vinyl acetate, ethylene and argon;
- (c) removing at least a portion of said vinyl acetate from said crude product stream to form a non-product stream;
- (d) compressing said non-product stream;
- (e) providing a membrane having a feed side and a permeate side, and being selectively permeable to ethylene over argon;
- (f) passing at least a portion of said non-product stream across said feed side under conditions in which there is a pressure drop from said feed side to said permeate side;
- (g) withdrawing from said feed side an argon-rich purge stream enriched in argon and depleted in ethylene compared with said non-product stream;
- (h) withdrawing from said permeate side an ethylene-rich permeate stream enriched in ethylene and depleted in argon compared with said non-product stream;
- (i) recirculating at least a portion of said ethylene-rich permeate stream to said compressing step (d).
- 20. The process of claim 19, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 30%.
- 21. The process of claim 19, wherein said membrane comprises silicone rubber.
- 22. The process of claim 19, wherein said ethylene-rich permeate stream contains at least 50% of the ethylene that was present in said portion of said non-product stream.
- 23. The process of claim 19, wherein said non-product stream further comprises carbon dioxide and wherein at least a portion of said non-product stream is treated to remove carbon dioxide and then recirculated to said reactor.
- 24. A process for producing vinyl acetate, comprising the following steps:
- (a) reacting ethylene, acetic acid and oxygen in a reactor to form vinyl acetate;
- (b) withdrawing from said reactor a crude product stream;
- (c) passing said crude product stream to one or more purification steps to produce a vinyl acetate stream, and a non-product stream comprising ethylene and argon;
- (d) providing a membrane having a feed side and a permeate side, and being selectively permeable to ethylene over argon;
- (e) passing at least a portion of said non-product stream across said feed side under conditions in which there is a pressure drop from said feed side to said permeate side;
- (f) withdrawing from said feed side an argon-rich purge stream enriched in argon and depleted in ethylene compared with said non-product stream;
- (g) withdrawing from said permeate side an ethylene-rich permeate stream enriched in ethylene and depleted in argon compared with said non-product stream;
- (h) recirculating at least a portion of said ethylene-rich permeate stream to said one or more purification steps.
- 25. The process of claim 24, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 30%.
- 26. The process of claim 24, wherein said membrane comprises silicone rubber.
- 27. The process of claim 24, wherein said ethylene-rich permeate stream contains at least 50% of the ethylene that was present in said portion of said non-product stream.
- 28. The process of claim 24, wherein said non-product stream further comprises carbon dioxide and wherein at least a portion of said non-product stream is treated to remove carbon dioxide and then recirculated to said reactor.
- 29. The process of claim 19, wherein said membrane has an ethylene/argon selectivity of at least about 4.
- 30. The process of claim 24, wherein said membrane has an ethylene/argon selectivity of at least about 4.
- 31. The process of claim 1, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 40%.
- 32. The process of claim 1, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 50%.
- 33. The process of claim 11, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 40%.
- 34. The process of claim 11, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 50%.
- 35. The process of claim 19, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 40%.
- 36. The process of claim 19, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 50%.
- 37. The process of claim 24, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 40%.
- 38. The process of claim 24, wherein said process is characterized by a stage-cut between said ethylene-rich permeate stream and said non-product stream of at least about 50%.
Parent Case Info
This is a continuation-in-part application of application Ser. No. 08/890,856, filed Jul. 10, 1997, now U.S. Pat. No. 5,817,841.
US Referenced Citations (20)
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
890856 |
Jul 1997 |
|