Production of ethanol from methanol
A process for converting methanol to ethanol which comprises reacting methanol and carbon monoxide in the presence of a catalyst to produce a product comprising at least 25 mole % methyl acetate and, in some instances, acetic acid. The acetic acid then is reacted with at least one alcohol to produce at least one acetate selected from methyl acetate, ethyl acetate, and butyl acetate. The at least one acetate (if produced) and the methyl acetate produced as a result of reacting methanol and carbon monoxide then are hydrogenated to produce ethanol. Syngas may be produced from biomass to produce all or a portion of the methanol, hydrogen, and carbon monoxide requirements for the process.
1. A process for converting methanol to ethanol, comprising:
(a) reacting methanol and carbon monoxide under conditions to produce a product comprising at least 25 mole % methyl acetate and acetic acid;
(b) reacting said acetic acid with at least one alcohol to produce at least one acetate; and
(c) hydrogenating said methyl acetate produced in step (a) and said at least one acetate produced in step (b), to produce ethanol.
2. The process of claim 1 wherein said methanol and said carbon monoxide are reacted at a molar ratio of methanol to carbon monoxide of from about 2 to about 10.
3. The process of claim 2 wherein said methanol and said carbon monoxide are reacted at a molar ratio of methanol to carbon monoxide of from about 2 to about 5.
4. The process of claim 1 wherein said methanol and said carbon monoxide are reacted at a temperature of from about 100° C. to about 350° C.
5. The process of claim 4 wherein said methanol and said carbon monoxide are reacted at a temperature of from about 120° C. to about 280° C.
6. The process of claim 5 wherein said methanol and said carbon monoxide are reacted at a temperature of from about 150° C. to about 250° C.
7. The process of claim 6 wherein said methanol and said carbon monoxide are reacted at a temperature of from about 150° C. to about 200° C.
8. The process of claim 1 wherein said methanol and said carbon monoxide are reacted at a pressure of from about 15 atm to about 100 atm.
9. The process of claim 8 wherein said methanol and said carbon monoxide are reacted at a pressure of from about 15 atm to about 50 atm.
10. The process of claim 9 wherein said methanol and said carbon monoxide are reacted at a pressure of from about 20 atm to about 50 atm.
11. The process of claim 1 wherein said methanol and said carbon monoxide are reacted in the liquid phase.
12. The process of claim 1 wherein said methanol and said carbon monoxide are reacted in the gas phase.
13. The process of claim 1 wherein said methanol and said carbon monoxide are reacted in the presence of a catalyst.
14. The process of claim 13 wherein said catalyst comprises rhodium.
15. The process of claim 14 wherein said catalyst comprises rhodium supported on a support selected from the group consisting of carbon and alumina.
16. The process of claim 13 wherein said catalyst is dispersed in an inert liquid medium.
17. The process of claim 16 wherein said inert liquid medium is an inert oil.
18. The process of claim 1 wherein, in step (a), said methanol is reacted with a CO-rich syngas.
19. The process of claim 1 wherein said acetic acid is reacted with said at least one alcohol at a temperature of from about 80° C. to about 250° C.
20. The process of claim 19 wherein said acetic acid is reacted with said at least one alcohol at a temperature of from about 80° C. to about 150° C.
21. The process of claim 20 wherein said acetic acid is reacted with said at least one alcohol at a temperature of from about 80° C. to about 120° C.
22. The process of claim 1 wherein said acetic acid is reacted with said at least one alcohol at a pressure of from about 1 atm to about 20 atm.
23. The process of claim 22 wherein said acetic acid is reacted with said at least one alcohol at a pressure of from about 1 atm to about 10 atm.
24. The process of claim 1 wherein said at least one alcohol is ethanol.
25. The process of claim 1 wherein said at least one alcohol is methanol.
26. The process of claim 1 wherein said at least one alcohol is butanol.
27. The process of claim 1 wherein said at least one alcohol includes methanol and ethanol.
28. The process of claim 1 wherein said methyl acetate is hydrogenated at a temperature of from about 150° C. to about 300° C.
29. The process of claim 28 wherein said methyl acetate is hydrogenated at a temperature of from about 170° C. to about 275° C.
30. The process of claim 29 wherein said methyl acetate is hydrogenated at a temperature of from about 225° C. to about 275° C.
31. The process of claim 1 wherein said methyl acetate is reacted with said hydrogen at a pressure of from about 10 atm to about 100 atm.
32. The process of claim 31 wherein said methyl acetate is reacted with said hydrogen at a pressure of from about 20 atm to about 60 atm.
33. The process of claim 1 , wherein, in step (b), said methyl acetate is hydrogenated by reacting said methyl acetate with a hydrogen-rich syngas.