Methods and apparatus for synthesis of alcohols from syngas

1. A method for producing ethanol and 2-propanol from methanol, said method comprising:

(a) converting methanol, in the presence of a methanol-to-olefins catalyst, into a stream including ethylene and propylene;

(b) feeding said stream from step (a) and water to a reactive-distillation unit including a first zone containing an propylene-hydration catalyst, a second zone containing a ethylene-hydration catalyst, an overhead stream, and a bottoms stream;

(c) operating said reactive-distillation unit under effective conditions for hydration of propylene to 2-propanol in said first zone and ethylene to ethanol in said second zone; and

(d) recovering ethanol and 2-propanol in one or more exit streams from said reactive-distillation unit.

2. The method of claim 1 , wherein said methanol is derived from syngas.

3. The method of claim 2 , wherein said syngas is derived from biomass.

4. The method of claim 1 , wherein said methanol-to-olefins catalyst comprises an aluminosilicate zeolite.

5. The method of claim 4 , wherein said aluminosilicate zeolite is selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, and ZSM-48.

6. The method of claim 1 , wherein said methanol-to-olefins catalyst comprises a silicoaluminophosphate.

7. The method of claim 6 , wherein said silicoaluminophosphate is selected from the group consisting of SAPO-5, SAPO-8, SAPO-11, SAPO-16, SAPO-17, SAPO-18, SAPO-20, SAPO-31, SAPO-34, SAPO-35, SAPO-36, SAPO-37, SAPO-40, SAPO-41, SAPO-42, SAPO-44, SAPO-47, and SAPO-56.

8. The method of claim 7 , wherein said silicoaluminophosphate is SAPO-34.

9. The method of claim 6 , wherein said silicoaluminophosphate further includes one or more transition metals.

10. The method of claim 9 , wherein said one or more transition metals is selected from the group consisting of Mn, Ni, and Co.

11. The method of claim 10 , wherein said silicoaluminophosphate includes Ni.

12. The method of claim 11 , wherein said methanol-to-olefins catalyst is Ni-SAPO-34.

13. The method of claim 9 , wherein the ratio of silicon to said transition metal is selected from about 1 to about 500.

14. The method of claim 13 , wherein said ratio is selected from about 10 to about 200.

15. The method of claim 1 , wherein in step (a), the molar ratio of ethylene to propylene is greater than about 2.

16. The method of claim 15 , wherein in step (a), said molar ratio of ethylene to propylene is greater than about 10.

17. The method of claim 1 , wherein said ethylene-hydration catalyst is selected from zeolites, supported acids, acidic resins, and heteropoly acids.

18. The method of claim 1 , wherein said propylene-hydration catalyst is selected from zeolites, supported acids, acidic resins, and heteropoly acids.

19. The method of claim 1 , wherein said ethylene-hydration catalyst and/or said propylene-hydration catalyst are each selected from zeolites.

20. The method of claim 1 , wherein at least a portion of water produced from reactions during step (a) is fed to said reactive-distillation unit during step (b).

21. The method of claim 20 , wherein all of said water produced during step (a) is fed to said reactive-distillation unit during step (b).

22. The method of claim 1 , wherein said overhead stream includes ethanol and 2-propanol.

23. The method of claim 1 , wherein said bottoms stream includes 2-propanol and water.

24. The method of claim 1 , wherein said reactive-distillation unit includes at least one side-draw stream for removing ethanol, 2-propanol, or both ethanol and 2-propanol.

25. The method of claim 24 , wherein said reactive-distillation unit includes at least two side-draw streams.

26. The method of claim 1 , wherein said reactive-distillation unit operates with a temperature profile from about 250° C. or less at the reboiler to about 100° C. or greater at the condenser.

27. The method of claim 26 , wherein said reactive-distillation unit operates with a temperature profile from about 235° C. or less at the reboiler to about 125° C. or greater at the condenser.

28. The method of claim 1 , wherein at least one olefin and water are in countercurrent flow within said reactive-distillation unit.

29. The method of claim 1 , wherein hydration is rate-limited by water in said first zone and/or said second zone.

30. The method of claim 1 , wherein said reactive-distillation unit is a distillation column.

31. The method of claim 30 , wherein said first zone is above said second zone.

32. The method of claim 30 , wherein the feed location to said distillation column is between said first zone and said second zone.

33. The method of claim 30 , wherein said stream including ethylene and propylene is introduced to a zone for propylene hydration before contacting a zone for ethylene hydration.

34. The method of claim 1 , comprising recovering water from the bottoms stream and recycling at least a portion of said water to step (b).

35. The method of claim 30 , wherein said distillation column employs trays.

36. The method of claim 30 , wherein said distillation column employs packing.

37. The method of claim 36 , wherein a portion of said packing comprises an ethylene-hydration catalyst.

38. The method of claim 36 , wherein a portion of said packing comprises a propylene-hydration catalyst.

39. The method of claim 30 , wherein a portion of said overhead stream is refluxed back to said distillation column at a position below said second zone.

40. The method of claim 1 , further comprising generating butenes during step (a).

41. The method of claim 40 , further comprising hydrating said butenes to 2-butanol during step (c).

42. The method of claim 1 , wherein during step (c), one or more dialkyl ethers are generated, and wherein said method further comprises recovering at least a portion of said dialkyl ethers from said reactive-distillation unit.