Methods for promoting syngas-to-alcohol catalysis
Improved methods of introducing promoters to catalysts are described. The present invention provides a convenient method of uniformly distributing a catalyst promoter, to provide for intimate contact between the promoter and the active catalyst sites. This intimate contact can enhance the activity and/or product selectivity of the promoted catalyst. In some embodiments, the method includes reacting an alkali metal with an alcohol in a non-aqueous medium, contacting the resulting solution with a starting catalyst, and depositing the alkali metal onto the starting catalyst to form an alkali-promoted catalyst.
1. A method of generating an alkali-promoted catalyst, said method comprising:
(a) providing an alkali metal in a non-aqueous medium;
(b) providing an alcohol;
(c) reacting, at least in part, said alkali metal with an excess of said alcohol, thereby producing a promoter solution comprising said alcohol and the alkoxide of said alkali metal;
(d) providing a starting catalyst; and
(e) contacting at least some of said promoter solution from step (c) with said starting catalyst, under effective conditions to deposit at least some of said alkali metal onto said starting catalyst, thereby producing an alkali-promoted catalyst.
2. The method of claim 1 , wherein said alkali metal is selected from the Group IA elements.
3. The method of claim 2 , wherein said alkali metal is K or Cs.
4. The method of claim 1 , wherein said non-aqueous medium comprises said alcohol.
5. The method of claim 2 , wherein said non-aqueous medium does not include said alcohol.
6. The method of claim 1 , wherein said non-aqueous medium does not include said alcohol.
7. The method of claim 1 , wherein said alcohol is selected from C 1 -C 8 linear or branched alcohols.
8. The method of claim 7 , wherein said alcohol is methanol.
9. The method of claim 1 , further comprising adjusting the concentration of said alkali metal in said non-aqueous medium to control the amount of said alkali metal deposited in step (e).
10. The method of claim 1 , further comprising adjusting the concentration of said alkali metal in said non-aqueous medium to control the distribution of said alkali metal deposited in step (e).
11. The method of claim 1 , wherein step (e) comprises generating an immobile salt of said alkali metal.
12. The method of claim 1 , wherein step (e) comprises reaction of said alkoxide with an acidic species at the surface of said starting catalyst.
13. The method of claim 1 , wherein step (d) further comprises treating said starting catalyst to generate a plurality of hydrogen acid sites.
14. The method of claim 1 , wherein step (e) further comprises treating said starting catalyst or said alkali-promoted catalyst with a gas containing H 2 and/or H 2 S.
15. The method of claim 1 , further comprising adding said alkali-promoted catalyst to a support phase.
16. The method of claim 15 , wherein the concentration of said alkali metal in said non-aqueous medium is adjusted to control the depth, into said support phase, of said alkali metal deposited in step (e).
17. The method of claim 1 , wherein said starting catalyst comprises Mo, Co, and S.
18. The method of claim 1 , further comprising use of said alkali-promoted catalyst for generation of one or more C 1 -C 4 alcohols from syngas.
19. A method of generating an alkali-promoted Mo—Co—S catalyst, said method comprising:
(a) providing an alkali metal in a non-aqueous medium, wherein said alkali metal is K or Cs;
(b) providing a C 1 -C 8 alcohol soluble in said non-aqueous medium;
(c) reacting, at least in part, said alkali metal with an excess of said alcohol, thereby producing a promoter solution comprising said alcohol and the alkoxide of said alkali metal;
(d) providing a starting Mo—Co—S catalyst; and
(e) contacting at least some of said promoter solution from step (c) with said starting catalyst, under effective conditions to deposit at least some of said alkali metal onto said starting catalyst, thereby producing an alkali-promoted Mo—Co—S catalyst.
20. A method of generating an alkali-promoted catalyst, said method comprising:
(a) providing an alkoxide comprising a selected alkali metal;
(b) providing an alcohol;
(c) dissolving said alkoxide into said alcohol, thereby producing a promoter solution comprising said alkoxide and said alcohol;
(d) providing a starting catalyst; and
(e) contacting at least some of said promoter solution from step (c) with said starting catalyst, under effective conditions to deposit at least some of said selected alkali metal onto said starting catalyst, thereby producing an alkali-promoted catalyst.
21. The method of claim 20 , wherein said alkali metal is selected from the Group IA elements.
22. The method of claim 21 , wherein said alkali metal is K or Cs.
23. The method of claim 20 , wherein said alcohol is selected from C 1 -C 8 linear or branched alcohols.
24. The method of claim 23 , wherein said alcohol is methanol.
25. The method of claim 20 , wherein said alkoxide is potassium methoxide.
26. The method of claim 20 , further comprising adjusting the concentration of said alkoxide in said alcohol to control the amount of said selected alkali metal deposited in step (e).
27. The method of claim 20 , further comprising adjusting the concentration of said alkoxide in said alcohol to control the distribution of said selected alkali metal deposited in step (e).
28. The method of claim 20 , wherein step (e) comprises generating an immobile salt of said selected alkali metal.
29. The method of claim 20 , wherein step (e) comprises reaction of said alkoxide with an acidic species at the surface of said starting catalyst.
30. The method of claim 20 , wherein said starting catalyst comprises Mo, Co, and S.
31. The method of claim 20 , further comprising use of said alkali-promoted catalyst for generation of one or more C 1 -C 4 alcohols from syngas.