Synthesis gas separation and reforming process
A method of obtaining purified hydrogen and purified carbon monoxide from crude synthesis gas. A first crude synthesis gas stream is passed through a first separation zone to separate a hydrogen stream from a stream comprising carbon monoxide and methane. The carbon monoxide and methane are subjected to thermal reforming to produce a second crude synthesis gas, which is passed through a second separation zone to separate carbon monoxide from the second crude synthesis gas stream.
1. A method of obtaining purified hydrogen and purified carbon monoxide from crude synthesis gas, said crude synthesis gas containing hydrogen, carbon monoxide, and methane, said method comprising:
(a) passing a first crude synthesis gas stream, said first crude synthesis gas stream comprising hydrogen, carbon monoxide, and methane through a first separation zone at a temperature from 4° C. to 450° C. and at a pressure from 100 psi to 1,250 psi, thereby separating said first crude synthesis gas stream into a first stream comprising hydrogen and a second stream comprising carbon monoxide and methane;
(b) reacting said second stream of step (a) comprising carbon monoxide and methane with oxygen and steam in an autothermal reformer, at a pressure of from about 300 psi to about 600 psi to produce a second crude synthesis gas stream comprising hydrogen, carbon monoxide, carbon dioxide, and residual water; and
(c) passing said second crude synthesis gas stream through a second separation zone, thereby separating said second crude synthesis gas stream into a stream comprising carbon monoxide and a stream comprising hydrogen and carbon dioxide.
2. The method of claim 1 , and further comprising:
(d) passing said first stream comprising hydrogen obtained in step (a) directly through a third separation zone to obtain a second stream comprising hydrogen and a tail gas stream comprising carbon dioxide and carbon monoxide, wherein said second stream comprising hydrogen has a higher purity than said first stream comprising hydrogen.
3. The method of claim 2 , and further comprising:
(e) passing said stream comprising carbon monoxide from step (c) directly through a fourth separation zone, to obtain a stream comprising carbon dioxide and a stream comprising carbon monoxide, said stream comprising carbon monoxide having a higher purity than said stream comprising carbon monoxide from step (c).
4. The method of claim 3 , and further comprising:
(f) carbonylating at least one alcohol with said carbon monoxide produced in step (e) to produce at least one acetate.
5. The method of claim 2 wherein said third separation zone includes a solvent-based scrubber unit.
6. The method of claim 5 wherein said solvent-based scrubber unit is a chilled methanol scrubber unit.
7. The method of claim 2 , and further comprising:
subjecting at least one acetate to hydrogenolysis with said second stream comprising hydrogen to produce at least one alcohol.
8. The method of claim 2 wherein said third separation zone includes a chilled methanol scrubber having one or more adsorption vessels, one or more refrigeration units, and one or more heat exchange units, one or more stripping or desorption columns, and a methanol recirculation pumping facility.
9. The method of claim 2 wherein said first separation zone contains a membrane and said third separation zone contains a chilled methanol scrubber, wherein carbon dioxide, methane, hydrocarbons, and water are removed to provide essentially pure hydrogen gas of at least 99.99% hydrogen.
10. The method of claim 1 wherein, in step (b), said second stream comprising carbon monoxide and methane is subjected to steam reforming in the presence of oxygen and steam.
11. The method of claim 1 wherein said first separation zone comprises a membrane which is permeable to hydrogen and retains carbon monoxide and methane.
12. The method of claim 1 , wherein, in step (c), said stream comprising hydrogen and carbon dioxide further comprises water.
13. The method of claim 1 wherein said second separation zone comprises at least one membrane which is permeable to hydrogen, carbon dioxide, and water, and is impermeable to carbon monoxide.
14. The method of claim 1 wherein, in step (b), said second stream comprising carbon monoxide and methane is subjected to autothermal reforming in the presence of a catalyst.
15. The method of claim 1 wherein said second separation zone comprises a carbon monoxide pressure swing adsorption zone.
16. The method of claim 1 wherein said second separation zone comprises (i) a membrane which is permeable to hydrogen and retains carbon monoxide and methane; and (ii) a carbon monoxide pressure swing adsorption zone.
17. The method of claim 1 wherein said first separation zone is operated at a pressure of from about 200 psi to about 1,100 psi.
18. The method of claim 1 wherein said first separation zone is operated at a temperature of from about 25° C. to about 120° C.
19. The method of claim 1 wherein said second separation zone is operated at a temperature of from about 50° C. to about 100° C.
20. The method of claim 1 wherein said autothermal reforming is effected in the presence of a catalyst comprising nickel oxide supported on an alpha alumina support.
21. The method of claim 1 , and further comprising:
carbonylating at least one alcohol with said carbon monoxide produced in step (c) to produce at least one acetate.
22. The method of claim 1 wherein said first separation zone includes a coalescing filter.
23. The method of claim 1 wherein said reacting of said second stream of step (a) with oxygen and steam is conducted at a pressure of from about 300 psi to about 450 psi.