Methods and apparatus for producing alcohols from syngas
Methods and apparatus for producing alcohols from syngas are disclosed herein. In some variations, syngas is catalytically converted to alcohols. The alcohols can be subjected to drying to produce an intermediate alcohol product, followed by distilling the intermediate product to produce a purified ethanol product for use in liquid fuels.
1. A method of purifying one or more alcohols selected from the group consisting of methanol, ethanol, propanol, and butanol, said method comprising the steps of (a) drying an initial mixture comprising methanol, ethanol, propanol, butanol, and water to produce an intermediate product; and then (b) distilling said intermediate product to produce one or more purified alcohols, wherein the amount of water in said initial mixture is between about 1% and about 50% by weight, wherein step (a) removes at least 75% of the water present in said initial mixture and wherein the amount of water in said intermediate product is less than about 5% by weight.
2. The method of claim 1 , wherein the amount of ethanol in said initial mixture is between about 25% and about 95% by weight.
3. The method of claim 1 , wherein the amount of methanol in said initial mixture is between about 0.1% and about 50% by weight.
4. The method of claim 1 , wherein said amount of said water in said intermediate product is less than about 0.5% by weight.
5. The method of claim 1 , wherein step (a) removes at least 95% of the water present in said initial mixture.
6. The method of claim 1 , wherein step (a) comprises passing said initial mixture through a membrane.
7. The method of claim 6 , wherein said membrane is a zeolite membrane.
8. The method of claim 1 , wherein step (a) comprises passing said initial mixture through a desiccant.
9. The method of claim 8 , wherein said desiccant is selected from the group consisting of SiO 2 , CaO, CaCO 3 , CaCl 2 , CuSO 4 , and CaSO 4 .
10. The method of claim 1 , wherein step (a) comprises passing said initial mixture through a molecular sieve.
11. The method of claim 10 , wherein said molecular sieve has an effective pore size of less than about 5 Angstroms.
12. The method of claim 11 , wherein said molecular sieve has an effective pore size of about 3 Angstroms.
13. The method of claim 1 , wherein one of said purified alcohols is ethanol.
14. The method of claim 1 , wherein one of said purified alcohols is 1-propanol.
15. The method of claim 1 , wherein one of said purified alcohols is 1-butanol.
16. The method of claim 1 , wherein said distilling produces a purified methanol product and a purified ethanol product.
17. The method of claim 1 , wherein said distilling produces a purified methanol product, a purified ethanol product, and a purified 1-propanol product.
18. The method of claim 13 , wherein the ethanol concentration of said purified ethanol is between about 95% and about 99.9% by weight.
19. The method of claim 13 , wherein said purified ethanol meets the ASTM D4806-07a specification for fuel ethanol.
20. The method of claim 1 , further comprising powering an internal combustion engine, at least in part, with said one or more purified alcohols.
21. The method of claim 1 , further comprising combining said one or more purified alcohols with at least one other hydrocarbon, thereby creating a liquid-fuel blend.
22. The method of claim 21 , further comprising powering an internal combustion engine, at least in part, with said liquid-fuel blend.
23. A method of producing a purified alcohol selected from the group consisting of methanol, ethanol, propanol, and butanol, said method comprising the steps of:
(a) devolatilizing a carbon-containing feed material to form a gas phase and a solid phase in a devolatilization unit;
(b) passing said gas phase and said solid phase through a heated reaction vessel to form syngas;
(c) converting said syngas to a mixture comprising ethanol, methanol, propanol, butanol, and water;
(d) drying said mixture to produce an intermediate product; and
(e) distilling said intermediate product to produce a purified alcohol;
wherein step (d) reduces the amount of water in said mixture by at least 95% and wherein the amount of water in said intermediate product is less than about 5% by weight.
24. The method of claim 23 , wherein said amount of water in said intermediate product is less than about 0.5% by weight.
25. The method of claim 23 , wherein step (d) comprises passing said mixture through a zeolite membrane.
26. The method of claim 23 , wherein step (d) comprises passing said mixture through a desiccant.
27. The method of claim 23 , wherein step (d) comprises passing said mixture through a molecular sieve.