Ethanol production from biological wastes

• US 20050266540A1
• Filed: 05/26/2005
• Published: 12/01/2005
• Est. Priority Date: 05/26/2004
• Status: Active Grant

• Current Assignee: Novus Energy, LLC
• Original Assignee: Novus Energy, LLC
• Inventors: Offerman, John D., McTavish, Hugh, Hogen, Delman R., Lighthart, Jeffrey W.
• Granted Patent: US 7,309,592 B2
• Time in Patent Office: Days
• US Class Current: 435/161
• CPC Class Codes: C02F 11/04 Anaerobic treatment; Production of methane by such processes
• CPC Class Codes: C02F 3/346 Iron bacteria
• CPC Class Codes: C07C 27/22 with the use of catalysts which are specific for this process
• CPC Class Codes: C07C 29/1518 one step being the formation of initial mixture of carbon oxides and hydrogen for synthesis
• CPC Class Codes: C07C 31/04 Methanol
• CPC Class Codes: C07C 31/08 Ethanol
• CPC Class Codes: C07C 31/10 containing three carbon atoms
• CPC Class Codes: C07C 31/12 containing four carbon atoms
• CPC Class Codes: C07C 31/125 containing five to twenty-two carbon atoms
• CPC Class Codes: C12M 21/04 for producing gas, e.g. biogas digesters for manure with production of biogas A01C3/028, biological treatment of water, waste water or sewage C02F3/00, C02F11/02, preparation of natural gas or syngas C10L3/06, C10L3/10
• CPC Class Codes: C12M 43/00 Combinations of bioreactors or fermenters with other apparatus
• CPC Class Codes: C12P 5/023 Methane
• CPC Class Codes: C12P 7/04 acyclic
• CPC Class Codes: C12P 7/08 produced as by-product or from waste or cellulosic material substrate
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel
• CPC Class Codes: Y02W 10/20 Sludge processing

Abstract

The invention provides methods, apparatuses, and kits for producing ethanol and other alcohols. The methods involve fermenting organic material in a fermentation mixture to a biogas comprising methane; converting at least a portion of the biogas to synthesis gas comprising CO and H₂; and contacting at least a portion of the synthesis gas with a catalyst to produce alcohol. In some embodiments, a microorganism that reduces ferric iron to ferrous iron is included in the fermentation mixture to enhance the efficiency of the fermentation and the yield of alcohol. The invention also provides a method of producing alcohol involving fermenting organic material to a biogas comprising methane; removing sulfhydryls from the biogas; converting at least a portion of the biogas to synthesis gas comprising CO and H₂; contacting at least a portion of the synthesis gas with a sulfur-free catalyst to produce a substantially sulfur-free alcohol; and purifying the alcohol wherein the purified alcohol is substantially sulfur-free and comprises less than 5% methanol and at least 70% C₂+ alcohols by weight.

Claims

1. A method of producing alcohol comprising:

fermenting organic material in a fermentation mixture to a biogas comprising methane;

removing sulfhydryls from the biogas;

converting at least a portion of the biogas to synthesis gas comprising CO and H₂;

contacting at least a portion of the synthesis gas with a sulfur-free catalyst to produce alcohol; and

purifying the alcohol, wherein the purified alcohol comprises less than 10 ppm sulfur atoms, less than 5% methanol, and at least 70% C₂+ alcohols by weight.

2. The method of claim 1 wherein the yield of C₂+ alcohols is at least 6 gallons per 1000 cubic feet of methane in the biogas, and the conversion of volatile organics in the fermentation mixture to biogas is at least 65% efficient.

3. The method of claim 1 wherein the step of removing sulfhydryls from the biogas comprises contacting the biogas with a metal cation that binds sulfhydryls.

4. The method of claim 3 wherein the metal cation is Fe²⁺ formed by reduction of Fe³⁺ in the fermentation mixture by a microorganism that reduces Fe³⁺ and produces at least one volatile organic acid from organic substrates.

5. The method of claim 4 wherein the fermentation mixture further comprises an iron source.

6. The method of claim 1 wherein the purified alcohol comprises less than 0.5% by weight methanol.

7. The method of claim 1 wherein the purified alcohol comprises at least 60% by weight ethanol.

8. The method of claim 1 wherein the step of purifying the alcohol comprises fractionating the alcohol into a C₂+-rich fraction and a methanol-rich fraction, wherein the method further comprises recirculating the methanol-rich fraction into the synthesis gas for contact with the catalyst.

38. A purified alcohol prepared by the process of claim 1

wherein the purified alcohol is comprises less than 10 ppm sulfur atoms, less than 5% methanol, and at least 70% C₂+ alcohols by weight.

39. The purified alcohol of claim 38

wherein the purified alcohol comprises at least 5% C₃+alcohols by weight.

9. A method of producing alcohol comprising:

fermenting organic material in a fermentation mixture to a biogas comprising methane, wherein the fermentation mixture comprises a microorganism that reduces Fe³+ and produces at least one volatile organic acid from organic substrates;

converting at least a portion of the biogas to synthesis gas comprising CO and H₂; and

contacting at least a portion of the synthesis gas with a catalyst to produce alcohol.

10. The method of claim 9 wherein the microorganism that reduces Fe³⁺ is derived from ATCC 55339.

11. The method of claim 9 wherein the fermentation mixture further comprises an iron source.

13. The method of claim 9 wherein the step of converting at least a portion of the biogas to synthesis gas comprises partially oxidizing at least a portion of the biogas.

14. The method of claim 9 further comprising purifying the alcohol, wherein the purified alcohol comprises less than 0.5% by weight methanol.

15. The method of claim 14 wherein the step of purifying the alcohol comprises fractionating the alcohol into a C₂+-rich fraction and a methanol-rich fraction, wherein the method further comprises recirculating the methanol-rich fraction into the synthesis gas for contact with the catalyst.

16. The method of claim 9 further comprising purifying the alcohol wherein the purified alcohol comprises at least 60% by weight ethanol.

17. The method of claim 9 wherein the contacting step produces heat that is used to heat the fermentation mixture.

18. The method of claim 9 wherein the iron-reducing microorganism produces Fe²⁺ that binds sulfhydryls in the fermentation mixture.

19. The method of claim 9 wherein the step of fermenting organic material to a biogas comprises the steps of feeding the organic material into a vessel, fermenting and mixing the organic material in anaerobic conditions in the vessel to form the biogas, discontinuing the mixing to allow particulate unfermented organic material to settle in the vessel resulting in the formation of a low-suspended-solid supernatant, decanting the supernatant from the vessel, and repeating at least the feeding and fermenting steps.

20. The method of claim 19 further comprising withdrawing at least a portion of the biogas from the vessel immediately before the settling.

21. The method of claim 9 wherein the organic material comprises dairy manure.

22. The method of claim 9 wherein the organic material comprises hog manure, turkey manure, chicken manure, slaughterhouse waste, municipal sewage, or crop waste.

23. The method of claim 22 wherein the organic material comprises crop waste, wherein the crop waste is sugar beet waste.

24. The method of claim 9 wherein the organic material comprises forest products waste.

25. The method of claim 9 wherein the alcohol comprises C₂+ alcohols, the yield of C₂+ alcohols is at least 6 gallons per 1000 cubic feet of methane in the biogas, and the conversion of volatile organics in the fermentation mixture to biogas is at least 65% efficient.

26. The method of claim 18 wherein the catalyst is sulfur-free and the alcohol comprises less than 10 ppm sulfur atoms.

27. The method of claim 26 wherein the alcohol comprises less than 1 ppm sulfur atoms.

28. The method of claim 26 wherein the method further comprises contacting the biogas with a sulfur scrubber separate from the Fe²⁺ produced by the iron-reducing microorganism.

12. The method of claim 111 wherein the iron source is magnetite.

29. A method of producing alcohol comprising:

fermenting organic material in a fermentation mixture to a biogas comprising methane;

converting at least a portion of the biogas to synthesis gas comprising CO and H₂;

contacting at least a portion of the synthesis gas with a catalyst to produce alcohol; and

purifying the alcohol, wherein the purified alcohol comprises less than 0.5% by weight methanol and at least 70% by weight C₂+ alcohols;

wherein the yield of C₂+ alcohols in the purified alcohol is at least 6 gallons per 1000 cubic feet of methane in the biogas, and the conversion of volatile organics in the fermentation mixture to biogas is at least 65% efficient.

30. The method of claim 29 wherein the step of converting at least a portion of the biogas to synthesis gas comprises partially oxidizing at least a portion of the biogas.

31. The method of claim 29 wherein the catalyst is sulfur-free and the method further comprises removing sulthydryls from the biogas;

wherein the alcohol comprises less than 10 ppm sulfur atoms.

32. The method of claim 31 wherein the alcohol comprises less than 1 ppm sulfur atoms.

33. The method of claim 29 wherein the fermentation mixture comprises a microorganism that reduces Fe³⁺ and produces at least one volatile organic acid from organic substrates.

34. The method of claim 33 wherein the microorganism is derived from ATCC 55339.

35. The method of claim 33 wherein the fermentation mixture further comprises an iron source.

36. The method of claim 29 wherein the organic material comprises dairy manure.

37. The method of claim 29 wherein the organic material comprises hog manure, turkey manure, chicken manure, slaughterhouse waste, municipal sewage, or crop waste.

40. An apparatus for producing ethanol from organic material, comprising:

(a) a fermentation vessel containing a fermentation mixture that comprises a microorganism that reduces Fe³⁺ and produces at least one volatile organic acid from organic substrates;

(a) being functionally coupled to

(b) a device for producing synthesis gas comprising CO and H₂ from biogas comprising CH₄, the device comprising a steam reformer, a partial oxidation unit, or both;

(b) being functionally coupled to

(c) a catalyst for converting synthesis gas to an alcohol mixture containing C₂+alcohol.

41. The apparatus of claim 40 wherein the microorganism is derived from ATCC 55339.

42. The apparatus of claim 40 wherein the fermentation mixture further comprises an iron source.

43. The apparatus of claim 40 further comprising:

(d) a purification unit functionally coupled to catalyst (c), the purification unit comprising a condenser to preferentially condense at least one C₂+ alcohol from the alcohol mixture, generating a C₂+-rich alcohol fraction and a methanol-rich fraction.

44. The apparatus of claim 43 further comprising:

(e) a recirculation unit functionally coupled to (c) and (d) to recirculate at least a portion of the methanol-rich fraction to catalyst (c) for reaction with synthesis gas.