초록 ▼

The invention provides methods for producing methanol, higher alcohols (containing 2 or more carbons), in particular ethanol, or diesel fuel from biological wastes such as manure, sewage, and crop wastes, as well as from other organic materials. In the methods, organic material is first fermented by

The invention provides methods for producing methanol, higher alcohols (containing 2 or more carbons), in particular ethanol, or diesel fuel from biological wastes such as manure, sewage, and crop wastes, as well as from other organic materials. In the methods, organic material is first fermented by anaerobic microorganisms to a biogas consisting primarily of methane and carbon dioxide. The biogas is then converted to synthesis gas consisting primarily of CO and H2. The synthesis gas is then contacted with a liquid fuel production catalyst to synthesize higher alcohols or other liquid fuels. The invention involves converting CO2 in the biogas to synthesis gas by combining a CO2 reforming reaction with steam reforming or partial oxidation to convert the biogas to synthesis gas. The invention also provides methods involving recirculating CO2 from the output of the liquid fuel production reaction to one or more of the fermentation reaction, the CO2 reforming reaction, or the liquid fuel production reaction.

대표청구항 ▼

1. A method of producing liquid fuel comprising: (a) fermenting organic material in a fermentation mixture to a biogas comprising methane and CO2;(b) converting at least a portion of the biogas to synthesis gas comprising CO and H2 by a process comprising: (i) a CO2 reforming reaction of CH4+CO2 to

1. A method of producing liquid fuel comprising: (a) fermenting organic material in a fermentation mixture to a biogas comprising methane and CO2;(b) converting at least a portion of the biogas to synthesis gas comprising CO and H2 by a process comprising: (i) a CO2 reforming reaction of CH4+CO2 to 2CO+2H2; and(ii) a partial oxidation reaction of CH4+½ O2 to CO+2H2 or a steam reforming reaction of CH4+H2O to CO+3H2; and(c) contacting the synthesis gas with a catalyst to produce a liquid fuel product mixture comprising alcohol or diesel fuel;wherein an amount of CO2 equal to at least 30% of the CO2 in the biogas is converted in the CO2 reforming reaction, and at least 30% of the CH4 in the biogas is converted in the partial oxidation reaction or steam reforming reaction. 2. The method of claim 1 wherein the liquid fuel product mixture comprises methanol, the method further comprising: (d) purifying methanol from the liquid fuel product mixture wherein the purified methanol comprises at least 90% methanol by weight. 3. The method of claim 1 wherein the liquid fuel product mixture comprises diesel, the method further comprising: (d) purifying diesel fuel from the liquid fuel product mixture, wherein at least 90% by weight of reduced carbon compounds in the purified diesel boil between 150° C. and 350° C. 4. The method of claim 3 wherein at least 50% by weight of reduced carbon compounds in the liquid fuel product mixture boil between 150° C. and 350° C. 5. The method of claim 3 wherein step (d) comprises fractionating the liquid fuel product mixture into a purified diesel fraction, a water-enriched fraction, a synthesis gas-enriched fraction, and a separate CO2-enriched fraction; wherein the synthesis gas-enriched fraction is recycled to the catalyst of step (c) and the CO2-enriched fraction is recycled to one or more of the fermentation mixture of step (a), the CO2 reforming reaction of step (b), and the catalyst of step (c). 6. The method of claim 3 wherein step (d) comprises fractionating the liquid fuel product mixture into a purified diesel fraction, a water-enriched fraction, and a synthesis gas-enriched fraction, wherein at least a portion of the synthesis gas-enriched fraction is burned to produce heat and CO2, and the heat is used to heat (i) the fermentation mixture, or (ii) the biogas in the CO2 reforming reaction, or (iii) the biogas in the steam reforming reaction if step (b)(ii) comprises a steam reforming reaction. 7. A method of producing alcohol comprising: (a) fermenting organic material in a fermentation mixture to a biogas comprising methane and CO2;(b) converting at least a portion of the biogas to synthesis gas comprising CO and H2 by a process comprising: (i) a CO2 reforming reaction of CH4+CO2 to 2CO+2H2; and(ii) a partial oxidation reaction of CH4+½ O2 to CO+2H2 or a steam reforming reaction of CH4+H2O to CO+3H2;(c) contacting the synthesis gas with a catalyst to produce an alcohol product mixture; and(d) purifying alcohol from the alcohol product mixture, wherein the purified alcohol comprises less than 5% methanol and at least 70% C2+ alcohols by weight;wherein an amount of CO2 equal to at least 30% of the CO2 in the biogas is converted in the CO2 reforming reaction, and at least 30% of the CH4 in the biogas is converted in the partial oxidation reaction or steam reforming reaction. 8. The method of claim 7 wherein reaction (ii) is a partial oxidation reaction. 9. The method of claim 7 wherein reaction (ii) is a steam reforming reaction. 10. The method of claim 7 further comprising before step (b) removing sulfhydryls from the biogas. 11. The method of claim 7 wherein at least 10% of CO2 in the biogas is not converted in step (b) to CO and is present in the synthesis gas contacted with the catalyst in step (c), wherein at least 10% of the CO2 in the synthesis gas reacts with H2 in step (c) to produce alcohol. 12. The method of claim 7 further comprising: separating at least a portion of the CO2 in the biogas from the biogas before step (b) and recycling the separated portion of CO2 into the fermentation mixture to stimulate methane production in the fermentation mixture. 13. The method of claim 7 wherein step (c) comprises contacting the synthesis gas with a first catalyst to form methanol, followed by contacting the methanol and unreacted synthesis gas with a second catalyst to form C2+ alcohols. 14. The method of claim 7 wherein step (d) comprises fractionating the alcohol product mixture into a purified alcohol fraction, a water-enriched fraction, a synthesis gas-enriched fraction, and a separate CO2-enriched fraction; wherein the synthesis gas-enriched fraction is recycled to the catalyst of step (c) and the CO2-enriched fraction is recycled to one or more of the fermentation mixture of step (a), and the CO2 reforming reaction of step (b). 15. The method of claim 7 wherein step (d) comprises fractionating the alcohol product mixture into a purified alcohol fraction, a water-enriched fraction, and a synthesis gas-enriched fraction, wherein at least a portion of the synthesis gas-enriched fraction is burned to produce heat and CO2, and the heat is used to heat (i) the fermentation mixture, or (ii) the biogas in the CO2 reforming reaction, or (iii) the biogas in the steam reforming reaction if step (b)(ii) comprises a steam reforming reaction. 16. The method of claim 15 wherein at least a portion of the CO2 produced from burning the synthesis gas is recycled to one or more of the fermentation mixture of step (a), the CO2 reforming reaction of step (b), and the catalyst of step (c). 17. The method of claim 14 wherein fractionating the alcohol product mixture into a purified alcohol fraction comprises fractionating the alcohol product mixture into an ethanol fraction and a C3+ alcohol fraction. 18. The method of claim 8 wherein the partial oxidation reaction is catalyzed by a partial oxidation catalyst. 19. The method of claim 18 wherein the CO2 reforming reaction is catalyzed by a CO2 reforming catalyst distinct from the partial oxidation catalyst. 20. The method of claim 9 wherein the CO2 reforming reaction is catalyzed by a CO2 reforming catalyst and the steam reforming reaction is catalyzed by a steam reforming catalyst distinct from the CO2 reforming catalyst. 21. The method of claim 7 wherein the yield of C2+ alcohols is at least 6 gallons per 1000 cubic feet of methane in the biogas. 22. The method of claim 21 wherein the conversion of volatile organics in the fermentation mixture to biogas is at least 65% efficient. 23. The method of claim 7 wherein the catalyst is sulfur-free and the alcohol comprises less than 10 ppm sulfur atoms. 24. The method of claim 23 wherein the alcohol comprises less than 1 ppm sulfur atoms.