BIOMASS LIQUEFACTION THROUGH GAS FERMENTATION
The invention provides methods and systems for the production of at least one product from the microbial fermentation of a gaseous susbtrate, wherein the gaseous substrate is derived from a biomass liquefaction process. The invention provides a method for improving efficiency of the fermentation by passing biomass accumulated in the fermentation process to the biomass liquefaction process for conversion to a gaseous substrate. In a particular aspect of the invention, the biomass liquefaction process is selected from pyrolysis or torrefaction.
1 . A method for producing at least one product from a gaseous substrate, the method comprising;
a. Converting at least a portion of a biomass feedstock to a gaseous substrate comprising CO by a biomass liquefaction process selected from pyrolysis or torrefaction the process carried out in a liquefaction zone;
b. Passing at least a portion of the gaseous substrate to a bioreactor comprising a culture of at least one carboxydotrophic acetogenic microorganism, and anaerobically fermenting at least a portion of the gaseous substrate to produce at least one fermentation product and a waste stream comprising a second biomass;
c. separating at least a portion of the second biomass from the waste stream; and
d. Passing a portion of the second biomass to the liquefaction zone.
2 . The method of claim 1 , wherein the gaseous substrate further comprises CO 2 and H 2 .
3 . The method of claim 2 wherein the biomass liquefaction process produces at least one non-gaseous product, and said non-gaseous product is gasified to produce a syngas stream comprising CO.
4 . The method of claim 3 wherein at least a portion of the syngas stream is passed to the bioreactor.
5 . The method of claim 1 wherein the at least one fermentation product is selected from the group consisting of ethanol, acetic acid and 2,3-butanediol.
6 . A method for producing at least one product from a gaseous substrate, the method comprising;
a. Passing a biomass feedstock to a pyrolysis zone, operated at conditions to produce a gaseous substrate comprising CO, CO 2 and H 2 , and at least one pyrolysis product, selected from the group consisting of pyrolysis oil and char;
b. Passing at least a portion of the gaseous substrate to a bioreactor comprising a culture of at least one carboxydotrophic acetogenic microorganism, and anaerobically fermenting at least a portion of the gaseous substrate to produce at least one fermentation product, a waste stream comprising a second biomass and an exit gas stream comprising hydrogen;
c. separating at least a portion of the second biomass from the waste stream; and
d. Passing a portion of the second biomass to the pyrolysis zone.
7 . The method of claim 6 wherein the exit gas stream is passed to a separation zone operated at conditions to provide a hydrogen rich stream.
8 . The method of claim 7 where the pyrolysis product is pyrolysis oil and the hydrogen rich stream and the pyrolysis oil are passed to a hydrogenation zone operated at conditions to produce a hydrogenated product.
9 . The method of claim 8 wherein the hydrogenated product is a hydrocarbon having from 6 to 20 carbons.
10 . The method of claim 6 further comprising passing the gaseous substrate from the pyrolysis zone to a separation zone operated at conditions to provide a CO 2 rich stream and an enriched CO and H 2 gaseous substrate and passing the enriched gaseous substrate to the bioreactor.
11 . The method of claim 10 where the pyrolysis product is char and the char and the CO 2 rich stream are passed to a reaction zone to produce a second substrate stream comprising CO, and passing the second substrate stream to the bioreactor.
12 . The method of claim 6 , further comprising prior to passing the biomass feedstock to the pyrolysis zone, the biomass feedstock is first passed to a torrefaction zone.
13 . A method for producing at least one product from a gaseous substrate, the method comprising;
a. Passing a biomass feedstock to a torrefaction zone to produce a torrefied biomass;
b. Passing the torrefied biomass to a pyrolysis zone to produce a gaseous substrate comprising CO, pyrolysis oil and char;
c. Passing at least a portion of the gaseous substrate to a bioreactor comprising a culture of at least one carboxydotrophic acetogenic microorganism, and anaerobically fermenting at least a portion of the gaseous substrate to produce at least one fermentation product, a waste stream comprising a second biomass and an exit gas stream comprising hydrogen;
d. separating at least a portion of the second biomass from the waste stream;
e. passing the exit gas stream to a separation zone operated at conditions to provide a hydrogen rich stream;
f. Passing a portion of the second biomass to the torrefaction zone; and
g. Passing the pyrolysis oil and the hydrogen rich stream to a hydrogenation zone operated at conditions to produce a hydrogenated product.
14 . The method of claim 13 wherein the torrefaction process produces a gaseous by-product stream comprising CO, and at least a portion of the gaseous by-product stream is passed to the bioreactor.
15 . The method of claim 13 wherein the char is passed to a gasification zone and gasified to produce a second gaseous substrate comprising CO, and passing the second gaseous substrate to the bioreactor.
16 . The method of claim 13 wherein the hydrogenated product is a hydrocarbon having from 6 to 20 carbons.
17 . The method of claim 13 wherein the carboxydotrophic acetogenic microorganism is selected from the group consisting of Clostridium autoethanogenum, Clostridium ljundahlii, Clostridium ragsdalei and Clostridium coskatii.