Process comprising sulfur dioxide and/or sulfurous acid pretreatment and enzymatic hydrolysis
First Claim
1. A process for producing a fermentation product from a lignocellulosic feedstock comprising:
- (i) soaking the lignocellulosic feedstock in a liquid comprising water to produce a soaked feedstock;
(ii) at least partially dewatering the soaked feedstock to produce an at least partially dewatered feedstock;
(iii) feeding the at least partially dewatered feedstock to a heating device;
(iv) adding steam and acid to the heating device, said steam heating the at least partially dewatered feedstock to a first temperature to provide a heated feedstock, said acid comprising at least one of sulfur dioxide and sulfurous acid;
(v) pretreating the heated feedstock in the presence of the acid in a pretreatment reactor to produce a pretreated feedstock, said pretreatment reactor disposed downstream of said heating device;
(vi) hydrolyzing cellulose in the pretreated feedstock with cellulase enzymes to produce glucose, wherein the concentration of dissolved solids in the pretreated feedstock fed to the hydrolysis is at least about 50% of the concentration of dissolved solids in the pretreated feedstock produced in step (v); and
(vii) fermenting the glucose to produce the fermentation product.
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Abstract
The disclosure provides a process for producing a fermentation product from a lignocellulosic feedstock. The process describes soaking a lignocellulosic feedstock in an aqueous solution to produce a soaked feedstock. The soaked feedstock is at least partially dewatered and the at least partially dewatered feedstock is subjected to pretreating in the presence of sulfur dioxide, sulfurous acid or a combination thereof to produce a pretreated feedstock composition. The pretreated feedstock composition is fed to an enzymatic hydrolysis in which the concentration of dissolved solids fed to the enzymatic hydrolysis is at least 50% (w/w) of the concentration of dissolved solids in the pretreated feedstock composition. The cellulose in the pretreated feedstock composition is hydrolyzed with cellulase enzymes in the presence of the dissolved solids to produce glucose. The glucose is fermented to produce the fermentation product.
43 Citations
20 Claims
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1. A process for producing a fermentation product from a lignocellulosic feedstock comprising:
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(i) soaking the lignocellulosic feedstock in a liquid comprising water to produce a soaked feedstock; (ii) at least partially dewatering the soaked feedstock to produce an at least partially dewatered feedstock; (iii) feeding the at least partially dewatered feedstock to a heating device; (iv) adding steam and acid to the heating device, said steam heating the at least partially dewatered feedstock to a first temperature to provide a heated feedstock, said acid comprising at least one of sulfur dioxide and sulfurous acid; (v) pretreating the heated feedstock in the presence of the acid in a pretreatment reactor to produce a pretreated feedstock, said pretreatment reactor disposed downstream of said heating device; (vi) hydrolyzing cellulose in the pretreated feedstock with cellulase enzymes to produce glucose, wherein the concentration of dissolved solids in the pretreated feedstock fed to the hydrolysis is at least about 50% of the concentration of dissolved solids in the pretreated feedstock produced in step (v); and (vii) fermenting the glucose to produce the fermentation product. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A process for producing a fermentation product from a lignocellulosic feedstock comprising:
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(i) feeding the lignocellulosic feedstock to at least one soaking tank, wherein the lignocellulosic feedstock is soaked in a liquid comprising water to produce a soaked feedstock; (ii) feeding the soaked feedstock to a dewatering device, wherein the soaked feedstock is at least partially dewatered to produce an at least partially dewatered feedstock having a consistency between 15 wt % and 40 wt %; (iii) feeding the at least partially dewatered feedstock to a heating device, wherein the at least partially dewatered feedstock is fluffed-up as it is conveyed therethrough, and wherein steam and acid are added to the at least partially dewatered feedstock to produce an acidified feedstock having a pH between 0.5 and 2.5, said acid comprising at least one of sulfur dioxide and sulfurous acid, a residence time of the heating device less than 1 minute; (iv) feeding the acidified feedstock to at least one pretreatment reactor disposed downstream of the heating device, wherein the acidified feedstock resides for a time between 30 seconds and 30 minutes at a temperature between 170°
C. and 230°
C. to produce a pretreated feedstock;(v) feeding the pretreated feedstock to at least one hydrolysis tank, wherein cellulose in the pretreated feedstock is hydrolyzed with cellulase to produce glucose, a concentration of dissolved solids in the pretreated feedstock fed to the hydrolysis at least about 50% of a concentration of dissolved solids in the pretreated feedstock produced in step (iv); and (vi) feeding a stream comprising the glucose to at least one fermentation tank, wherein the glucose is fermented to produce the fermentation product.
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20. A system for producing a fermentation product from a lignocellulosic feedstock comprising:
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at least one tank for soaking the lignocellulosic feedstock in at least one of water and an aqueous solution; a dewatering device disposed downstream of the at least one tank for at least partially dewatering the soaked feedstock to produce an at least partially dewatered feedstock; a heating device disposed downstream of the dewatering device for fluffing up the at least partially dewatered feedstock, said heating device having at least one inlet for introducing steam and an acid to the at least partially dewatered feedstock, said acid comprising at least one of sulfur dioxide and sulfurous acid; at least one pretreatment reactor disposed downstream of the heating device, said at least one pretreatment reactor including at least one outlet for discharging a pretreated feedstock; at least one hydrolysis tank disposed downstream of said at least one outlet for hydrolyzing cellulose in the pretreated feedstock with cellulase enzymes to produce glucose; at least one system disposed between the at least one outlet and the at least one hydrolysis tank, said at least one system including at least one of a cooling system, a pH adjustment system, a solid liquid separator, a washing system, and a dilution system, said at least one system feeding the pretreated feedstock to the at least one hydrolysis tank such that a concentration of dissolved solids in the pretreated feedstock fed to the hydrolysis is at least about 50% of the concentration of dissolved solids in the pretreated feedstock produced by the at least one pretreatment reactor; and at least one fermentation tank disposed downstream of the at least one pretreatment reactor for fermenting the glucose to produce the fermentation product.
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Specification