Continuous or semi-continuous process for treating biomass to produce materials useful for biofuels
View Patent ↗Fermentable sugar useful for the production of biofuels is produced from biomass in a continuous or semi-continuous manner by providing pumpable biomass.
1. A continuous or a semi-continuous process for treating biomass comprising:
(a) providing a biomass containing polysaccharides;
(b) contacting the biomass with a solution containing at least one α-hydroxysulfonic acid at a temperature within the range of about 50 ° C. to about 150° C. and a pressure within the range of 1 barg to about 10 barg to provide a biomass solution, wherein said biomass solution contains in the range of about 1 wt % to about 25 wt % of biomass based on the solution, and thereby hydrolyzing the biomass to produce at least one fermentable sugar containing product;
(c) removing at least a portion of the α-hydroxysulfonic acid in its component form from the product by heating and/or reducing pressure to produce an acid-removed product containing at least one fermentable sugar;
(d) separating a high solids/liquid mixture from said acid-removed product to form a wet solids stream containing at least 12 wt % undissolved solids based on wet solids stream, and a bulk liquid stream containing fermentable sugar;
(e) recycling said removed α-hydroxysulfonic acid to step (b) as components or in its recombined form; and
(f) recycling at least a portion of the bulk liquid stream to step (b);
wherein the bulk liquid stream comprise greater than about 2 wt % of the fermentable sugar based on the bulk liquid stream.
2. The process of claim 1 wherein the α-hydroxysulfonic acid is present in an amount of from about 1% wt. to about 55% wt., based on the solution.
3. The process of claim 2 wherein the biomass solution contains greater than about 5 wt % of fermentable sugar.
4. The process of claim 3 wherein the biomass content in the biomass solution is less than about 20 wt %.
5. The process of claim 4 wherein the biomass content in the biomass solution is less than about 15 wt %.
6. The process of claim 5 wherein the biomass content in the biomass solution is about 10 wt % or less.
7. The process of claim 1 wherein the separation of step (d) is by centrifugal force.
8. The process of claim 1 wherein the separation of step (d) is by filtration.
9. The process of claim 1 wherein the separation of step (d) is by decantation.
10. The process of claim 1 further separating a pentose-containing stream from the liquid stream.
11. The process of claim 1 wherein the hexose content of the wet solid stream is greater than about 0.5 wt % based on the wet solid stream.
12. The process of claim 11 wherein the wet solid stream contains less than 0.5 wt % furfural.
13. The process of claim 12 wherein the wet solid stream contains less than 0.2 wt % furfural.
14. The process of claim 1 wherein the α-hydroxysulfonic acid is produced from (a) a carbonyl compound or a precursor to a carbonyl compound with (b) sulfur dioxide or a precursor to sulfur dioxide and (c) water.
15. The process of claim 1 wherein the α-hydroxysulfonic acid is in-situ generated.
16. The process of claim 2 wherein the biomass is contacted with the α-hydroxysulfonic acid at a temperature of 120° C. or less.
17. The process of claim 2 wherein the α-hydroxysulfonic acid is produced from (a) a carbonyl compound or a precursor to a carbonyl compound with (b) sulfur dioxide or a precursor to sulfur dioxide and (c) water.
18. The process of claim 2 wherein the α-hydroxysulfonic acid is in-situ generated.
19. The process of claim 1 wherein the at least one fermentable sugar comprises a hexose.
20. The process of claim 1 wherein in step (b) at least one pentose and at least one hexose is produced.
21. The process of claim 1 further comprising (g) hydrolyzing the liquid/solid mixture thereby producing a sugar stream.
22. The process The process of claim 21 further comprising (h) fermenting the sugar stream thereby producing fermented products.
23. The process of claim 2 further comprising hydrolyzing and fermenting the stream containing fermentable sugar thereby producing fermented products.
24. The process of claim 1 wherein the α-hydroxysulfonic acid is present in an amount of from about 1% wt. to about 40% wt., based on the solution.
25. The process of claim 1 wherein in step (c) the acid-removed product is substantially free of the α-hydroxysulfonic acid.
26. The process of claim 25 wherein in step (c) no more than about 2 wt % of alpha-hydroxysulfonic acid is present in the acid-removed product.