PROCESSES FOR CO-PRODUCING XYLITOL WITH ETHANOL OR OTHER FERMENTATION PRODUCTS
What is disclosed is a biorefining process to co-produce xylitol with ethanol or other products. In some variations, a process for producing ethanol and xylitol from lignocellulosic biomass, comprises: extracting hemicelluloses from lignocellulosic biomass, wherein the hemicelluloses include xylose oligomers and other sugar oligomers; hydrolyzing the xylose oligomers and the other sugar oligomers, using an acid catalyst or enzymes, to generate xylose and other sugar monomers, respectively; fermenting the other sugar monomers to ethanol using a suitable ethanol-producing microorganism; removing at least some of the ethanol (to increase concentration of xylose); fermenting the xylose to xylitol using a suitable xylitol-producing microorganism; and recovering the xylitol at high concentration.
1 . A process for producing xylitol and another fermentation product from lignocellulosic biomass, said process comprising:
(a) extracting hemicelluloses from a feedstock comprising lignocellulosic biomass, wherein said hemicelluloses include xylose oligomers and other sugar oligomers;
(b) hydrolyzing said xylose oligomers and said other sugar oligomers, to generate xylose and other sugar monomers, respectively, using an acid catalyst or enzymes;
(c) fermenting said other sugar monomers to a first fermentation product, using a suitable first microorganism;
(d) optionally removing at least some of said first fermentation product;
(e) fermenting said xylose to a second fermentation product comprising xylitol, using a suitable second microorganism;
(f) recovering said first fermentation product, derived from step (c) and/or, if conducted, step (d); and
(g) recovering said xylitol derived from step (e).
2 . The process of claim 1 , wherein said other sugar oligomers include C 6 sugars.
3 . The process of claim 1 , wherein said first fermentation product comprises ethanol.
4 . The process of claim 1 , wherein step (a) utilizes steam and/or hot water, optionally with an extraction catalyst.
5 . The process of claim 1 , wherein step (a) utilizes an extraction catalyst, a solvent for lignin, and water.
6 . The process of claim 1 , wherein step (b) utilizes a sulfur-containing acid catalyst.
7 . The process of claim 6 , wherein sulfur-containing acid catalyst is derived from step (a).
8 . The process of claim 1 , wherein steps (c) and (e) are conducted simultaneously.
9 . The process of claim 1 , wherein steps (c) and (e) are conducted sequentially.
10 . The process of claim 1 , said process further comprising removing lignin derived from said lignocellulosic biomass.
11 . The process of claim 1 , said process further comprising recovering or generating a cellulose-rich material from said lignocellulosic biomass, wherein said cellulose-rich material is selected from the group consisting of market pulp, dissolving pulp, fluff pulp, purified cellulose, functionalized cellulose, nanocellulose, paper, boxes, boards, pellets, and combinations thereof.
12 . A process for producing xylitol and another fermentation product from lignocellulosic biomass, said process comprising:
(a) extracting hemicelluloses from a feedstock comprising lignocellulosic biomass, wherein said hemicelluloses include xylose oligomers and other sugar oligomers;
(b) hydrolyzing said xylose oligomers and said other sugar oligomers, to generate xylose and other sugar monomers, respectively, using an acid catalyst or enzymes;
(c) co-fermenting said xylose to a first fermentation product comprising xylitol and said other sugar monomers to a second fermentation product, using a suitable microorganism or combination of microorganisms;
(d) continuously removing said second fermentation product to increase concentration of said xylitol; and
(e) recovering said xylitol.
13 . The process of claim 12 , wherein said other sugar oligomers include C 6 sugars.
14 . The process of claim 12 , wherein said second fermentation product comprises ethanol.
15 . The process of claim 12 , wherein step (a) utilizes steam and/or hot water, optionally with an extraction catalyst.
16 . The process of claim 12 , wherein step (a) utilizes an extraction catalyst, a solvent for lignin, and water.
17 . The process of claim 12 , wherein step (b) utilizes a sulfur-containing acid catalyst.
18 . The process of claim 17 , wherein sulfur-containing acid catalyst is derived from step (a).
19 . The process of claim 12 , said process further comprising removing lignin derived from said lignocellulosic biomass.
20 . The process of claim 12 , said process further comprising recovering or generating a cellulose-rich material from said lignocellulosic biomass, wherein said cellulose-rich material is selected from the group consisting of market pulp, dissolving pulp, fluff pulp, purified cellulose, functionalized cellulose, nanocellulose, paper, boxes, boards, pellets, and combinations thereof.