Process for the organosolv treatment of lignocellulosic biomass
The present invention is directed at a process for fractionating lignocellulosic biomass for the purpose of reducing processing costs, increasing delignification, reducing side-reactions, in particular reducing hemicelluloses degradation, improving cellulose hydrolysis and increasing the nativity of the obtained lignin, by performing organosolv fractionation of the biomass with a treatment liquid at a temperature below 170° C., wherein the treatment liquid comprises a non-hydroxylic organic solvent, in particular a ketone, water and some acid, and optionally subjecting the cellulose-enriched product stream to enzymatic hydrolysis.
1. A process for fractionating lignocellulosic biomass and converting hemicellulose into xylose, the process comprising treating the biomass with a treatment liquid at a temperature of 100° C.-160° C., wherein the treatment liquid comprises:
(i) 20-70 wt % of non-hydroxylic organic solvent comprising an ether and/or a carbonyl moiety;
(ii) 20-80 wt % of water; and
(iii) 0.5-100 g acid per kg biomass, and
wherein the treating yields a pulp comprising cellulose and a liquor comprising lignin and xylose.
2. The process according to claim 1 , wherein the non-hydroxylic organic solvent comprises ketones.
3. The process according to claim 2 , wherein the non-hydroxylic organic solvent is acetone.
4. The process according to claim 1 , wherein the treatment liquid comprises:
(i) 30-60 wt % of a non-hydroxylic organic solvent comprising an ether and/or a carbonyl moiety;
(ii) 40-70 wt % of water; and
(iii) 5-75 g acid per kg biomass.
5. The process according to claim 1 , wherein the treatment liquid comprises a weight ratio of organic solvent(s) to water between 40/60 and 65/35.
6. The process according to claim 1 , wherein the treatment liquid comprises between 0.01 wt % and 2.0 wt % of the acid.
7. The process according to claim 1 , wherein the acid has a pKa value of 4.5 or lower.
8. The process according to claim 1 , wherein the acid is sulfuric acid.
9. The process according to claim 1 , wherein the lignocellulosic biomass is selected from the group consisting of herbaceous biomass, softwood, hardwood, and combinations thereof.
10. The process according to claim 9 , wherein the lignocellulosic biomass comprises herbaceous biomass.
11. The process according to claim 9 , wherein the lignocellulosic biomass is herbaceous biomass and/or hardwood.
12. The process according to claim 1 , wherein the treatment is performed at a liquid to solid ratio (L/S) below 12/1.
13. The process according to claim 12 , wherein the L/S ratio is below 8/1.
14. The process according to claim 1 , further comprising extracting the biomass with an extracting liquid at a temperature below 100° C. prior to the treatment step, wherein the extracting liquid comprises water and/or an organic solvent.
15. The process according to claims 14 , wherein the extracting liquid comprises at least 80 wt % water.
16. The process according to claim 15 , wherein the extracting liquid comprises at least 50 wt % of an organic solvent.
17. The process according to claim 16 , wherein the organic solvent is selected from C 2 -C 4 alcohols and C 3 -C 5 ketones.
18. The process according to claim 1 , wherein a cellulose-enriched pulp is obtained, which pulp is subjected to enzymatic hydrolysis.
19. The process according to claim 18 , wherein the enzymatic hydrolysis yields a hydrolysate which is subjected to fermentation.