Integrated methods for treating lignocellulosic material

1. A process for the hydrolysis of cellulose pulp, comprising:

(i) contacting the cellulose pulp with water, a first limited-solubility solvent, and a first limited-solubility acid, thereby forming a slurry, wherein the first limited-solubility solvent has an aqueous solubility of less than 40% wt/wt at 20° C., wherein the first limited-solubility acid comprises a dicarboxylic acid, and wherein the first limited-solubility acid has an aqueous solubility of less than 1% wt/wt at 4° C.;

(ii) heating the slurry to a temperature of about 200-400° C., thereby forming a treated slurry;

(iii) recovering a cellulosic hydrolysate comprising glucose in a ratio to total monosaccharides greater than 0.80 from the treated slurry; and

(iv) recovering the first limited-solubility dicarboxylic acid by precipitation, wherein at least 80% of the first limited-solubility dicarboxylic acid is recovered.

2. The process of claim 1 , wherein the first limited-solubility acid has at least one pKa value between 1.9 and 3.5 in water.

3. The process of claim 1 , wherein the first limited-solubility acid is fumaric acid.

4. The process of claim 1 , wherein the aqueous solubility of the first limited-solubility solvent at 20° C. is between 10% and less than 40% wt/wt.

5. The process of claim 1 , wherein the first limited-solubility solvent comprises a 4- to 8-carbon ketone.

6. The process of claim 1 , wherein the first limited-solubility solvent is methylethyl ketone.

7. The process of claim 1 , wherein the first limited-solubility solvent is a 4 to 8-carbon ketone having an aqueous solubility of between 10 and less than 40% wt/wt at 20° C., and wherein the first limited-solubility acid is a dicarboxylic acid having an aqueous solubility of less than 1% wt/wt at 4° C.

8. The process of claim 1 , further comprising pretreating the cellulose pulp prior to the contacting of (i), wherein the pretreating comprises:

(a) contacting the cellulose pulp with water, a second limited-solubility solvent, and a second limited-solubility acid, thereby forming a pretreatment slurry;

(b) heating the pretreatment slurry to a temperature of 160-220° C. in a closed system; and

(c) opening the closed system to rapidly release pressure.

9. The process of claim 1 , wherein the cellulose pulp comprises:

(i) cellulose;

(ii) hemicellulose in an amount up to 5% weight/weight relative to total solids;

(iii) ash in an amount up to 6% weight/weight relative to total solids; and

(iv) sulfate in an amount up to 3% weight/weight relative to total solids.

10. The process of claim 9 , wherein the cellulose pulp further comprises lignin.

11. The process of claim 9 , wherein the cellulose pulp comprises less than 5% water soluble carbohydrates at 20° C.

12. The process of claim 1 , comprising at least 10 kg of the cellulose pulp.

13. The process of claim 1 , wherein the recovering the cellulosic hydrolysate comprises phase separation of an aqueous phase comprising the cellulosic hydrolysate from an organic phase comprising the first limited-solubility solvent.

14. The process of claim 1 , further comprising, prior to the contacting step:

(a) extracting hemicellulose sugars from a lignocellulosic biomass, thereby obtaining a hemi-depleted remainder, the hemi-depleted remainder comprising lignin and cellulose;

(b) treating the hemi-depleted remainder with a third limited-solubility solvent, a third limited-solubility acid, and water, wherein the third limited-solubility solvent and the water form an organic phase and an aqueous phase; and

(c) separating the organic phase from the aqueous phase, wherein the aqueous phase comprises the cellulose pulp.

15. The process of claim 14 , wherein the separating comprises contacting the aqueous phase with CO 2 at a pressure of at least 2 barg to produce a carbonated aqueous phase.