GRADIENT PRETREATMENT OF LIGNOCELLULOSIC BIOMASS

• US 20140273105A1
• Filed: 03/05/2014
• Published: 09/18/2014
• Est. Priority Date: 03/12/2013
• Status: Abandoned Application

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: FOX, BRADLEY CURT, CHEUNG, PATRICIA, LAU, MING WOEI, SELBY, JOSEPH MICHAEL, SHANKWITZ, GREGORY PAUL, THOMAS, STUART M, WARNER, RYAN ERIC
• Application Number:
  US14/197,241
• Publication Number:
  US 20140273105A1
• Time in Patent Office: Days
• US Class Current: 435/99
• CPC Class Codes: C08H 8/00 Macromolecular compounds derived from lignocellulosic materials pretreatment thereof B27N
• CPC Class Codes: C12P 19/02 Monosaccharides 2-ketogulonic acid C12P7/60
• CPC Class Codes: C12P 19/14 produced by the action of a carbohydrase (EC 3.2.x), e.g. by alpha-amylase , e.g. by cellulase, hemicellulase
• CPC Class Codes: C12P 2201/00 Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis
• CPC Class Codes: C12P 2203/00 Fermentation products obtained from optionally pretreated or hydrolyzed cellulosic or lignocellulosic material as the carbon source ethanol C12P7/10
• CPC Class Codes: C12P 7/10 substrate containing cellulosic material
• CPC Class Codes: C13K 1/02 obtained by saccharification of cellulosic materials manufacture of fodder A23K10/32
• CPC Class Codes: C13K 13/002 Xylose
• CPC Class Codes: D21C 1/00 Pretreatment of the finely-divided materials before digesting of waste paper D21C5/02
• CPC Class Codes: D21C 3/024 with NH3 or H2O
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

Lignocellulosic biomass pretreated with ammonia where the concentration of the biomass in the reaction mixture is reduced over time was found to produce more sugars following saccharification, as compared to equivalent biomass pretreated at constant concentration. The concentration of biomass is a solids concentration, which is the percent of dry biomass relative to the total pretreatment reaction mixture on a weight to weight basis.

Claims

1. A process for producing fermentable sugars from cellulosic biomass comprising:

a) providing in a reaction vessel at starting time t₀, a reaction mixture comprising;

i) a solids concentration of cellulosic biomass of between about 40% and about 70%, measured as percent of dry biomass relative to the total mixture on a weight to weight basis; and

ii) ammonia, having a loading concentration of between about 4% and about 24% relative to dry weight of the biomass;

b) increasing the liquid content of the reaction mixture over time to a final time t_n wherein the solids concentration decreases by between about 20% and about 30% producing a pretreated biomass; and

c) contacting the pretreated biomass with a saccharification enzyme consortium under suitable conditions to produce fermentable sugars.

2. The process of claim 1 wherein the temperature of the reaction mixture is maintained at temperature between about 100°

C. and about 200°

C. for a reaction time.

3. The process of claim 2 wherein the reaction time is between about 10 minutes and about 2 hours.

4. The process of claim 1 wherein the liquid content of the reaction mixture is increased by the introduction to the reaction vessel of an agent selected from the group consisting of steam, water, ammonia solution, and combinations thereof.

5. The process of claim 1 wherein the decrease in percent of biomass solids from t₀ to t_n is linear, is monotonic but not linear, or is step wise with the concentration of solids being held constant at least once between t₀ and t_n for a period of time.

6. The process of claim 1 wherein the ammonia is selected from the group consisting of ammonia solution, anhydrous ammonia, ammonia vapor, and mixtures thereof.

7. The process of claim 1 wherein the ammonia comprises recycled ammonia.

8. The process of claim 1 wherein the temperature is varied between t₀ and t_n.

9. The process of claim 8 wherein the temperature is increased or decreased between t₀ and t_n.

10. The process of claim 1 wherein the cellulosic biomass comprises cellulose, hemicellulose and lignin.

11. The process of claim 10 wherein the cellulosic biomass is selected from the group consisting of corn stover, corn cob, corn grain fiber, grasses, beet pulp, wheat straw, wheat chaff, oat straw, barley straw, barley hulls, hay, rice straw, rice hulls, switchgrass, miscanthus, cord grass, reed canary grass, waste paper, sugar cane bagasse, sorghum bagasse, sorghum stover, soybean stover, components obtained from milling of grains, trees, branches, roots, leaves, wood chips, sawdust, palm waste, shrubs and bushes, vegetables, fruits, flowers and animal manure.

12. The process of claim 1 wherein the fermentable sugars provide a carbohydrate source for a biocatalyst for a fermentation process.

13. The process of claim 1 wherein the fermentable sugars are produced in at least about 3% greater yield than yield from a process with constant biomass solids concentration.

14. The process of claim 1 wherein the fermentable sugars are contacted with a biocatalyst for the production of a target compound.

15. The process of claim 14 wherein the target compound is selected from the group consisting of ethanol, methanol, propanol, butanol, 1,3-propanediol, glycerol, xylitol, mannitol, lactic acid, acetic acid, formic acid, succinic acid, glutamic acid, 3-hydroxypropionic acid, fumaric acid, maleic acid and butyric acid.