Hydrothermal-mechanical conversion of lignocellulosic biomass to ethanol or other fermentation products

Patent metadata

Field	Value
Publication number	US-10344303-B2
Application number	US-201815957480-A
Country	US
Kind code	B2
Filing date	Apr 19, 2018
Priority date	Feb 19, 2015
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A low-cost process is provided to render lignocellulosic biomass accessible to cellulase enzymes, to produce fermentable sugars. Some variations provide a process to produce ethanol from lignocellulosic biomass (such as sugarcane bagasse or corn stover), comprising introducing a lignocellulosic biomass feedstock to a single-stage digestor; exposing the feedstock to a reaction solution comprising steam or liquid hot water within the digestor, to solubilize the hemicellulose in a liquid phase and to provide a cellulose-rich solid phase; refining the cellulose-rich solid phase, together with the liquid phase, in a mechanical refiner, thereby providing a mixture of refined cellulose-rich solids and the liquid phase; enzymatically hydrolyzing the mixture in a hydrolysis reactor with cellulase enzymes, to generate fermentable sugars; and fermenting the fermentable sugars to produce ethanol. Many alternative process configurations are described. The disclosed processes may be employed for other fermentation products.

First claim

What is claimed is:

1. A process to produce ethanol from lignocellulosic biomass, said process comprising:
(a) introducing a lignocellulosic biomass feedstock to a single-stage digestor, wherein said feedstock contains cellulose, hemicellulose, and lignin;
(b) exposing said feedstock to a reaction solution comprising steam or liquid hot water within said single-stage digestor, to solubilize at least a portion of said hemicellulose in a liquid phase and to provide a cellulose-rich solid phase;
(c) enzymatically hydrolyzing said cellulose-rich solid phase in a first hydrolysis reactor configured for cellulose liquefaction, thereby providing a first hydrolyzed cellulose mixture containing said liquid phase;
(d) refining said first hydrolyzed cellulose mixture in a mechanical refiner to reduce average particle size of said first hydrolyzed cellulose mixture, thereby providing a second hydrolyzed cellulose mixture;
(e) enzymatically hydrolyzing said second hydrolyzed cellulose mixture in a second hydrolysis reactor configured for cellulose saccharification, thereby generating fermentable sugars, wherein said second hydrolysis reactor includes a self-cleaning filter to remove cellulosic fiber strands;
(f) recycling at least a portion of said cellulosic fiber strands back to said first hydrolysis reactor and/or to said mechanical refiner; and
(g) fermenting at least some of said fermentable sugars in a fermentor to produce ethanol,
wherein there is no separation of said liquid phase from said cellulose-rich solid phase between step (b) and step (c).

2. The process of claim 1 , wherein said lignocellulosic biomass feedstock is selected from the group consisting of hardwoods, softwoods, sugarcane bagasse, sugarcane straw, energy cane, corn stover, corn cobs, corn fiber, and combinations thereof.

3. The process of claim 1 , wherein said lignocellulosic biomass feedstock is pretreated, prior to step (a), using one or more techniques selected from the group consisting of cleaning, washing, presteaming, drying, milling, particle size-classifying, and combinations thereof.

4. The process of claim 1 , wherein at least a portion of said reaction solution is introduced to said feedstock in a pre-impregnator prior to step (b).

5. The process of claim 1 , wherein step (b) includes a digestor residence time from about 2 minutes to about 4 hours.

6. The process of claim 1 , wherein step (b) includes a digestor temperature from about 150° C. to about 220° C.

7. The process of claim 1 , wherein step (b) is conducted at a digestor liquid-solid weight ratio from about 1 to about 4.

8. The process of claim 1 , wherein step (b) is conducted at a digestor pH from about 3 to about 5.

9. The process of claim 1 , wherein said reaction solution further comprises acetic acid.

10. The process of claim 1 , wherein vapor is separated from said liquid phase prior to step (c).

11. The process of claim 10 , wherein heat is recovered from at least some of said vapor.

12. The process of claim 10 , wherein at least some of said vapor is condensed or compressed and returned to said digestor.

13. The process of claim 1 , wherein said mechanical refiner is selected from the group consisting of a hot-blow refiner, a hot-stock refiner, a blow-line refiner, a disk refiner, a conical refiner, a cylindrical refiner, an in-line defibrator, an extruder, a homogenizer, and combinations thereof.

14. The process of claim 1 , wherein said second hydrolysis reactor is a multiple-stage hydrolysis reactor.

15. The process of claim 1 , wherein said self-cleaning filter is disposed between two stages of said multiple-stage hydrolysis reactor.

16. The process of claim 1 , wherein step (e) includes enzymatic hydrolysis of hemicellulose oligomers to generate fermentable monomer sugars.

17. The process of claim 16 , wherein at least a portion of said fermentable monomer sugars are also fermented to produce said ethanol.

18. The process of claim 1 , said process further comprising concentrating said ethanol by distillation.

Assignees

• Api Ip Holdings Llc
• Granbio Intellectual Property Holdings Llc

Inventors

• Retsina Theodora
• Pylkkanen Vesa
• Rutherford Steven R
• Monclin Jean-Pierre

Classifications

• D21C9/00

  After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters {; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere (polysaccharides, derivatives thereof C08B; paper-making D21B - D21H)} · CPC title

• D21C3/00

  Pulping cellulose-containing materials (digesters D21C7/00) · CPC title

• C12P2201/00

  Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis · CPC title

• C12P7/14 Primary

  Multiple stages of fermentation; Multiple types of microorganisms or re-use of microorganisms · CPC title

• C12P2203/00

  Fermentation products obtained from optionally pretreated or hydrolyzed cellulosic or lignocellulosic material as the carbon source · CPC title