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

Patent metadata

Field	Value
Publication number	US-10557154-B2
Application number	US-201916433407-A
Country	US
Kind code	B2
Filing date	Jun 6, 2019
Priority date	Feb 19, 2015
Publication date	Feb 11, 2020
Grant date	Feb 11, 2020

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 a fermentation product 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 digestor, to solubilize at least a portion of said hemicellulose in a liquid phase and to provide a cellulose-rich solid phase;
(c) refining said cellulose-rich solid phase, together with said liquid phase, in a mechanical refiner to reduce average particle size of said cellulose-rich solid phase, thereby providing a mixture comprising refined cellulose-rich solids and said liquid phase;
(d) enzymatically hydrolyzing said mixture in a hydrolysis reactor with cellulase enzymes, to generate fermentable sugars from said mixture, wherein said hydrolysis reactor includes one or more hydrolysis stages; and
(e) fermenting at least some of said fermentable sugars in a fermentor to produce a fermentation product,
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 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.

3. 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).

4. The process of claim 1 , wherein said reaction solution further comprises an acid.

5. The process of claim 1 , wherein said process employs a blow tank configured for receiving said cellulose-rich solid phase or said refined cellulose-rich solids at a pressure lower than digestor pressure.

6. The process of claim 5 , wherein said blow tank is disposed downstream of said digestor and upstream of said mechanical refiner.

7. The process of claim 5 , wherein said blow tank is disposed downstream of said digestor and downstream of said mechanical refiner.

8. The process of claim 5 , wherein vapor is separated from said blow tank.

9. The process of claim 8 , wherein heat is recovered from at least some of said vapor.

10. The process of claim 8 , wherein at least some of said vapor is condensed or compressed and returned to said digestor.

11. The process of claim 1 , wherein a first blow tank is disposed upstream of said mechanical refiner and a second blow tank is disposed downstream of said mechanical refiner.

12. 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.

13. The process of claim 1 , said process comprising utilizing multiple mechanical refiners at different parts of said process.

14. The process of claim 13 , said process comprising, between steps (c) and (d), conveying at least a portion of said mixture to a second mechanical refiner operated at a lower refining pressure compared to that of said mechanical refiner in step (c).

15. The process of claim 14 , wherein said mechanical refiner in step (c) is a pressurized refiner and said second mechanical refiner is an atmospheric refiner.

16. The process of claim 1 , wherein step (d) utilizes single-stage enzymatic hydrolysis configured for cellulose liquefaction and saccharification, wherein said single-stage enzymatic hydrolysis includes one or more tanks or vessels.

17. The process of claim 1 , wherein step (d) utilizes multiple-stage enzymatic hydrolysis configured for cellulose liquefaction followed by saccharification, wherein each stage includes one or more tanks or vessels.

18. The process of claim 17 , said process further comprising additional mechanical refining of said mixture, or a partially hydrolyzed form thereof, following at least a first stage of enzymatic hydrolysis.

19. The process of claim 18 , said process further comprising:
introducing said mixture to a first enzymatic-hydrolysis reactor under effective hydrolysis conditions to produce a liquid hydrolysate comprising sugars from said refined cellulose-rich solids and optionally from said hemicellulose, and a residual cellulose-rich solid phase;
optionally separating at least some of said liquid hydrolysate from said residual cellulose-rich solid phase;
conveying said residual cellulose-rich solid phase through an additional mechanical refiner and/or recycling said residual cellulose-rich solid phase through said mechanical refiner, to generate refined residual cellulose-rich solids; and
introducing said refined residual cellulose-rich solids to a second enzymatic-hydrolysis reactor under effective hydrolysis conditions, to produce additional sugars.

20. The process of claim 1 , wherein a self-cleaning filter is configured downstream of said hydrolysis reactor to remove cellulosic fiber strands, and wherein said cellulosic fiber strands are recycled back to said hydrolysis reactor.

Assignees

• Granbio Intellectual Property Holdings Llc

Inventors

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

Classifications

• D21C1/02

  with water or steam · CPC title

• 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

• C12P2203/00

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

• C12P2201/00

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