METHOD AND APPARATUS FOR LIGNOCELLULOSE PRETREATMENT USING A SUPER-CELLULOSE-SOLVENT AND HIGHLY VOLATILE SOLVENTS

• US 20090229599A1
• Filed: 03/16/2009
• Published: 09/17/2009
• Est. Priority Date: 03/14/2008
• Status: Active Grant

• Current Assignee: Virginia Tech Intellectual Properties, Inc.
• Original Assignee: Virginia Tech Intellectual Properties, Inc.
• Inventors: ZHANG, Y.H. Percival
• Granted Patent: US 8,663,392 B2
• Time in Patent Office: Days
• US Class Current: 127/1
• CPC Class Codes: C08B 1/003 Preparation of cellulose solutions, i.e. dopes, with different possible solvents, e.g. ionic liquids solutions used in the manufacture of monocomponent artificial filaments or cellulose or derivatives thereof D01F2/02
• CPC Class Codes: C08H 8/00 Macromolecular compounds derived from lignocellulosic materials pretreatment thereof B27N
• CPC Class Codes: C13K 1/02 obtained by saccharification of cellulosic materials manufacture of fodder A23K10/32
• CPC Class Codes: D21C 3/04 with acids, acid salts or acid anhydrides D21C3/003 and D21C3/222 take precedence
• CPC Class Codes: D21C 3/22 Other features of pulping processes
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel

Abstract

Embodiments of the present invention overcome the well-known recalcitrance of lignocellulosic biomass in an economically viable manner. A process and a system are provided for the efficient fractionation of lignocellulosic biomass into cellulose, hemicellulose, and lignin. The cellulose and hemicellulose thus obtained are highly amorphous and can be readily converted into highly concentrated mixtures of five and six carbon sugars using known methods. Typical yields of sugars exceed 100 grams of sugars per liter of sugar solution. Other products, such as alcohols, can easily be prepared according to methods of the invention. The modest process conditions and low solvent/solid ratios of some embodiments of the invention require relatively low capital and processing costs.

Claims

1. A method for fractionating lignocellulosic biomass, the process comprising:

digesting lignocellulose with polyphosphoric acid;

precipitating cellulose and hemicellulose and solubilizing lignin with a first solvent;

separating the solubilized lignin from the precipitated cellulose and hemicellulose; and

stripping the first solvent from the precipitated cellulose and hemicellulose by exposing the cellulose, hemicellulose, and solvent to steam, vacuum, or a combination of these,

wherein the process provides a mixture of hydrated amorphous cellulose and hydrated amorphous hemicellulose.

2. The method of claim 1, wherein the method does not comprise separating cellulose from hemicellulose.

3. The method of claim 1, wherein the first solvent comprises ethanol at approximately 80% concentration.

4. The method of claim 3, wherein the first solvent further comprises CO₂, SO₂, O₃, or mixtures of two or all three of these.

5. The method of claim 1, wherein the method does not comprise use of a solvent in addition to the first solvent.

6. The method of claim 1, which is a method of producing sugars from lignocellulose, wherein the method further comprises:

hydrolyzing the hydrated amorphous cellulose and hydrated amorphous hemicellulose to produce a composition comprising one or more sugars.

7. The method of claim 6, wherein the composition comprises sugars at a concentration of at least 30 grams per liter.

8. The method of claim 6, wherein the composition comprises sugars at a concentration of at least 50 grams per liter.

9. The method of claim 6, wherein the composition comprises sugars at a concentration of at least 100 grams per liter.

10. The method of claim 6, which results in a mixture of pentoses and hexoses.

11. A system for fractionating lignocellulosic biomass, the system comprising:

a precipitation tank for precipitation of cellulose and hemicellulose, and for solubilization of lignin;

a washer for washing the precipitated cellulose and hemicellulose; and

a stripper for stripping solvent from the precipitated cellulose and hemicellulose,

wherein the system does not comprise a separator for separating cellulose from hemicellulose.

12. The system of claim 11, further comprising a digester for digestion of raw materials comprising lignocellulose into particles having a size of about 0.5 cm or smaller.

13. The system of claim 11, further comprising a hydrolysis tank for hydrolyzing the precipitated cellulose and hemicellulose.

14. The system of claim 11, further comprising a distillation column for separating components of a wash solution from the washer, wherein the distillation column is not a fractionation-distillation column.

15. The system of claim 14, further comprising a furnace.