Comprehensive process for selectively separating lignocellulosic biomass into purified components with high yield

Patent metadata

Field	Value
Publication number	US-10145063-B2
Application number	US-201515505465-A
Country	US
Kind code	B2
Filing date	Aug 28, 2015
Priority date	Aug 29, 2014
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A comprehensive process for treating lignocellulosic biomass in order to separate the biomass into its component parts, the process comprising: a) contacting the lignocellulosic biomass with a first solvent for a period of time and at a first temperature at a severity in the range of about 2 to about 4 to remove extractive components and a portion of ash from the biomass; b) contacting the biomass from step (a) with a second solvent, and optional catalyst, at a second temperature at a severity in the range of about 1 to 5 to remove hemicelluloses and additional ash from the biomass; and c) separating the biomass from step (b) into a lignin product and a cellulose product by contacting the biomass from step (b) with a third solvent at a severity in the range of about 1.5 to 5 to provide a spent liquor product and a solid fraction containing cellulose.

First claim

What is claimed is:

1. A comprehensive process for treating lignocellulosic biomass in order to separate the biomass into its component parts, the process comprising:
a) contacting the lignocellulosic biomass with a first solvent for a period of time and at a first temperature at a severity in the range of about 2 to about 4 to remove extractive components and a portion of ash from the biomass; and
b) separating the biomass after step (a) into a lignin product and a cellulose product by contacting the biomass after step (a) with a second solvent at a severity in the range of about 1.5 to 5 to provide a black liquor and a solid fraction containing cellulose,
the severity (R o ′) in steps (a) and (b) being determined by the formula R o ′=log R o −pH wherein R o =(t)×(exp (Tr-Tb)/14.75) ), wherein t is time in minutes, Tr is a fractionation temperature in ° C. and Tb is a baseline temperature from about 90 to about 110° C.

2. The process of claim 1 further comprising, prior to step (b), contacting the biomass from step (a) with a third solvent, with or without a catalyst, at a second temperature at a severity in the range of about 1 to 5 to remove hemicelluloses and additional ash from the biomass,
wherein the severity (R o ′) being determined by the formula
R o ′=log R o −pH

wherein R o =(t)×(exp (Tr-Tb)/14.75) ), wherein t is time in minutes, Tr is a fractionation temperature in ° C. and Tb is a baseline temperature from about 90 to about 110° C.

3. The process of claim 1 wherein the black liquor is processed by adding salt or water, or water immiscible solvent to induce a phase separation resulting in an organic phase and an aqueous phase, wherein the organic and aqueous phases each contain a significant amount of lignin, extracting the lignin by removing the solvent in each phase using a spray drier, rotary evaporator, or other distillation method.

4. The process of claim 1 , wherein the lignin product has a purity of about 90 wt. % or greater.

5. The process of claim 1 wherein the lignin product is further processed by washing the material with methanol to obtain two sub-fractions of lignin characterized by a lower molecular weight lignin fraction and a higher molecular weight lignin fraction, wherein a methanol rinsate contains the lower molecular weight lignin and the higher molecular weight lignin remains as a solid, and wherein the methanol rinsate containing the lower molecular weight lignin is distilled on a rotary evaporator or spray-dried to provide a yield of lower molecular weight lignin yield ranging from about 40 wt. % to about 60 wt. %.

6. The process of claim 1 wherein the black liquor is processed by spray-drying or the solvent is removed from the solution on a rotary evaporator or similar distillation process.

7. The process of claim 6 wherein the resulting lignin is washed with ether to remove residual solvent or other contaminants and additional solvent removal is applied to isolate the purified lignin product.

8. The process of claim 7 wherein the lignin product is further processed by washing the material with methanol to obtain two sub-fractions of lignin characterized by a lower molecular weight lignin fraction and a higher molecular weight lignin fraction, wherein a methanol rinsate contains the lower molecular weight lignin and the higher molecular weight lignin remains as a solid, and wherein the methanol rinsate containing the lower molecular weight lignin is distilled on a rotary evaporator or spray-dried to provide a yield of lower molecular weight lignin yield ranging from about 40 wt. % to about 60 wt. %.

9. The process of claim 6 wherein the resulting lignin is washed with water to remove residual, sugars, ethanol, or other contaminants and additional solvent removal is applied to isolate the purified lignin product.

10. The process of claim 9 wherein the lignin product is further processed by washing the material with methanol to obtain two sub-fractions of lignin characterized by a lower molecular weight lignin fraction and a higher molecular weight lignin fraction, wherein a methanol rinsate contains the lower molecular weight lignin and the higher molecular weight lignin remains as a solid, and wherein the methanol rinsate containing the lower molecular weight lignin is distilled on a rotary evaporator or spray-dried to provide a yield of lower molecular weight lignin yield ranging from about 40 wt. % to about 60 wt. %.

11. The process of claim 6 wherein the resulting lignin is washed with water to remove residual, sugars, ethanol, or other contaminants; the resulting lignin is washed with ether to remove residual solvent, sugars, or other contaminants; and additional solvent removal is applied to isolate the purified lignin product.

12. The process of claim 11 wherein the lignin product is further processed by washing the material with methanol to obtain two sub-fractions of lignin characterized by a lower molecular weight lignin fraction and a higher molecular weight lignin fraction, wherein a methanol rinsate contains the lower molecular weight lignin and the higher molecular weight lignin remains as a solid, and wherein the methanol rinsate containing the lower molecular weight lignin is distilled on a rotary evaporator or spray-dried to provide a yield of lower molecular weight lignin yield ranging from about 40 wt. % to about 60 wt. %.

13. The process of claim 1 wherein the lignin product has a number average molecular weight of from about 1000 to about 5000 and a polydispersity index ranging from about 3 to about 5.

14. The process of claim 1 wherein the first solvent and second solvent comprise a solvent selected from the group consisting of water, ethanol, ketone, and a combination of two or more of the foregoing.

15. The process of claim 1 wherein the second solvent comprises a mixture of water, ethanol and ketone in a weight ratio ranging from about 1:1:2 to about 1:2:4.

16. The process of claim 1 wherein the lignocellulosic biomass comprises switchgrass or poplar.

17. The process of claim 1 wherein the lignin product has a polydispersity index ranging from about 3 to about 5.

18. The process of claim 1 further comprising producing a foam from the lignin product.

19. The process of claim 1 further comprising producing an electrospun fiber from the lignin product.

20. The process of claim 1 further comprising producing carbon fibers from the lignin product.

21. A comprehensive process for treating lignocellulosic biomass in order to separate the biomass into its component parts, the process comprising:
a) contacting the lignocellulosic biomass with a first solvent with or without a catalyst at a temperature at a severity in the range of about 1 to 5 to remove hemicelluloses and ash from the biomass; and
b) separating the biomass after step (a) into a lignin product and a cellulose product by contacting the biomass after step (a) with a second solvent at a severity in the range of about 1.5 to 5 to provide a black liquor and a solid fraction containing cellulose,
the severity (R o ′) in steps (a) and (b) being determined by the formula R o ′=log R o −pH wherein R o =(t)×(exp (Tr-Tb)/14.75) ), wherein t is time in minutes, Tr is a fractionation temperature in ° C. and Tb is a baseline temperature from about 90 to about 110° C.

22. The process of claim 21 wherein the black liquor is processed by adding salt or water, or water immiscible solvent to induce a phase separation resulting in an organic phase and an

Assignees

• Univ Tennessee Res Found

Inventors

• Bozell Joseph
• Harper David
• Labbe Nicole
• Hosseinaei Omid
• Rials Timothy

Classifications

• D01D5/0038

  the fibre formed by solvent evaporation, i.e. dry electro-spinning · CPC title

• C08B37/0057

  beta-D-Xylans, i.e. xylosaccharide, e.g. arabinoxylan, arabinofuronan, pentosans; (beta-1,3)(beta-1,4)-D-Xylans, e.g. rhodymenans; Hemicellulose; Derivatives thereof · CPC title

• D21C11/0007 Primary

  Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for (volatile compounds obtained by decomposition of spent liquors in order to regenerate them D21C11/125; compounds obtained by fractionating the liquors in order to regenerate them D21C11/0042) · CPC title

• D21C3/20

  with organic solvents {or in solvent environment} · CPC title

• D01C1/02

  by chemical methods to obtain bast fibres · CPC title