Method for extracting lignin

• US 10,407,452 B2
• Filed: 01/09/2015
• Issued: 09/10/2019
• Est. Priority Date: 01/10/2014
• Status: Active Grant

• Current Assignee: CH-Bioforce Oy
• Original Assignee: CH-Bioforce Oy
• Inventors: Von Schoultz, Sebastian
• Primary Examiner(s): McAvoy, Ellen M
• Assistant Examiner(s): Graham, Chantel L
• Application Number:
  US15/109,669
• Publication Number:
  US 20160326203A1
• Time in Patent Office: 1,705 Days
• CPC Class Codes: C07G 1/00 Lignin; Lignin derivatives
• CPC Class Codes: C08B 1/00 Preparatory treatment of cellulose for making derivatives thereof , e.g. pre-treatment, pre-soaking, activation
• CPC Class Codes: C10L 2200/0469 Renewables or materials of biological origin
• CPC Class Codes: C10L 2290/06 Heat exchange, direct or indirect
• CPC Class Codes: C10L 2290/30 Pressing, compressing or compacting
• CPC Class Codes: C10L 2290/544 Extraction for separating fractions, components or impurities during preparation or upgrading of a fuel
• CPC Class Codes: C10L 5/363 Pellets or granulates
• CPC Class Codes: C10L 5/442 Wood or forestry waste
• CPC Class Codes: D21C 1/10 Physical methods for facilitating impregnation
• CPC Class Codes: D21C 3/02 with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
• 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

The invention relates to a method for removing lignin from lignocellulosic biomass. The method comprises feeding of lignocellulosic biomass and a first aqueous solution into a reactor vessel, the lignocellulosic biomass and the first aqueous solution forming a reaction mixture; reducing the pressure in the reactor vessel below 0.8 bar absolute pressure, preferably 0.5 bar absolute pressure, more preferably below 0.2 bar absolute pressure; keeping the reaction mixture in a predetermined extraction temperature, and adding at least one extraction chemical, such as base or acid, to the reaction vessel and extracting lignin from the biomass to the liquid phase of the reaction mixture.

Claims

1. A method for removing lignin from lignocellulosic biomass, the method comprising:

contacting lignocellulosic biomass with a first aqueous solution, which comprises at least 95 weight-% of water, within a reactor vessel, the lignocellulosic biomass and the first aqueous solution forming a reaction mixture,

reducing a pressure in the reactor vessel below 0.8 bar absolute pressure, and then heating the reaction mixture to a predetermined extraction temperature of 70-250°

C., and

adding at least one extraction chemical, which comprises a base, to the reaction vessel when the extraction temperature is reached, and extracting lignin from the biomass to a liquid phase of the reaction mixture at a pH of 12 or greater.

2. The method according claim 1, further comprising adding the at least one extraction chemical as one single dose when the predetermined extraction temperature is reached.

3. The method according claim 1, wherein the base comprises a member selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, and sodium sulfide.

4. The method according to claim 1, further comprising using lignin rich extract from a previous extraction as the at least one extraction chemical.

5. The method according to claim 1, wherein the predetermined extraction temperature is in the range of 110-250°

C.

6. The method according to claim 1, wherein a pressure inside the reactor vessel during the extraction of lignin is 5-8 bar absolute pressure.

7. The method according to claim 1, wherein the pH of the aqueous solution is 3-10.

8. The method according to claim 1, further comprising adding at least one chemical oxygen scavenger to the first aqueous solution.

9. The method according to claim 1, further comprising continuing the lignin extraction by circulating the liquid phase of the reaction mixture through the biomass as long as a desired reduced lignin content of the biomass is reached.

10. The method according to claim 1, wherein the extracting provides a treated biomass, and further comprising using the treated biomass,

for production of paper, board, or the like;

for production of dissolving pulp or nanocellulose;

for production pellets or as raw material for fuel; and

/or

for production of particle board (chipboard).

11. The method according to according to claim 1, further comprising using the extracted lignin for production of energy or fuel and/or as raw material for chemical products.

12. The method according to claim 1, wherein the biomass is fed to the reaction vessel, the pressure in the reactor vessel is reduced to below 0.8 bar absolute pressure, and the first aqueous solution is fed to the reactor vessel while the pressure is kept reduced.

13. The method according to claim 1, wherein the pressure in the reactor vessel is reduced below 0.5 bar absolute pressure.

14. The method according to claim 1, wherein the pressure in the reactor vessel is reduced below 0.2 bar absolute pressure.

15. The method according to claim 1, wherein the pH during the extracting of lignin is greater than 13.

16. The method according to claim 1, wherein the predetermined extraction temperature is in the range of 135-160°

C.

17. A method for removing lignin from lignocellulosic biomass, the method comprising:

extracting an amount of carbohydrates from a lignocellulosic biomass to form a carbohydrate-reduced lignocellulosic biomass by contacting the lignocellulosic biomass with an aqueous solution comprising at least 75 weight % water, wherein the contacting is done at a pressure of 0.8 bar absolute pressure or below to define an oxygen poor environment having an oxygen concentration of 0.01 or less kg oxygen per kg of the aqueous solution, and wherein the oxygen poor environment reduces occurrence of condensation reactions of the lignin within the reaction mixture; and

extracting an amount of lignin from the carbohydrate-reduced lignocellulosic biomass at a temperature of from 70-250°

C. in the presence of at least one extraction compound.

18. The method of claim 17, wherein the at least one extraction compound comprises a basic compound, and wherein the extracting of an amount of lignin is done at a pH of 12 or greater.

19. The method of claim 17, wherein the extracting an amount of carbohydrates provides a first liquid fraction comprising a 85% or greater yield of carbohydrates from the biomass, and the extracting an amount of lignin from the carbohydrate-reduced lignocellulosic biomass provides a second liquid fraction comprising a 90% or greater yield of lignin from the biomass.