Method for fractionating lignin

Patent metadata

Field	Value
Publication number	US-9896469-B2
Application number	US-201314405873-A
Country	US
Kind code	B2
Filing date	Jun 5, 2013
Priority date	Jun 6, 2012
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

The present invention relates to a method for fractionating lignin, wherein the method comprises the following steps: (i) dissolving lignin into a mixture containing organic solvent and water; and (ii) ultrafiltrating the mixture formed in step (i) through one or more filtration membranes for producing a predetermined number of lignin fractions, wherein each fraction contains lignin with a molecular weight within a predetermined range. The present invention further relates to a lignin fraction and to the uses thereof.

First claim

The invention claimed is:

1. A method for fractionating lignin, wherein the method comprises the following steps:
(i) dissolving lignin into a mixture including organic solvent and water, wherein step (i) is performed at a temperature of 50-120° C., wherein the lignin is a wood-based lignin, wherein the wood-based lignin includes kraft lignin derived from black liquor, lignin from an alkaline pulping process, lignin from a soda process, or any combination thereof;
(ii) ultrafiltrating the mixture formed in step (i) through one or more filtration membranes for producing a predetermined number of lignin fractions, wherein each fraction includes lignin with a molecular weight within a predetermined range; and
(iii) subjecting at least one of the lignin fractions formed in step (ii) to ion exchange treatment.

2. The method according to claim 1 , wherein the method further comprises the following step:
(iv) removing the organic solvent from at least one of the fractions obtained from step (ii) or obtained from step (iii) for precipitating lignin.

3. The method according to claim 2 , wherein the method further comprises the following step:
(v) filtrating the precipitated lignin.

4. The method according to claim 1 , wherein 10-100 weight-%, preferably 30-90 weight-% of the lignin is dissolved in the mixture including organic solvent and water.

5. The method according to claim 1 , wherein step (i) is performed at a temperature of 50-90° C.

6. The method according to claim 1 , wherein the organic solvent is selected from a group consisting of acetone, acetonitrile, butylacetate, dimethyl sulfoxide, dimethylformamide, tetrahydrofuran, propylene carbonate, ethanol, isopropanol, n-propanol, n-butanol, and any combination thereof.

7. The method according to claim 1 , wherein step (ii) comprises preventing evaporation of the organic solvent during ultrafiltration.

8. The method according to claim 1 , wherein the filtration membrane is a ceramic membrane or a polymer membrane.

9. The method according to claim 1 , wherein two or more filtration membranes having different cut-off values are used in step (ii).

10. The method according to claim 1 , wherein step (ii) comprises passing the mixture formed in step (i) through two or more filtration membranes arranged one after the other such that the cut-off value of the preceding filtration membrane is higher than the cut-off value of the following filtration membrane.

11. The method according to claim 1 , wherein step (i) is performed at a temperature of 50-70° C.

12. The method according to claim 1 , wherein method does not result in an increase in ash content.

13. The method of claim 1 , wherein the wood-based lignin is kraft lignin, biomass originating lignin, lignin from alkaline pulping process, lignin from soda process, lignin from organosolv pulping, chemically modified lignin, or any combination thereof.

Assignees

• Upm Kymmene Corp

Inventors

• Eskelinen Kati
• Valkonen Sanna
• Pietarinen Suvi

Classifications

• C08H6/00 Primary

  Macromolecular compounds derived from lignin, e.g. tannins, humic acids · CPC title

• C09J197/005

  Lignin · CPC title

• D01F9/17

  from lignin · CPC title

• C08L97/005

  Lignin · CPC title

• C07G1/00 Primary

  Low-molecular-weight derivatives of lignin (high-molecular-weight derivatives of lignin {C08H6/00}) · CPC title