Depolymerisation of lignin in biomass
A method of obtaining depolymerized lignin from biomass using a transition metal catalyst and a solvent mixture of organic solvent and water. The invention further relates to a composition obtainable by the method and the production of fuel.
1. A method of depolymerizing lignin comprising:
a. Providing biomass in particulate form wherein the biomass contains lignin, a solvent mixture comprising an organic solvent and water, and a transition metal catalyst; wherein the biomass is wood in the form of saw dust or wood chips;
b. Mixing the biomass, the solvent mixture and the transition metal catalyst to obtain a mixture;
c. Heating the mixture to at least 160° C. and depolymerize the lignin at a pressure of not more than 50 bar without adding hydrogen; and
d. Optionally isolating the depolymerized lignin; and
wherein at least 20 weight % of the depolymerized lignin is 2-methoxy-4-(prop-1-enyl)phenol.
2. The method according to claim 1 wherein the transition metal catalyst is based on palladium.
3. The method according to claim 1 wherein the mixture is heated to at least 180° C.
4. The method according to claim 1 wherein the depolymerized lignin has an average molecular weight (M w ) of not more than 1500 g/mol.
5. The method according to claim 4 wherein the lignin has an average molecular weight (Mw) of not more than 1000 g/mol.
6. The method according to claim 1 wherein the mixture is heated for at least 15 minutes.
7. The method according to claim 6 wherein the mixture is heated for at least 1 hour.
8. The method according to claim 1 wherein the organic solvent is an alcohol.
9. The method according to claim 8 wherein the alcohol is methanol or ethanol.
10. The method according to claim 1 wherein the concentration of transition metal catalyst is at least 1 mol % based on the lignin content.
11. The method according to claim 10 wherein the concentration of transition metal catalyst is at least 3 mol %.
12. The method according to claim 1 wherein no added base is used.
13. The method according to claim 1 wherein no formic acid or hydride is added.
14. The method according to claim 1 wherein the depolymerization is conducted in air.
15. The method according to claim 1 wherein the pressure is 35 bar or less.
16. A method of producing one or more compounds having the formula of:
wherein each R1 and R2 is H or OCH 3 and R3 is (CH 2 ) 2 CH 3 , (CH 2 ) 3 OH or (CH) 2 CH 3 comprising:
a. Providing biomass in particulate form wherein the biomass contains lignin, a solvent mixture comprising an organic solvent and water, and a transition metal catalyst; wherein the biomass is wood in the form of saw dust or wood chips;
b. Mixing the biomass, the solvent mixture and the transition metal catalyst to obtain a mixture;
c. Heating the mixture to at least 160° C. and depolymerize the lignin at a pressure of not more than 50 bar without adding hydrogen;
d. Optionally isolating the one or more compounds produced; and
wherein at least 20 wt % of the compounds is (2-methoxy-4-(prop-1-enyl)phenol) R1 is H, R2 is OCH 3 and R3 is (CH) 2 CH 3 .
17. The method according to claim 16 wherein the pressure is 35 bar or less.