Hydroxide catalysts for lignin depolymerization
View Patent ↗Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.
1. A method for degrading lignin, comprising:
contacting a stream consisting essentially of lignin with a layered double hydroxide (LDH) catalyst in the presence of a liquid solvent to produce a lignin degradation product; and
isolating the lignin degradation product, wherein:
the LDH catalyst comprises hydrotalcite (HTC) and nickel (Ni),
an amount of the Ni combined with the HTC is between 5 wt % Ni/HTC and 15 wt % Ni/HTC, and
the lignin degradation product comprises at least one of an aromatic or an alkane.
2. The method of claim 1 , wherein the liquid solvent comprises at least one of an aqueous solvent or an organic solvent.
3. The method of claim 2 , wherein the liquid solvent is methyl isobutyl ketone.
4. The method of claim 2 , wherein the liquid solvent is ethanol.
5. The method of claim 2 , wherein the liquid solvent is water.
6. The method of claim 1 , wherein the contacting is carried out at a temperature between 200° C. and 400° C.
7. The method of claim 1 , wherein the contacting is carried out at a temperature of at least 200° C.
8. The method of claim 7 , wherein the contacting is carried out for less than one hour.
9. The method of claim 1 , wherein the contacting is carried out for at least 15 minutes.
10. The method of claim 1 , further comprising removing the LDH catalyst from the liquid solvent by filtration.
11. The method of claim 1 , wherein the nickel is in a form of a water-soluble nickel salt.
12. The method of claim 11 , wherein the water-soluble nickel salt is nickel nitrate.