Hydrogenolysis and hydrodeoxygenation of lignin in a two-step process to produce hydrocarbons and alkylphenols

Abstract

Valuable fuels and chemicals production from biomass with high yields is always a big challenge in the energy utilization field. Herein, a two-step process for the catalytic conversion of lignin was proposed to form the fuels. In the first step, the depolymerization of lignin occurred efficiently via the hydrogenolysis reaction, resulting in 19.2% aromatic monomers under the catalysis of Pd/C and CrCl3. The catalysts exhibited a synergistic effect on the cleavage of β-O-4 bonds and the hydrogenation procedure, which prevented the condensation of intermediate products remarkably. Afterwards, the aromatic monomers were extracted out with octane solvent successfully (extraction degree 89.7%) and then used as a substrate in a second hydrodeoxygenation (HDO) step. Product mixture composed of 26.5% hydrocarbons (increased from 5.5%) and 49.7% alkylphenols (increased from 42.9%) were obtained after the HDO upgrading, which exhibited high potential to be used as fuels. This two-step approach is very promising to be a practical chemical engineering process for the fuel production from lignin.