Lignin Depolymerization in Hydrogen-Donor Solvents

Summary The conversion of different types of lignin to monophenolic compounds has been studied between 500 and 650 K, under typical coal liquefaction conditions using 9,10-dihydroanthracene (AnH 2 ) and 7 H -benz[ de ]anthracene (BzH) as the hydrogen-donor solvents. The yield of phenolic compounds was found to increase with the capacity of the hydrogen donor. The application of a polar cosolvent appeared to be beneficial as well. The differences in product distribution could be related to the origin of lignin. The maximum yield amounted to 11 % after 4 h at 625 K using milled wood lignin in AnH 2 . It has been found that lignin itself is a hydrogen-donating substance and capable of cleaving aromatic ketones such as α-phenoxyacetophenone.