Depolymerization of lignin by catalytic oxidation with aqueous polyoxometalates

Abstract In this work a method for the depolymerization of lignin by catalytic oxidation was studied. Using H 5 PMo 10 V 2 O 40 as the catalyst, various lignin spices including pyrolytic lignin, hydrolytic lignin, alkali lignin, sodium lignosulfonate and calcium lignosulfonate were tested for the oxidative degradation. The influence of reaction conditions, i.e. reaction temperature, solvent, reaction time, initial O 2 pressure and catalyst concentration were investigated. Under optimized conditions, the highest yield of 65.21% of the oxidative degradation products was achieved from pyrolytic lignin, and the main products were aromatic compounds and dimethyl succinate. Moreover, the H 5 PMo 10 V 2 O 40 catalyst was recycled for five times without significant deactivation.