Hydrogenolysis of lignin with endogenous hydrogen from aqueous phase reforming of methanol

Catalytic hydrogenolysis of the renewable aromatic polymer of lignin to value-added fine chemicals without external molecular hydrogen is of great significance. In this work, catalytic conversion of lignin with in situ H 2 produced from the aqueous phase reforming (APR) of methanol is studied in the presence of ZnO-modified Pd/AC (Pd-Zn/AC). 259.8 mg g -1 yield of monophenols is obtained when the lignin depolymerization is catalyzed by Pd-Zn/AC-10 in a methanol aqueous solution ( V C H 3 OH / V H 2 O =9/1) at 250 °C for 4 h. Extensive analysis showed that this effective process should be attributed to the synergistic effect between Pd-Zn alloy and the metallic Pd, which promote the H 2 production from the APR of methanol and the hydrogenolysis of lignin, respectively. Moreover, a plausible pathway for selective hydrogenolysis of lignin is proposed based on the comparative characterization of the raw lignin, residual lignin, and the transformation behavior of lignin model compounds. • Cascade process of methanol APR and lignin hydrogenolysis was constructed. • 259.8 mg g -1 yield of monophenols was achieved. • Pd-Zn alloy promoted methanol APR, metallic Pd enhanced lignin hydrogenolysis. • Pd-Zn/AC-10 catalyzed the direct cleavage of β-O-4 bond.