Selective hydrogenolysis of lignin and model compounds to monophenols over AuPd/CeO2

The mild depolymerization of lignin into aromatic monomer is a grand challenge owing to the various aryl ether C-O bonds, particularly for the most abundant beta-O-4, alpha-O-4 and 4-O-5 linkages. Rod-shaped CeO2 supported AuPd bimetallic catalysts fabricated by sol-immobilization method presented robust alloy structure, as evidenced by TEM, XPS, UV-vis, and CO-DRIFTS. For the hydrogenolysis of C-O bond model compound with formic acid, Au1Pd1/CeO2 showed about 23.5 and 6 folds increase in activity compared with its monometallic counterparts Au/CeO2 and Pd/CeO2, respectively. The outstanding performance was mainly ascribed to the increased adsorption ability of electron-deficient Pd for aromatic C-O bond. Additionally, formic acid-mediated Au1Pd1/CeO2 has efficiently performed hydrogenolysis of real lignin into a variety of valuable monophenols, achieving 44.1% yield at low temperature.