Catalytic hydrogenolysis of organosolv lignin: cleaving C–O bonds over CuMgAlOx-layered porous metal oxide catalysts for oriented monophenols production

Abstract

To understand the catalytic conversion of lignin into high-value products, lignin depolymerization was performed using a layered polymetallic oxide (CuMgAlOx) catalyst. The effects of the conversion temperature, hydrogen pressure, and reaction time were studied, and the ability of CuMgAlOx to break the C–O bond was evaluated. The CuMgAlOx (Mg/Al=3:1) catalyst contained acidic sites and had a relatively homogeneous elemental distribution with a high pore size and specific surface area. The β-O-4 was almost completely converted by disassociating the C–O bond, resulting in yields of 14.74% ethylbenzene, 47.58% α-methylphenyl ethanol, and 36.43% phenol. The highest yield of lignin-derived monophenols was 85.16% under reaction conditions of 280 °C and 3 Mpa for 4h. As the reaction progressed, depolymerization and condensation reactions occurred simultaneously. Higher temperatures (>280 °C) and pressures (>3 Mpa) tended to produce solid char. This study establishes guidelines for the high-value application of industrial lignin in the catalytic conversion of polymetallic oxides.