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 (CuMgAlO_x) catalyst. The effects of the conversion temperature, hydrogen pressure, and reaction time were studied, and the ability of CuMgAlO_x to break the C–O bond was evaluated. The CuMgAlO_x (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 4 h. As the reaction progressed, depolymerization and condensation reactions occurred simultaneously. Higher temperatures (> 280 ℃) 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.