Highly active Mo-V-based bifunctional catalysts for catalytic conversion of lignin dimer model compounds at room temperature

Abstract

A novel strategy was proposed for the cleavage of COC bonds in β-O-4 lignin substrate. 2-(2′-methoxyphenoxyl)-1-phenylethanol was used as a lignin dimer model compound with a β-O-4 ether linkage and a hydroxyl group on α-C position. Mo-V-based bifunctional catalysts have been developed to selectively catalyze the oxidation of Cα-OH and depolymerize β-O-4 dimers under mild reaction conditions. In addition, the catalysts were characterized by XRD, SEM, TPR, NH3-TPD and N2 adsorption. At room temperature, the conversion of dimer reached up to 89% within 4 h. Based on the analysis of HPLC-MS results, a two-step oxidation-cleavage pathway for lignin depolymerization was proposed. In the catalytic reaction process, the Cα-OH in the lignin dimer was first oxidized to obtain Cα ketone, and then the Cα ketone intermediate was further catalyzed to break the β-O-4 bond. In the study, aromatic monomer compounds were obtained under the Mo-V-based bifunctional catalysts.