Highly Efficient Conversion of Lignin into Diethyl Maleate Catalyzed by Molybdenum-Based Hybrid Catalysts

The direct oxidative depolymerization of lignin, a natural aromatic heteropolymer, poses a significant challenge due to its intricate structure and interconnected cross-linked linkages. In this study, a cost-effective MoS 2 –MoC@NC 800 catalyst is developed and employed in the catalytic oxidative depolymerization of bamboo lignin by using ethanol as a solvent. Experimental results demonstrated that, at a moderate temperature of 150 °C over 3 h, 86.6% of bamboo lignin was transformed, producing 1374.2 mg g –1 of small-molecule esters, including 564.8 mg g –1 of diethyl maleate. The superior catalytic properties of the MoS 2 –MoC@NC 800 catalyst are attributed to the synergistic catalytic effects of α-MoC and MoS 2, which enabled the direct catalysis and ring opening of the aromatic rings in lignin and subsequent esterification with ethanol to generate small-molecule ester products. The detailed characterizations and control experiments reinforced these findings. This study offers promising opportunities for the utilization of green and sustainable lignin resources in the production of high-value small-molecule chemicals.