Efficient hydrogenolysis of lignin over CeO2/AC catalyst prepared by a simple impregnation method

Abstract

There are limited renewable sources of aromatic chemicals, with lignin being one of the most prominent, accounting for approximately 30% of the planet's organic carbon. Due to its intricate and irregular structure, lignin is recalcitrant to chemical conversion, often resulting in low yields of mixtures of products when it is depolymerized. This study synthesized a CeO2/AC catalyst via an impregnation technique and then explored its ability to depolymerize lignin via an oxidation-reduction strategy. The CeO2/AC catalyst efficiently depolymerized lignin by an oxidation-reduction strategy. At 200 °C, an argon pressure of 1 MPa, and a reaction time of 4 h, the conversion of the lignin model compound reached 98.5%. When using lignin derived from poplar, birch, pine, and cotton stalk, the total yields of phenolic monomers were 36.2 wt.%, 31.2 wt.%, 17.4 wt.%, and 12.1 wt.%, respectively. The CeO2/AC catalyst exhibited a higher surface oxygen vacancy concentration than CeO2, which was crucial for facilitating the hydrogenolysis of lignin.