Efficient Method for Kraft Lignin Depolymerization to Phenolic Monomers via Modified Spinel Catalysts

The rational modification and assembly of catalysts with regulable active sites for selective conversion of lignin to phenolic monomers remain challenging. In this work, a new modified spinel catalyst (NixCo3–xO4–Mo2C) is proposed for the selective production of phenolic monomers from Kraft lignin. The performance of the catalysts is greatly improved by the synergistic effect on Mo2C and NixCo3–xO4 spinel. The NiCo2O4–Mo2C catalyst achieved an outstanding catalytic conversion (up to 86.2 wt %) for the Kraft lignin depolymerization and excellent selective cleavage for phenolic monomers to 34.9 wt %. The characterization of the catalyst shows that Mo2C provided more acidic sites and improved the hydrogenation performance by changing the arrangement of spinel. Additionally, the hydrogenolysis of lignin model compounds further confirmed the outstanding performance of the modified spinel catalysts.