Selective production of phenolic monomers via high efficient lignin depolymerization with a carbon based nickel-iron-molybdenum carbide catalyst under mild conditions

• Formation of β-Mo 2 C promoted by Ni-Fe metals favors for lignin depolymerization. • Synergistic effect between Ni-Fe-Mo 2 C shows high selectivity for monomer phenols. • Maximally 35.53% of monomer phenols from lignin depolymerization was obtained. • Side chain hydrogenolysis ability of the catalyst was controlled by metal decoration. • Water was used as a green solvent with methanol as a co-solvent. Lignin is an abundant renewable source of bio-aromatics and its valorization is of great importance. In this work, an efficient non-precious carbon based metal-Mo 2 C catalytic system for selective production of phenolic monomers (PMs) from organosolv lignin depolymerization is proposed. With the optimized catalyst of Ni-Fe-Mo 2 C, 89.56% of liquefaction and 35.53% of PMs yields were achieved under 260 ℃ for 4 h with water-methanol (4:1 v/v) solvent. Characterization of the catalysts shows that the induction of Ni-Fe species was favor for the formation of β-Mo 2 C, and efficiently promoted the lignin liquefaction. The decoration of Ni/Fe can also change the side chain hydrogenolysis ability of the catalyst and exhibite high yield for 4-ethylphenol (14.77%) production. Methanol, used as co-solvent, was found to play an important role in PMs production and lignin depolymerization. These results demonstrated that the Ni-Fe-Mo 2 C catalytic system has potential to produce valuable phenolic monomers from lignin under mild conditions.