N-doped biochar supported Ni-Co alloy catalyst for efficient hydrocracking of enzymatic hydrolysis lignin to monophenols in water

During the fermentation of straw to produce bioethanol, enzymatic hydrolysis lignin (EHL) is generated in significant quantities, which retains the original structure of lignin and thus exhibits a great potential for the production of monophenols. Herein, we fabricated a highly dispersed Ni-Co alloy catalyst loaded on N-doped biochar (10Ni-3Co/NAC) by a deposition precipitation method, which could completely convert α-O-4, β-O-4, and 4-O-5 lignin model compounds into monomers under mild conditions. 10Ni-3Co/NAC significantly catalyzed the hydrocracking of EHL in water at 220 °C under 3 MPa of initial hydrogen pressure for 8h, achieving a total monophenol yield of 42.8 wt% and a high 2,6-dimethoxy-4-propylphenol proportion (48.5 %). The study results suggest that 10Ni-3Co/NAC possesses high adsorption and activation capacity for oxygen-containing substrates, and the interspecies electron transfer within Ni-Co alloys in 10Ni-3Co/NAC facilitates the formation of dissociated active hydrogen, which attacks the C-O group in EHL leading in the highly selective cleavage of the C-O bond to produce monophenols.