Highly efficient hydrodeoxygenation of lignin-derived vanillin over CoN/C catalysts with isopropanol

As the richest renewable aromatic biomass in the world, lignin and its catalytic depolymerization products exhibit significant application potential and strategic value in the areas of energy, chemical industry, materials and environmental science. In this work, three catalysts (NiN/C, CoN/C, and CoNiN/C) were prepared using one-pot impregnation-pyrolysis and tested for the catalytic hydrodeoxygenation (HDO) of vanillin (VAN) to produce 2-methoxy-4-methylphenol (MMP), a valuable chemical intermediate for pharmaceutical or fuel applications. Among the three catalysts, CoN/C exhibited excellent catalytic performance and remarkable stability. Experimental results demonstrated that 30 mg of CoN/C achieved highly efficient conversion of VAN under the optimal reaction conditions (240 °C, 1.5 MPa H 2 , 15 mL isopropanol, 4 h), affording a VAN conversion of 99.94% and an MMP selectivity of 96.15%. Characterization results further confirm that the CoN/C catalyst exhibited a large surface area, developed mesoporosity, and rich Lewis acid sites. These features work together to promote its catalytic activity and benefit the HDO of VAN. Further density functional theory (DFT) calculations reveal that the CoN/C catalyst exhibits a moderate adsorption energy of −1.04 eV. This work provides a meaningful route to simple, eco-friendly, and highly active metal catalysts, and offers a reference for lignin conversion into high-value chemicals.