Rational design of glucose-assisted hydrothermal Co-Ni-Al catalysts for the selective hydrodeoxygenation of vanillin to 4-methylcyclohexanol

FJH prepared carbon-coated Co-Ni-Al LDH catalysts and suppressed metal sintering. • Co 1 Ni 2 Al-850 catalyst afforded 100% vanillin conversion and 94.3% MCH yield in isopropanol solvent. • Ni species activated isopropanol to produce active hydrogen, while oxophilic Co promoted the cleavage of C-O bonds. • The Co 1 Ni 2 Al-850 catalyst effectively converted various lignin model compounds under mild conditions. Hydrodeoxygenation (HDO) is a key process for upgrading lignin derived bio-oil to high-quality fuels and chemicals. In this study, Co x Ni y Al-T catalysts with varying Co/Ni molar ratios and calcination temperatures were fabricated through flash Joule heating assisted carbon coating, with layered double hydroxides (LDHs) adopted as precursors. These catalysts were used for the hydrodeoxygenation of vanillin to 4-methylcyclohexanol (MCH). Under the optimized reaction conditions (180 °C, 2.5 h, 1 MPa N 2 ) with isopropanol serving as both hydrogen donor and solvent, the Co 1 Ni 2 Al-850 catalyst achieved nearly 100% vanillin conversion and a 94.3% yield of MCH. Based on various characterization results, Co 1 Ni 2 Al-850 catalysts exhibited suitable specific surface area, pore structure and acid sites. The excellent performance of Co 1 Ni 2 Al-850 catalyst was also attributed to the Co-Ni synergistic effect: Ni species accelerated the activation and dissociation of isopropanol to supply sufficient active hydrogen species for HDO; Co species promoted removal of methoxy groups in MMP. In addition, the presence of Al enhanced the structural stability. Based on the product distribution and characterization results, the possible reaction mechanism of the catalytic system was proposed. This study provides a new way for the development of efficient non noble metal catalysts for the hydrodeoxygenation system of biomass derivatives.