Acidic site and support decoupling bifunctional catalyst Ni-HSiW/h-BN for hydrodeoxygenation of 4-ethylphenol into aviation fuel ethylcyclohexane

Catalytic hydrodeoxygenation (HDO) is a promising strategy for upgrading phenolic bio-oil into cycloalkanes. Conventional catalysts often rely on strongly acidic supports, which tend to suffer from rapid deactivation. In this study, 4-ethylphenol was selected as a model compound derived from lignin bio-oil to investigate the effects of active sites on an inert support during the hydrogenation and deoxygenation of the phenolic group. Acid-site–support decoupling catalysts, denoted as Ni-HSiW/h-BN, were successfully prepared and were applied in the HDO of 4-ethylphenol to produce ethylcyclohexane. Using 0.5 g of 4-ethylphenol as the substrate and n-dodecane (30 mL) as solvent, the optimal reaction conditions were identified as a temperature of 300 °C, a reaction time of 3 h and the use of 15% Ni-HSiW 0.25 /h-BN catalyst. Under these conditions, complete conversion of 4-ethylphenol was achieved with 100% selectivity toward ethylcyclohexane. When the temperature was lowered to 180 °C and the reaction time reduced to 1 h using 15% Ni/h-BN, the main product shifted to ethylcyclohexanol with a selectivity of 94.4%. A reaction mechanism was proposed, indicating that the combination of Ni and HSiW synergistically enhances HDO efficiency.