Al-Content-Tuned Ni-Based amorphous Silica-Alumina catalysts for efficient hydrodeoxygenation of lignin phenols under mild conditions

Catalytic hydrodeoxygenation (HDO) serves as a crucial strategy for the valorization of lignin-derived oil into hydrocarbon fuels. Although earth-abundant transition-metal catalysts offer compelling economic advantages, their practical implementation in HDO is constrained by intrinsically inferior activity, necessitating harsh operating conditions. One way to overcome this limitation resides in the rational engineering the support to creating tailored active sites that synergistically couple with the metallic phase, thereby markedly enhancing HDO performance under milder conditions. In this study, nickel-based catalysts supported on amorphous silica-alumina (Ni/ASA) catalysts with tailoring Al content were synthesized. Precise modulation of Al content directly governs catalyst morphology, Ni dispersion, and acid site distribution. Among the series, Ni/ASA-1Al, featuring a large specific surface area, minimal Ni particle size, and maximum density of strong acid sites, exhibited optimal catalytic performance. Under optimized conditions (200 °C, 4 h, 1 MPa H 2 ), complete guaiacol conversion was achieved with a cyclohexane yield of 93.3%. Moreover, Ni/ASA-1Al showed excellent versatility in the HDO of diverse phenolic monomers, dimers, and bio-oil. This work provides fundamental insights into the Al-mediated modulation of ASA-supported catalysts and establishes a scalable strategy for designing cost-effective catalysts for bio-oil upgrading.