Superior Catalytic Performance of Si-Modified Al2O3 Nanosheets Supported PtPd Alloy in Selective Hydrogenation of Naphthalene

The construction of advanced catalysts with well-defined structural properties is crucial for the selective hydrogenation of polyaromatic hydrocarbons in modern fossil fuel upgrading. In this work, a PtPd alloy catalyst supported on Si-modified Al2O3 nanosheet (Pt-Pd/A-Si-12) is synthesized, which exhibits three key structural advantages: a high specific surface area (422 m2 g–1), a large pore volume (0.8 cm3 g–1), and a surface enriched with finely modulated weak acid sites. Systematic characterization reveals that the hierarchical porous structure not only promotes uniform dispersion of active metal species but also facilitates mass transfer of macromolecular reactants, leading to a diffusion rate 1.47 times that of the unmodified Pt-Pd/A-Si-0 catalyst. Moreover, the tailored weak acid sites play a dual role: enhancing the metal–support interaction through electronic effects while concurrently creating a highly selective hydrogenation environment. As a result, the Pt-Pd/A-Si-12 catalyst achieves nearly complete conversion (∼100%) and a selectivity up to 93% under 250 °C and 5 MPa H2, along with significantly improved stability and high sulfur resistance. This study provides fundamental insights into the structure–performance relationship in selective hydrogenation and offers an effective strategy for the design of efficient industrial catalysts.