Bimetallic Pt-Pd nanoparticles on hierarchical core-shell zeolite for deep hydrogenation of naphthalene

Abstract

A hierarchical core-shell structured catalyst was designed to address the mass transfer limitations and low selectivity of noble metal catalysts in the deep hydrogenation of polycyclic aromatic hydrocarbons (PAHs). The modified support was subsequently functionalized with Pt-Pd bimetallic nanoparticles through incipient wetness impregnation to construct a high-performance naphthalene hydrogenation catalyst. Characterization revealed that mesopores (6–11 nm) were created by the alkaline treatment, while the original microporous structure was retained, resulting in enhanced mass transfer efficiency. The distribution of acidic sites was effectively modulated through the desilication process. Uniform Pt-Pd alloy nanoparticles (3–5 nm) were shown to exhibit strong electronic synergy, as evidenced by a 0.3 eV positive shift in the Pd 3d binding energy, which improved hydrogen activation. The 0.75 wt% Pt-Pd/H-Beta-73 catalyst achieved 99 % naphthalene conversion with 68.6 % decalin selectivity at 240 °C, representing a significant improvement over monometallic catalysts. The hierarchical pore structure facilitated both reactant diffusion and accessibility to acidic sites, while the interaction between Pt-Pd alloys and Brønsted acid sites promoted deep hydrogenation via hydrogen spillover and substrate adsorption. This research introduces a “mesopores-acid-metal” optimization strategy, providing new insights into the development of advanced catalytic systems for converting polycyclic aromatics into high-value chemicals.