Enhanced catalytic activity on the naphtalene hydrogenation reaction over Pt-Pd/Al₂O3-CeO₂ catalysts

Alumina (Al2O3) and Alumina-Ceria (Al2O3-CeO2) supports with different CeO2 loadings (0, 2, 5, 10 and 50 wt.%) were prepared by the sol-gel method and impregnated with 0.5% of Pt and 0.5 % of Pd (wt.%). The catalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy (DRS), and scanning electron microscopy (SEM). The present work aims to study the influence of the ceria content over the catalytic activity of Pt-Pd/Al2O3-CeO2 samples during the naphthalene hydrogenation reaction. The cerium oxide content increases, the intensity of the diffraction peaks corresponding to this oxide also increases due to the high crystallinity of the ceria. At low CeO2 contents, a shift of the peaks towards lower angles is observed, suggesting an incorporation of Al2O3 into the CeO2 lattice. Raman analyzes show a single band around 440 cm-1 attributed to the formation of ceria. The aggregation of the ceria in the support also results in a decrease in the BET area of these materials. This enhancement in the catalytic performance was related to a supplementary contribution from naphthalene adsorbed on acidic sites on the support and reacting with hydrogen migrating from platinum and palladium surface by a spillover effect.

Keywords: naphthalene hydrogenation, Al2O3-CeO2 supports, metal-support interactions, acid sites.