Abstract: The SiO₂-Al₂O₃ carriers with different SiO₂ contents were prepared by using the amorphous aluminosilicate with mass fraction of 40% SiO₂ and aluminum hydroxide gel as raw materials, and Pt-Pd/SiO₂-Al₂O₃ catalysts were prepared by equal volume impregnation method with chloroplatinic acid and palladium chloride as precursors of Pt and Pd. The prepared catalyst was characterized by N₂ adsorption-desorption, XRD, TPD, metallographic microscope, TEM and other methods. On a 10 mL fixed bed hydrogenation unit, the hydrogenation activity of the catalyst was evaluated with the model compound containing 2% tetralin + 10% decalin + 88% isooctane as the raw material. The results showed that the specific surface of the catalysts increased with the increase of SiO₂ content in the range of 20%-40%, the crystal phase composition remained unchanged, the amount of B acid and medium acid increased but L acid declined.The dispersion of Pt-Pd on SiO₂-Al₂O₃ carriers was gradually changed from eggshell type to homogeneous type,the degree of dispersion increased, and the hydrogenation activity of tetralin increased. With the increase of the concentration of hydrochloric acid in the impregnation solution, the dispersion of the catalyst first increased and then decreased. The Pt-Pd/SiO₂-Al₂O₃ active component had the best dispersion at the concentration of 0.1 mol/L hydrochloric acid, and the tetralin hydrogenation activity of the catalyst was the highest.

Key words: Pt-Pd catalyst, amorphous silica-alumina, aromatic hydrogenation, SiO₂ content, impregnating solution