Abstract: A series of metal-acid bifunctional catalysts were prepared by impregnation of Pt on γ-Al₂O₃/Y zeolite composite support with controlled Pt loading location and concentration, and their catalytic performance was evaluated in the isomerization of endo-tetrahydrodicyclopentadiene (Endo-THDCPD) to exo-tetrahydrodicyclopentadiene (Exo-THDCPD). The physicochemical properties of the catalysts were characterized by X-ray diffraction, transmission electron microscopy, N₂ adsorption-desorption,CO adsorption infrared spectroscopy, pyridine adsorption infrared spectroscopy, and temperature-programmed desorption of ammonia. The results show that Pt loading location does not significantly affect Pt dispersion, catalyst acidity, or pore structure. When Pt is loaded on Y zeolite, the metal-acid contact distance is short, resulting in high Endo-THDCPD conversion but low Exo-THDCPD selectivity; when Pt is loaded on γ-Al₂O₃, the metal-acid contact distance is moderate, giving slightly lower Endo-THDCPD conversion but higher Exo-THDCPD selectivity. The matching of metal-acid concentrations also influences the catalytic performance. At a metal-acid concentration ratio (CPt/CA) of 0.0084, the highest Exo-THDCPD selectivity of 95.10% is achieved.

Key words: composite support, Y zeolite, Pt loading, isomerization, Endo-THDCPD, Exo-THDCPD