Abstract: In this paper, the nanometer TiO₂-SiO₂ composite oxide, which has a higher surface area and better thermal stability, was prepared by sol-gel and supercritical CO₂ fluid drying method. The effects of feed composition and calcinations temperature on the specific surface area, thermal stability and acidity of the composite oxide were examined. Through hydrodesulfurization(HDS) reactions, the feasibility of the composite oxide as the support of hydrofining catalyst was also examined. The results indicate that nanometer particles of the composite oxide were obtained. When n(Ti)/n(Si) ratio was equal to 1, the specific surface area and pore volume of the composite oxide were maximum. Compared with pure TiO₂, the addition of SiO₂ obviously improved the thermal stability and crystal stability of the composite oxide. The source of producing Brnsted acid sites was Ti-O-Si bonds, coming from the composite oxide. That the surface of the composite oxide was rich in Ti was conducive to improve the intensity of Lewis acid. The hydrofining catalyst supported on this composite oxide had a better HDS activity at a low temperature. The acidic characteristics of TiO₂-SiO₂ support has influence on the HDS activity of the catalyst.

Key words: Supercritical fluid drying, Sol-gel method, TiO₂-SiO₂, Hydrogenation catalyst