Abstract:

A series of TiO2-SiO2 composite oxides, with different Ti/Si atomic ratios, were obtained by using the sol-gel method combined with the CO2 supercritical fluid drying (SCFD) method. The effects of the Ti/Si atomic ratio and calcination temperature on the properties of TiO2-SiO2 composite oxides, including specific surface area, pore structure, acidity and atomic coordination, were studied. The hydrodesulfurization(HDS) property of catalysts supported on TS-1 and TS-4 was investigated by using the residual fluid catalytic cracking(RFCC) diesel oil as feedstock. The experimental results showed that the pore structure stability and crystalline state stability of TiO2 modified by SiO2 increased dramatically. The acidity and interaction between the atoms of the TiO2-SiO2 varied with Ti/Si atomic ratio. The crystalline state and acidity of supports influenced the HDS property of catalysts. The presence of anatase TiO2 in the TiO2-SiO2, strengthened the interaction of the supports and active metals, and enhanced the HDS activity of the catalysts. The different acidic sites of catalysts showed different HDS properties to different type of sulfur compounds. The catalysts with a larger number of Bronsted acidic sites showed better HDS performance for the simple structure sulfur compounds. On the contrary, the catalysts with a larger number of Lewis acidic sites showed better HDS performance for the complicated structure sulfur compounds.