TiO2-SiO2复合氧化物载体及其加氢脱硫催化剂

分别采用溶胶-凝胶法和共沉淀法制备了TiO2-SiO2复合氧化物,并以此复合氧化物为载体制备了加氢脱硫催化剂.采用氮气恒温吸附脱附、X射线衍射、傅立叶变换红外光谱(FT-IR)和NH3程序升温脱附实验(NH3-TPD)对TiO2-SiO2复合氧化物及其催化剂进行表征,并考察催化剂的加氢脱硫性能.结果表明,TiO2经SiO2复合改性后,其热稳定性和晶相稳定性得到了提高.溶胶-凝胶法与共沉淀法相比,能使Ti物种和Si物种混合得更均匀,从而有利于制得具有较大比表面积和孔容的TiO2-SiO2复合氧化物.Ti含量增加,复合氧化物中Ti的分散度会降低.TiO2-SiO2复合氧化物中以Lewis酸中心为主,共沉淀法制备的复合氧化物比溶胶-凝胶法制备的复合氧化物具有更多的酸性中心.具有较大比表面积和较高酸性的催化剂对模型化合物噻吩和锦西重油催化裂化柴油的加氢脱硫性能较高.

Titania-Silica Composite Oxide Supports and Hydrodesulfurization Catalysts

The titania-silica composite oxides were prepared by sol-gel method and co-precipitation method, respectively, and the hydrodesulfurization (HDS) catalysts supported on the titania-silica composite oxides were obtained. The titania-silica composite oxides and the catalysts were characterized by means of N2-isothermal adsorption and desorption, X-ray diffraction (XRD), pyridine adsorption in-situ Fourier transformed infrared spectroscopy(FT-IR) and temperature-programmed desorption (NH3-TPD),and HDS performance of catalysts prepared by different methods were investigated.The results indicated that the crystalline state stability and thermal stabilty of TiO2 modified by SiO2 were improved. The sol-gel method was better than the co-precipitation method to promote homogeneity of Ti species and Si species and more suitable to prepare titania-silica composite oxides with larger specific surface area and pore volume.With the increase of Ti content, the Ti dispersion in the composite oxides decreased. The Lewis acid sites were the dominating acid sites of the composite oxides and the composite oxides prepared by co-precipitation method had more acid sites than that prepared by sol-gel method. The catalysts with larger specific surface area and more acid sites had higher HDS performance for thiophene and Jinxi residual fluid catalytic cracking diesel.