纳米TiO_2-SiO_2复合氧化物的制备与性质

Preparation and Properties of the Nanometer Composite Oxide TiO_2-SiO_2

采用溶胶 -凝胶结合 CO2 超临界干燥方法制备了比表面积大、热稳定性好的纳米 Ti O2 -Si O2 复合氧化物 .考察了原料组成和焙烧温度对复合氧化物比表面积、热稳定性和酸性的影响 ,通过加氢脱硫反应考察了该复合氧化物作为加氢精制催化剂载体的可行性 .结果表明 ,采用该方法制备的复合氧化物为纳米颗粒 ,在n(Ti) /n(Si) =1时 ,其比表面积和孔容最大 ;与纯 Ti O2 相比 ,引入 Si O2 明显提高了复合氧化物的热稳定性和晶型稳定性 ;以此复合氧化物为载体的加氢精制催化剂具有很好的低温脱硫活性 ,Ti O2 -Si O2 复合氧化物载体的酸性特征影响了催化剂的加氢脱硫活性 .

In this paper, the nanometer TiO 2-SiO 2 composite oxide, which has a higher surface area and better thermal stability, was prepared by sol-gel and supercritical CO 2 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 TiO 2, the addition of SiO 2 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 TiO 2-SiO 2 support has influence on the HDS activity of the catalyst.