共沉淀法制备钛锆复合载体及其在加氢脱硫催化剂中应用的探讨

PREPARATION OF COMPOSITE TITANIUM-ZIRCONIUM OXIDES AND THEIR APPLICATION IN HYDRODESULFURIZATION CATALYST

采用共沉淀法制备了n(TiO2):n(ZrO2)=4:1,3:2,1:1,2:3,1:4的锆钛复合氧化物及单一TiO2、ZrO2氧化物,并用浸渍法制备了10%MoO3/TiO2-ZrO2,10%MoO3/TiO2,10%MoO3/ZrO2催化剂。用X射线衍射、N2吸附方法对催化剂进行表征,在间歇式高压反应釜上进行活性评价。结果表明,550℃煅烧2h后,TiO2-ZrO(21:1),TiO2-ZrO(22:3),TiO2-ZrO(23:2)为无定型,其余载体出现不同程度的结晶。复合氧化物的比表面积均大于单一氧化物,其中TiO2-ZrO(21:1)的比表面积最大(191.20m2/g)。以噻吩的加氢脱硫反应作为模型反应来评价催化剂的活性,结果表明催化剂的活性随着ZrO2在复合载体中含量的增加而呈先升后降的变化趋势,其中10%MoO3/TiO2-ZrO(21:1)的活性最高,单一ZrO2载体催化剂的活性最低。

TiO2, ZrO2 and composite titanium-zirconium oxides with various Ti to Zr molar ratios （4 ：1, 3 ： 2, 1 ： 1,2 ： 3 and 1 ： 4） were prepared by coprecipitation method, and active components （ 10% MoO3） were impregnated on these supports to form relative catalysts. These catalysts were characterized by X-ray diffraction, nitrogen adsorption and their hydrodesulfurization activities were evaluated using a high-pressure reactor. Results showed that after calcination at 550 ℃ for 2 h, TiO2-ZrO2（ 1 ： 1 ）, TiO2-ZrO2（2 ： 3 ） and TiO2-ZrO2（3 ： 2） supports were all amorphous, the other two supports exhibited certain crystallization.In comparison with the single metal oxide, mixed oxides had larger surface areas, among them the surface area of TiO2-ZrO2（ 1 ： 1 ） was the largest （191.2 m^2/g）.Thiophene hydrodesulfurization was taken as the model reaction for evaluating the HDS activities of these catalysts. It was found that HDS activities increased with the increase of zirconia content in mixed oxides and a maximum activity was observed for the 10% MOO3/ TiO2-ZrO2（ 1 ： 1 ） catalyst. With further increase of zirconia content, the catalytic activities decreased and the minimum activity belonged to the catalyst using ZrO2 support.