制备条件对Co-Mo/TiO_2-Al_2O_3汽油HDS催化剂性能的影响

Effect of preparation conditions on performance of Co-Mo/TiO_2-Al_2O_3 catalysts for FCC gasoline hydrodesulfurization

以蔗糖为辅助剂,采用溶胶-凝胶法制备了介孔氧化铝及相应的Co-Mo/TiO2-Al2O3汽油脱硫催化剂,并对其进行了TEM、XRD和N2吸附表征。以FCC汽油重馏分为原料,重点考察了不同条件下制得的Al2O3对催化剂选择性加氢脱硫性能的影响。结果表明,蔗糖(sucrose)添加量和pH值对Al2O3织构产生影响,进而影响到对应催化剂的加氢脱硫性能;在Al/sucrose摩尔比1∶1、pH值5.4时Al2O3的比表面积最大、孔径分布最窄,对应催化剂的选择性加氢脱硫活性最好;Al2O3的最可几孔径随pH值的增加而增大;溶胶老化温度对Al2O3的比表面积和孔容影响较大,但对最可几孔径和孔径分布影响较小。与Co-Mo/TiO2-sAl2O3(以sAl2O3表示市售Al2O3)催化剂相比,Co-Mo/TiO2-Al2O3催化剂具有较好的选择性加氢脱硫活性,在考察的条件范围内,脱硫率相同时其对应的烯烃饱和度低5%～15%左右。

Mesoporous alumina was prepared by the sol-gel method using sucrose as assistant agent and the corresponding Co-Mo/TiO2z-Al2O3 catalysts were obtained. The samples were characterized by TEM, XRD and N2 adsorption. The effects of A12O3 prepared under different conditions on the selective HDS performance of the catalysts for FCC gasoline heavy fraction hydrodesulfurization were investigated. The results showed that sucrose and pH affected A12O3 structure, which in turn affected the HDS performance of the corresponding catalysts. The A12O3 prepared under the condition A1/sucrose molar ratio 1 ： 1, pH： 5.4 had the largest specific surface area and the narrowest pore size distribution, and the corresponding catalyst exhibited the best HDS activity. The most probable pore size of Al2O3 increased with increasing pH. The aging temperature had significant impact on specific surface area and pore volume, but had little influence on the most probable pore size and pore size distribution. Compared with commercially available Co-Mo/TiO2-Al2O3, the as-prepared Co Mo/TiO2-Al2O3 had a good selective HDS activity. In the range examined, the corresponding saturation of olefins for the Co-Mo/TiO2-A12 Oa catalyst was lower by 5%—15% than that of the counterpart at the same desulfurization rate.