TiO_2-Al_2O_3复合载体的制备条件对选择加氢反应的影响

EFFECT OF PREPARATION CONDITIONS OF TiO_2-Al_2O_3 COMPLEX SUPPORT ON SELECTIVE HYDROGENATION PERFORMANCE

采用改进的溶胶-凝胶法制备了TiO2-Al2O3复合载体,研究了该复合载体对负载Ni、Mo制成的NiMo/TiO2-Al2O3催化剂选择加氢性能的影响;考察了复合载体的制备条件对催化剂性能的影响。结果表明,复合载体的最优制备条件为:模板剂与硝酸铝及模板剂与钛酸丁酯摩尔比均为0.5,将钛溶胶缓慢滴加到Al2O3和水的混合物中,n(TiO2)∶n(Al2O3)=0.25,滴定终点pH值为3.5。采用小型固定床反应器,以催化裂化轻汽油为原料,对制备的NiMo/TiO2-Al2O3催化剂进行评价,在反应温度140℃、氢分压2MPa、体积空速3 h-1、氢油体积比35∶1的条件下,二烯烃转化率大于99%,单烯烃转化率小于5%。

TiO2-Al2O3 complex support was prepared by a modified sol-gel method, and the effect of the preparation conditions on the selective hydrogenation of NiMo/TiO2-Al2O3 catalyst prepared by said complex support was investigated. The test results showed that the optimum preparation conditions of TiO2-Al2O3 complex support were the mole ratios of template to aluminum and to titanium of both 0.5 ; the titanium sol was added slowly to the mixture of alumina and water at a TiO2/Al2O3 mole ratio of 0.25 and with a titration terminal pH of 3.5. A NiMo/TiO2-Al2O3 catalyst was prepared using the above complex support and selective hydrogenation test was carried out in a small fixed bed reactor using light FCC cracked naphtha as feedstock under the conditions of a reaction temperature of 140 ℃ ,a hydrogen partial pressure of 2 MPa,VHSV of 3 h^-1 and a hydrogen to oil volume ratio of 35. The results showed that the conversion of dienes was over 99 % and the conversion of mono-alkene was less than 5%.