Al_2O_3-TiO_2复合载体用于乙炔选择加氢反应

采用共沉淀法制备了A l2O3-T iO2复合载体(简称复合载体),研究了该复合载体负载Pd后制备的Pd/A l2O3-T iO2催化剂在乙炔选择加氢反应中的催化性能。考察了复合载体合成条件(复合载体中T iO2的含量、中和反应温度、沉淀终点pH、A lC l3的质量浓度、沉淀物老化时间)对Pd/A l2O3-T iO2催化剂活性和选择性的影响。实验结果表明,复合载体的最佳合成条件为:T iO2质量分数30%,中和反应温度40℃,沉淀终点pH=9,A lC l3的质量浓度0.20g/mL,沉淀物不老化。采用最佳条件下合成的复合载体所制备的Pd/A l2O3-T iO2催化剂(Cat-02)的选择性大于85%,乙炔转化率达到90%以上,优于Pd/A l2O3催化剂。与工业催化剂G-58C相比,Cat-02在活性上还有一定差距,但具有更好的选择性。

Al2O3-TiO2 Support for Pd Catalyst Used in Acetylene Selective Hydrogenation

Al_2O_3-TiO_2 complex supports for Pd catalyst were prepared by co-precipitation.The performance of catalyst in selective hydrogenation of acetylene was studied.Effects of preparation conditions of support,namely TiO_2 content,neutralization temperature,precipitation terminal pH,mass concentration of AlCl_3 and aging time of precipitation,on catalytic performance were investigated.Optimal conditions for support preparation were:TiO_2 mass fraction 30%,neutralization temperature(40℃,)precipitation terminal pH 9,mass concentration of AlCl_3 0.20g/mL,and precipitation without aging time.Activity and selectivity of Pd/Al_2O_3-TiO_2 catalyst(named Cat-02)with support prepared under optimal conditions were higher than those of conventional Pd/Al_2O_3 catalysts.Selectivity of(Cat-02) were even higher than that of industrial catalyst G-58C.Under following conditions in micro-reactor:mole fraction of C_2H_2 0.25%,n(H_2) ∶n(C_2H_2)1.36,gas hourly space velocity(GHSV)(10 000)h~(-1) and 0.2MPa,conversion of acetylene and selectivity of ethylene on Cat-02 could reach more than 90% and more than 85%,respectively.