ZnSO_4/Al_2O_3催化剂上异丁烯齐聚反应的研究

Study on the properties and catalytic performance of ZnSO_4/Al_2O_3 catalyst for isobutene oligomerization

利用等体积浸渍法制备负载型ZnSO_4/Al_2O_3催化剂并用于异丁烯齐聚催化反应研究,采用XRD、NH_3-TPD、Py-IR、N_2吸附-脱附、SEM等表征方法对催化剂进行表征,考察了催化剂的焙烧温度、硫酸盐负载量对催化剂的表面酸性、催化反应活性及产物分布的影响。实验结果表明,在Al_2O_3载体表面,当ZnSO_4负载量低于15%(w)时具有良好的分散度,表面酸中心主要是以L酸为主,B酸数量较少,且B酸中心数量随着焙烧温度降低而逐渐减少;当焙烧温度低于350℃时,催化剂表面B酸中心消失,较高的硫酸盐分散度和L酸中心数量有利于提高催化活性和二聚体产物的选择性。

Supported ZnSO4/Al2O3 catalyst was prepared by equivalent-volume impregnation, and it was tested in the oligomerization reaction of isobutene. The catalysts were characterized by XRD,NH3-TPD,Py-IR,N2 adsorption-desorption and SEM. The influences of calcination temperatures of the catalysts and ZnSO4 loadings on surface acidity,catalytic reaction activity and product distributions of the catalysts were studied. It was found that crystalline grain of ZnSO4 was highly dispersed on Al2O3 surface with the presence of L acid and a small number of B acid when ZnSO4 loadings were below 15%(w). The amounts of B acid decreased with the decreasing calcination temperature of the catalysts and it vanished at a temperature below 350 ℃. The results indicated that the highly dispersed ZnSO4 and L acid are in favour of catalytic activity and C8^= selectivity.