Al_2O_3/WO_3/ZrO_2固体强酸催化剂对正丁烷异构化的催化性能

Catalytic Activity of Al_2O_3/WO_3/ZrO_2 Strong Solid Acid Catalyst for n-Butane Isomerization

通过沉淀、回流、浸渍和焙烧等步骤制备了Al2 O3 /WO3 /ZrO2 固体强酸催化剂 .采用XRD ,N2 吸附 ,UV Vis光谱 ,NH3 TPD和H2 TPR等技术测定了Al2 O3 对WO3 /ZrO2 催化剂的结构、表面酸性、氧化还原性及正丁烷异构化反应性能的影响 .结果表明 ,在WO3 /ZrO2 中引入适量的Al2 O3 对其表面酸强度及酸量无显著影响 ,但可使催化剂中的ZrO2 组分以稳定的四方相形式存在 ,并能有效地抑制催化剂中WO3 的聚集长大 ,从而提高催化剂的稳定性和正丁烷异构化的转化率和选择性 .添加铂于Al2 O3 /WO3 /ZrO2 中可进一步提高其催化性能 .还考察了催化剂的焙烧温度、Al含量。

A series of Al 2O 3/WO 3/ZrO 2(AWZ) strong solid acid catalysts were prepared via precipitation, refluxing, impregnation and calcination. The effects of Al 2O 3 on the structural, acidic and redox features of WO 3/ZrO 2 (WZ) were investigated by X ray powder diffraction, N 2 adsorption, UV visible diffuse reflectance spectroscopy, NH 3 temperature programmed desorption and H 2 temperature programmed reduction. The results showed that Al 2O 3 doping on tungstated zirconia made the zirconia tetragonal phase stable, prevented the growth of WO 3 particles and had less effect on the acid site strength. The n butane isomerization was performed in a fixed bed flow reactor. In comparison with WZ, AWZ improved the isomerization conversion and the catalyst stability in the presence of hydrogen. The optimum Al loading in these catalysts was around 0 5% and calcination temperature was 850 ℃. The reaction results indicated that H 2 was essential for the satisfied performance of the catalysts. Pt/AWZ showed higher selectivity and stability than AWZ.