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

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.