Direct Dehydrogenation of n-Butane Over Platinum-Tin Catalysts Supported on Alumina

Al2O3 supports prepared by a sol-gel method were calcined at various temperatures. Pt/Sn/Al2O3 catalysts were then prepared by a sequential impregnation method, and they were applied to the direct dehydrogenation of n-butane to n-butenes and 1,3-butadiene. The effect of calcination temperature of alumina on the catalytic performance of Pt/Sn/Al2O3 catalysts in the direct dehydrogenation of n-butane was investigated. Physicochemical properties of Pt/Sn/Al2O3 catalysts were strongly influenced by the calcination temperature of alumina. It was found that platinum surface area and acidity of Pt/Sn/Al2O3 catalysts decreased with increasing calcination temperature of alumina. In the dehydrogenation of n-butane, platinum surface area and acidity of Pt/Sn/Al2O3 catalysts were closely related to conversion of n-butane and selectivity for total dehydrogenation products (TDP, n-butenes and 1,3-butadiene), respectively. Conversion of n-butane decreased with decreasing platinum surface area of the catalyst and selectivity for TDP decreased with increasing acidity of the catalyst. Among the catalysts tested, Pt/Sn/Al2O3-700 (a platinum-tin catalyst supported on alumina that had been calcined at 700 degrees C) showed the best catalytic performance in terms of yield for TDP.