Effect of reduction method on the activity of Pt–Sn/SiO2 for dehydrogenation of propane

Abstract

The effect of reduction method (direct reduction (DR), decomposition in inert gas (DI) and calcination-reduction (CR)) on the catalytic performances of Pt–Sn/SiO2 catalyst in the dehydrogenation of propane was investigated. The Pt–Sn/SiO2 (DR) showed the highest activity among the catalysts tested. The order of activities of Pt/SiO2 and Pt–Sn/SiO2 catalysts was Pt/SiO2 (DR)≦Pt–Sn/SiO2 (CR)<Pt–Sn/SiO2 (DI)<Pt–Sn/SiO2 (DR). The results of structural characterization by X-ray diffraction (XRD), CO pulse, transmission electron microscopy (TEM), and Pt LIII and Sn K-edges X-ray absorption fine structure (XAFS) spectroscopy indicated that Pt3Sn alloy nanoparticle was mainly formed on the Pt–Sn/SiO2 (DR). In the case of the Pt–Sn/SiO2 (CR) catalyst, PtSn alloy particle was mainly dispersed on SiO2. On the other hand, Pt metal particles and highly dispersed SnO2 were present on the Pt–Sn/SiO2 (DI). The relationship between activity and structure of platinum-tin catalysts suggested that Pt3Sn alloy acts as active site for dehydrogenation of propane, whereas PtSn alloy shows low or no activity.