Isolated Sn on mesoporous silica as a highly stable and selective catalyst for the propane dehydrogenation

Tin oxide supported on silica (SnO 2 /SiO 2 ) were prepared by incipient-wetness impregnation method and examined for propane dehydrogenation at 600 °C. The physicochemical properties of SnO 2 /SiO 2 were characterized by N 2 -physisorption, XRD, UV–vis-DRS and H 2 -TPR. The results indicate that, at Sn loading ≤ 1.78 wt%, SiO 2 contains a uniform distribution of Sn as isolated species in tetrahedral coordination, while crystalline SnO 2 together with isolated Sn species are found for the higher Sn loadings. The reducibility of various Sn species was studied by a combination of XPS, H 2 -TPR, and reduction-reoxidation-TPR techniques. The results reveal that after high-temperature H 2 reduction, crystalline SnO 2 is fully reduced to metallic Sn, whereas isolated Sn are stabilized in the Sn 2+ state with high dispersion due to a strong interaction between isolated Sn and support. Catalytic activity tests showed that these Sn 2+ species exhibits both high activity and stability for propane dehydrogenation.