Effect of Potassium on the Structure, Physic-Chemical and Catalytic Properties of Vanadium-Incorporated Mesoporous Catalysts for the Oxidative Dehydrogenation of Propane

Abstract

The potassium-modified vanadium-incorporated mesoporous silica catalysts (K/V-KIT-6) were synthesized by an incipient wetness impregnation method assisted by ultrasonic and vacuumed treatments. The effect of potassium on the structure and physic-chemical properties of V-KIT-6 mesoporous silica catalysts has been studied by a variety of techniques including N2 adsorption–desorption, XRD, TEM, UV–Vis DRS, H2-TPR and Raman spectroscopy. The catalytic behaviors over K/V-KIT-6 catalysts with low and high V contents for the oxidative dehydrogenation of propane (ODHP) were also comparatively evaluated. For the V0.5-KIT-6 catalyst with low V content, the K-modification can promote the formation of isolated VOx species with strongly distorted structures. It shows a positive effect on the conversion of propane and selectivity of propylene. In contrast, for the V1.8-KIT-6 catalyst with relatively high V content, potassium reacts with vanadium oxide species and alters the structural and physic-chemical properties, because there is a strong interaction between K+ and vanadia species, which results in changing the structure of vanadia species and forming new species. The catalytic performance demonstrates that these transformations of active species are unfavorable for the oxidative dehydrogenation of propane to propylene.