Effect of Vanadium Oxides Composition Loaded on γAl2O3 Catalyst for Oxidative Dehydrogenation of Propane to Propylene

Abstract

AbstractThe catalysts were prepared by impregnation method, and the mass fraction of vanadium on γAl2O3 was 3%, 6%, 9%, 12%, 15%, respectivley (denoted as 3 V‐γAl2O3, 6 V‐γAl2O3, 9 V‐γAl2O3, 12 V‐γAl2O3 and 15 V‐γAl2O3). X‐ray diffraction(XRD), Raman spectroscopy(Raman), cyclic voltammetry(CV) and in‐situ infrared spectroscopy (FT‐IR) were used to study the properties of series of vanadium oxides composition loaded on γAl2O3 catalyst for oxidative dehydrogenation of propane to propylene. The results show that the V−O‐Al bond and the V=O bond are formed at the 3 V‐γAl2O3 and 6 V‐γAl2O3 catalysts, and the vanadium oxides are uniformly dispersed on γAl2O3. With the increasing of vanadium loading, for 9 V‐γAl2O3, 12 V‐γAl2O3 and 15 V‐γAl2O3 catalysts, except V−O‐Al and V=O bond, there was appeared V−O‐V bond, indicating the formation of V2O5 crystal supported on γAl2O3 obviously. The uniform dispersion for low vanadium loading on γAl2O3, is favorable for the selectivity of propylene, and for high vanadium loading catalysts, the V2O5 crystal will accelerate the deep oxidation of propane. At 500°C, the propylene selectivity of the 3 V‐γAl2O3 catalyst was 75.9%, and the propane conversion was 12.5%. Whereas the propylene selectivity of the 15 V‐γAl2O3 catalyst was 67.3%, and the propane conversion was 10.7%.