Impact of preparation method on physico-chemical and catalytic properties of VO x/γ-Al 2O 3 materials

Abstract

Two preparation methods (wet saturation impregnation with vanadyl acetylacetonate and ball-milling of γ-Al 2O 3 with crystalline V 2O 5) were applied to produce two sets of VO x /γ-Al 2O 3 catalysts with increasing vanadium loadings. Materials from both sets were characterized by XRD, SEM, Raman, TPR and UV/vis-DRS (UV/vis diffuse reflectance spectroscopy) to elucidate the influence of the preparation method on the morphology of VO x species and on their behavior in the oxidative dehydrogenation of propane (ODP). Edge energies from UV/vis-DRS experiments were correlated with activity and selectivity data; the lower the edge energy, the lower catalytic activity and the higher propene selectivity. Both preparation methods result in materials with comparable physico-chemical and catalytic properties although very different precursors were used. Especially the calcination step during catalyst preparation seems to transform the different precursor molecules to dispersed VO x species by an equilibration process on the support material surface.