Structure and dispersion of supported-vanadia catalysts. Influence of the oxide carrier Original Research Article

The influence of the oxide carrier (i.e., HY zeolite, SiO2, ZrO2, TiO2, γ-Al2O3 and MgO) on the reduction pattern and oxygen chemisorption of supported V2O5 (4.7–5.3 wt%) catalysts has been investigated by temperature programmed reduction (TPR) and high temperature oxygen chemisorption (HTOC) measurements. The influence of redox and acid–base properties of the oxide support on the reduction pattern of the investigated systems has been assessed. The reducibility scale based on the inverse sequence of the onset temperature of reduction (To,red):V2O5/TiO2>V2O5/ZrO2>V2O5/Al2O3>V2O5/SiO2>V2O5/HY zeolite>V2O5/MgOindicates that the reduction of V2O5 catalysts is controlled by the oxide–support interaction which affects both the structure and dispersion of the active phase. The mathematical analysis of TPR profiles has allowed the influence of the support on the extent of the various surface VV species to be highlighted. A direct relationship between reducibility and vanadia dispersion is pointed out.