VANADIUM TITANIUM-OXIDE CATALYSTS - INFLUENCE OF THE PREPARATION METHOD ON THE OMICRON-XYLENE SELECTIVE OXIDATION

Vanadium oxide supported on titania catalysts prepared by the ''Equili brium Deposition followed by Filtration'' method (EDF) and the convent ional Wet-impregnation method (WI) were extensively characterized by t he joint use of various physicochemical techniques (BET, XRD, FT-IR, D RS, XPS, AEM, TPR, and TPD of NH3) and were tested for the partial gas -phase oxidation of o-xylene. It was found that the EDF method leads t o more selective monolayer catalysts. The increased selectivity has be en attributed to the reduction of the surface acidity, to the enhancem ent of the V(V)/V(IV) ratio and to the redox properties induced in thi s catalyst by the above preparation method.