An XRD and ESR study of V2O5/ZrO2 catalysts: influence of the phase transitions of ZrO2 on the migration of V4+ ions into zirconia

A series of undoped and potassium-doped catalysts for the oxidative dehydro genation of propane, based on zirconia-supported V2O5 was investigated by X RD and ESR techniques. The chemical state of the surface and bulk vanadium species and of the ZrO2 matrix was investigated as a function of the calcin ation temperature and the presence of dopants. It was found that potassium improves the dispersion of surface vanadium species and affects the tempera ture of the phase transitions of zirconia. These two effects facilitate the incorporation of vanadium (IV) into the ZrO2 matrix. The formation of subs titutional solid solution was revealed by Rietveld analysis. (C) 1999 Elsev ier Science B.V. All rights reserved.