EPR CHARACTERIZATION OF V2O5/TIO2 EUROCAT CATALYSTS

The Eurocat catalysts TiO2 (EL10) and V2O5/TiO2 with vanadium contents 1 and 8% (EL10V1 and EL10V8) have been studied by Electron Paramagnetic Resonance (EPR). No dispersed V(IV) ions were detected on the received samples degassed at room temperature. It has been shown that with V the transformation of the EL10 anatase phase into rutile occurs at a relatively high temperature (1373 K) compared to that reported in the literature for pure TiO2. The inhibition in this transformation could be due to the presence in the solids of certain specific impurities including the vanadium added. On EL10V1 and EL10V8, a few V (IV) ions are present as V4+ clusters in form of polycrystalline vanadia. These are easily removed either by acid attack or by calcination at high temperature, resulting in the formation of a few VO2+ ions presumably as vanadyl sulfate, or as a solid solution of V4+ in the TiO2 matrix.