ESCA STUDY OF MODEL ALLYL-BASED MO/SIO2 CATALYSTS

Stoichiometric redox measurements and X-ray photoelectron spectroscopy (XPS or ESCA) studies were performed on an allyl-based Mo/SiO2 catalyst (1.7 wt % Mo) obtained by the sublimation of Mo(eta3-C3H5)4 onto SiO2 at 40-degrees-C. The average oxidation state estimated from stoichiometric measurements correlated well with those reported in the literature. ESCA results indicated that reduction of the MO/SiO2 catalyst at 550-degrees-C primarily led to the formation of Mo2+. Also, the results were consistent the reported reversibility of the redox cycle. However, the reported formation of discrete Mo4+ by oxidation of the reduced catalyst at room temperature could not be substantiated.