PHOTOREDUCTION STUDY OF MO ALLYL-BASED MO SIO2 CATALYSTS/

X-ray photoelectron spectroscopy (XPS or ESCA) measurements were perfo rmed on a photoreduced Mo allyl-based Mo/SiO2 catalyst (1.7 wt % Mo). Photoreduction was carried out in CO at room temperature for increasin g lengths of time. Factor analysis, deconvolution, and curve fitting w ere used to determine the number and positions of components present i n the series of XPS Mo 3d spectra obtained for the oxidic and photored uced Mo/SiO2 catalyst. The results indicated the formation of a single oxidation state Mo+ (Mo 3d(5/2) binding energy at 232.1 eV) after 2 h of photoreduction and the appearance of Mo4+ as in MoO2 (Mo 3d(5/2) b inding energy at 230.2 eV) with continued photoreduction. Average oxid ation state studies indicated that the species designated as Mo-x+ sho uld also be assigned to Mo4+ but in an environment different than that of MoO2.