Supported vanadium oxide nanoparticles: effect of preparation method, support and type of precursor on the catalytic performances in the ODH of methanol to formaldehyde

(eng) The deposition of vanadia on silica and titania/silica supports was achieved by chemisorption of a reactive vanadium precursor (VO(O-Pri)3) onto surface hydroxyl groups of the mentioned supports. This method was also used for the preparation of the (TiO2/SiO2) support by grafting tetra-isopropoxide on the silica. A detailed study of the chemical adsorption of vanadyl alkoxide on the surface of the TiO2/SiO2 support was carried out. The influence of this preparation method on the surface structure, acidic properties and catalytic activity was demonstrated by examining also the corresponding conventionally impregnated catalysts. The catalysts were characterized by chemical analysis, BET, TPD, RAMAN and XPS spectroscopies and tested in the ODH of methanol to formaldehyde. The main findings of this work showed that the surface dispersion of vanadia species is an important parameter to obtain good performances both in terms of activity and selectivity.