SYNTHESIS AND CHARACTERIZATION OF SUPPORTED VANADIUM-OXIDES BY ADSORPTION OF THE ACETYLACETONATE COMPLEX

Supported vanadium oxide catalysts are prepared by adsorption and calc ination of vanadium acetylacetonate complexes on the surfaces of silic a and alumina. The interaction of the complex with the support is stud ied by FTIR, XRD, TGA and chemical analysis. The synthesis parameters are optimized in order to obtain a well dispersed layer on the surface . After calcination, the acetylacetonate complexes decompose and form a surface layer of VOx species. These surfaces have been studied with V-51 NMR, UV-VIS diffuse reflectance and XRD spectroscopies. The metho d of acetylacetonate adsorption on silica enables the creation of supp orted VOx catalysts with a V loading of 0.5 mmol g(-1) (2.5 wt.% V), w ith all species in a strictly tetrahedral configuration and no formati on of microcrystallites. On the alumina surface, vanadium loadings tha t are 5 times higher can be achieved without induced crystallinity.