PREPARATION OF SUPPORTED VANADIUM-OXIDE CATALYSTS - ADSORPTION AND THERMOLYSIS OF VANADYL ACETYLACETONATE ON A SILICA SUPPORT

Adsorption and subsequent thermolysis of vanadylacetylacetonate [VO(ac ac)(2)] on a silica support yields supported V-O structures. The initi al concentrations of the complex, the drying temperature and the calci nation are the factors with the highest impact on the nature of the va nadium oxide coating. Too high initial concentrations of the complex i nduce coalescence and clustering of the adsorbed product. During the d rying or curing step, important rearrangements occur in the adsorbed l ayer, creating additional covalent bonds between the complex and the s ubstrate. Calcination is accompanied by thermolysis: a conversion of t he supported VO(acac)(2) towards supported vanadium oxide. The evolved products were identified and a conversion mechanism is suggested. The thermolysis of adsorbed VO(acac), is a fast and effective way to crea te supported vanadium oxide catalysts with a high surface area.