Preparation of supported vanadium oxide catalysts. Adsorption and thermolysis of vanadyl acetylacetonate on a silica support

Abstract

Adsorption and subsequent thermolysis of vanadylacetylacetonate [VO(acac)₂] on a silica support yields supported V—O structures. The initial concentrations of the complex, the drying temperature and the calcination are the factors with the highest impact on the nature of the vanadium oxide coating. Too high initial concentrations of the complex induce coalescence and clustering of the adsorbed product. During the drying or curing step, important rearrangements occur in the adsorbed layer, creating additional covalent bonds between the complex and the substrate. Calcination is accompanied by thermolysis: a conversion of the 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)₂ is a fast and effective way to create supported vanadium oxide catalysts with a high surface area.