Sol−Gel Method for Preparing Vanadium−Antimony Oxide Catalysts

Abstract

Vanadium−antimony oxide selective oxidation catalysts are prepared using a novel peroxide-based sol−gel synthesis procedure. The catalysts are prepared by reaction of soluble peroxovanadium complexes with antimony trioxide under refluxing conditions. The procedure produces a stable colloidal sol of microcrystalline rutile vanadium antimonate having an average particle size of 6.7 nm. Drying the sol gives a gel consisting of pure rutile vanadium antimonate having the vanadium/antimony ratio of about 1/1, consistent with the stoichiometry of the well-characterized crystalline phase V8/9Sb8/9□2/9O4. The driving force for the formation of this phase is the redox reaction between a V5+peroxo complex and Sb3+oxide to form the V4+,Sb5+-containing vanadium antimonate. The peroxide-based sol−gel preparation procedure allows formation of vanadium antimonate under milder conditions than previous synthesis methods that rely on heating of mixtures of vanadium and antimony oxides.