Propane ammoxidation on bulk, diluted and supported VSb oxides

VSb oxides diluted with Mg, Al and Zr displayed substantially higher selectivity for propane ammoxidation to acrylonitrile than their bulk and supported analogues. Diluted catalysts were found to consist of oxide compounds of antimony with diluent element, such as AlSbO₄ or MgSb₂O₆, and small amounts of individual oxides of antimony and diluent element. No VSbO₄ phase was detected in their body in contrast with bulk and supported catalysts. It appears that better isolation of vanadium and antimony entities in the structure of diluted oxides was responsible for their enhanced catalytic behavior. Tungsten loaded to the surface of diluted catalysts further improved their selectivity through tuning the surface acidity.