Dependence of the catalytic behavior of V—Sb-oxides in propane ammoxidation to acrylonitrile from the method of preparation Original Research Article

The catalytic behavior in propane ammoxidation to acrylonitrile of V—Sb-oxides prepared by four different methods and with a Sb : V ratio in the 0.8–3.0 range was studied and analyzed in relation to the structural/composition features of these samples determined by XRD, IR and SEM-EDX techniques. In particular, the following aspects are discussed: (i) composition, (ii) local homogeneity and morphology of the samples, (iii) presence, amount and dimensions of crystalline phases, (iv) presence and nature of the amorphous phases, and (v) crystallographic and non-stoichiometric features of the ≈VSbO4 phase. It is suggested that the selective behavior in propane ammoxidation is related principally to the non-stoichiometry of the ≈VSbO4 phase and especially the creation of a Sb-rich ≈VSbO4 phase, the formation of which depends on the microstructure of the catalyst, chemistry of preparation and Sb : V ratio.