Comparison between gamma-alumina and aluminum niobate supported vanadium oxides in propane oxidative dehydrogenation

The catalytic properties of vanadium oxides supported by alumina and aluminum niobium oxides (AINbO) are compared in propane oxidative dehydrogenation. VO x /AlNbO are less active than VO x /γ-Al 2 O 3 , but more selective in the transformation into propene. For the first system, selectivity is maximum at an intermediate calcination temperature of the supports, corresponding to an amorphous AINbO structure. Bridging oxygens (V-O-V) from the two dimensional VO 4 array are suggested to be active sites on both catalysts. However, it is not possible to correlate the catalytic properties of superficial vanadium oxides only with their degree of condensation; it is suggested that the structure and the acid-base properties of the support also define the redox function of supported vanadates.