Mechanistic approach of the oxidative dehydrogenation of propane over VMgO catalysts by in situ spectroscopic and kinetic techniques

The mechanism of the oxidative dehydrogenation of propane (ODHP) was investigated over a series of thoroughly characterized VMgO catalysts by means of kinetic experiments combined with in situ techniques such as DRIFT and XPS spectroscopies, electrical conductivity and isotopic transient kinetics. All ODHP products were shown to be essentially primary From the description of the active surface under reaction conditions, a unique active site was assumed to include surface V5+ ions, lattice oxygen ions and anionic vacancies. A derailed mechanism was tentatively proposed which accounted for the main observed kinetic trends. Both the weak dependence of selectivity and the marked dependence of intrinsic activity on catalyst structure and composition within a large range of vanadium content were also discussed on the basis of the proposed mechanism.