A TAP reactor investigation of the oxidative dehydrogenation of propane over a V–Mg–O catalyst

The oxidative dehydrogenation of propane (ODHP) was studied over an optimised V–Mg–O catalyst at 500°C using the vacuum transient kinetic technique in the temporal-analysis-of-products (TAP) reactor. The only products detected were C 3H 6 and CO x . The experiments reveal that both, propene and carbon oxides are primary reaction products and that CO x is also produced by secondary oxidation of propene. Partial and deep oxidation of propane occur at the same surface site but involve different forms of reactive oxygen, associated to different site arrangements: nucleophilic lattice oxygen takes part in the propane partial oxidation to propene, while adsorbed electrophilic oxygen adspecies, originating from the gas-phase oxygen, are involved in the direct deep oxidation process of propane. The secondary oxidation of propene could involve both types of oxygen species. In the absence of gas-phase oxygen, the oxidation state of the catalyst determines the importance of the consecutive propene total oxidation.