On the reactivity of K2O-, CaO- and P2O5-doped nickel molybdate catalysts in a periodic-flow reactor

The propane oxydehydrogenation with monolayer lattice oxygen of undoped and K2O-, CaO- and P2O5-NiMoO4 was investigated by using a periodic-flow react or (PFR). The influence of the nature and the extent of the promoter has be en emphasized relative to the doped catalysts with respect to pure NiMoO4 p hases. It was observed that calcium and potassium promoters satisfactorily enhance propylene selectivity, and phosphorus promoter specifically increas es the total activity while maintaining the propylene selectivity. Evidence found by thermogravimetric (TG) analyses (oxygen depletion rate) has shown a dependence on lattice oxygen mobility due to the presence of promoters. This dependence has been correlated to the propane conversion while the pro pylene selectivity was attributed to the acid-base properties.