Propane Oxidative Dehydrogenation on ZnCoMo and NiCoMo Catalysts Obtained from ϕ_<i>y</i> and ϕ_<i>x</i> Precursors

The synthesis and characterization of trimetallic oxides of the type MCo–Mo (with M = Ni or Zn) in both ϕ_<i>y</i>- and ϕ_<i>x</i>-type phases (depending on the compensation ion) is described. The materials were calcined at 673 K to obtain mixed oxides with surface areas between 27 and 32 m² g^–1 that were found to be nonstoichiometric. The catalysts were tested in the oxidative dehydrogenation of propane at moderate temperature (673 K). It was found that precursors with a ϕ_<i>y</i>-type phase provide higher catalytic performance than those obtained as ϕ_<i>x</i>-type materials, which could be related to the higher suface area and better reducibility properties of the former. The influence of Ni on the catalytic performance was found to be positive in the two types of structures compared to the undoped CoMo catalysts. On the other hand, Zn introduction had a negative effect on the intrinsic reaction rate for both ϕ_<i>y</i>- and ϕ_<i>x</i>-derived catalysts. The NiCoMoϕ_<i>y</i>400 catalyst exhibited the best performance; thus, further tests were performed with this catalyst at a lower space velocity, and a higher propene yield was obtained. The NiCoMoϕ_<i>y</i>400 catalyst exhibited good stability after being used for 24 h. The yields achieved were around 5%, which is a good result compared with similar systems described in the literature