Kinetics of oxidative dehydrogenation of propane on the β phase of nickel molybdate

Abstract

Kinetics of the oxidative dehydrogenation of propane on the more selective polymorphic β phase of nickel molybdate has been studied in order to understand the mechanism of the reaction. The kinetic equations describing the rate of the global reaction were considered to fit the data of the experimental runs performed on NiMoO 4 in a tubular quartz reactor. Among the possible reaction steps the adsorption of propane, the desorption of propene and the intervention of lattice oxygen have been considered to play a determinant role for the overall transformation. Under the operating conditions selected for the study, it was found that the partial order with respect to the propane and oxygen were, respectively, about one and almost zero, therefore it can be postulated that the limiting reaction step controlling the overall reaction rate is the adsorption of propane on the catalyst surface or the reaction between adsorbed propane and the oxygen of NiMoO 4. The catalysts were diluted in the silicon carbide powder to limit thermal gradient and specific tests have been carried out to avoid thermal diffusion problems.