Studies on the reaction between manganic oxide and molybdenum trioxide

The kinetics and mechanism of the reaction between manganic oxide (Mn2O3) and molybdenum trioxide (MoO3) forming manganese molybdate in the solid state have been studied. The reactants were mixed in a stoichiometric ratio. The conversion data were recorded at four temperatures, viz. 460, 480, 500 and 520°C, and were tested with various mathematical models of solid-solid reactions corresponding to different mechanisms. The reaction was found to belong to the diffusion-controlled reaction mechanism. Among these models, the Valensi-Carter model was found to be the most suitable. The activation energy was calculated to be 44.7 kcal g-1 mol-1 and the Arrhenius equation was given by 11.37×109 exp(-44700/RT). Experiments to study the effect of a vacuum of 2 × 10-4 mm Hg on the conversion and kinetics of this reaction were also conducted. The conversion was found to increase under vacuum, with the same conditions of temperature and time, compared to that under atmospheric pressure. The activation energy was found to be 40.7 kcal g-1 mol-1 an the Arrhenius equation was given by 10.548×108 exp(-40700/RT). © 1984.