Methanol oxidation over iron molybdate catalysts. Main and side reactions kinetics

The kinetics of methanol to formaldehyde oxidation over iron molybdates catalysts has been studied. Data were obtained in integral reactor conditions and the rates of the products formation were computed by differentiation of experimental data yield versus contact time. Catalytic tests were performed over stoichiometric (Mo/Fe=1.5 at. ratio) and Mo rich (Mo/Fe=3 at. ratio) catalysts prepared by coprecipitation and sol-gel like techniques. The Mo/Fe atomic ratio of the catalysts seems to have a null effect on the methanol to formaldehyde kinetics what is coherent with the attribution of the active phase to the Fe2(MoO4)3, the main phase of the tested catalysts. A direct correlation between the CO formation and the Mo/Fe atomic ratio was not inferred mainly due to the different degrees of reduction of the tested catalysts (Fe2+/Fe3+), but the Mo/Fe ratio plays an important role on the consecutive oxidation of formaldehyde to CO thus controlling catalyst selectivity.