MODIFICATION OF KINETIC-PARAMETERS BY ACTION OF OXYGEN SPILLOVER IN SELECTIVE OXIDATION OF ISOBUTENE TO METHACROLEIN

A kinetic study of the oxidation of isobutene to methacrolein was carr ied out by varying the reaction temperature and the oxygen and isobute ne partial pressure. Catalysts were prepared by mechanically mixing, i n different propositions, alpha-Sb2O4 and MoO3, synthesized separately . Pure oxides and their mechanical mixtures were tested under identica l experimental reaction conditions. The presence of alpha-Sb2O4 change s the reaction orders and the activation energy of the reaction. The c hanges in the kinetic parameters are explained by a remote control mec hanism via spillover oxygen (RCM). A new model which incorporates both the mechanism of site creation (via RCM) and the catalytic reaction a t the thus created (or controlled) active sites fits well the experime ntal data. All the parameters of the new model have a precise physical meaning.