PROPOSAL OF A NEW KINETIC-MODEL BASED ON THE REMOTE-CONTROL MECHANISMTO FIT EXPERIMENTAL-DATA DURING THE SELECTIVE OXIDATION OF ISOBUTENE TO METHACROLEIN ON BIPHASIC CATALYSTS

A new kinetic model based on the classical Mars-van Krevelen mechanism is proposed. The new model incorporates both the mechanism of site cr eation (via a remote control) and the catalytic reaction at the thus c reated (or controlled) active site. The model has been tested in the s elective oxidation of isobutene to methacrolein on catalysts made of m echanical mixtures of alpha-Sb2O4 + MoO3. The good fitting of the mode l with the experimental results shows that the remote control mechanis m can explain the difficulties to represent the kinetics of allylic ox idation reactions by the traditional Mars-van Krevelen mechanism. The fraction of the surface of MoO3 which selectively realises the oxidati on via the oxidoreduction process depends on the degree of irrigation of MoO3 by spillover oxygen produced on alpha-Sb2O4 and cannot be cons idered as constant. The possible use of the model for further progress in the kinetic description of selective oxidation reactions is briefl y outlined.