Origin of Active Oxygen in a Ternary CuOx/Co3O4-CeO2 Catalyst for CO Oxidation

We have studied CO oxidation over a ternary CuOx/Co3O4CeO2 catalyst and employed the techniques of N-2 adsorption/desporption, XRD, TPR, TEM, in situ DRIFTS, and QMS (quadrupole mass spectrometry) to explore the origin of active oxygen. DRIFTS-QMS results with labeled O-18(2) indicate that the origin of active oxygens in CuOx/Co3O4CeO2 obeys a model, called a queue mechanism. Namely gas-phase molecular oxygens are dissociated to atomic oxygens and then incorporated in oxygen vacancies located at the interface of Co3O4CeO2 to form active crystalline oxygens, and these active oxygens diffuse to the COCu+ sites thanks to the oxygen vacancy concentration magnitude and react with the activated CO to form CO2. This process, obeying a queue rule, provides active oxygens to form CO2 from gas-phase O-2 via oxygen vacancies and crystalline oxygen at the interface of Co3O4CeO2.