Origin of Active Oxygen in a Ternary CuOx/Co3O4–CeO2Catalyst for CO Oxidation

We have studied CO oxidation over a ternary CuO x /Co 3 O 4 –CeO 2 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 18 O 2 indicate that the origin of active oxygens in CuO x /Co 3 O 4 –CeO 2 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 Co 3 O 4 –CeO 2 to form active crystalline oxygens, and these active oxygens diffuse to the CO–Cu + sites thanks to the oxygen vacancy concentration magnitude and react with the activated CO to form CO 2 . This process, obeying a queue rule, provides active oxygens to form CO 2 from gas-phase O 2 via oxygen vacancies and crystalline oxygen at the interface of Co 3 O 4 –CeO 2 .