The Dynamics of Oxygen Storage in Ceria–Zirconia Model Catalysts Measured by CO Oxidation under Stationary and Cycling Feedstream Compositions

Measurements were made of the dynamics of CO oxidation over a series of fresh and aged CeO2–ZrO2 catalysts of different composition. In order to evaluate the varying contributions to oxygen storage/release capacity, we carried out the reaction under transient “anaerobic environment” (in both pulse and cycling mode) and steady-state conditions. The presence of ZrO2 was of little or no benefit to stoichiometric CO oxidation carried out under stationary conditions. Under these conditions, catalytic activity is strongly dependent on surface area and on the number of exposed cerium atoms. The highest performance level is achieved with pure ceria. The beneficial effect of CeO2–ZrO2 mixed oxides on catalytic performance was observed when CO oxidation was carried out in transient pulse mode or under cycling feedstream composition. In this case, catalysts having the composition CexZr1−xO2 with 0.5