Oxygen defects: The key parameter controlling the activity and selectivity of mesoporous copper-doped ceria for the total oxidation of naphthalene

Mesoporous CeO2 modified by the addition of copper has shown high efficiency for the total oxidation of naphthalene. High activity and 100% selectivity to carbon dioxide throughout the whole range of temperatures studied were achieved for copper loadings of 3.6% and lower. The catalytic behaviour has been related to the concentration of surface oxygen defects. A clear correlation between the concentration of surface oxygen defects (determined by XPS and DRIFTS) and the catalytic performance has been identified. Catalytic activity increased as copper was incorporated into the ceria up to 3.6%. In this range of copper content the copper was incorporated into the cubic fluorite lattice of CeO2 and this was confirmed using XRD and electron diffraction studies. For copper ceria catalysts with higher copper contents the concentration of oxygen defects decreased and an additional dispersed monoclinic CuO phase with a low intrinsic activity was formed, thus leading to a decrease of both the activity and the selectivity to CO2. (C) 2012 Elsevier B.V. All rights reserved.