CO oxidation over CuO/Ce1−xCuxO2−δ and Ce1−xCuxO2−δ catalysts: Synergetic effects and kinetic study

A series of CuO/Ce1−xCuxO2−δ catalysts were prepared, and corresponding Ce1−xCuxO2−δ catalysts were obtained with nitric acid treatment. X-ray diffraction and Raman spectroscopic results revealed the presence of surface CuO species and CuxCe1−xO2−δ solid solution in the catalysts. CO oxidation testing found that the CO conversion was proportional to the concentrations of chemisorbed CO and oxygen vacancies in the CuO/Ce1−xCuxO2−δ catalysts, suggesting synergetic effects of the surface CuO species and CuxCe1−xO2−δ solid solution on the reactivity, as the former provided sites for CO chemisorption and the latter promoted reducibility of the catalyst for oxygen activation. Kinetic studies showed that the apparent activation energy was 42 kJ mol−1 for CuO/Ce1−xCuxO2−δ and 95 kJ mol−1 for Ce1−xCuxO2−δ. The power-law rate expression was image for CuO/Ce1−xCuxO2−δ and image for the Ce1−xCuxO2−δ catalyst, indicating that the reaction pathway followed a Mars–van Krevelen type mechanism.