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

A series of CuO/Ce1-xCuxO2-delta catalysts were prepared, and corresponding Ce1-xCuxO2-delta catalysts were obtained with nitric acid treatment. X-ray diffraction and Raman spectroscopic results revealed the presence of surface CuO species and Ce1-xCuxO2-delta 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-delta catalysts, suggesting synergetic effects of the surface CuO species and CuxCe1-xO2-delta 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-delta and 95 kJ mol(-1) for CeCe1-xCuxO2-delta. The power-law rate expression was r(CO) = k(1)P(CO)(0.74)P(O2)(0) for CuO/Ce1-xCuxO2-delta and r(CO) = k(2)P(CO)(1.04)P(O2)(0), for the Ce1-xCuxO2-delta catalyst, indicating that the reaction pathway followed a Mars-van Krevelen type mechanism. (C) 2012 Elsevier Inc. All rights reserved.