Enhanced Activity for CO Preferential Oxidation over CuO Catalysts Supported on Nanosized CeO2 with High Surface Area and Defects

Nanosizedceria (n-CeO2) was synthesized by a facile method in 2-methylimidazolesolution. The characterization results of XRD, N2 adsorption-desorption, Raman and TEM indicate that n-CeO2 shows a regular size of 10 ± 1 nm, a high surface area of 130 m2·g−1 and oxygen vacancies on the surface. A series of CuO/n-CeO2 catalysts (CuCeOX) with different copper loading were prepared for the preferential oxidation of CO in H2-rich gases (CO-PROX). All CuCeOX catalysts exhibit a high catalytic activity due to the excellent structural properties of n-CeO2, over which the 100% conversion of CO is obtained at 120 °C. The catalytic activity of CuCeOX catalysts increases in the order of CuCeO12 < CuCeO3 < CuCeO6 < CuCeO9. It is in good agreement with the order of the amount of active Cu+ species, Ce3+ species and oxygen vacancies on these catalysts, suggesting that the strength of interaction between highly dispersed CuO species and n-CeO2 is the decisive factor for the activity. The stronger interaction results in the formation of more readily reducible copper species on CuCeO9, which shows the highest activity with high stability and the broadest temperature “window” for complete CO conversion (120–180 °C).