CuxO/CeO2 nanocomposites: synthesis and reactivity with NO

CuxO/CeO2 nanocomposite powders were prepared by wet impregnation of nanosized ceria powder (Cu/Ce nominal atomic ratio from 0.05 to 0.5). XP analysis reveals the presence of Cu2O in the samples with lower Cu/Ce atomic ratio whereas CuO is prevalent in the samples richer in copper. The surface Cu/Ce atomic ratio obtained from XPS data is always higher than the nominal one suggesting the surface segregation of copper. A plateau value (0.9-1.0) is reached for the samples with a nominal Cu/Ce atomic ratio 65 0.2 suggesting an island growing mechanism. The nanocomposite samples and the supporting ceria were exposed to a NO+CO mixture (2% CO, 2% NO, 96% He) and the reactivity was investigated by means of DRIFT spectroscopy and QMS. At 523 K (i.e. the temperature at which the nanocatalysts activity is higher) the capability for NO reduction increases with increasing the Cu/Ce atomic ratio