Activities of supported copper oxide catalysts in the NO plus CO reaction at low temperatures

The activities of copper oxide supported on CeO2, gamma -Al2O3 and ceria-modified gamma -Al2O3 catalysts for the NO + CO reaction at low temperature (200 degreesC) have been investigated. The results show that the activities of the surface-dispersed copper species are greatly enhanced due to the presence of ceria, whether it was used as a support or as the pre-dispersed species on gamma -Al2O3. The activities decrease in the order: CuO/CeO2 > CuO/CeO2/gamma -Al2O3 > CuO/gamma -Al2O3. For the CuO/CeO2/gamma -Al2O3 catalysts, it is shown that NO conversions are not improved significantly with the increasing of CuO and/or ceria loadings, however, the him-over number for the catalysts is found to be strongly relative to ceria loadings. Ey a combination of X-ray diffraction (XRD), electron spin resonance (ESR) and temperature programmed reduction (TPR) results, the states and properties of copper oxide species, as well as the interactions among the surface-dispersed copper oxide species, ceria species and support, are also studied. All the results are tentatively discussed according to the incorporation model proposed previously. (C) 2000 Published by Elsevier Science B.V.