Combustion synthesis of copper catalysts for selective CO oxidation

Copper catalysts supported on ceria, zirconia and niobia were prepared by combustion method with urea, containing a CuO loading of 6 wt.%, and tested on selective oxidation of CO. The characterization of the samples by X-ray diffraction (XRD) presented the formation of solid solution on CuO–CeO2 catalyst and a change in crystalline structure of the support with copper insertion on ZrO2 and Nb2O5 catalysts. The analysis of temperature-programmed reduction (TPR) revealed different interaction degrees of copper with the supports, with reduction peaks between 222 and 390 °C. The temperature-programmed desorption of CO (TPD-CO) profiles showed formation of CO2 and H2 only for the ceria and zirconia catalysts. In relation to the catalytic tests, the CuO–CeO2 catalyst presented the best performance, with CO conversion of 95% at 150 °C up to 45 h on stream, and CO2 selectivity of 55%.