Catalytic oxidative properties and characterization of CuO/CeO2 catalysts

The oxidative properties and characterization of CuO, CeO2 and CuO/CeO2 catalysts were examined by means of a CO micro-reactor GC system, TPR, XPS and X-ray diffraction Rietveld methods. The results show that either CuO or CeO2 activity is quite low for CO oxidation. However, when CuO and CeO2 are mixed, the oxidative activity of the catalyst increases significantly, probably owing to the valency status of copper species (Cu2+ and Cu+) on the CeO2 surface, the dispersion and reducibility. XPS surface analysis shows that CuO loading is very important in forming of either Cu2+ or 4(+) Cu+. Rietveld analysis shows that some CuO, which has smaller ion radius than Cc, enters the CeO2 lattice after CuO and CeO2 are mixed. When the CuO loading reaches 5.0 %, the size of CuO crystals is a minimum (6.1 nm) and the micro-strain value is a maximum (2.86 x 10(-3)), resulting in high surface energy and the best activity for CO oxidation.