Catalytic Oxidative Properties and Characterization of CuO/CeO_2 Catalysts

摘要

The oxidative properties and characterization of CuO, CeO_2 and CuO/CeO_2 catalysts were examined hy means of a CO micro-reactor GC system, TPR, XPS and X-ray diffraction Rietveld methods. The results show that either CuO or CeO_2 activity is quite low for CO oxidation. However, when CuO and CeO_2 are mixed, the oxidative activity of the catalyst increases significantly, probably owing to the valency status of copper species (Cu~(2+) and Cu~+) on the CeO_2 surface, the dispersion and reducibility. XPS surface analysis shows that CuO loading is very important in forming of either Cu~(2+) or Cu~+. Rietveld analysis shows that some CuO, which has smaller ion radius than Ce~(4+), enters the CeO_2 lattice after CuO and CeO_2 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.