Resumo

DA COSTA, María et al. Preparation and characterization of supported Ce/Tb mixed oxide for use in TWC catalysts. Rev. Téc. Ing. Univ. Zulia [online]. 2009, vol.32, n.3, pp.256-265. ISSN 0254-0770.

The CeTbO_X/La₂O₃-Al₂O₃, CeO₂/La₂O₃-Al₂O₃, CeTbO_X/SiO₂ and CeO₂/SiO₂ catalysts were prepared by incipient wetness impregnation technique from aqueous solutions of cerium, terbium and lanthanum chlorides. The catalysts were characterized by X-ray fluorescence (XRF), Surface area, Temperature-programmed reduction (TPR), Temperature-programmed desorption of hydrogen (TPD-H₂), Oxygen storage capacity (OSC). The catalytic behavior was studied using methane oxidation reaction after different thermal treatments. The TPR study showed that the addition of Tb ion improves the reduction properties of cerium oxide. TPR profiles showed appreciable changes in the nature of the superficial phases in surface after the different thermal treatments, and that the oxides supported on silica reduce in a temperature range lower than those corresponding to the modified alumina-supported catalysts; this effect is advantageous but it does not correlate with the low values of OSC and catalytic activity. The higher OSC and the higher conversions were obtained with CeTbO_X/La₂O₃-Al₂O₃ catalyst. The methane oxidation reaction is not favored with the increase of the oxygen partial pressure.

Palavras-chave : Three-way catalysts; TPR; TPD; methane oxidation.