Preparation and characterization of supported Ce/Tb mixed oxide for use in TWC catalysts

the cetbox/la2o3-al2o3, ceo2/la2o3-al2o3, cetbox/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 cetbox/la2o3-al2o3 catalyst. the methane oxidation reaction is not favored with the increase of the oxygen partial pressure.