Abstract

Catalysts supported on SiO2, CeO2/SiO2, Ce0,6Zr0,4Ox/SiO2 and Ce0,7Tb0,3Ox/SiO2 were prepared by incipient wetness impregnation, using a Pd content of 0,5% w/w. The catalysts were characterized by X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Temperatureprogrammed Reduction (TPR) and CO Chemisorption. The catalytic behavior was studied using CH4 oxidation reaction in stoichiometric conditions. XRD patterns indicated that the crystallinity of the samples was not affected after two catalytic reaction cycles. The TPR results showed that the addition of Tb or Zr promoted the reducibility of cerium oxide at lower temperatures and the formation of -PdHx phase after two reaction cycles. The CO/Pd ratio decreases with increasing reduction temperature of samples which could possibly suggest the Pd decoration by ceria. The catalytic activity increased after two reaction cycles due to the presence of large PdO particles.