Abstract

Pd catalysts supported on Al2O3, CeO2/La2O3-Al2O3, Ce0,73Tb0,27Oδ-x/La2O3-Al2O3 and Ce0,6Zr0,4Ox/La2O3-Al2O3 were prepared, using the incipient wetness impregnation technique. The catalysts were characterized by the techniques of X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Temperature Programmed Reduction (TPR), CO Chemisorption and Oxygen Storage Capacity (OSC). The catalytic activity was studied by the reaction of reduction of NO by CO in stoichiometric feed conditions. XRD patterns showed that the crystallinity of the samples was not affected by thermal treatments. TPR results showed that addition of Tb or Zr promoted the reducibility of cerium oxide at lower temperature and the formation of β-PdHx phase after two reaction cycles as well as an increase in the OSC values. The catalytic activity after two reaction cycles was improved, being 0,5%Pd/Ce0,6Zr0,4Ox/La2O3-Al2O3 the most active catalyst. This result suggests changes in PdO species that together with the CeZr mixed oxide, generated species that are more active.