Characterization of Pd/Ce0.8Tb0.2Ox/La2O3-Al2O3 by means of Thermal Programmed Reduction (TPR), Thermal Programmed Desorption (TPD) and Thermal Gravimetric Analysis (TGA)

A Pd/Ce0.8Tb0.2Ox/La2O3-Al2O3 catalyst was prepared and characterized by using TPD of H2 and O2, TPR and TGA measurements. Pd/CeO2 and Pd/Al2O3 catalysts were used as reference samples. Pd/Ce0.8Tb0.2Ox/La2O3-Al2O3 and Pd/Al2O3 catalysts showed a deactivation with the increase of the reduction temperature, specially at 700°C. The Pd/Ce0.8Tb0.2Ox/La2O3-Al2O3 catalyst had irreversible changes when it is heated at high temperatures (900°C). The studies of TPR showed that the Pd is reduced in two steps, and that the Pd/Ce0.8Tb0.2Ox/La2O3-Al2O3 catalyst is reduced in a larger interval of temperature than the Pd/CeO2 catalyst. In the TGA diagrams of Pd/Ce0.8Tb0.2Ox/La2O3-Al2O3 and Pd/Al2O3 catalysts, was observed the existence of hysteresis in the redox couple PdO Pdo. These results, in good agreement with the TPD–O2 ones, showed that in the supported mixed oxide of Ce/Tb the palladium oxidation occurs at higher temperatures than in the Pd/Al2O3 catalyst.