Effect of the Reduction Step on the Catalytic Performance of Pd–CeMO2 Based Catalysts (M = Gd, Zr) for Propane Combustion

Abstract

The effect of a reduction step on the catalytic activity of Pd supported doped ceria catalysts was investigated for the propane combustion. Two different oxides based on ceria zirconia (CZ), as a reference three-way catalyst support, and Gadolinia doped ceria (GDC), a mixed ionic electronic conductor, have been used to support Pd nanoparticles. The samples were characterized by H2–CO chemisorption, temperature programmed reduction, and XPS. In addition, the reduction step in H2 was in situ observed by environmental transmission electron microscopy. It was found that the catalytic activity of Pd supported on ceria-based supports can be strongly promoted by a reduction step whereas it does not change on alumina. This effect was attributed, in particular on GDC, to the reduction of a surface interaction phase, PdxCeO2−δ, which induces a re-dispersion of metallic Pd nanoparticles.