Synthesis and physicochemical characterization of palladium-cerium oxide catalysts for the low-temperature oxidation of carbon monoxide

The effect of CeO2 preparation procedure on the electronic and structural states of the active component of Pd/CeO2 catalysts and their activity in the low-temperature reaction of CO oxidation was studied. The following two nonequivalent states of palladium were detected in the catalysts having low-temperature activity using XPS and IR spectroscopy: Pd0(Pdδ+) as the constituent of a palladium-reduced interaction phase and Pd2+ as the constituent of a palladium-oxidized interaction phase PdxCeO2 −δ. It was found that the procedure used for preparing a CeO2 support considerably affected the formation of these phases and quantitative ratios between them. It was demonstrated that the palladium-oxidized interaction phase was responsible for low-temperature activity, whereas the palladium-reduced interaction phase was responsible for activity in the region of medium and high temperatures.