Metal-Support Interaction at Palladium-Composite Manganese Oxide Interface and CO Oxidation Activity

Pd-loaded perovskite composite manganese oxide (Pd/AMnO(3), A = Ca, Sr, La) catalysts were prepared by coprecipitation method, in order to reveal metal-support interaction (MSI). Particulate PdO with sizes of a few ten nanometers were randomly formed on CaMnO3. On the other hand, fibrous PdO with diameter approximately 20 nm was formed on LaMnO3. Both shape of PdO were formed on SrMnO3. HAXPES measurement showed a down shift of valence band of deposited PdO depending on the composite manganese oxide. Our characterization indicates that the MSI at Pd-AMnO(3) interface affects not only the shape but the electronic structure of deposited PdO on AMnO(3). The CO oxidation activity was in order of Pd/LaMnO3 > Pd/SrMnO3 > Pd/CaMnO3, which corresponds to the order of the PdO valence band shift trend. We proposed that the observed correlation between the valence band shift and the CO oxidation activity for Pd/AMnO(3) can be understood in terms of the CO adsorption strength.

Automated summary

In this study, Pd-loaded perovskite composite manganese oxide catalysts were prepared and characterized to investigate the metal-support interaction on the morphology and electronic structure of PdO. The results showed that the CO oxidation activity of the catalysts followed the trend of PdO valence band shift, with Pd/LaMnO3 having the highest activity. The correlation observed can be understood in terms of the CO adsorption strength.