Effect of CeO2 addition into Pd/Zr–Pr mixed oxide on three-way catalysis and thermal durability

XPS shows that the surface chemical state of Pd in Pd/ZrPrOx is mainly Pd4 +, which is likely doped in ZrPrOx. However, the Pd4 + is segregated out as PdO when Pd/ZrPrOx is exposed at 1000 °C in air, resulting in the particle growth of Pd and deterioration. It has been found that the mixing Pd/ZrPrOx with CeO2 enhances the catalytic activity and thermal durability. Analysis using XPS and HAADF-STEM shows that the mixing effect of ceria is to stabilize Pd4 + at the high temperature and ceria also functions as an excellent support for the segregated PdO, which migrates from ZrPrOx to CeO2.

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► Pd/Zr–Pr mixed oxide shows high resistance to the thermal ageing.
► RS proved that Pr-doping leads to the formation of peroxide and superoxide adspecies.
► Main chemical state of Pd in fresh catalyst was Pd4 + before reaction.
► In thermal ageing, Pd4 + ions segregate out as PdO, resulting in Pd particle growth.
► Mixing Pd/Pr-doped ZrO2 with ceria improved performance and thermal tolerance.