Metal–Support Interaction between Pd Oxide and YCoO₃ Effective for NO Reduction with CO and C₃H₆

The metal–support interaction (MSI) between platinum-group metals, such as Pd or Rh, and metal oxides significantly affects the catalytic performance. This study shows the catalytic activity for purifying exhaust gases on a Pd catalyst supported on Y1–xBaxCoO3−δ, which is a perovskite structure with different symmetries depending on the ratio of Y and Ba. For the NO–CO–C3H6–O2 reaction, the catalytic activity of Pd/YCoO3 is considerably higher than that of Pd/Y0.5Ba0.5CoO3−δ or Pd/BaCoO3 and comparable with that of Pd/Al2O3 even though the surface area of the Pd/YCoO3 catalyst is extremely small. In Pd/YCoO3, a unique MSI occurs between Pd oxide and YCoO3, and Pd oxide is thinly dispersed on YCoO3. By contrast, an aggregated PdO species is observed on BaCoO3 and Y0.5Ba0.5CoO3−δ. Density functional theory calculations indicate that charge transfer from Pd oxide to YCoO3 induces the formation of Pd–O–Co bonds and suppresses the aggregation of the Pd species. These findings highlight the importance of MSIs and offer valuable insights into the development of advanced catalysts.