Promotion Effect of Cu for CO Oxidation on Ceria Supported PdxCuy Bimetallic Catalysts

The surface composition and structure of bimetallic catalysts are important for the catalytic performance. In this work, PdxCuy/CeO2 catalysts with various Pd/Cu ratios were prepared and characterized by surface-sensitive techniques combined with ex-situ pretreatment. CO oxidation was used to correlate the surface composition with the catalytic performance. Compared with the monometallic Pd/CeO2 and Cu/CeO2, the PdxCuy/CeO2 bimetallic catalysts with a small amount of Cu show much higher CO oxidation activities. High-sensitivity low-energy ion scattering spectroscopy (HS-LEIS) combinded with X-ray photoelelctron spectroscopy (XPS) and temperature-programmed reduction (H-2-TPR) results indicate that adding a small amount of Cu can efficiently promote the surface dispersion of Pd and affect the redox properties, whereas the CO oxidation activity is significantly suppresssed after adding a larger amount of Cu, which may be mainly induced by the preference for surface segregation of Cu that blocks the active site of Pd.

Automated summary

The surface composition and structure of bimetallic catalysts play a crucial role in their catalytic performance. This study demonstrates that the addition of a small amount of Cu to PdxCuy/CeO2 catalysts can enhance the CO oxidation activity and promote the surface dispersion of Pd.