Catalytic Performance in NO Reduction and Loading State of Precious Metal for Pt–Rh Loading Catalysts on Oxygen Storage Components

Abstract

This report is the investigation results regarding the effect of Ce oxide (CeO₂), Ce–Zr double oxide (Ce_0.7Zr_0.3O₂), Ce–Pr double oxide (Ce_0.9Pr_0.1O₂) and Pr oxide (Pr₆O₁₁) on the catalytic performances, structure and electronic state of Pt and Rh loaded on these oxides.
Based on the TPR evaluation results, it was found that the oxygen absorption-desorption performance of Pt–Rh/Ce_0.9Pr_0.1O₂ and Pt–Rh/Pr₆O₁₁ are superior to Pt–Rh/CeO₂ and Pt–Rh/Ce_0.7Zr_0.3O₂.
Based on the XPS analysis results, it was found that the oxidation state of surface of Pt on Pt–Rh/Ce_0.9Pr_0.1O₂ and Pt–Rh/Pr₆O₁₁ are higher than that on Pt–Rh/CeO₂ and Pt–Rh/Ce_0.7Zr_0.3O₂.
Based on XAFS analysis results, it was found that Rh on Pt–Rh/Ce_0.9Pr_0.1O₂ and Pt–Rh/Pr₆O₁₁ are close to metallic in comparison with that on Pt–Rh/CeO₂ and Pt–Rh/Ce_0.7Zr_0.3O₂.
The state of precious metals and catalytic performances depend on the strong interaction between the precious metals and oxygen storage components (OSC).