Effect of preparation methods on the structure and redox behavior of platinum-ceria-zirconia catalysts

Platinum was introduced into ceria-zirconia solid solutions to form nominal Ce_0.66Zr_0.32Pt_0.02O₂ solid solutions by sol-gel. It was found that, through sol-gel method, the Pt ions could be inserted into the ceria lattice according to the results of XRD, XPS and TPR analyses. This brought about a different synergistic effect between the Pt and Ce components in Ce_0.66Zr_0.32Pt _0.02O₂ compared with the Pt/Ce_0.67Zr _0.33O₂ system prepared by traditional impregnation, such as increased the oxygen mobility in ceria-zirconia solid solutions and improved the stability of metallic state for platinum at high temperature. The lower surface Pt content leads to a worse three-way catalytic activity over the Pt-doped sample at low temperature. However, it features a better thermal stability after aging at 950°C for 20 h, implying a self-generation mechanism of noble metals. This, in return, provides this material with a potential to be used in eliminating pollutants from auto exhaust. © 2005 Elsevier B.V. All rights reserved.