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 Ce0.66Zr0.32Pt0.02O2 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 Ce0.66Zr0.32Pt0.02O2 compared with the Pt/Ce0.67Zr0.33O2 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.