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It has been recently shown that (Ce, Zr)O2 mixed oxides provide improved catalytic performances compared to pure CeO2. Cerium oxide is the active Oxygen Storage Capacity (OSC) component in three way catalysts. However, higher performances, including OSC enhancement, can be achieved with thermally stable solid solutions of Ce and Zr oxides. In the present paper, we describe the structure and the advantages of Ce rich (Ce, Zr)O2 solid solutions and the improved catalytic properties of these materials when used in association with platinum. Various analytical techniques were used including thermo-reduction methods, OSC measurements, surface area measurements, XRD, HRTEM, XPS, and XANES/EXAFS.

Rare earths compounds, especially CeO2, are widely used in automotive catalysis. Cerium dioxide contributes to the stabilization of precious metals but is particularly well known to be the active component for oxygen storage capacity (OSC). Standard cerium dioxide has poor thermal stability at temperatures higher than 800°C. A new generation of metal based oxides has been studied possessing high thermal and OSC stability. We have demonstrated that commercially available Ce rich solid solutions of (Ce, Zr)O2 showed the highest surface areas with remarkably improved OSC and phase stability versus temperature.