Elsevier

Journal of Catalysis

Volume 168, Issue 2, June 1997, Pages 386-392
Journal of Catalysis

Regular Article
Relationship between the Zirconia-Promoted Reduction in the Rh-Loaded Ce0.5Zr0.5O2Mixed Oxide and the Zr–O Local Structure

https://doi.org/10.1006/jcat.1997.1644Get rights and content

Abstract

Rh/CeO2–ZrO2mixed oxides show improved redox properties compared to Rh/CeO2due to a low-temperature reduction in the bulk. In the present work we have investigated the Zr–O and Ce–O local structure in Rh/Ce0.5Zr0.5O2by means of EXAFS and Raman spectroscopy. By introducing Zr4+into the CeO2lattice, the oxygen sublattice is strongly modified compared to the ideal fluorite structure of CeO2: the Ce4+ions retain their coordination while the number of oxygens around the Zr4+decreases from 8 to 6 due to a displacement of two oxygens to a nonbonding distance. It is suggested that this distortion of the oxygen sublattice generates some mobile oxygens in Rh/Ce0.5Zr0.5O2which are responsible for the improved redox properties.

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