4 Pages

The role of metal-support interaction on the oxidation of noble metals supported on cerium based oxides

HREM has provided relevant information about the oxidation, under conditions relevant to TWC catalysis, of metal nanoparticles present in a 0.5% Rh/Ceo.8Tb0.202_x catalyst. The formation of the low pressure, high temperature form of the orthorrombic sesquioxide, Rh20 3-0, takes place. The oxidised particles are grown epitaxially over the fluorite-type Ce-Tb mixed oxide support. The crystallographic features of these epitaxial relationships have been established. Moreover, according to the correlation established between the structure of the metal f.c.c. phase and that of Rh20 3-0, these epitaxial relationship have been determined to be directly related to the original parallel epitaxial growth observed between the metal particles and the support prior to the oxidation treatment. This interpretation suggests that the particles and the support during the reduction

and parallel to the interface, Figure 5(d). Moreover,

structural interaction established between the metal