Abstract

Ceria-based mixed oxide supported metal catalysts are important materials, from a scientific and technological point of view, due to its application as a TWC for the purification of the air coming from the exhaust system of the automobiles. At the same time they are promising candidates to be used for the production of hydrogen from methane, a challenge area of research at the present moment. In both applications the characterization of the supported metal particles and the red-ox behaviour of the mixed oxide are key parameters to understand the properties of the catalysts.

The application of High Resolution Electron Microscopy (HREM), in combination with image analysis and image simulation tools, to retrieve structural and chemical information from these catalysts is presented. Fine details about the metal particles, such as the size, the morphology, oxidation state and the interaction with the support, as well as the bulk structure of the ceria-based mixed oxide, have been established at different red-ox treatments.

One important feature to face for the interpretation of HREM images of metal/support discrete interfaces is the development of a methodology to construct the complex super-cells which are required as input data for the multi-slice simulation programs. This presentation includes a description of a proposed approach to model size, shape, faceting, and relative orientation of metal and support particles.