Characterization of supported catalyst systems with surface spectroscopies

Supported catalysts of transition metals and their oxides are widely used for a variety of reactions. They typically consist of a high surface area oxide as support material (e.g. Al2O3, TiO2, SiO2) and finely dispersed metal or metal oxide particles (e.g. Rh, MoO3, V2O5) as active components (or their precursor) and promoters. The catalytic properties are determined by these components, their structural arrangement, and their interactions. Studies of real and model catalyst systems are reported for which low-energy ion scattering (LEIS) is used in combination with other spectroscopies, such as RES, AES, TDS, XPS, and Raman spectroscopy. The applicability of these techniques to real systems and the relevance of model catalysts is discussed. The results shown demonstrate the usefulness of these spectroscopies for the characterization of supported catalysts, in particular for the analysis of the composition and the arrangement of the topmost atomic layers. Among the examples given are special aspects of catalyst impregnation, the investigation of solid-solid wetting which may be relevant to catalyst preparation and strong metal-support interactions (SMSI effect) in supported Rh metal catalysts.