Oxide supported metal catalysis, structure reactivity studies

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Oxide supported metal catalysts are key materials in heterogeneous processes ranging from emissions remediation to hydrocarbon oxidation to fuel cell technology. These catalysts generally involve disperse metal particles of nano to micrometer size dispersed in the matrix of an oxide such as silica, alumina or zirconia. Despite their widespread use, many questions remain unanswered for oxide supported metal catalysts: what is the role of the support?, what are the active sites?, what are the reaction mechanisms?, what are the intermediates and how do they interfere with the reaction? Even in the extremely high loading cases used in the electro-catalysts of fuel cells, issues regarding active sites, mechanism, and intermediates remain unclear.The objective of the proposed research program is to address some of these questions by establishing structure-reactivity relationships and studying intermediates in situ. The potential for interplay between low and high loading materials has gone unrecognized owing to differences in support material as well as dramatic differences in catalyst loading. We intend to study, at the molecular level, the processes occurring on metal nanoparticles supported on yttria stabilised zirconia due to their potential in heterogeneous catalysis as well as in the solid oxide fuel cell industry.The experimental approach involves the preparation and testing of porous "real" catalysts. These materials are fully characterised for electronic and morphological structure using diffraction and microscopy techniques and tested for activity in reactor or fuel cell setups. At the same time, "model" catalysts are studied under ultra high vacuum conditions using spectroscopy and microscopy. The comparison of structure-reactivity relationships obtained for model catalysts and for real catalyst has a good potential for the understanding and improvement of catalytic processes. The approach is meant to provide a rationale for targeting the preparation of catalysts with the desired properties.