Control of strong metal-support interactions in catalysts made of colloidally prepared metal nanoparticles and transition metal oxides

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The colloidal preparation of metal nanocrystals enables a high degree of control over structural properties such as the particle size and shape by using organic ligands in the synthesis. The structure control opens the possibility to realize supported catalysts with highly defined properties for heterogeneous catalysis. In the framework of the funded project entitled 'Supported Catalysts Based on Colloidally Prepared Metal Nanoparticles: Reaction Control by Structure Control' (German title: 'Trägerkatalysatoren auf Basis kolloidal hergestellter Metallnanopartikel: Reaktionskontrolle durch Strukturkontrolle'), colloidally prepared Pt-based nanocrystals were examined with respect to their application potential in heterogeneous gas phase catalysis in selected test reactions, with the focus on the hydrogenation of organic compounds. It was successfully demonstrated that the preparation of defined bimetallic nanoparticles as well as the usage of organic ligands are indeed suitable strategies to influence in a positive manner on the activity and selectivity of supported metal nanoparticles. Emerging from those results, the intention of the proposed prolongation project is to use the colloidal chemistry approach now to develop model systems suitable to investigate strong metal-support interactions (SMSI effects). The aim is to create model systems situated between highly defined model catalysts under vacuum conditions on the one hand, and real catalysts on the other hand. Concerning the materials, mono- and bimetallic Pt-based model catalysts shall be realized. Thereby, the nature of the contact between the metallic and oxidic components will be systematically varied. The materials will be characterized in detail and investigated as catalysts for CO oxidation and the preferential oxidation of CO in the presence of hydrogen (CO PROX). Considering these test reactions, it is possible to cover a broad range of more oxidative or reductive reaction conditions, which may significantly influence on the occurrence of SMSI effects.