Preparation of Oxide-Supported Metal Catalysts – A Surface Science Approach
Institute of Physics, University of Graz, Universitätsplatz 5, A-8010 Graz
Oxide-supported metal nanoparticles represent an important class of heterogeneous catalysts. Their catalytic activity depends on various parameters such as nanoparticle size, morphology, or nature of the support. Maximizing the abundance of active sites is the primary goal for catalysis and is achieved by choosing appropriate preparation conditions. Surface science studies of metal nanoparticles grown on single-crystalline oxide supports contributed substantially to the understanding of the physical and chemical properties of these systems and with the availability of spectroscopic methods that allow for in situ studies at elevated pressure, even reactivity studies under realistic pressure conditions are possible. While ultrahigh vacuum (UHV) model systems are typically prepared by physical vapor deposition of the metal onto clean oxide surfaces, most preparation procedures used for technical catalysts are based on wet chemical procedures. The mechanism of catalyst precursor interaction with the support and the functionalization of the oxide surface differ in the two approaches, which may have consequences for the properties of the final (model) catalyst.
In this talk, I will address the issue of catalyst preparation and present a surface science approach to supported metal catalyst preparation utilizing thin, single-crystalline oxide films as substrates, including the interaction of vapor-deposited metals with hydroxylated oxide surfaces and the preparation of oxide-supported metal nanoparticles on sinlge-crystalline supports applying procedures used for the preparation of technical catalysts. I will discuss results for Pd supported on silica, MgO and Fe3O4 thin film substrates.