Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Poster Session III - MA 141/144 (Methods: Atomic and Electronic Structure; Particles and Clusters; Heterogeneous Catalysis; Semiconductor Substrates: Epitaxy and Growth+Adsorption+Clean Surfaces+Solid-Liquid Interfaces; Oxides and Insulators: Solid-Liquid Interfaces+Epitaxy and Growth; Phase Transitions; Metal Substrates: Adsorption of Inorganic Molecules+Epitaxy and Growth; Surface Chemical Reactions; Bimetallic Nanosystems: Tuning Physical and Chemical Properties; Oxides and insulators: Adsorption; Organic, polymeric, biomolecular films; etc.)
O 55.17: Poster
Mittwoch, 27. Februar 2008, 18:30–19:30, Poster F
Trends in Reactivity: Gold Catalysis — •Guido Walther1, Søren Jensen2, and Sebastian Horch1 — 1CAMD, Department of Physics, DTU, 2800 Lyngby, Denmark — 2MIC, Department of Micro and Nanotechnology, DTU, 2800 Lyngby, Denmark
Gold, as the noblest of all the metals, becomes catalytically active for several chemical reactions, when its particle size is less than 5 nm. Beside the particle size, there are many other effects, which maybe contribute to the surprisingly high activity of gold nano-particles, like support and/or electronic effects. But it is still not understood in detail yet, what accounts for these unique properties of nano-sized gold.
In a new microreactor setup, CO and H2 oxidation were studied on TiO2 supported Au catalysts of various well defined particle sizes. The particle size was confirmed using TEM. To analyze the reaction products, the microreactor was interfaced to a gas chromatograph.
We show a trend in reactivity in catalysis by gold for these reactions. By switching the oxidation agent from O2 to N2O, an investigation whether the rate-limiting step is associated with O2 or CO, was feasible. This gives an experimental indication that CO oxidation follows an alternative pathway via a CO–O2 intermediate.