Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 28: Surface reactions II
O 28.7: Vortrag
Dienstag, 28. März 2006, 17:15–17:30, WIL C207
Adsorption and Reaction of Methanol on Partially Oxidized Pd Model Catalysts — •Björn Brandt1, Tobias Schalow1, Swetlana Schauermann1, Jörg Libuda2, and Hans-Joachim Freund1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Department of Chemical Physics, Faradayweg 4-6, 14195 Berlin, Germany — 2Friedrich-Alexander-Universität Erlangen-Nürnberg, Lehrstuhl für Physikalische Chemie II, Egerlandstrasse 3, 91058 Erlangen, Germany
The chemical state of metal nanoparticles under oxidizing reaction conditions and its influence on the reactivity is a subject of enduring discussion for many catalytic systems. On transition metal surfaces, a variety of different oxygen species has been reported, whose role in reaction kinetics is poorly understood. In this study we present first results on the interaction of methanol with well-defined Pd/Fe3O4 model catalysts, applying molecular beam methods combined with TR-IRAS. Previously, we have shown that oxidation of iron oxide supported Pd particles above 500 K results in the formation of Pd oxides, located primarily at the particle/support interface. We probe the reactivity of partially oxidized and pristine metallic Pd nanoparticles for methanol decomposition and oxidation. On the pristine Fe3O4 support, the formation of stable methoxy species was observed up to 350 K. On Pd particles, methanol decomposition undergoes two competing reaction pathways, resulting in formation of CO and carbonaceous species. The influence of Pd particle oxidation on the two decomposition pathways was studied by transient and steady-state experiments, combined with TR-IRAS.