Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 45: Heterogeneous catalysis
O 45.7: Vortrag
Donnerstag, 26. März 2009, 12:00–12:15, SCH A215
Bifunctional Nanostructured Model Catalysts: Metal/Oxide Interaction Controls Initial NOx Storage Mechanism — •Thorsten Staudt1, Aine Desikusumastuti1, Zhihui Qin2, Markus Happel1, Yaroslava Lykhach1, Mathias Laurin1, Friedemann Rohr3, Shamil Shaikhutdinov2, and Jörg Libuda1 — 1Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin — 3Umicore AG & Co. KG, Hanau
In order to get detailed insights into the underlying mechanism and microkinetics, we investigated the initial NOx uptake on a model nitrogen storage and reduction (NSR) catalyst. This model system is prepared under UHV conditions by co-deposition of noble metal particles (Pd) and Ba-containing oxide particles, representing the storage compound, onto an ordered alumina film on a NiAl(110) substrate.
Using a combination of vibrational spectroscopy (IRAS), molecular-beam methods (MB) and scanning tunnelling microscopy (STM), we were able to show that the reaction mechanism is critically controlled by the metal-oxide interaction between the active noble metal particles and the NOx storage compound [1][2]. We suggest that a reverse spillover of activated oxygen species from the NOx storage compound to the noble metal is facilitated by the strong interaction between both components. A partial oxidation of the metal particles and a simultaneous stabilization of surface nitrite intermediates are a consequence of this process. [1] A. Desikusumastuti et al., ChemPhysChem 9 (2008), 2191-2197 [2] A. Desikusumastuti et al., Surf. Sci. Lett. in press