Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 31: Surface Chemical Reactions and Heterogeneous Catalysis I
O 31.5: Vortrag
Dienstag, 27. März 2007, 16:45–17:00, H38
Interaction of O2, CO, and Methanol with Bimetallic Model Catalysts — T. Nowitzki1, B. Jürgens1, H. Borchert1, •V. Zielasek1, T. Risse2, H.-J. Freund2, S. Giorgio3, C.R. Henry3, and M. Bäumer1 — 1Institut für Angewandte und Physikalische Chemie, Universität Bremen — 2Fritz-Haber-Institut der Max-Plack-Gesellschaft, Berlin — 3CRMCN-CNRS, Campus de Luminy, Marseille
Bimetallic particles may exhibit catalytic activities which reach far beyond those of the monometallic components. For the Co/Pd combination which is, e.g., of technological relevance for the hydrogenation of CO on the route from natural gas to liquid fuel, we have studied the interaction of model catalysts with CO, O2, and methanol on the molecular scale. Experiments were performed in UHV by TPD, FTIR, and ferromagnetic resonance, as well as in ambient conditions by DRIFTS and gas phase analysis. In UHV, mono- and bimetallic nanoparticles were prepared by physical vapour deposition on thin epitaxial alumina films on NiAl(110). Upon exposure to O2 and annealing, a complex oxidation-reduction scheme of the particles is observed which involves the substrate and depends on the particle composition. After exposure to methanol, we find a CO-desorption-limited route of decomposition via C-H bond scission which is universal for monometallic and bimetallic particles. We will show close correlations between the results obtained in UHV and turn-over experiments for CO oxidation and methanol decomposition at Pd and CoPd nanoparticles on MgO in ambient conditions.