Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 42: Oberfl
ächenreaktionen II
O 42.8: Vortrag
Dienstag, 8. März 2005, 12:30–12:45, TU EB407
A RAIRS investigation of methanol dehydrogenation on a Rh(111)/V islands surface — •Robert Schennach, Hans Peter Koch, and Georg Krenn — Institute of Solid State Physics, Graz University of Technology, Petersgasse 16/2, 8010 Graz, Austria
Fundamental insights in the dehydrogenation reaction of methanol is of interest due to the importance of this reaction in methanol powered fuel cells. In this work the methanol dehydrogenation on a Rh(111) surface with V islands has been investigated using reflection absorption infra red spectroscopy (RAIRS). The surface consists of two to four layer high V islands with an average island diameter of about 9 nm, which cover about 25% of the Rh(111) surface. The reactivity of this surface for methanol dehydrogenation is about 6 times as high as the reactivity of the V free Rh(111) surface. But the reactivity of the Rh(111)/V islands surface decreases over time due to CO dissociation on the V islands. However, the deactivated islands are still significantly more reactive towards methanol dehydrogenation than Rh(111). The RAIRS measurements show that the reaction mechanism changes markedly going from Rh(111) to the Rh(111)/V islands surface. This is mainly due to an increased stability of methanol on the V islands. In addition a new reaction pathway via methanol C-O bond opening yielding CH3 on the surface has been found on the Rh(111)/V islands surface. The reactivity of the deactivated islands seems to be due to a slight stabilization of methanol on this surface.