Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 15: Heterogeneous catalysis I

O 15.10: Vortrag

Montag, 26. März 2012, 18:15–18:30, MA 042

Dynamic distribution patterns of ultrathin VOx films on Rh(111) during the O2+CH3OH reaction. — •Martin Hesse and Ronald Imbihl — Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstr. 3a, 30167 Hannover, Germany

Vanadium oxides play an important role as catalysts in partial oxidation of hydrocarbons. As a model system for VOx based catalysts we studied the behavior of ultrathin VOx films on a Rh(111) surface in the O2+CH3OH reaction. VOx catalyzes the production of formaldehyde. The reaction was investigated in the 10-4 - 10-5 mbar range with photoemission electron microscopy (PEEM) as a spatial resolving method. We observed that at T > 600°C the distribution of VOx on Rh(111) is no longer homogeneous but a stationary macroscopic concentration pattern developed consisting of parallel stripes of VOx surrounded by bare Rh(111) surface. In analogy to the patterns formed in the O2 + H2 reaction on Rh(111)/VOx we interpret the patterns as being due to reactive phase separation[1]. The dependence of the rate of formaldehyde production on the distribution pattern of vanadium oxide on Rh(111) was studied.

[1] F. Lovis et. al, J. Phys. Chem. C 115, 2011, 19141