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Abstract

A flow reactor for the investigation of heterogeneous catalytic reactions on single crystalline metal oxide model catalysts has been designed. It is located in a high pressure cell attached to an UHV analysis chamber where the model catalysts can be prepared and characterized by surface science techniques. It can also be run in a batch modus. After sample transfer the high pressure cell can be completely separated from the UHV chamber and it can be used for oxidation treatments and reaction studies at gas pressures up to 1 bar. A new heating system provides direct heating of the sample by laser light up to 1200 K. Product analysis is done by gas chromatography coupled with mass spectrometry, which allows detection in the ppb range. The single crystal flow reactor provides new insight into the atomic scale surface chemistry of metal oxides under real catalysis conditions and bridges the pressure gap for model systems prepared and characterized under UHV conditions. Results on the dehydrogenation of ethylbenzene to styrene over epitaxial potassium-iron oxide films are presented and correlated to thermal desorption measurements on the same films under UHV conditions.