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19: Iron oxide model catalysts: adsorption & catalysis
Abstract:
In order to study the dehydrogenation of ethylbenzene to styrene, epitaxial iron oxide model catalyst
films with Fe3O4(111), a-Fe2O3(0001) and KFexOy(111) stoichiometry were prepared in single crystal
quality on Pt(111). They were investigated using surface science techniques before and after
atmospheric pressure reaction experiments in a newly designed single crystal flow reactor. As
expected from low pressure measurements, Fe3O4(111) is catalytically inactive. The catalytic activity
of a-Fe2O3(0001) starts after an activation period of about 45 minutes. After that, the surface is
essentially clean but shows a high concentration of defects. On the potassium promoted films, however,
the activation period is much longer, the activity then is higher and the surface gets covered completely
with carbon and oxygen during reaction. This indicates a different reaction pathway on the promoted
films with a carbon-oxygen species as catalytically active species
