作者: W. Weiss , D. Zscherpel , R. Schlögl
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摘要: The dehydrogenation of ethylbenzene to styrene was studied over single-crystalline iron oxide model catalyst films grown epitaxially onto Pt(111) substrates. role the stoichiometry and atomic surface defects for catalytic activity investigated by preparing single-phased Fe3O4(111) α-Fe2O3(0001) with defined structures varying concentrations defects. structure composition were controlled low-energy electron diffraction (LEED) Auger spectroscopy (AES), defect determined from diffuse background intensities in LEED patterns. These ultrahigh vacuum experiments combined batch reactor performed water–ethylbenzene mixtures a total gas pressure 0.6 mbar. No formation is observed on Fe3O4 films. α-Fe2O3 are catalytically active, rate increases increasing concentration these This reveals as active sites unpromoted α-Fe2O3. After 30 min reaction time, deactivated hydrocarbon deposits. deactivation process monitored imaging deposits photoelectron emission microscope (PEEM). It starts at extended exhibits pattern after further growth. indicates that site-selective process. Post-reaction AES analysis partly reduced Fe2O3 films, which shows reduction takes place during also deactivates