Fe K‐Edge X‐ray Absorption Fine Structure Determination of γ‐Al2O3‐Supported Iron‐Oxide Species

Abstract The structure of FeO x species supported on γ‐Al 2 O 3 was investigated by using Fe K‐edge X‐ray absorption fine structure (XAFS) and X‐ray diffraction (XRD) measurements. The samples were prepared through the impregnation of iron nitrate on Al 2 O 3 and co‐gelation of aluminum and iron sulfates. The dependence of the XRD patterns on Fe loading revealed the formation of α‐Fe 2 O 3 particles at an Fe loading of above 10 wt %, whereas the formation of iron‐oxide crystals was not observed at Fe loadings of less than 9.0 wt %. The Fe K‐edge XAFS was characterized by a clear pre‐edge peak, which indicated that the FeO coordination structure deviates from central symmetry and that the degree of FeOFe bond formation is significantly lower than that in bulk samples at low Fe loading (<9.0 wt %). Fe K‐edge extended XAFS oscillations of the samples with low Fe loadings were explained by assuming an isolated iron‐oxide monomer on the γ‐Al 2 O 3 surface.