XAFS study of Fe- and Mn-promoted sulfated zirconia.
The local structure around Fe and Mn in Fe. Mn-promoted sulfated zirconia was investigated by means of in-situ XAFS. The Mn atoms are found to be present as MnSO 4 on the surface. The first post-edge peak of the Mn K-edge XANES spectrum was sharpened in a working state, and restored by evacuation. Fe K-edge XANES spectra showed that Fe is in a trivalent state and located at a center of a distorted octahedron. Fe atoms were suggested to be interstitially located into ZrO 2 to form a solid solution. An)' procedure did not change the Fe K-edge EXAFS and the shape and edgepositions of the XANES spectra. The reaction gases are in contact with Mn atoms, but not with the Mn atoms of the catalyst.