Determination of Fe-substituted sites in the MFI structure by Fe K-edge EXAFS

The local structure around iron in the MFI structured ferrisilicate was investigated by the Fe K-edge extended X-ray absorption fine structure (EXAFS) method to identify the Fe substituted sites in the framework. After removal of the intense first neighbor Fe-O peak, the second and further peaks in the Fourier transformed EXAFS spectra of the MFI structured ferrisilicate were analyzed by comparing the experimentally-obtained spectra with the simulated ones for twelve Si sites in the MFI framework. The results suggest that a few of the twelve Si sites in the framework are selectively substituted by Fe.