Redistribution of iron ions in porous ferrisilicates during redox treatments

Abstract

Abstract Relocation of iron ions in microporous Fe-FER, (Al+Fe)-FER, Fe-MFI (FER: ferrierite, MFI: silicalite) and in mesoporous Fe-MCM-41 ferrisilicate (MCM: Mobile Crystalline Material) samples was followed during redox treatments primarily by tool of the in situ Mössbauer spectroscopy. Coexistence of various Fe3+ and Fe2+ species is demonstrated. In microporous Fe-FER and Fe-MFI existence of combined μ-oxo iron dimers, Fe3+FW-O-Fe2+EFW can be proposed. The presence of these dimers can easily be correlated with catalytic effect shown in certain oxidation processes. Structural rearrangement can also be revealed in mesoporous Fe-MCM-41 which result in improvement of catalytic performance in CO oxidation.