Iron Nitrosyl Species in Fe-FER: A Complementary Mossbauer and FTIR Spectroscopy Study

International audience; FTIR spectroscopy was applied to the investigation of the nitrosyl complexes formed with the extra-framework iron species in Fe-ferrierite (Fe-FER). To clarify the loading effect oil the nature Of file species formed. six ferrierites with Fe loadings varying between 0 and 3.7 wt % were prepared via ionic exchange and investigated. A Fe/SiO(2) and a Fe-FER sample containing iron oxide were also Studied for comparison purposes. Adsorption of NO on Fe-FER (containing no iron oxide species) gives different nitrosyl species. and different iron sites call be evidenced depending on the iron concentration. The bands are assigned to mononitrosyl oil iron whose oxidation state is determined to be +2 thanks to Mossbauer spectroscopy. In particular, one specific Fe(2+)-cation (typical of a highly loaded sample) appears to be easily converted to Fe(3+) upon oxygen treatment, which makes these sites excellent candidates for catalytically active redox sites.