E.p.r. study on the incorporation of Fe(III) ions in ZSM-5 zelites in dependence on the preparation conditions

Reduction of N2O with CO over FeMFI zeolites: influence of the preparation method on the iron species and catalytic behavior

“…A certain oxidation of iron(II) was also observed in Fe/ZSM-5 and Fe-ZSM-5 but was hardly visible in Al-free ex-Fe-silicalite. In agreement with our results, previous Mössbauer investigations of FeZSM-5 zeolites, prepared by adding Fe to the synthesis gel, have concluded a more favorable formation of Fe 2+ in matrices with relatively high Al contents [30].…”

“…Accordingly, the framework composition of the zeolite plays an essential role in determining the iron speciation. In particular, the presence of Al in the MFI structure destabilizes framework iron, promoting extraction and clustering of extraframework species [19,21,30]. Berlier et al [56] recently concluded, based on infrared studies, that Al favors the dispersion of extraframework iron species in isomorphously substituted FeZSM-5 as compared to Fe-silicalite.…”

Characterization and catalytic investigation of Fe-ZSM5 for urea-SCR

“…The observed signals are common for Fe-ZSM5 zeolites [16,17] and also for Fe 3+ ions in other oxide matrices. The number and positions of EPR transitions for Fe 3+ ions observable in a powder spectrum depend sensitively on the local crystal powder spectrum of these sites and possible magnetic interactions between them.…”

Catalytic oxidation of trichloroethylene over Fe-ZSM-5: Influence of the preparation method on the iron species and the catalytic behavior

“…7). The observed signals at g values of 2.03, 4.3, and 6.3, are common for Fe-ZSM-5 and also for Fe 3+ ions in other oxide matrices [34,35]. However, the resolution of the spectra (measured by the narrowness of the peaks) was quite different, depending on the preparation method employed.…”