Fe-MOR and Fe-FER as catalysts for abatement of N2O with CH4: in situ UV-vis DRS and operando FTIR study

The catalytic reduction of N2O with CH4 in absence or in presence of O2 (CRN2O or SCRN2O) and H2O (hydro-thermal conditions) was studied on Fe-MOR and Fe-FER catalysts with similar Al distribution and iron-loading. In N2O decomposition and SCRN2O Fe-FER catalysts were more active than Fe-MOR, whereas in CRN2O the catalysts exhibited similar activity. In situ FTIR and UV-vis spectroscopies of thermally activated catalysts revealed that Fe (II) species are better stabilized in FER than in MOR topology. In the presence of CH4, Fe(III)-oxo species were reduced to Fe(II) in both zeolites and became active sites for the CRN2O process. In SCRN2O the presence of O2 decreased the activity of Fe-MOR due to a partial re-oxidation of the active sites. The addition of H2O to the feed caused a poor and reversible deactivation. Operando FTIR experiments provided insights into the reaction pathways and suggested formaldehyde and formate surface species as intermediates.