The reaction mechanisms of selective catalytic reduction (SCR) of N 2O with CH4 and N2O decomposition over Fe ion-exchanged zeolite catalysts (Fe-BEA, Fe-MFI) were studied. In O 2-TPD studies, we observed new desorption peaks from Fe-BEA catalyst after N2O treatment. However, the new adsorbed oxygen species hardly reacted with CH4. This indicates that coexistence of N2O and CH4 is necessary for the high SCR activity. In infrared (FTIR) spectroscopy, most of Fe-OH species (the OH group on Fe ion species) took part in the N2O+CH4 reaction, and the methoxy and formate species were formed. The methoxy species were oxidized with N2O more rapidly than O2, while the formate species were oxidized with both N2O and O2 at almost the same rate. The isotopic tracer study using 18O(a) showed that O2 formation during N 2O decomposition proceeds via Eley-Rideal (ER) mechanism. A possible mechanism is discussed in terms of active oxygen species formed from N 2O, which may play an important role in the activation/oxidation of CH4 at initial steps.
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry