In-Situ Observation of Reaction Intermediate in the Selective Catalytic Reduction of N2O with CH4 over Fe Ion-Exchanged BEA Zeolite Catalyst for the Elucidation of Its Reaction Mechanism Using FTIR

The selective catalytic reduction (SCR) of N 2 O with CH 4 in the absence and presence of excess O 2 has been studied over ion-exchanged Fe−BEA catalyst by the combination of an activity test with in-situ infrared spectroscopy to understand the nature of the surface species involved in the SCR of N 2 O with CH 4 . From the results of flow reaction studies, the Fe−BEA catalyst exhibited high activity in the SCR of N 2 O with CH 4, even in the presence of excess oxygen, which demonstrates that the active Fe species for the SCR are formed on the ion-exchanged Fe−BEA catalyst. In the FTIR spectra of fresh catalysts, the OH band on Fe ion species (Fe−OH) was observed on the Fe−BEA catalyst, and the Fe−OH species can be involved in the SCR of N 2 O with CH 4 . Furthermore, the reaction intermediates of methoxy and formate species over the Fe−BEA catalyst were observed during the reaction. We measured the oxidation rates of these surface species with N 2 O and O 2, and found that the methoxy species were oxidized with N 2 O more rapidly than O 2, while the formate species were oxidized with both N 2 O and O 2 at almost the same rate. On the basis of these results, we discuss the reaction mechanism of the SCR of N 2 O with CH 4 .