The selective catalytic reduction (SCR) of N
2O with CH
4 in the presence of excess O
2 was studied over ion-exchanged Fe-BEA catalyst by the observation of reaction intermediates in order to elucidate the reaction mechanism. From the results of activity tests, SCR of N
2O with CH
4 in the presence of excess O
2 proceeded at much lower reaction temperature than N
2O decomposition over the Fe-BEA catalyst. The profiles of temperature programmed desorption of O
2 after N
2O pretreatment gave a new desorption peak at lower desorption temperatures compared to the case of O
2 pretreatment. However, the oxygen species desorbed at the lower temperatures did not react with CH
4 in the profiles of temperature programmed reaction. From the structural analysis by means of extended X-ray absorption fine structure, a Fe-Fe bond was observed on the Fe-BEA catalyst after N
2O treatment. This suggests that binuclear species can be formed over the Fe-BEA catalyst. In the
in-situ FTIR observation, the methoxy and formate species were observed during the SCR reaction. We measured the reaction rates of these surface species with N
2O and O
2, and this is related to the selective reduction of N
2O with CH
4.
抄録全体を表示