The Role of Nascent Oxygen Transients in Decomposition and Selective Catalytic Reduction of N_2O

摘要

Nitrous oxide, which also contributes to catalytic stratospheric ozone destruction, is a strong greenhouse-effect gas with a global warming potential (GWP) per molecule of about 300 times that of carbon dioxide (CO_2). From the point of view of environment, therefore, it is important to study removal of N_2O in the emission gases. Recently, we reported that selective catalytic reduction (SCR) of N_2O with CH_4 over an Fe ion-exchanged zeolite catalyst (BEA or MFI) took place effectively at low temperatures (ca. 200°C ～ 300°C) even in the presence of excess O_2 (4N_2O+CH_4 → 4N_2+CO_2+2H_2O). In this work, the reaction mechanisms of N_2O decomposition and SCR of N_2O with CH_4, as well as the nature of the active sites in Fe zeolite catalysts, have been studied by means of pulse reaction and isotopic tracer techniques, O_2-TPD and IR spectroscopy.