The positive effect of NO on the N2O decomposition activity of Fe-ZSM-5: A combined kinetic and in situ IR spectroscopic study

NO-assisted N2O decomposition over four different Fe-ZSM-5 samples prepared by wet ion exchange (WIE) or chemical vapor deposition (CVD) of FeCl3 was investigated by steady-state kinetics, in situ infrared (IR) spectroscopy, and transient response methods. Despite their lower iron loading, the samples prepared by WIE had the highest activity for N2O decomposition in the presence of NO. The in situ IR experiments showed that the most active sample was characterized by a high concentration of adsorbed NO, as well as adsorbed NO2 under reaction conditions. Step response experiments proved that NO2 is an intermediate of the catalytic cycle and functions as intermediate oxygen storage. IR and transient kinetic experiments showed that WIE catalysts behave qualitatively different in NO-assisted N2O decomposition than CVD catalysts. These differences are discussed in terms of the different structure of the iron species in the two types of samples.