FTIR and TPD studies of adsorption properties of nitrogen monooxide over copper ion-exchanged zeolites

The relations of the adsorption properties and the behavior of catalytic decomposition of nitrogen monooxide over various copper ion-exchanged zeolites were studied by the means of in situ FTIR and temperature-programmed desorption (TPD), The results demonstrated that NO+, O--Cu-NO and NOB species were formed on the surface of the zeolites and desorbed at 350 similar to 400 K(denoted as alpha), 400 similar to 480 K (beta) and 650 similar to 700 K (gamma), respectively. It was found that the kinds and the amounts of the species were greatly changed with the zeolite structure and the copper ion exchange level, i. e. Cu-MFI, Cu-MOR and Cu-OFF/ ERI gave alpha, beta and gamma peaks; Cu-FER gave alpha and beta peaks; Cu-LTL and Cu-FAU only gave a peak. The amounts of desorption were increased linearly;with the exchange level of copper on Cu-MFI. The O-2 desorption peak appeared at the same temperature as that of the gamma peak. In addition, by comparing the present; results with the behavior of catalytic decomposition of NO, it is also found that NO3- species play a key role in the catalytic decomposition of NO and the formation of O-2 over the zeolites.