Direct and NO-assisted N_2O decomposition over Cu-zeolites

摘要

In this work, the direct and NO-assisted N_2O decomposition over Cu-faujasites are investigated. In these zeolites, Cu exchanges preferentially at the I' sites in the sodalite cages. However, as these sites are inaccessible for N_2O, they do not contribute to the overall activity in the N_2O decomposition reaction. Only the Cu atoms located in the supercages can react with N_2O. Furthermore, as O-migration is hampered at the isolated, EPR active Cu sites, the activity in the direct N_2O decomposition can be attributed to EPR-silent Cu sites in the supercages. Adding NO results in the scavenging of the deposited O atoms, thereby transporting them into the gas phase. Hence an alternative oxygen migration pathway is created which has the highest impact on activity of the isolated EPR detectable Cu sites.