DIFFERENCES IN THE STRUCTURE OF COPPER ACTIVE-SITES FOR DECOMPOSITIONAND SELECTIVE REDUCTION OF NITRIC-OXIDE WITH HYDROCARBONS AND AMMONIA

Cu ion co-ordination-location in zeolites of MFI, erionite, mordenite matrices has been determined and the activity of the individual Cu sit es compared for NO decomposition and its selective reduction by hydroc arbons or ammonia. It appears that Cu ions in the vicinity of one fram ework Al (site II), able to form stable Cu+-dinitrosyl complexes, and abundant in MFI structure, are responsible for high activity in NO dec omposition. The Cu ions neighbouring two framework Al atoms (site I), and forming mostly mononitrosyl complexes, which dominate in erionite structure, provide a high activity in selective reduction of NO.