ON THE MECHANISM OF NITRIC-OXIDE DECOMPOSITION OVER CU-ZSM-5

Cu-ZSM-5, a copper-containing zeolite, catalytically decomposes NO at temperatures below those of other catalysts. A mechanism is proposed which is based on active sites consisting of coordinatively unsaturated cupric (Cu2+) ions in a square planar configuration. These sites are posited to chemisorb NO molecules in the gem-dinitrosyl form. The pair of adsorbed NO molecules desorbs as N2 and O2. This mechanism accounts for the experimental behavior in chemisorption and decomposition without invoking a cyclical oxyreduction of the surface sites.