Reaction of nitric oxide adsorbed on platinum clusters in X zeolites. Effect of cluster size and nature of alkali cations

Adsorption and temperature-programmed desorption of NO was studied over Pt/ alkali zeolites. Platinum clusters of three different sizes were prepared b y different decomposition routes of [Pt(NH3)(4)](2+) partially ion-exchange d in NaX zeolite. The effect of various alkali ions (Li, Na and K) was also examined. Similarly to platinum supported by alumina, the conversion of ad sorbed NO to nitrogen increases with increasing Pt particle size. increasin g electropositivity of the alkali cations shifts the desorption to lower te mperatures.