FORMATION OF METAL-CLUSTERS IN ALKALINE-EARTH-CATION-EXCHANGED X-ZEOLITES

Alkaline-earth-cation-exchanged X zeolites were reacted with sodium metal vapor and studied by electron spin resonance (ESR), diffuse reflectance (DR), and far-infrared (far-IR) spectroscopies. The ESR results show that alkaline-earth-metal clusters formed inside the zeolites. The temperature dependence of the ESR intensity indicated that the cluster size is constrained by the zeolite so that there is a quantum size effect on the small alkaline-earth metal clusters formed. The DR spectra show colors consistent with discrete energy levels and a quantum size effect. Electron transfer from sodium atoms to exchanged cations in the zeolites is also indicated by far-IR data for Mg-X and Ba-X zeolites.