XE-129 NMR-STUDY OF SMALL SODIUM PARTICLES IN NAY ZEOLITE

The distribution of sodium metal particles inside the cavities of a Na Y zeolite has been investigated using Xe-129 NMR spectroscopy. For a s ample prepared by vapor-phase deposition at 520 K, the Xe-129 NMR spec trum shows three lines which are interpreted in terms of domains of a nonuniformly distributed metal particles, oxidized particles, and empt y cavities. After annealing the sample at 670 K, the Xe-129 spectrum c ollapses to one single line, characteristic of a narrow particle size distribution. Oxidation of the sample by oxygen decreases the chemical shift of the Xe-129 NMR line, which is mainly due to a loss of parama gnetism and a volume contraction of the small sodium metal particles.