Movements of Ions in Zeolite A Containing Hydrogen Ion

Movements of ions in dehydrated Na 11 H 1 -A zeolite (LTA) were studied by dielectric spectroscopy and vapor adsorption techniques, and site affinities of ions were discussed. Two relaxation losses were measured in the ranges of 2 < log( f /Hz) < 6.5 and 342 ≤ T /K ≤ 524. The losses were simultaneously influenced by water molecules adsorbed at a very low degree of hydration, and hence their origins were attributed to a common ion. The relaxations in the lower and higher frequency sides showed activation energies of E I = 51 kJ mol -1 and E II = 33 kJ mol -1, respectively. From comparisons of spectrum profiles, activation energies, and cation distributions among closely related zeolites, the measured two relaxation losses were attributed to the cation on the site S3 (cation/S3). Cation/S3 was concluded to be sodium ion on the bases of adsorption properties, variations of dielectric spectrum with hydration, an activation energy, and a relaxation model. It was found that the hydrogen ion has a stronger trend to avoid S3 than the sodium ion, and hence sodium ion reluctantly occupies S3 in Na 11 H 1 -A as well as Na 12 -A. The activation energies of movements of Na + /S3 were lower in Na 11 H 1 -A than Na 12 -A. The lowering of activation energies was due to the reduction of Coulombic repulsion. The reduction was considered to be brought by two effects concerning with hydrogen ion, a formation of covalent bond and an increase of cation−cation distance.