The electrical properties of anhydrous synthetic faujasites, exchanged with various monovalent cations were measured between 250 and 730K in the frequency range of 200 to 107Hz. The zeolites had Si/Al ratios of 1.22, 1.75,

2.51 and 2.98. An ionic conduction phenomenon was predominant, especially above room temperature. The conductivity was determined by the mobility of the supercage cations. The migration from site II to the neighbouring site III′ was the rate-controlling step. The activation energies ranged from 50 to 90kJ/mol. They were the sum of two terms: cation-lattice interaction and cation–cation repulsion. The latter was only appreciable in the samples with K+, Rb+ or Cs+ on sites III′. Below room temperature an intense dielectric relaxation was observed in samples with Si/Al ratios of 1.22 and 1.75. The activation energies for this process ranged from 30 to 43kJ/mol. This relaxation was associated with the local motion of exchangeable cations over two neighbouring sites III′. It was very weak or nonexistent in samples with Si/Al ratios of 2.51 and 2.98, indicating that no, or nearly no, cations were located on sites III′.

Electrical Properties of Crystalline Synthetic Zeolites Types X and Y, Exchanged with Monovalent Cations. F.J.Jansen, R.A.Schoonheydt: Journal of the Chemical Society - Faraday Transactions 1, 1973, 69, 1338-55

Table 53

Diffusivity of Aromatics in

NaY Zeolite at 298K