The electrical conductivity of anhydrous Linde zeolite types A, X, and Y in various cationic forms has been measured between 20 and 400°C. The conductivity is ohmic, essentially noncapacitive, and appears to be strictly ionic with unusually low activation energy. From the effect of zeolite channel size, type of cation and cation density on ΔH, ΔG, and ΔS for the conduction process, some conclusions as to the zeolite internal structure and surface energy have been obtained. The heterogeneity of the internal surface energy found by the measurement of adsorption heats is discussed in the light of these conclusions.
The direct synthesis is reported of a 3R 2 polytype of a hydrotalcite-like mineral by the hydrothermal treatment of aluminium oxide and magnesium oxide.
The electrical conductivity of Linde synthetic crystalline zeolites type X and type A has been measured as a function of various adsorbed phases in the crystals. The potential energy barrier for the conduction process is decreased by the interaction of the adsorbed molecules with the electrostatic field or the field gradient in the lattice. Polar molecules, such as water and ammonia, exhibit a strong association through ion-dipole interactions with the most mobile cations.
The mechanism of adsorption of various molecules and the self-diffusion of sodium ions in these phases at discussed in terms of changes in the activation energy, free energy, and entropy of the conduction process. The relative importance of the electrostatic, dispersion, and quadrupole contributions to the interaction energy of the adsorbate with the zeolite is described.
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