engleski

Diffusion of iodine into exchanged zeolite A and X

Ion-exchange of Na+ ions from zeolite with Ag and Zn cation from solution, and introduction of iodine into system distort zeolite A and ZX framework on certain SBU positions (4R, D4R, 6R, D6R) what can be detected by XRD and FTIR spectroscopy. Introduction of gas I2 at elevated temperature into zeolite shows 3 interactions: 1. Formation of the MeI with movable cation, 2. capture of elemental I2 (complexes of different size, even nanocrystals) within voids of ZA and ZX, 3. ionic form of iodine in complex reaction with MeI/zeolite framework obtained by disproportination of iodine molecules at 210 C. Strong interaction of iodine molecules with zeolite framevork and exchangeable cation (capturing of I2 molecules within zeolite voids) indicate anomalous diffusion. Therefore, ordinary equations for gas diffusion into zeolites are not suitable for determination of diffusion coefficients.

gas diffusion; host-guest interaction; zeolite

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