Crystallites of zeolite LSX with a diameter of about 10μm were synthesized. Crystals of this size were shown to permit the simultaneous investigation of intracrystalline mass transfer phenomena of water molecules and lithium ions in hydrated zeolite Li-LSX by NMR diffusometry. Using MAS NMR spectroscopy, with 1H and 6Li nuclei, the water molecules and lithium ions were found to yield two signals, a major and a minor one, which could be attributed to locations in the sodalite cages and the super-cages, respectively. Using 1H and 6Li exchange spectroscopy the mean residence times in the sodalite cages at 373K were found to be about 150ms for the water molecules and about 40ms for the lithium cations. PFG NMR self-diffusion measurements at 373K yielded a diffusivity of about 2 x 10-11m2/s for the lithium ions, which was about one order of magnitude below the water diffusivity.

Ion and Water Mobility in Hydrated Li-LSX Zeolite Studied by 1H, 6Li and 7Li NMR Spectroscopy and Diffusometry. D.Freude, S.Beckert, F.Stallmach, R.Kurzhals, D.Täschner, H.Toufar, J.Kärger, J.Haase: Microporous and Mesoporous Materials, 2013, 172, 174-81