Time-resolved, in situ X-ray diffraction studies of intercalation in lamellar hosts

Energy dispersive X-ray diffraction (EDXRD) has been used to perform in situ kinetic studies on the intercalation of a range of guest molecules in layered lattices. The kinetics of the intercalation of cations (K+, PyH+ (Py = C5H5N), NMe4+) and the long chain ammonium ions C(12)TMA, C(16)TMA, C(18)TMA (C(12)TMA = dodecyltrimethylammonium, C(16)TMA = hexadecyltrimethylammonium and C(18)TMA = octadecyltrimethylammonium) into crystals of MnPS3 have been determined. These reactions are very fast, and in some cases novel transient phases are observed. The rate of cobaltocene, Co(eta-C5H5)(2), intercalation in layered metal dichalcogenides ZrS2, 2H-SnS2, 2H-SnSe2, 2H-TaS2, 2H-NbS2, IT-TaS2 and TiS2 has also been investigated. Integrated intensities of the Bragg reflections have been used to determine the extent of reaction (or) versus time for each of these reactions. A number of kinetic models have been considered, including the Avrami-Erofeyev (m = 1.5) deceleratory nuclei-growth model and statistical simulation. The concentration and solvent dependence of the rate of Co(eta-C5H5), intercalation into 2H-SnS2 has also been determined. Surprisingly, we find that the rate of intercalation is invariant to the initial Co(eta-C5H5)(2) concentration over a wide concentration range. The rate of intercalation of the lithium salts (LiX; X = Cl, Br, NO3 and OH) into Gibbsite (gamma-Al(OH)(3)) giving the layered double hydroxides [LiAl2(OH)(6)]X . nH(2)O (X = Cl, Br, NO3 and OH) and [LiAl2(OH)(6)](2)SO4. nH(2)O has been studied. The temperature dependence of the rate of intercalation of LiCl yields an activation energy of 27 kJ mol(-1). The reaction was also found to be half order with respect to the initial concentration of LiCl. Time-resolved in situ energy dispersive X-ray powder diffraction (EDXRD) spectra have been recorded following the addition of an aqueous solution of hexadecyltrimethylammonium chloride (C16H33N+Me3Cl- = C(16)TMACl) to kanemite (NaHSi2O5. 3H(2)O). The diffraction data suggest that initially a layered phase forms due to intercalation of the alkylammonium ions which then transforms into a silicate-organic mesophase which is the precursor to the hexagonal mesoporous silicate, FSM-16. (C)2000 Elsevier Science Ltd All rights reserved.