日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

Solid-state NMR studies of layerd clay minerals and their intercalation compounds are reviewed. Kaolinite is treated as a representative of the clay minerals in this article. ²⁹Si NMR spectra confirm the presence of two inequivalent Si sites, and ²⁷Al NMR spectra also suggest the presence of two inequivalent Al sites. ¹H wide-line NMR spectra demonstrate rigidity of the hydroxy groups. The ¹H chemical shift obtained by use of the CRAMPS technique indicates the basic nature of the hydroxyl groups. Natural Kaolinites contain a considerable amount of paramagnetic impurities such as Fe³⁺, which have a great effect on the linewidth of the NMR spectrum and the nuclear relaxation time. NMR studies of heat-treated kaolinite samples give us information on spatial distribution of residual hydroxyl groups in the dehydroxylation process and change in the coordination number of Al atoms. NMR studies of the intercalation compounds present changes in the structure of the host lattice caused by the intercalation and the sites and the dynamics of guest molecules. However, further studies are necessary to specify the saites and the dynamics unequivocally.