A Series of LiCl/γ-Al2O3 samples were prepared by mixing and then heating at 400℃ for 30 hours. 7Li MAS NMR was used to investigated their structures. The 7Li MAS NMR signal of LiCl in the dispersion phase was observed for the first time, and its chemical shift was at 0.25ppm.After the dispersion threshold of LiCl on γ-Al2O3 was achieved, the 7Li signal in the crystallme phase LiCl appears at -1.01ppm and its intensity increases with the increasing in LiCl loading.From the 2D nutation NMR spectra, it can be seen that the electric field gradient surrounding the lithium nuclei in the dispersion state is larger and so the quadrupole interaction is stonger than that in the crystalline state. The dispersion threshold indicated by NMR is in agreement with that deduced from XRD, which is about 0.136gLiCl/gγ-Al2O3.
XRD and FT-IR methods were applied to the studies of organic monolayer dispersionsystems. Naphthalene, borneol, benzoic acid, salicylic acid, phthalic acid and tartaric acid weremixed with γ-Al2O3 and SiO2 separately. The results showed that the organic compounds canalso disperse spontaneously onto the surfaces of different oxide-supports to become high dispersionstates like the behavior of inorganic salts and oxides. The organic substances studied are moreready to disperse with 1ess carboxyl or hydroxyl groups on their aromatic nucleus, suggesting themigration on the surface of the support is rate-determining during the dispersion. This point ofview is supported by the result of IR spectroscopy. The IR spectra of dispersed systems suggestthat the carboxy1 may react with the surface hydroxyl groups of the support to form salt-likestructures on the surface.
