MAS NMR Spectra of Montmorillonite and Its Thermal Treatment Products

The montmorillonite in Heping, Guangdong province was studied by chemical analysis, DTA, TG, XRD, IR, AFM and MAS NMR It is found that when the temperature is between 500～700  C, The Si and Al spectra of montmorillonite display the spectrum characteristic of meta montmorillonite When the thermal treatment temperature reaches 659  C, the hydroxyl in octahedra sheet begins dehydrating, but the layer structure is maintaining, this process is corresponding to Al( Ⅵ) turning to Al(Ⅳ) in octahedra sheet When the temperature reaches 900  C, the Si spectra relevant to montmorillonite disappear, that means the layer structure of montmorillonite is destroyed, and the new mineral phase χ SiO 2 is found When the temperature reaches 1000 c C, there is more χ SiO 2 phase produced by phase change, meanwhile the Al spectra of thermal products change greatly When the temperature reaches 1200  C, cristobalite and mullite phases appear When the temperature r eaches 1350  C, the cristobalite and mullite phases reduce a few, and more cordierite phases appear