蒙脱石热活化与微结构变化关系研究

Microstructure changing in montmorillonite thermal treatment process

对广东和平蒙脱石及其热处理产物进行了化学分析、差热和热重分析、X射线粉末衍射、扫描电子显微镜、顺磁共振及魔角旋转核磁共振等研究.蒙脱石在热处理温度达到659℃时,八面体片中的羟基开始脱失,但层状结构仍然保持,这种羟基的脱失过程对应着八面体片中AlⅥ向AlⅣ的转变.当温度达到900℃时,蒙脱石的层状结构完全被破坏,并有新的矿物相μ-堇青石产生,当温度为1200℃时,则出现方英石及莫来石相.当热处理温度达到1 350℃时,方英石及莫来石的含量略有减少,并出现较多的含铁堇青石相.

The montmorillonite in Heping,Guangdong province has been studied through chemical analysis,DAT,TG, XRD,IR,AFM and MAS NMR.The hydroxyl in octahedra sheets begins dehydrating,when the thermal treatment temperature reaches 659℃,but the layer structure remains unchanged,the corresponding Al~Ⅵ turns into Al~Ⅳ in octahedra sheets.When the temperature reaches 900℃,the layer structure of montmorillontite is destroyed,and the new mineral phase ,μ-eordierite is found.When at 1 200℃,tile/z-cordierite phase loses stability,and decomposes into cristobalite phase and mullite phase,mean- while,the re-crystallization phenomenon in thermally treated products is obvious.There is a small quantity of Al~Ⅵ signals in MAS NMR spectrum,this Al~Ⅵ corresponds to the A1 of mullite.When at 1 350℃,the cristobalite and mullite phases reduce slightly, and more Fe-cordierite phases appear.There is correspondingly Fe-cordierite spectrum in XRD and MAS NMR.