高岭石-甲醇插层复合物的结构及热分解行为

Structure and Thermal Decomposition Behavior of Kaolinite-Methanol Intercalation Compound

采用多次置换插层法制得高岭石-甲醇插层复合物,用X射线衍射、傅里叶变换红外光谱、热重和差示扫描量热技术对产物的结构和热分解行为进行了表征。结果表明：甲醇插入到高岭石层间,高岭石层间距由0.71 nm扩大到0.93 nm,插层率为100%。插层复合物中,甲醇分别以与高岭石内表面范德华力结合、氢键键合及嵌入复三方孔穴三种形态存在。在加热过程中,插层复合物分三步分解。第一步分解发生于30~120℃,为层间范德华力结合的甲醇分子的脱嵌过程;第二步发生于120~350℃,是氢键键合的甲醇的脱嵌过程;第三步发生在400~600℃,对应于高岭石脱羟基和嵌入高岭石晶格内部的甲醇的脱嵌过程。计算得到复合物体系中高岭石与甲醇的分子摩尔比为1∶0.7,其中以范德华力结合、氢键键合和嵌入复三方孔穴的甲醇的摩尔比为5.2∶11.8∶1。

The kaolinite / methanol intercalation compound was prepared via multipe displacements intercalation. The structure and thermal decomposition behavior of the compound were characterized by X-ray diffraction（ XRD） and Fourier transformation infrared（ FT-IR）,simultaneous thermogravimetricdifferentialscanning calorimetry（ TG-DSC）. The result shows that intercalation of methanol into kaolinite increases the basal spacing from 0. 71 to 0. 93 nm,and the intercalation rate is 100%. Intercalated methanol molecules existed in three status between the sheets of kaolinite,which were methanol bonded by hydrogen,Van der Waals forces and embedded into the ditrigonal cavities of the kaolinite tetrahedral silica side. The compound decomposes in three steps during heat, the first step at 30-120 ℃ is the deintercalation process of methanol bonded by Van der Waals forces,the second step at 120-350 ℃ is the deintercalation process of hydrogen-bonded methanol; the third step at 400-600 ℃ is the dehydroxylation process of kaolinite,accompanied by the deintercalation of the methanol embedded into the lattice of kaolinite. The molar ratio of kaolinite and methanol in the intercalation system is 1 ∶ 0. 7,and the molar ratio of methanol bonded by Van der Walals forces,hydrogen-bonded methanol and embedded methanol is 5. 2∶ 11. 8∶ 1.