高岭石-甲醇夹层复合体的合成及其特性

以水合联胺,10 mol尿素水溶液及甲醇先后与高岭石反应,合成了晶面间距为1.0 nm的高岭石甲醇夹层复合物。复合物不太稳定,在常温下 (约放置72 h) 或1050C加热下 (2 min)晶面间距收缩为0.85 nm。于2000C加热时,晶面间距进一步收缩为0.79 nm。0.79 nm复合物在3000C条件下长时间加热也未再发生变化。由层间膨胀值的大小及甲醇分子的最小厚度推测,0.85 nm及0.79 nm夹层复合体中甲醇分子明显地嵌入了高岭石的结构内部。其甲基可能嵌入了硅氧四面体的六角环空洞中,而羟基嵌入了铝氧八面体内。IR图谱表明0.79 nm复合物中甲醇分子与高岭石的相互作用较之0.85 nm复合物更强。

SYNTHESIS AND PROPERTIES OF KAOLINITE-METHANOL INTERCALATED COMPLEX

A kaolinite-methanol intercalated complex with inter-spacing of 1.0 nm was synthesized by washing kaolinite with hydrazine monohydrate, 10 mol aqueous solution of urea, and pure methanol successively. The complex was unstable at the beginning and under ambient conditions for 72 hrs or the temperature of 105 OC for 2 min, the inter-spacing reduced to 0.85 nm, and further to 0.79 nm under the temperature of 200 OC. It remained unchanged even if the complex was put under the temperature of 300 OC for 24 hrs. The change in inter-spacing under heat treatment and the IR spectra of the resultant 0.85 nm and 0.79 nm intercalates clearly showed presence of methanol in the interspace of the complex. Judging from the expansion value and the minimum diameter of a methanol molecular, only a single layer of the organic molecules was intercalated with a considerable amount of bonds (lower inter-spacing of the intercalates indicating higher extent to which methanol molecules were inserted). It was deduced that methyls were possibly inserted into hexagonal rings of silica tetrahedrons and hydroxyls into octahedrons. Perturbation and shift of infrared absorption bands attributed to hydroxyls in kaolinite structure suggested that interaction between methanol molecule and kaolinite was stronger in 0.79 nm intercalate than in 0.85 nm intercalate.