改性层状粘土矿物固体酸酸强度及其催化性能研究

用盐酸对高岭石和蒙脱石进行酸活化改性,再对酸活化后的蒙脱石进行羟基铝柱撑改性,然后采用X射线衍射仪对改性前后的矿物结构进行表征,并在此基础上,采用Hammett指示剂法,以正丁胺-环己烷滴定在H0为+4. 8～-5. 6酸强度范围的固体表面酸上,测出各粘土在不同酸强度下的酸量,拟合得到其酸强度分布曲线,最后以异丙苯裂解转化为模型考察了各粘土固体酸的催化性能。实验结果表明,高岭石和蒙脱石经酸活化后虽然可以提高异丙苯转化率,但是催化稳定性却有所降低;蒙脱石经过羟基铝柱撑改性后不仅大幅度提高了异丙苯转化率,而且还提高了催化稳定性。

A study of acid strength and catalytic performance of modified layered clay solid acid

The kaolinite and montmorillonite were activated and modified by hydrochloric acid. Then a pillared montmorillonite was prepared by acided montmorillonite and hydroxyl aluminum.The structure of mineral sample was characterized by X-ray diffraction. By using Hammett indicator method and butylamine-cyclohexane solution the authors measured the surface acidity of clay with H₀ value in the range of +4.8~-5.6, and obtained the distribution curves of acid strength by fitting. The authors studied the catalytic performance of clay solid acid by pyrolysis of cumene converted into a model reaction. The result shows that cumene conversion has been improved through being catalyzed by acid-actived clay solid acid, but the catalytic stability is reduced. The modification of montmorillonite by hydroxyaluminum pillars not only greatly increases the conversion of cumene but also improves the catalytic stability.