内蒙古煤系硬质高岭土碱改性研究

Modification of Inner Mongolia Coal Measure Hard Kaolin with Alkali

考察了碱处理对内蒙古煤系硬质高岭土（简称高岭土）的物理化学性能及其裂化性能的影响。采用X射线衍射、魔角旋转固体核磁共振法表征了高岭土的组成和结构；采用BET法测定了碱改性高岭土的比表面积和孔径分布。实验结果表明，高岭土经1060℃煅烧1h后，大量的非晶态SiO2和γ—Al2O3分凝，这种非晶态的SiO2具有与碱反应的活性；高岭土中的六配位铝（Al（Ⅵ））比四配位铝（Al（Ⅳ））更易与碱反应，延长碱处理时间可提高Al（Ⅳ）的含量，降低Al（Ⅵ）的含量，有利于裂化反应的进行；碱改性高岭土的孔半径主要分布在2～8nm；随碱处理时间的延长，碱改性高岭土的裂化活性和裂化选择性提高。

Effects of alkali modified process on physio-chemical properties and catalytic cracking performances of Inner Mongolia coal measure hard kaolin from Inner Mongolia were studied. Compositions and structures of original kaolin, calcined kaolin and alkali modified kaolin were characterized by means of XRD,^29Si MAS NMR and ^27Al MAS NMR. Specific surface area and pore size distribution of alkali modified kaolins were determined by BET method. When kaolin was calcined at 1 060 ℃ for 1 h, quite a part of amorphous SiO2 and γ-Al2O3 segregated, where the amorphous SiO2 was easy to react with NaOH solution and then to be removed from the system. Octahedral Al （ Al （Ⅵ） ） was easier to react with NaOH solution than tetrahedral Al （ Al（ Ⅳ ）, With increasing of alkali treating time, content of Al （Ⅳ）increased, which was favorable to catalytic cracking. Catalytic cracking performances of alkali modified kaolin improved with increasing of alkali treating time.