低质量分数表面活性剂作模板合成MCM-41中孔分子筛的机理探讨

The Mechanism of the Synthesis of Mesoporous Molecular Sieve MCM-41 Using Surfactant of Low Mass Fraction as Template

在MCM-41中孔分子筛合成工艺研究的基础上从表面活性剂相行为、无机物种缩聚过程、界面分子识别(包括静电力、范德华力、空间结构)等方面入手,探讨了低质量分数表面活性剂(CTMABr)作模板剂的离子型合成体系中MCM-41的形成机理。研究结果表明体系中的齐聚硅酸根阴离子与带正电的表面活性剂棒状胶束通过协同作用形成了MCM-41前驱体(类液晶相结构的六角胶束有序体),煅烧脱模即得全硅MCM-41中孔分子筛。按此机理解释了pH条件对合成MCM-41的影响。

The mechanism of the synthesis of pure silica mesoporous molecular sieve MCM-41,using surfactant(CTMABr) of low mass fraction as template, was studied according to the bulk behavior of surfactant, the condensation of inorganic species, and the molecular recognition on the interface(including static force, Van der Waals attraction, stereostructure ). It was found that the precursor (an ordered hexagonal micelle liking liquidcrystal structure) was formed by the cooperative actions of negativelycharged polymerized silicon acid and positivelycharged surfactant micelle liking robe, and the precursor can be changed into silica molecular sieve MCM-41 by calcing to remove the template. Based on this mechanism the effect of pH on the synthesis of MCM-41 was illustrated.