介孔分子筛V-MCM-41的水热法制备与合成机理

Hydrothermal Synthesis of V-MCM-41 Mesoporous Molecular Sieves and Synthesis Mechanism

以十六烷基三甲基溴化铵为模板剂,廉价的工业级高模数比(3.3)的硅酸钠为硅源,通过水热法合成了V-MCM-41介孔分子筛.考察了合成条件对产物织构的影响,并采用低温氮吸附法分析探讨了介孔分子筛V-MCM-41的合成机理.结果表明,模板剂用量、pH值、加料方式、晶化温度、晶化时间、陈化时间和焙烧气氛等合成条件对介孔分子筛的制备均有影响,其中晶化温度、pH值和模板剂用量的影响最为明显.X射线衍射谱表明合成的介孔分子筛具有六方晶体结构.红外光谱和紫外可见光谱表明V进入了介孔分子筛的骨架结构.

V-MCM-41 mesoporous materials were synthesized by the hydrothermal method using cetyltrimethylammonium bromide （CTAB） as the template and industrial Na2O·3.3SiO2 as the silica source, which is much cheaper than conventional organic precursors. The effects of synthesis conditions on the structure of V-MCM-41 were investigated and the synthesis mechanism was studied by N2 adsorption. The results indicated that many factors affected the synthesis, including the molar ratio of Si source and CTAB, pH value, crystallization temperature and time, aging time, calcination atmosphere, and feeding mode. The most important factors involved crystallization temperature, pH value, and molar ratio of Si to CTAB. X-ray diffraction results showed that the samples had a highly ordered hexagonal structure. Fourier transform infrared and ultraviolet visible spectra provided strong evidence that most vanadium ions were incorporated into the framework of mesoporous siliceous MCM-41.