水热合成过程中Silicalite-1晶体形貌和尺寸的调控

发布时间：2018-11-24 18:12

【摘要】：以气相SiO2为硅源、四丙基铵(TPA)为模板剂,水热合成了Silicalite-1分子筛,考察了合成液的水量、碱度(Na2O含量)、四丙基铵(TPA)含量和晶化条件(合成时间和搅拌方式)对Silicalite-1分子筛晶体形貌和尺寸的影响,采用X射线衍射(XRD)、扫描电镜(SEM)、激光粒度仪(LLS)等技术对合成的Silicalite-1分子筛晶体进行表征。结果表明,减少水量和增大碱度可以使Silicalite-1晶体由棺形转变为球形,但碱度过高或过低时,分子筛晶体的产率很低;增加TPA浓度和缩短晶化时间可以减小Silicalite-1分子筛晶体的粒径,且均能获得较高的收率;不同的搅拌方式会影响晶体的粒径大小和分布,转动式合成能够得到粒径较为均一的晶体,而搅拌式合成能得到粒径分布较广的晶体,粒径相对较小。因此,通过调节合成液组成和合成条件,可以控制Silicalite-1晶体的形貌和尺寸。
[Abstract]:Silicalite-1 molecular sieve was synthesized by hydrothermal method using gas phase SiO2 as silicon source and tetrapropylammonium (TPA) as template. The water content and basicity (Na2O content) of the synthesized solution were investigated. The effects of (TPA) content and crystallization conditions (synthesis time and stirring mode) of tetrapropylammonium on the morphology and size of Silicalite-1 molecular sieve were studied by X-ray diffraction (XRD), scanning electron microscope (SEM),). The synthesized Silicalite-1 molecular sieve crystals were characterized by laser particle size analyzer (LLS). The results show that reducing water and increasing alkalinity can change Silicalite-1 crystal from coffin shape to spherical shape, but when alkalinity is too high or too low, the yield of molecular sieve crystal is very low. Increasing the concentration of TPA and shortening the crystallization time can reduce the particle size of Silicalite-1 molecular sieve crystal and obtain higher yield. Different stirring modes can affect the size and distribution of the crystal. The crystal with uniform particle size can be obtained by rotational synthesis, while the crystal with wider particle size distribution can be obtained by stirring synthesis, and the particle size is relatively small. Therefore, the morphology and size of Silicalite-1 crystals can be controlled by adjusting the composition and synthesis conditions.
【作者单位】：浙江大学化学工程与生物工程学院;
【基金】：国家自然科学基金(21236006) 中国博士后科学基金(2014M550326)项目资助
【分类号】：O643.36

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