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使用四丁基氢氧化铵-正硅酸四乙酯-水(TBAOH-TEOS-H2O)简单体系一步水热制备了具有多级孔道的微米级MEL结构分子筛聚集体.得到的silicalite-2微米球直径大于10μm且具有高达460 m2·g-1的比表面积和0.74 cm3·g-1的孔体积.微米球的生成一定程度上解决了催化应用过程中催化剂的分离和回收问题.同时,水热晶化过程中由纳米粒子自组装而成的晶间介孔缩短了反应物分子的扩散路径,保持了分子筛纳米晶粒的优势.此外,钛活性位的引入并未明显影响MEL微米球的形貌和结构,含钛的MEL微米球TS(钛硅分子筛)-2在苯酚羟基化反应中具有与纳米尺寸TS-1(100-200 nm)相当的催化活性,且TS-2可以通过简单过滤得到,简化了纳米级TS-1的分离和回收过程.
The microstructure of micron-scale MEL molecular sieve with multi-level pores was prepared by one-step hydrothermal method using tetrabutylammonium hydroxide-tetraethylorthosilicate-water (TBAOH-TEOS-H2O) simple system.The obtained silicalite-2 micron spheres were larger than 10μm and has a specific surface area up to 460 m2 · g-1 and a pore volume of 0.74 cm3 · g-1. The formation of the microspheres solves the problem of separation and recovery of the catalyst during the catalytic application to some extent. Meanwhile, hydrothermal crystallization In the process, the intergranular mesopores formed by the self-assembly of nanoparticles shorten the diffusion path of the reactant molecules and maintain the advantages of the nanocrystalline zeolite. In addition, the introduction of titanium active sites did not significantly affect the morphology of the MEL microspheres and Structure, the titanium-containing MEL microspheres TS (titanium silicalite) -2 have comparable catalytic activity to the nanosize TS-1 (100-200 nm) in the hydroxylation of phenol and TS-2 can be obtained by simple filtration, Simplifies the separation and recovery of nanoscale TS-1.