Direct hydrothermal synthesis of hierarchically porous siliceous zeolite by using alkoxysilylated nonionic surfactant.
Direct hydrothermal synthesis of hierarchically porous siliceous zeolite by using alkoxysilylated nonionic surfactant.
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DOI：
10.1021/la902764s
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
R. Mukti;Hirotomo Hirahara;Ayae Sugawara;Atsushi Shimojima;T. Okubo
中科院分区：
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作者：
R. Mukti;Hirotomo Hirahara;Ayae Sugawara;Atsushi Shimojima;T. Okubo
以三烷基氧基化烷基聚氧乙烯醚为介孔导向剂，水热合成了一种具有窄介孔的多级多孔硅质MFI分子筛（硅石-1）。在反应初期形成了介观结构的二氧化硅-表面活性剂复合材料，在随后的水热处理中进行沸石结晶。结晶产物的扫描电镜（SEM）和透射电镜（TEM）观察表明，微孔和介孔分层排列在独特的颗粒形态中，表面凹凸不平。固体（29）Si和（13）C核磁共振表明，煅烧前产物中存在沸石骨架与介孔导向剂之间的共价键。采用非硅烷化烷基聚氧乙烯醚或硅烷化烷基三甲基铵型阳离子表面活性剂合成硅石-1，最终产物为介孔二氧化硅与沸石的混合物，说明共价相互作用和非静电电荷匹配相互作用有利于分层介孔硅质沸石的形成。该烷氧基化非离子表面活性剂还可扩展合成铝硅酸盐MFI分子筛（ZSM-5）。
A hierarchically porous siliceous MFI zeolite (silicalite-1) with narrow mesoporosity has been hydrothermally synthesized by using trialkoxysilylated alkyl poly(oxyethylene ether) as mesopore-directing agent. A mesostructured silica-surfactant composite was formed at the early stage of the reaction, and zeolite crystallization proceeded during subsequent hydrothermal treatment. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations of the crystallized products showed that micro- and mesopores were hierarchically assembled in unique particle morphology with rugged surfaces. Solid-state (29)Si and (13)C NMR revealed that the covalent bonds between the zeolite framework and mesopore-directing agent were present in the products before calcination. The use of nonsilylated alkyl poly(oxyethylene ether) or a silylated alkytrimethyl-ammonium-type cationic surfactant for the synthesis of silicalite-1 resulted in a mixture of mesoporous silica and zeolite as the final product, which suggests that the covalent interaction and nonelectrostatic charge matching interaction favor the formation of hierarchically mesoporous siliceous zeolite. This alkoxysilylated nonionic surfactant can also be extended to synthesize aluminosilicate MFI zeolite (ZSM-5).