Pillared MFI Zeolite Nanosheets of a Single-Unit-Cell Thickness,Journal of the American Chemical Society

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Pillared MFI Zeolite Nanosheets of a Single-Unit-Cell Thickness
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2010-03-31 , DOI: 10.1021/ja908382n
Kyungsu Na ₁ , Minkee Choi ₁ , Woojin Park ₁ , Yasuhiro Sakamoto ₁ , Osamu Terasaki ₁ , Ryong Ryoo ₁

Affiliation

Zeolite MFI nanosheets of 2-nm thickness have been hydrothermally synthesized via cooperative assembly between silica and an organic surfactant, which is functionalized with a diquaternary ammonium group. The zeolite nanosheets have been further assembled into their ordered multilamellar mesostructure through hydrophobic interactions between the surfactant tails located outside the zeolite nanosheet. This assembly process involves successive transformations from an initially hexagonal mesophase to a multilamellar mesophase without crystallinity and then to a lamellar mesophase with a crystalline zeolite framework. The mesopore volume in the interlamellar space could be retained by supporting the zeolite nanosheets with silica pillars, as in pillared clays, even after surfactant removal by calcination. The mesopore diameters could be controlled according to the surfactant tail lengths. Due to the interlamellar structural coherence, the hierarchically mesoporous/microporous zeolite could exhibit small-angle X-ray diffraction peaks up to the fourth-order reflections corresponding to the interlayer distance. In addition, an Ar adsorption analysis and transmission electron microscopic investigation indicated that the pillars were highly likely to be built with an MFI structure. The present approach using a zeolite structure-directing functional group contained in a surfactant would be suitable for the synthesis of other related nanomorphous zeolites in the future.

中文翻译：

单晶胞厚度的柱状 MFI 沸石纳米片

2nm 厚的沸石 MFI 纳米片是通过二氧化硅和有机表面活性剂之间的协同组装水热合成的，有机表面活性剂用二季铵基团进行了功能化。通过位于沸石纳米片外部的表面活性剂尾部之间的疏水相互作用，沸石纳米片进一步组装成其有序的多层介观结构。该组装过程涉及从最初的六边形中间相到没有结晶度的多层中间相，然后到具有结晶沸石骨架的层状中间相的连续转变。即使在通过煅烧去除表面活性剂之后，通过用二氧化硅柱支撑沸石纳米片，如在柱撑粘土中一样，可以保留层间空间中的中孔体积。中孔直径可以根据表面活性剂尾部长度进行控制。由于层间结构相干性，分级介孔/微孔沸石可以表现出小角度 X 射线衍射峰，直至对应于层间距离的四阶反射。此外，Ar 吸附分析和透射电子显微镜研究表明，这些支柱很可能是用 MFI 结构建造的。目前使用表面活性剂中含有的沸石结构导向官能团的方法将适用于未来其他相关纳米晶沸石的合成。分级介孔/微孔沸石可以表现出小角度 X 射线衍射峰，最高可达与层间距离对应的四阶反射。此外，Ar 吸附分析和透射电子显微镜研究表明，这些支柱很可能是用 MFI 结构建造的。目前使用表面活性剂中含有的沸石结构导向官能团的方法将适用于未来其他相关纳米晶沸石的合成。分级介孔/微孔沸石可以表现出小角度 X 射线衍射峰，最高可达与层间距离对应的四阶反射。此外，Ar 吸附分析和透射电子显微镜研究表明，这些支柱很可能是用 MFI 结构建造的。目前使用表面活性剂中含有的沸石结构导向官能团的方法将适用于未来其他相关纳米晶沸石的合成。

更新日期：2010-03-31

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