Synthesis of novel microporous materials based on the elucidation of formation of zeolites in nanolevel

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In this research project, investigation on zeolite precursors during the stages of nucleation and crystal growth is performed at the level of atomic scale by means of various in situ characterization techniques. The formation process of zeolite crystals is recognized here as a kind of reaction network.As for the clarification of zeolite precursors, generation of ring structures which are composed of hetero-atoms such as oxides of Si, Al, and/or other metals, and the roles of alkali metals in the generation were focused on. High-Energy X-Ray Diffraction (HEXRD) is utilized for the investigation of ring structures of aluminosilicate species involved in the formation process of zeolites. We could clarify by the tool the critical roles of hetero-atoms on the ring species and of alkali metals on the assembly of the rings. We could successfully lead the conclusion that introduction of Al into the ring structure decreased the proportional contribution of odd-numbered rings, and the addition of Zn enhanced the formation of three-membered ring. It is noted that the ring number distribution is already determined in the amorphous phase of reactant aluminosilicate hydrogel prior to crystallization to each zeolitic phase. In the successive stage, nucleation and growth, we concluded that three kinds of particles of primary and secondary units and crystal exist in the aqueous phase of solution, by our original contribution using Small Angle X-ray Scattering(SAXS)-Wide Angle X-ray Scattering(WAXS) in situ measurement. We finally proposed a whole schematic process of crystallization of zeolite through these explorations.We also succeeded to obtain much smaller nano-crystal of zeolite than previously reported, owing to the knowledge obtained above. In this method, nano-crystals at higher concentration were achieved to crystallize without addition of organic additives, which are conventionally accepted as an indispensable reagent for such a type of nano-crystal.