| Research Abstract |
Zeolites have been synthesized by the hydrothermal synthetic method Recently, the dry gel conversion method as the technique of zeolite crystallization was developed. In this report, we investigated the crystallization mechanism of various type of zeolites synthesized by the conventional hydrothermal synthetic method and novel dry gel conversion method. We focus particularly on the aluminosilicate species in not only the atomic scale level, but also in a nano-scale level.
In the case of the hydrothermal synthesis of MFI-type zeolite, when the solubility of aluminosilicate species was low, it was obvious that MFI-type zeolite consisted of aggregate of nano-particles in a diameter of several dozen nanometers. Moreover, it was possible that silicateli-1 was formed by the solid-solid transformation directly from amorphous nano-particles to fine MFI-type crystals.
In the case of the synthesis of EMT-type zeolite by using the dry gel conversion method, we found out that nano-particles fuse and the surface of the dry gel is rearranged, resulting in a distinct hexagonal shape for the EMT crystals.
Additionally, since we suggested that alinninosilicate species having die framework structure of ZSM-5 zeolite exist in the filtrate of alkaline dissolution of ZSM-5, we succeeded the mesoporous materials having a strong acidity caused by the structure of zeolite framework was synthesized by using the aluminosilicate species in the filtrate of alkaline dissolution of ZSM-5.
In conclusion, we investigated the crystallization mechanism of zeolites, focusing on the structural species in a nano-scale level, and the novel acidic catalyst was prepared by using the species having the framework structure of zeolite in a nano-scale.
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