Elucidation of Nucleation -Crystal Growth Mechanism of Zeolites in an Atomic Scale, and its Application to Novel Process

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The objectives of this study are elucidation of crystal growth mechanism of LTA and FAU zeolites in an atomic scale, and the development of the rational synthesis process based on the mechanism.In the first year, the detection of precursor and its contribution to the crystal growth in dilute system was focused. The same positions on the top surface of the seed crystals were repeatedly observed in the course of the growth. In one solution, LTA was grown on LTA, and FAU was grown on FAU. When Al content was reduced, LTA was grown on LTA, but FAU was unchanged. The solution was characterized by Raman spectroscopy. As the Al content was reduced, the ration of 4MR to 6MR was increased. These experimental results were accounted for by assuming that the precursor of LTA was 4MR, and that of FAU was 6MR.In the second year, further investigation was performed on the crystal growth. By observing the top surface carefully, the structure of the growing surface was elucidated. These results also supported that the precursor of LTA was 4MR, and that of FAU was 6MR. The species in the solution was characterized by novel method. High-Energy X-ray Diffraction (HE-XRD) of gel was performed at Spring-8 SR facility. We first succeeded in demonstrating that there are differences in the ring structure before crystallization.