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Title: 3-D Network-Structural Analysis in the crystallization process of zeolite by X-ray Spectroscopy
Keywords: Synchrotron X-ray spectroscopy, Crystallization mechanism, Structural evolution, Zeolites
Abstract: Zeolites are crystalline porous materials composed of SiO4 tetrahedra, widely used in catalysis and adsorption due to their shape selectivity and solid acidity. However, their hydrothermal synthesis does not follow classical nucleation theory, requiring deeper insight into precursor evolution. In this study, we investigate the crystallization mechanism of Fe-containing MWW-type zeolites using synchrotron-based X-ray techniques, specifically X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES). These methods reveal structural changes in the zeolite framework by focusing on oxygen and silicon atoms. Our results show significant changes in the bonding state of oxygen, especially in O–Si–O–Si torsional angles, linked to the formation of interlayer ten-membered rings. XES spectra further indicate the development of staggered SiO4 units, crucial for the zeolite framework. This work demonstrates the effectiveness of XES in tracking three-dimensional network changes in zeolites and other amorphous materials, providing valuable insights into their structural evolution. These findings contribute to a better understanding of zeolite crystallization and advance the field of material synthesis and characterization.
