Strucral analysis of SDA-containing zeolites for the elucidation of zeolite crystallization mechanism

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The crystal structure of SDA-containing zeolites were analyzed in order to extract a requirement for an SDA molecule to crystallize a certain structure of zeolite. Several organic SDAs having a similar structural feature were employed to synthesize LEV-type zeolites having a small lev cage, and the obtained zeolites were analyzed using X-ray powder diffraction data. The analysis results demonstrated that an SDA molecule was occluded in a lev cage and was tangent to an oxygen atom in lev cage in their van der Waals radii, which would be a size requirement for an SDA. SDAs with larger molecular sizes gave CHA-type zeolite having a larger cha cage. Considering that these two zeolites can be constructed from the same building unit, the framework of these zeolites could be constructed from the same building unit, and the size of SDA could decide the resulting phase of zeolite.