CRYSTALLIZATION MECHANISM FOR ATMOSPHERIC SYNTHESIS OF HIGH-SILICA ZSM-5

High-silica ZSM-5 was synthesized under atmospheric conditions at temperatures below 100-degrees-C. The initial progress of crystallization could be observed easily because of the very long induction period. Thin, plate-like lamellae were found as the first solid phase; they were then broken into smaller intermediate particles. The nucleation and crystallization of high siliceous crystals initially occurred on the surface of these intermediate particles and thereafter aluminium incorporated into the zeolite framework, resulting in further growth of the crystals.