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Study on the Course of Crystallization of Gallosilicate with MFI Structure
Author(s) -
Tuan V. A.,
Fricke R.,
Jänchen J.,
Kosslick H.
Publication year - 1992
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170270605
Subject(s) - crystallization , nucleation , zeolite , crystal growth , alkalinity , crystal (programming language) , crystallography , gallium , chemistry , chemical engineering , materials science , catalysis , organic chemistry , computer science , programming language , engineering
The kinetics of nucleation and crystallization of zeolite Ga‐ZSM‐5 crystallized in the system 15 Na 2 O * x Ga 2 O 3 * 100 SiO 2 * 13 TPABr * 4400 H 2 O is investigated. The course of crystallization is followed by different methods: XRD, MIR, TG‐DTA, n‐hexane adsorption. NH 3 ‐TPD and pH‐measurement. The low apparent activation energies of nucleation E n = 42.5 KJ/mole and crystallization E c = 20.4 KJ/mole show that the incorporation of gallium into the framework of the zeolite is not as difficult as expected from the disruptive nature of this process. Other synthesis parameters, e.g. temperature, alkalinity and gel composition have a major influence on the crystallization process. Here the nucleation is pronounced influenced whereas the crystal growth is only marginally influenced. The physico‐chemical characterization proves the formation of „reactive” and catalytic active gallosilicate species already in the gel, which are assumed to take part directly in the crystal growth process.