Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9617667 | Microporous and Mesoporous Materials | 2005 | 12 Pages |
Abstract
The major synthesis routes described in the literature so far for zeolite Y (FAU) with an elevated nSi/nAl-ratio and larger crystallite sizes were systematically re-investigated. Syntheses in the presence of triethanolamine with or without added bis(2-hydroxyethyl)dimethylammonium chloride yielded large crystals (10-100 μm) of faujasite-type zeolites. However, only products with low nSi/nAl-ratios below 1.8 were obtained, and zeolite P was an inevitable side product or even the main product. Furthermore, the outcome of these syntheses was poorly reproducible. Following another known literature procedure, phase-pure zeolite Y could be obtained with the cyclic polyether 15-crown-5 as a structure-directing agent. The influence of ageing, homogenization and seeding of the synthesis gel, the crystallization time and temperature, different Si- and Al-sources and the addition of NaF as a mineralizer or of co-templates such as triethanolamine, ethylene glycol or 1,3,5-trioxane on the resulting product was investigated. A carefully optimized procedure led to large crystals of highly phase-pure zeolite Y with well defined octahedral morphology and a narrow crystal size distribution in the range of 4-5 μm. Such crystals can be reproducibly synthesized in high yields with an nSi/nAl-ratio of 3.4-4.0. Neither crystallization seeds nor an ageing of the synthesis gel before hydrothermal crystallization are required.
Related Topics
Physical Sciences and Engineering
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Authors
Christine Berger, Roger Gläser, Rainer A. Rakoczy, Jens Weitkamp,