Details
| Original language | English |
|---|---|
| Pages (from-to) | 153-161 |
| Number of pages | 9 |
| Journal | Microporous and Mesoporous Materials |
| Volume | 124 |
| Issue number | 1-3 |
| Early online date | 7 May 2009 |
| Publication status | Published - Sept 2009 |
Abstract
Synthesis conditions for the preparation of uniform and well-shaped ITQ-29 crystals, i.e. synthesis time and the chemical composition of the batch such as the contents of water, structure-directing agent, hydrofluoric acid and germanium, were investigated at 423 K. The gels were prepared with molar compositions of (1 - x)SiO2: xGeO2: yROH: (0.5 - y)TMAOH: zHF: wH2O, where x was varied from 0 to 1, y from 0 to 0.5, z from 0 to 0.5, and w from 7 to 80. The crystal morphology and size, phase purity and Si/Ge ratio of the crystals were characterized by SEM, XRD and EDXS, respectively. For Corma's standard recipe, a crystallization time of 5 days is found to be optimum for the synthesis of ITQ-29 crystals in this study. The crystal size increases with increasing dilution; crystal sizes of 1, 7, 12 and 30 μm are obtained for water contents w = 7, 30, 40 and 80, respectively. An appropriate amount of ROH and TMAOH is required to form uniform and phase pure ITQ-29 crystals. High quality ITQ-29 crystals can be formed not only at neutral but also at alkaline and acidic conditions although the crystals morphology and size are different. Without germanium or without silicon in the starting gel, no ITQ-29 crystals can be obtained. Without silicon in the batch, germanium oxide crystallizes as AST crystals. The Si/Ge ratio of the synthesis batch is found to be reflected by the ITQ-29 and AST crystals.
Keywords
- Cation-free LTA, Hydrothermal synthesis, ITQ-29 crystals
ASJC Scopus subject areas
- Chemistry(all)
- General Chemistry
- Materials Science(all)
- General Materials Science
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Mechanics of Materials
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In: Microporous and Mesoporous Materials, Vol. 124, No. 1-3, 09.2009, p. 153-161.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Hydrothermal synthesis of uniform and well-shaped ITQ-29 crystals
AU - Huang, Aisheng
AU - Caro, Jürgen
PY - 2009/9
Y1 - 2009/9
N2 - Synthesis conditions for the preparation of uniform and well-shaped ITQ-29 crystals, i.e. synthesis time and the chemical composition of the batch such as the contents of water, structure-directing agent, hydrofluoric acid and germanium, were investigated at 423 K. The gels were prepared with molar compositions of (1 - x)SiO2: xGeO2: yROH: (0.5 - y)TMAOH: zHF: wH2O, where x was varied from 0 to 1, y from 0 to 0.5, z from 0 to 0.5, and w from 7 to 80. The crystal morphology and size, phase purity and Si/Ge ratio of the crystals were characterized by SEM, XRD and EDXS, respectively. For Corma's standard recipe, a crystallization time of 5 days is found to be optimum for the synthesis of ITQ-29 crystals in this study. The crystal size increases with increasing dilution; crystal sizes of 1, 7, 12 and 30 μm are obtained for water contents w = 7, 30, 40 and 80, respectively. An appropriate amount of ROH and TMAOH is required to form uniform and phase pure ITQ-29 crystals. High quality ITQ-29 crystals can be formed not only at neutral but also at alkaline and acidic conditions although the crystals morphology and size are different. Without germanium or without silicon in the starting gel, no ITQ-29 crystals can be obtained. Without silicon in the batch, germanium oxide crystallizes as AST crystals. The Si/Ge ratio of the synthesis batch is found to be reflected by the ITQ-29 and AST crystals.
AB - Synthesis conditions for the preparation of uniform and well-shaped ITQ-29 crystals, i.e. synthesis time and the chemical composition of the batch such as the contents of water, structure-directing agent, hydrofluoric acid and germanium, were investigated at 423 K. The gels were prepared with molar compositions of (1 - x)SiO2: xGeO2: yROH: (0.5 - y)TMAOH: zHF: wH2O, where x was varied from 0 to 1, y from 0 to 0.5, z from 0 to 0.5, and w from 7 to 80. The crystal morphology and size, phase purity and Si/Ge ratio of the crystals were characterized by SEM, XRD and EDXS, respectively. For Corma's standard recipe, a crystallization time of 5 days is found to be optimum for the synthesis of ITQ-29 crystals in this study. The crystal size increases with increasing dilution; crystal sizes of 1, 7, 12 and 30 μm are obtained for water contents w = 7, 30, 40 and 80, respectively. An appropriate amount of ROH and TMAOH is required to form uniform and phase pure ITQ-29 crystals. High quality ITQ-29 crystals can be formed not only at neutral but also at alkaline and acidic conditions although the crystals morphology and size are different. Without germanium or without silicon in the starting gel, no ITQ-29 crystals can be obtained. Without silicon in the batch, germanium oxide crystallizes as AST crystals. The Si/Ge ratio of the synthesis batch is found to be reflected by the ITQ-29 and AST crystals.
KW - Cation-free LTA
KW - Hydrothermal synthesis
KW - ITQ-29 crystals
UR - http://www.scopus.com/inward/record.url?scp=67649784543&partnerID=8YFLogxK
U2 - 10.1016/j.micromeso.2009.05.004
DO - 10.1016/j.micromeso.2009.05.004
M3 - Article
AN - SCOPUS:67649784543
VL - 124
SP - 153
EP - 161
JO - Microporous and Mesoporous Materials
JF - Microporous and Mesoporous Materials
SN - 1387-1811
IS - 1-3
ER -