Effect of surfactant/silica molar ratios on the formation of mesoporous molecular sieves: Inorganic mimicry of surfactant liquid-crystal phases and mechanistic implications
- Central Research Lab., Princeton, NJ (United States)
- Paulsboro Research Lab., NJ (United States); and others
The influence of surfactant/silica molar ratio (Sur/Si) in the synthesis of mesoporous molecular sieve materials (M41S) was studied in a simple ternary synthesis system containing tetraethylorthosilicate (TEOS), water, and the cetyltrimethylammonium (CTMA) cation at 100{degrees}C. The resulting silicate materials were characterized by X-ray diffraction, {sup 29}Si NMR, and FTIR. As the Sur/Si molar ratio increased from 0.5 to 2, the siliceous products obtained could be classified into four separate groups: MCM-41 (hexagonal), MCM-48 (cubic), thermally unstable M41S, and a molecular species, the cubic octamer [(CTMA)SiO{sub 2.5}]{sub 8}. One of the thermally unstable structures has been identified as a lamellar phase. These results are consistent with known micellar phase transformations that occur at various surfactant concentrations and reinforce the concept that liquid-crystal structures serve as templating agents for the formation of M41S type materials. 48 refs., 13 figs., 5 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 39390
- Journal Information:
- Chemistry of Materials, Vol. 6, Issue 12; Other Information: PBD: Dec 1994
- Country of Publication:
- United States
- Language:
- English
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