Low silica MCM-41 composites and mesoporous solids
- Univ. of California, Santa Barbara, CA (United States)
Aluminosilicate MCM-41 mesophase solids have been prepared under alkaline conditions with high degrees of mesoscopic order and silicon-to-aluminum molar ratios approaching unity. One- and two-dimensional solid-state NMR techniques, in conjunction with elemental analyses, infrared spectroscopy, and powder X-ray diffraction (XRD), establish that high concentrations of aluminum have been incorporated into the aluminosilicate MCM-41 frameworks, with retention of mesoscopic order. Hexagonal low silica MCM-41 has been prepared with a bulk molar Si/Al ratio as low as 1.3, while retaining a minimum of three indexable p6mm reflections in the XRD pattern prior to calcination. Following calcination to remove the structure-directing surfactant molecules, the hexagonal MCM-41 structures are preserved. The decreased thermal stabilities and dealumination of the materials with higher aluminum contents have been studied using 2D {sup 27}Al{l_brace}{sup 1}H{r_brace} heteronuclear correlation NMR and {sup 27}Al MAS intensity calibration techniques to examine surface structures and quantify Al species present before and after calcination.
- OSTI ID:
- 351553
- Journal Information:
- Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 5 Vol. 11; ISSN CMATEX; ISSN 0897-4756
- Country of Publication:
- United States
- Language:
- English
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