Effect of structural aluminium on the mesoporous structure of MCM-41
- 1 January 1995
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions
- Vol. 91 (17) , 2955-2959
- https://doi.org/10.1039/ft9959102955
Abstract
X-ray diffraction (XRD), 27Al magic-angle-spinning (MAS) NMR, N2 adsorption measurements and transmission electron microscopy (TEM) show that the one-dimensional channels of the mesoporous aluminosilicate MCM-41 containing only structural (four-coordinate) aluminium are much shorter in the sample with an Si/Al ratio of 34.1 (ca. 160 Å) than in purely siliceous MCM-41 (ca. 400 Å). The quality of the XRD patterns rapidly deteriorates as the aluminium content of the solid increases. However, aluminosilicate MCM-41 still preserves a perfect mesoporous structure with an average pore diameter of ca. 30 Å, a surface area of 990 m2 g–1 and a pore volume of 0.74 cm3 g–1. When the Na+ form of aluminosilicate MCM-41 is transformed into the Brønsted acidic H+ form, and some of the aluminium is removed from the structure, the uniform hexagonal mesopores partially collapse and macropores 200–2000 Å in diameter are formed.Keywords
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