Deformation of Ordered Mesoporous Silica Structures on Exposure to High TemperaturesReport as inadecuate




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Journal of Nanomaterials - Volume 2014 2014, Article ID 754076, 13 pages -

Research ArticleSchool of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST, UK

Received 14 July 2014; Revised 20 August 2014; Accepted 21 August 2014; Published 15 September 2014

Academic Editor: Anukorn Phuruangrat

Copyright © 2014 John B. Lowe and Richard T. Baker. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Ordered mesoporous silica materials are of interest for a wide range of applications. In many of these, elevated temperatures are used either in the preparation of the material or during its use. Therefore, an understanding of the effect of high temperature treatments on these materials is desirable. In this work, a detailed structural study is performed on silicas with three representative pore structures: a 2-D hexagonal pore arrangement SBA-15, a continuous 3D cubic bimodal pore structure KIT-6, and a 3D large cage pore structure FDU-12. Each silica is studied as prepared and after treatment at a series of temperatures between 300 and 900°C. Pore structures are imaged using Transmission Electron Microscopy. This technique is used in conjunction with Small-Angle X-ray Diffraction, gas physisorption, and

Si solid state Nuclear Magnetic Resonance. Using these techniques, the pore size distributions, the unit cell dimensions of the mesoporous structures, and the relative occupancy of the distinct chemical environments of Si within them are cross correlated for the three silicas and their evolution with treatment temperature is elucidated. The physical and chemical properties before, during, and after collapse of these structures at high temperatures are described as are the differences in behavior between the three silica structures.





Author: John B. Lowe and Richard T. Baker

Source: https://www.hindawi.com/



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