In situ NMR and XRD studies of the growth mechanism of SBA-1

C. C. Egger, M. W. Anderson, G. J T Tiddy, J. L. Casci

    Research output: Contribution to journalArticlepeer-review

    Abstract

    In situ 17O, 14N and 29Si nuclear magnetic resonance (NMR) coupled with in situ energy dispersive X-ray diffraction (EDXRD) have been used to investigate the growth of the siliceous mesoporous material, SBA-1, synthesised under acidic conditions from a micellar solution of the surfactant hexadecyltriethylammonium bromide (HTEAB) and tetraethylorthosilicate (TEOS). For the last decade, the mechanism of growth of such materials has been thought to be driven by electrostatic interactions described as a co-assembly process between the silica species (I+) and the micelles (S+X-). However, this postulated model referred to as the "charge density matching model" has never been fully supported by experimental data for the acidic syntheses. We have carried out a detailed in situ study which challenges the so-called S+X -I+ pathway and instead suggests that a salting-out effect coupled with a drastic change in the water activity are responsible for the composite I13 (SBA-1 space group P m3̄n) mesophase precipitation. Substantial reorganisation of the precipitated phase then results in the final structure. © The Owner Societies 2005.
    Original languageEnglish
    Pages (from-to)1845-1855
    Number of pages10
    JournalPhysical Chemistry Chemical Physics
    Volume7
    Issue number8
    DOIs
    Publication statusPublished - 21 Apr 2005

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