Transformation of Layered Docosyltrimethyl- and Docosyltriethylammonium Silicates Derived from Kanemite into Precursors for Ordered Mesoporous Silicas
2002; American Chemical Society; Volume: 18; Issue: 24 Linguagem: Inglês
10.1021/la026041l
ISSN1520-5827
AutoresTatsuo Kimura, Daigo Itoh, Tetsuro Shigeno, Kazuyuki Kuroda,
Tópico(s)Clay minerals and soil interactions
ResumoThe transformation of layered silicate−surfactant materials derived from a layered polysilicate kanemite into precursors for ordered mesoporous silicas was investigated. When kanemite was allowed to react with docosyltrimethylammonium (C22TMA) and docosyltriethylammonium (C22TEA) surfactants, layered C22TMA− and C22TEA−silicate materials were formed. The 29Si MAS NMR spectra of the layered intermediates clearly indicated that fragmented silicate sheets were present in the silicate−surfactant materials. These layered materials can be transformed by acid treatment into mesostructured precursors with three-dimensional (3-d) silicate networks that afford uniform mesopores after the removal of the surfactants. Ordered mesoporous silica with a 2-d hexagonal structure (FSM-16) can be obtained by using C22TEA with a larger headgroup. The results here successfully support the proposed formation mechanism of FSM-16, which consists of assembling of fragmented layered silicate sheets with surfactants and the subsequent structural transformation to the 2-d hexagonal mesophase.
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