In Situ Synchrotron Small-Angle X-ray Scattering/X-ray Diffraction Study of the Formation of SBA-15 Mesoporous Silica
Citations Over TimeTop 10% of 2004 papers
Abstract
The initial stages of the formation of SBA-15 have been studied by in situ SAXS/XRD using synchrotron radiation. Modeling of both the diffuse scattering and the X-ray diffraction patterns obtained at different stages of the reaction results in a detailed description of the different reaction steps. The first step in the formation is the liquid-liquid phase separation of spherical P123-silicate hybrid micelles after which nucleation and growth of the 2D hexagonal phase occurs. Two-dimensional electron density maps calculated on the basis of the intensities of the Bragg reflections suggest that changes in the degree of intermicellar condensation are responsible for the time-dependent observations. The silica source (alkoxysilanes) may be partially unhydrolyzed long after formation of the hexagonal structure, since the kinetics of the mesophase evolution is notably slower when TEOS is used as the silica precursor as compared to TMOS. The results obtained for SBA-15 are compared with other published data on the formation ofSBA-15 and of the smaller pore MCM-41 materials.
Related Papers
- → In-situ monitoring for mesophase formation processes of various pitches by means of high-temperature 13C-NMR(1991)21 cited
- → Chemistry and development of mesophase in pitch(1984)20 cited
- → A Method for the Determination of Mesophase Contents in Mesophase Pitch by Image Analysis(1993)
- → Quantitative analysis on carbonaceous mesophase from fused-state 13C-NMR spectra^|^mdash;Molecular structure, orientation and fluctuations of the constituents^|^mdash;(2012)
- Formation Behavior of Bulk Mesophase Pitch(1988)