Title: Combined NMR, SAXS, and DLS study of concentrated clear solutions used in silicalite-1 zeolite synthesis
Authors: Aerts, Alexander ×
Follens, Lana
Haouas, Mohamed
Caremans, Tom
Delsuc, Marc-Andre
Loppinet, Benoit
Vermant, Jan
Goderis, Bart
Taulelle, Francis
Martens, Johan
Kirschhock, Christine #
Issue Date: Jul-2007
Publisher: American Chemical Society
Series Title: Chemistry of Materials vol:19 issue:14 pages:3448-3454
Abstract: Concentrated clear solutions, as used for the preparation of Silicalite-1 zeolite, were synthesized from tetrapropylammonium hydroxide, tetraethylorthosilicate, and water. The solutions were analyzed using three techniques: quantitative Si-29 NMR, synchrotron small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS). Si-29 NMR showed the coexistence of silicate oligomers and particles. For the first time, both fractions were analyzed simultaneously, providing a global, quantitative description of the clear solution microstructure. The SAXS patterns, typical of interacting particles, could be used together with the Si-29 NMR deduced particle volume fraction to estimate a particle size. A careful analysis of DLS data of the dynamics of the suspensions revealed the occurrence of two diffusive processes. The faster process is a collective particle diffusion. The slower process corresponds to the particle self-diffusion and is present because of the presence of polydispersity in size, shape, and/or surface charge. The self-diffusion coefficient provides a means to estimate the equivalent hydrodynamic radius. The observations hence reveal a complex, polydisperse mixture of particles present at the onset of the Silicalite-1 zeolite formation. Implications on the proposed zeolite formation mechanisms are briefly discussed.
ISSN: 0897-4756
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Centre for Surface Chemistry and Catalysis
Soft Matter, Rheology and Technology Section
Molecular Imaging and Photonics
Polymer Chemistry and Materials
× corresponding author
# (joint) last author

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