Issue 10, 2016

Establishing hierarchy: the chain of events leading to the formation of silicalite-1 nanosheets

Abstract

In applying a multi-scale spectroscopic and computational approach, we demonstrate that the synthesis of stacked zeolite silicalite-1 nanosheets, in the presence of a long-tail diquaternary ammonium salt surfactant, proceeds through a pre-organised phase in the condensed state. In situ small-angle X-ray scattering, coupled to paracrystalline theory, and backed by electron microscopy, shows that this phase establishes its meso-scale order within the first five hours of hydrothermal synthesis. Quasi in situ vibrational and solid-state NMR spectroscopy reveal that this meso-shaped architecture already contains some elementary zeolitic features. The key to this coupled organisation at both micro- and meso-scale, is a structure-directing agent that is ambifunctional in shaping silica at the meso-scale whilst involved in molecular recognition at the micro-scale. The latter feature is particularly important and requires the structure-directing agent to reside within the silica matrix already at early stages of the synthesis. From here, molecular recognition directs stabilization of precursor species and their specific embedding into a lattice, as shown by force-field molecular dynamics calculations. These calculations, in line with experiment, further show how it is possible to subtly tune both the zeolite topology and aspect ratio of the condensating crystals, by modifying the headgroup of the structure-directing agent.

Graphical abstract: Establishing hierarchy: the chain of events leading to the formation of silicalite-1 nanosheets

Supplementary files

Article information

Article type
Edge Article
Submitted
22 Mar 2016
Accepted
22 Jun 2016
First published
22 Jun 2016
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2016,7, 6506-6513

Establishing hierarchy: the chain of events leading to the formation of silicalite-1 nanosheets

X. Zhu, M. G. Goesten, A. J. J. Koekkoek, B. Mezari, N. Kosinov, G. Filonenko, H. Friedrich, R. Rohling, B. M. Szyja, J. Gascon, F. Kapteijn and E. J. M. Hensen, Chem. Sci., 2016, 7, 6506 DOI: 10.1039/C6SC01295G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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