Morphology-dependent zeolite intergrowth structures leading to distinct internal and outer-surface molecular diffusion barriers
| Autor: | Machteld M. Mertens, Simon R. Bare, Norma Kahn, Bert M. Weckhuysen, Lukasz Karwacki, Ally S. Chan, Jan Kornatowski, Neena S. John, Wolfgang Schmidt, D. A. Matthijs de Winter, Johannes D. Meeldijk, Pablo Cubillas, Martyn R. Drury, Marianne H. F. Kox, Michael W. Anderson, Eli Stavitski |
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| Rok vydání: | 2009 |
| Předmět: |
Diffraction
Molecular diffusion Materials science Mechanical Engineering General Chemistry Condensed Matter Physics Heterogeneous catalysis Ion Crystal Crystallography X-ray photoelectron spectroscopy Mechanics of Materials Transmission electron microscopy Chemical physics Microscopy General Materials Science |
| Zdroj: | Nature Materials. 8:959-965 |
| ISSN: | 1476-4660 1476-1122 |
| DOI: | 10.1038/nmat2530 |
| Popis: | Zeolites play a crucial part in acid–base heterogeneous catalysis. Fundamental insight into their internal architecture is of great importance for understanding their structure–function relationships. Here, we report on a new approach correlating confocal fluorescence microscopy with focused ion beam–electron backscatter diffraction, transmission electron microscopy lamelling and diffraction, atomic force microscopy and X-ray photoelectron spectroscopy to study a wide range of coffin-shaped MFI-type zeolite crystals differing in their morphology and chemical composition. This powerful combination demonstrates a unified view on the morphology-dependent MFI-type intergrowth structures and provides evidence for the presence and nature of internal and outer-surface barriers for molecular diffusion. It has been found that internal-surface barriers originate not only from a 90∘ mismatch in structure and pore alignment but also from small angle differences of 0.5∘–2∘ for particular crystal morphologies. Furthermore, outer-surface barriers seem to be composed of a silicalite outer crust with a thickness varying from 10 to 200 nm. Characterizing the internal architecture of zeolites is crucial for understanding their structure–function relationships, and for acid–base heterogeneous catalysis. Using a unique combination of diffraction and microscopy techniques provides a unified picture of the morphology of intergrowth structures and confirmation of surface barriers for molecular diffusion. |
| Databáze: | OpenAIRE |
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