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Intracrystalline Diffusion in Mesoporous Zeolites

Authors

  • Dirk Mehlhorn,

    1. Faculty of Physics and Earth Science, University of Leipzig, Linnèstr. 5, 04103 Leipzig (Germany)
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  • Dr. Rustem Valiullin,

    Corresponding author
    1. Faculty of Physics and Earth Science, University of Leipzig, Linnèstr. 5, 04103 Leipzig (Germany)
    • Faculty of Physics and Earth Science, University of Leipzig, Linnèstr. 5, 04103 Leipzig (Germany)
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  • Prof. Dr. Jörg Kärger,

    1. Faculty of Physics and Earth Science, University of Leipzig, Linnèstr. 5, 04103 Leipzig (Germany)
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  • Kanghee Cho,

    1. Center for Functional Nanomaterials, Department of Chemistry and Graduate School of Nanoscience and Technology (WCU), KAIST, Daejeon 305-701 (Korea)
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  • Prof. Dr. Ryong Ryoo

    Corresponding author
    1. Center for Functional Nanomaterials, Department of Chemistry and Graduate School of Nanoscience and Technology (WCU), KAIST, Daejeon 305-701 (Korea)
    • Center for Functional Nanomaterials, Department of Chemistry and Graduate School of Nanoscience and Technology (WCU), KAIST, Daejeon 305-701 (Korea)
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Abstract

Specially synthesized extra-large crystallites of zeolite LTA with intentionally added mesoporosity are used for an in-depth study of guest diffusion in hierarchical nanoporous materials by the pulsed field gradient NMR technique. Using propane as a guest molecule, intracrystalline mass transfer is demonstrated to be adequately described by a single effective diffusivity resulting from the weighted average of the diffusivities in the two (micro- and meso-) pore spaces. Gas-kinetic order-of-magnitude estimates of the diffusivities are in satisfactory agreement with the experimental data and are thus shown to provide a straightforward means for predicting and quantifying the benefit of hierarchically structured nanoporous materials in comparison with their purely microporous equivalent.

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