Porosimetrie mittels Diffusionsanalyse
Zusammenfassung der Projektergebnisse
The pulsed field gradient technique of NMR was applied to study transport and structural properties of novel, hierarchically-organized porous solids. By focusing primarily on micro-mesoporous and bi-mesoporous materials, methodological and theoretical approaches for quantifying the most essential, technologically-relevant parameters, including the effective transport rates, transport characteristics of interpenetrating sub-networks forming hierarchical pore spaces, and exchange properties between them, have been developed. The very first experimental studies of molecular transport in zeolite with added mesoporosity at different amounts have been used to identify the conditions under which long-range intercrystalline and intracrystalline diffusivities could be obtained. The effect of mesoporosity on both these quantities was quantified. The methods developed have been extended to materials with less-ordered structures, such as hierarchical porous carbons. As a particular point, it has been discussed under which conditions the formation of additional mesoporosity can give rise to transport improvement of microporous materials. The experimental results have been analyzed using a microscopic model allowing to predict transport properties of hierarchical materials with arbitrary organization of the pore network geometries. The results obtained can be used for a purposeful design of porous solids with optimized transport characteristics.
Projektbezogene Publikationen (Auswahl)
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Dynamics of water diffusion in mesoporous zeolites. Microporous Mesoporous Mat., 142 (2011) 236
Valiullin, R., J. Kärger, K. Cho, M. Choi, and R. Ryoo
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Guest Diffusion in Interpenetrating Networks of Micro- and Mesopores. J . Am . Chem. Soc., 133 (2011) 2437 133 (2011) 2437
Furtado,F., P. GaIvosas, M. Goncalves, F.-D. Kopinke, S. Naumov, F. Rodriguez-Reinoso, U. RoIand, R. Valiullin, and J. Kärger
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Diffusion in Hierarchical Mesoporous Materials: Applicability and Generalization of the Fast-Exchange Diffusion Model. Langmuir, 28 (2012) 3621
Zeigermann, P., S. Naumov, S. Mascotto, J. Kärger, B.M. Smarsly, and R. Valiullin
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Exploring the hierarchy of transport phenomena in hierarchical pore systems by NMR diffusion measurement. Microporous Mesoporous Mat., 164 (2012) 273
Mehlhorn, D., R. Valiullin, J. Kärger, K. Cho, and R. Ryoo
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Probing mesopore connectivity in hierarchical nanoporous materials. Carbon, 50 (2012) 4804
Kirchner, T., A. Shakhov, P. Zeigermann, R. Valiullin, and J. Kärger
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Diffusion in microporous materials with embedded mesoporosities. Microporous Mesoporous Mat., 178 (2013) 84
Zeigermann, P., J. Kärger, and R. Valiullin
