Materials 2012, 5(4), 617-633; doi:10.3390/ma5040617
Article

X-Nuclei NMR Self-Diffusion Studies in Mesoporous Silica Foam and Microporous MOF CuBTC

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Received: 21 February 2012; in revised form: 30 March 2012 / Accepted: 1 April 2012 / Published: 12 April 2012
(This article belongs to the Special Issue Diffusion in Micropores)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: A standard X-observe NMR probe was equipped with a z-gradient coil to enable high-sensitivity pulsed field gradient NMR diffusion studies of Li+ and Cs+ cations of aqueous salt solutions in a high-porosity mesocellular silica foam (MCF) and of CO2 adsorbed in metal-organic frameworks (MOF). The coil design and the necessary probe modifications, which yield pulsed field gradients of up to ±16.2Tm−1, are introduced. The system was calibrated at 2H resonance frequency and successfully applied for diffusion studies at 7Li, 23Na, 13C and 133Cs frequencies. Significant reductions of the diffusivities of the cations in LiClac and CsClac solution introduced into MCFs are observed. By comparison of the diffusion behavior with the bulk solutions, a tortuosity of the silica foam of 4.5 ± 0.6 was derived. Single component self-diffusion of CO2 and CH4 (measured by 1H NMR) as well as self-diffusion of the individual components in CO2/CH4 mixtures was studied in the MOF CuBTC. The experimental results confirm high mobilities of the adsorbed gases and trends for diffusion separation factors predicted by MD simulations.
Keywords: probe design; diffusion; 7Li; 13C; 133Cs; PFG NMR; CuBTC; MCF
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MDPI and ACS Style

Schlayer, S.; Pusch, A.-K.; Pielenz, F.; Beckert, S.; Peksa, M.; Horch, C.; Moschkowitz, L.; Einicke, W.-D.; Stallmach, F. X-Nuclei NMR Self-Diffusion Studies in Mesoporous Silica Foam and Microporous MOF CuBTC. Materials 2012, 5, 617-633.

AMA Style

Schlayer S, Pusch A-K, Pielenz F, Beckert S, Peksa M, Horch C, Moschkowitz L, Einicke W-D, Stallmach F. X-Nuclei NMR Self-Diffusion Studies in Mesoporous Silica Foam and Microporous MOF CuBTC. Materials. 2012; 5(4):617-633.

Chicago/Turabian Style

Schlayer, Stefan; Pusch, Anne-Kristin; Pielenz, Friederike; Beckert, Steffen; Peksa, Mikuláš; Horch, Carsten; Moschkowitz, Lutz; Einicke, Wolf-Dietrich; Stallmach, Frank. 2012. "X-Nuclei NMR Self-Diffusion Studies in Mesoporous Silica Foam and Microporous MOF CuBTC." Materials 5, no. 4: 617-633.


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