X-Nuclei NMR Self-Diffusion Studies in Mesoporous Silica Foam and Microporous MOF CuBTC
| Autor: | Carsten Horch, Frank Stallmach, Lutz Moschkowitz, Wolf-Dietrich Einicke, Steffen Beckert, Stefan Schlayer, Friederike Pielenz, Mikulás̆ Peksa, Anne-Kristin Pusch |
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| Rok vydání: | 2012 |
| Předmět: |
133Cs
Self-diffusion probe design Diffusion Analytical chemistry 02 engineering and technology PFG NMR 010402 general chemistry lcsh:Technology 01 natural sciences Tortuosity Article 7Li Adsorption General Materials Science 13C lcsh:Microscopy lcsh:QC120-168.85 CuBTC Aqueous solution MCF lcsh:QH201-278.5 lcsh:T Chemistry diffusion Microporous material Mesoporous silica 021001 nanoscience & nanotechnology 0104 chemical sciences lcsh:TA1-2040 lcsh:Descriptive and experimental mechanics lcsh:Electrical engineering. Electronics. Nuclear engineering lcsh:Engineering (General). Civil engineering (General) 0210 nano-technology Pulsed field gradient lcsh:TK1-9971 |
| Zdroj: | Materials; Volume 5; Issue 4; Pages: 617-633 Materials, Vol 5, Iss 4, Pp 617-633 (2012) Materials |
| ISSN: | 1996-1944 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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