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

Schlayer, Stefan; Pusch, Anne-Kristin; Pielenz, Friederike; Beckert, Steffen; Peksa, Mikuláš; Horch, Carsten; Moschkowitz, Lutz; Einicke, Wolf‐Dietrich; Stallmach, Frank

doi:10.3390/ma5040617

Cited by 25 publications

(25 citation statements)

References 37 publications

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“…However this has to be confirmed by binary self-diffusion studies in the future. As recently demonstrated for the MOF CuBTC, such diffusion studies in binary mixtures of CH 4 and CO 2 can be performed by joint application of 1 H and 13 C PFG NMR (Schlayer et al 2012). For the ZIF-8 samples studied here, the corresponding experiments are currently being performed in our laboratory.…”

Section: Resultsmentioning

confidence: 96%

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NMR studies of carbon dioxide and methane self-diffusion in ZIF-8 at elevated gas pressures

Pusch¹,

Splith²,

Moschkowitz³

et al. 2012

Adsorption

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Self-diffusion measurements with methane and carbon dioxide adsorbed in the Zeolitic Imidazolate Framework-8 (ZIF-8) were performed by 1 H and 13 C pulsed field gradient nuclear magnetic resonance (PFG NMR). The experiments were conducted at 298 K and variable pressures of 7 to 15 bar in the gas phase above the ZIF-8 bed. Via known adsorption isotherms these pressures were converted to loadings of the adsorbed molecules. The self-diffusion coefficients of carbon dioxide measured by PFG NMR are found to be independent of loading. They are in good agreement with results from molecular dynamic (MD) simulations and resume the trend previously found by IR microscopy at lower loadings. Methane diffuses in ZIF-8 only slightly slower than carbon dioxide. Its experimentally obtained self-diffusion coefficients are about a factor of two smaller than the corresponding values determined by MD simulations using flexible frameworks.

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Section: Resultsmentioning

confidence: 96%

“…These spectrometers operate at a proton ( 1 H) resonance frequency of 125 MHz and 400 MHZ, respectively. The 13 C NMR studies were carried out only at the FEGRIS FT NMR spectrometer (Stallmach and Galvosas 2007) at 100.6 MHZ resonance frequency using the z-gradient and probe system, described in Schlayer et al (2012).…”

Section: Nmr Measurementsmentioning

confidence: 99%

NMR studies of carbon dioxide and methane self-diffusion in ZIF-8 at elevated gas pressures

Pusch¹,

Splith²,

Moschkowitz³

et al. 2012

Adsorption

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“…39 We will use the diffusion coefficients 39 derived for a further interpretation of our relaxation measurements. For this reason we should at first discuss in which way our correlation times for a jump-like local motion may be related to the diffusion coefficients.…”

Section: Discussionmentioning

confidence: 99%

Investigation of the spin-lattice relaxation of 13CO and 13CO2 adsorbed in the metal-organic frameworks Cu3(btc)2 and Cu3−xZnx(btc)2

Gul‐E‐Noor

Michel

Krautscheid

et al. 2013

The Journal of Chemical Physics

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The (13)C nuclear spin-lattice relaxation time of (13)CO and (13)CO2 molecules adsorbed in the metal-organic frameworks (MOFs) Cu2.97Zn0.03(btc)2 and Cu3(btc)2 is investigated over a wide range of temperatures at resonance frequencies of 75.468 and 188.62 MHz. In all cases a mono-exponential relaxation is observed, and the (13)C spin-lattice relaxation times (T1) reveal minima within the temperature range of the measurements and both frequencies. This allows us to carry out a more detailed analysis of the (13)C spin relaxation data and to consider the influence due to the spectral functions of the thermal motion. In a model-free discussion of the temperature dependence of the ratios T1 (T)∕T1,min we observe a motional mechanism that can be described by a single correlation time. In relation to the discussion of the relaxation mechanisms this can be understood in terms of dominating translational motion with mean jump distance being larger than the minimum distances between neighboring adsorption sites in the MOFs. A more detailed discussion of the jump-like motion observed here might be carried out on the basis of self-diffusion coefficients. From the present spin relaxation measurements activation energies for the local motion of the adsorbed molecules in the MOFs can be estimated to be 3.3 kJ∕mol and 2.2 kJ∕mol, for CO and CO2 molecules, respectively. Finally, our findings are compared with our recent results derived from the (13)C line shape analysis.

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“…These studies have not been limited to proton, but have included other nuclei as well (e.g., 13 C, 19 F, 7 Li, etc.) . In the case of oxygen gas, the NMR properties of 17 O (nuclear spin of 5/2 and a quadrupolar moment that leads to very short relaxation times – T 1 , T 2 < 5 ms), coupled with low sensitivity (natural abundance of 0.037%) and paramagnetism hamper the direct detection of its signal.…”

Section: Introductionmentioning

confidence: 99%

Determination of Oxygen Permeability in Acrylic‐Based Hydrogels by Proton NMR Spectroscopy and Imaging

Compañ

Mollá

Vallejos

et al. 2014

Macro Chemistry & Physics

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Polymer network membranes with a high capacity for water absorption are obtained by radical polymerization of N‐[2‐(2‐hydroxyethoxy)ethyl]methacrylamide (HEEMAM). The permeability, solubility, and diffusion coefficients of oxygen in hydrogels are determined using nuclear magnetic resonance (NMR) methods based on the paramagnetic effect of dissolved oxygen gas on the proton spin‐lattice relaxation times of water, and the results are compared with those obtained with electrochemical procedures. The results of NMR measurements of oxygen transport coefficients in distilled water show excellent agreement with corresponding literature values. The results of the potentiostatic and NMR oxygen transport measurements in hydrogels are in reasonable agreement and support the viability of the NMR method.

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

Cited by 25 publications

References 37 publications

NMR studies of carbon dioxide and methane self-diffusion in ZIF-8 at elevated gas pressures

NMR studies of carbon dioxide and methane self-diffusion in ZIF-8 at elevated gas pressures

Investigation of the spin-lattice relaxation of 13CO and 13CO2 adsorbed in the metal-organic frameworks Cu3(btc)2 and Cu3−xZnx(btc)2

Determination of Oxygen Permeability in Acrylic‐Based Hydrogels by Proton NMR Spectroscopy and Imaging

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