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Baniani A, Rivera MP, Lively RP, Vasenkov S. Quantifying diffusion of organic liquids in a MOF component of MOF/Polymer mixed-matrix membranes by high field NMR. J Memb Sci 2021; 640:119786. [DOI: 10.1016/j.memsci.2021.119786] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Audu CO, Chen D, Kung CW, Snurr RQ, Nguyen ST, Farha OK, Hupp JT. Transport Diffusion of Linear Alkanes (C 5-C 16) through Thin Films of ZIF-8 as Assessed by Quartz Crystal Microgravimetry. Langmuir 2021; 37:9405-9414. [PMID: 34338528 DOI: 10.1021/acs.langmuir.1c00672] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report uptake capacities and transport diffusivities, D, for each of eight linear alkanes (ranging from C5 to C16) in quartz crystal-supported films of solvent-evacuated ZIF-8. Analyses of the alkane uptake profiles revealed that the transport dynamics are governed by guest diffusion through metal-organic framework (MOF) (ZIF-8) crystallites rather than by rates of entry into films at the MOF/vapor interface. The obtained diffusivities range from just over 10-18 m2/s to just under 10-14 m2/s. Notably, minimum cross-sectional widths for all guests exceed the crystallographically measured width of ZIF-8's largest apertures and imply consistently with previous experimental and computational studies that apertures expand to accommodate guest uptake. On average, each additional carbon decreases the transport diffusivity of an alkane by twofold. Closer examination, however, reveals an odd-even effect such that linear alkanes having even numbers of carbons diffuse more rapidly than alkanes featuring one more or one less carbon atom. Thus, ZIF-8's differentiation of transport diffusivities for pairs of alkanes differing in length by only one carbon atom can be significantly greater than the aforementioned factor of 2. Elucidation of the microscopic basis for the odd-even behavior, however, awaits the outcome of molecular dynamics calculations that are beyond the scope of the present study. For compact, solvothermally prepared films, guest transport is dominated by 1D diffusion from the film/vapor interface and toward the underlying quartz crystal. For much lower density, electrophoretically deposited (EPD) films, crystallites behave nearly independently, and guest transport can be adequately modeled by assuming rapid permeation of macroscopic voids between crystallites, followed by entry and rate-limiting radial diffusion into isolated crystallites. One consequence is that EPD films can be much more rapidly infiltrated by molecular guests than can compact, solvothermally grown films. The combined results have potentially favorable implications for the development of kinetic separation schemes for closely related analytes.
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Affiliation(s)
- Cornelius O Audu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
| | - David Chen
- Department of Chemical & Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3120, USA
| | - Chung-Wei Kung
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
- Department of Chemical Engineering, National Cheng Kung University, Tainan City 70101, Taiwan
| | - Randall Q Snurr
- Department of Chemical & Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3120, USA
| | - SonBinh T Nguyen
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
| | - Omar K Farha
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
- Department of Chemical & Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3120, USA
| | - Joseph T Hupp
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
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Berens SJ, Yahya A, Fang J, Angelopoulos A, Nickels JD, Vasenkov S. Transition between Different Diffusion Regimes and Its Relationship with Structural Properties in Nafion by High Field Diffusion NMR in Combination with Small-Angle X-ray and Neutron Scattering. J Phys Chem B 2020; 124:8943-8950. [PMID: 32931279 DOI: 10.1021/acs.jpcb.0c07249] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pulsed field gradient (PFG) NMR at high field was utilized to directly observe a transition between two different diffusion regimes in a Nafion 117 membrane loaded with water and acetone. Although water self-diffusivity at small water loadings was observed to be diffusion time-independent in the limit of small and large diffusion times, it showed a significant decrease with increasing diffusion time at intermediate times corresponding to root mean square displacements on the order of several microns. Under our experimental conditions, no self-diffusivity dependence on diffusion time was found for water at large water loadings and for acetone at all studied acetone loadings. The diffusion time-dependent self-diffusivity at small water concentration is explained by the existence of finite domains of interconnected water channels with sizes in the range of several microns that form in Nafion in the presence of acetone. The domain sizes and permeance of transport barriers separating adjacent domains are estimated based on the measured PFG NMR data. At large water concentrations, the water channels form a fully interconnected network, resulting in time-independent self-diffusivity. The absence of such a percolation-like transition with increasing molecular concentration for acetone is attributed to a difference in the regions available for water and acetone diffusion in Nafion. The diffusion data are correlated with and supported by structural data obtained using small-angle X-ray and neutron scattering techniques. These techniques reveal distinct water channels with radial dimensions in the nanometer range increasing upon water addition, while acetone appears to be in an interfacial perfluoroether region, reducing the size of the radial channel dimension.
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Affiliation(s)
- Samuel J Berens
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, United States
| | - Ahmad Yahya
- Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Junchuan Fang
- Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Anastasios Angelopoulos
- Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Jonathan D Nickels
- Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Sergey Vasenkov
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, United States
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Abstract
AbstractBased on the molecular understanding of the interplay of diffusion and adsorption, new membrane materials can be developed and the operational conditions of gas separation membranes can be optimized. Therefore, numerous diffusion and adsorption studies are conducted to optimize membrane materials. However, in an opposite way, transport or Fickian diffusion coefficients DT can be derived from membrane permeation studies with surprising accuracy. From measuring the gas transport through nanoporous supported thin-layer membranes or through mixed matrix membranes with nanoporous fillers in a polymer matrix, the transport diffusion coefficients DT of gases in novel nanoporous materials such as zeolites, MOFs, COFs… can be estimated.
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Baniani A, Berens SJ, Rivera MP, Lively RP, Vasenkov S. Potentials and challenges of high-field PFG NMR diffusion studies with sorbates in nanoporous media. ADSORPTION 2021; 27:485-501. [DOI: 10.1007/s10450-020-00255-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Abstract
Metal-organic frameworks (MOFs) represent the largest known class of porous crystalline materials ever synthesized. Their narrow pore windows and nearly unlimited structural and chemical features have made these materials of significant interest for membrane-based gas separations. In this comprehensive review, we discuss opportunities and challenges related to the formation of pure MOF films and mixed-matrix membranes (MMMs). Common and emerging separation applications are identified, and membrane transport theory for MOFs is described and contextualized relative to the governing principles that describe transport in polymers. Additionally, cross-cutting research opportunities using advanced metrologies and computational techniques are reviewed. To quantify membrane performance, we introduce a simple membrane performance score that has been tabulated for all of the literature data compiled in this review. These data are reported on upper bound plots, revealing classes of MOF materials that consistently demonstrate promising separation performance. Recommendations are provided with the intent of identifying the most promising materials and directions for the field in terms of fundamental science and eventual deployment of MOF materials for commercial membrane-based gas separations.
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Affiliation(s)
- Qihui Qian
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Patrick A Asinger
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Moon Joo Lee
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Gang Han
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Katherine Mizrahi Rodriguez
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Sharon Lin
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Francesco M Benedetti
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Albert X Wu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Won Seok Chi
- School of Polymer Science and Engineering, Chonnam National University, Buk-gu, Gwangju 61186, Korea
| | - Zachary P Smith
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Abstract
AbstractMeasurement of molecular diffusion in nanoporous host materials, which are typically inhomogeneous and anisotropic, often involves an intricate web of factors and relations to be taken into account since the associated diffusivities are a function of the diffusion path of the guest molecules during a given observation time. Depending on the observation time, therefore, the result of the experimental measurement can point to completely different conclusions about the underlying diffusion phenomena. The risk of misinterpretation of the experimental data, by correlating them with irrelevant phenomena, may be reduced if there is an option to compare the data with the results of totally independent measurements. The present communication addresses this issue with reference to the particular potentials of pulsed field gradient NMR and microimaging by infrared microscopy as techniques of microscopic diffusion measurement.
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Alqaheem Y, Alomair AA. Microscopy and Spectroscopy Techniques for Characterization of Polymeric Membranes. Membranes (Basel) 2020; 10:membranes10020033. [PMID: 32102383 PMCID: PMC7074137 DOI: 10.3390/membranes10020033] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/21/2020] [Accepted: 01/24/2020] [Indexed: 12/16/2022]
Abstract
Polymeric membrane is a proven technology for water purification and wastewater treatment. The membrane is also commercialized for gas separation, mainly for carbon dioxide removal and hydrogen recovery. Characterization techniques are excellent tools for exploring the membrane structure and the chemical properties. This information can be then optimized to improve the membrane for better performance. In this paper, characterization techniques for studying the physical structure such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) are discussed. Techniques for investigating the crystal structure such as X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS) are also considered. Other tools for determining the functional groups such Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and nuclear magnetic resonance (NMR) are reviewed. Methods for determining the elemental composition such as energy-dispersion X-ray spectroscopy (EDS), X-ray fluorescent (XRF), and X-ray photoelectron spectroscopy (XPS) are explored. The paper also gives general guidelines for sample preparation and data interpretation for each characterization technique.
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Forman EM, Baniani A, Fan L, Ziegler KJ, Zhou E, Zhang F, Lively RP, Vasenkov S. Relationship between Ethane and Ethylene Diffusion inside ZIF-11 Crystals Confined in Polymers to Form Mixed-Matrix Membranes. J Memb Sci 2020; 593:117440. [PMID: 32863548 PMCID: PMC7449132 DOI: 10.1016/j.memsci.2019.117440] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Self-diffusivities of ethane were measured by multinuclear pulsed field gradient (PFG) NMR inside zeolitic imidazolate framework-11 (ZIF-11) crystals dispersed in several selected polymers to form mixed-matrix membranes (MMMs). These diffusivities were compared with the corresponding intracrystalline self-diffusivities in ZIF-11 crystal beds. It was observed that the confinement of ZIF-11 crystals in ZIF-11 / Torlon MMM can lead to a decrease in the ethane intracrystalline self-diffusivity. Such diffusivity decrease was observed at different temperatures used in this work. PFG NMR measurements of the temperature dependence of the intracrystalline self-diffusivity of ethylene in the same ZIF-11 / Torlon MMM revealed similar diffusivity decrease as well as an increase in the diffusion activation energy in comparison to those in unconfined ZIF-11 crystals in a crystal bed. These observations for ethane and ethylene were attributed to the reduction of the flexibility of the ZIF-11 framework due to the confinement in Torlon leading to a smaller effective aperture size of ZIF-11 crystals. Surprisingly, the intra-ZIF diffusion selectivity for ethane and ethylene was not changed appreciably by the confinement of ZIF-11 crystals in Torlon in comparison to the selectivity in a bed of ZIF-11 crystals. No ZIF-11 confinement effects leading to a reduction in the intracrystalline self-diffusivity of ethane and ethylene were observed for the other two studied MMM systems: ZIF-11 / Matrimid and ZIF-11 / 6FDA-DAM. The absence of the confinement effect in the latter MMMs can be related to the lower values of the polymer bulk modulus in these MMMs in comparison to that in ZIF-11 / Torlon MMM. In addition, there may be a contribution from possible differences in the ZIF-11/polymer adhesion in different MMM types.
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Affiliation(s)
- Evan M. Forman
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - Amineh Baniani
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - Lei Fan
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - Kirk J. Ziegler
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - Erkang Zhou
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Fengyi Zhang
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Ryan P. Lively
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Sergey Vasenkov
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
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Berens S, Chmelik C, Hillman F, Kärger J, Jeong HK, Vasenkov S. Ethane diffusion in mixed linker zeolitic imidazolate framework-7-8 by pulsed field gradient NMR in combination with single crystal IR microscopy. Phys Chem Chem Phys 2018; 20:23967-23975. [PMID: 30211405 DOI: 10.1039/c8cp04889d] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Pulsed field gradient (PFG) NMR was used in combination with single crystal IR microscopy (IRM) to study diffusion of ethane inside crystals of a mixed linker zeolitic imidazolate framework (ZIF) of the type ZIF-7-8 under comparable experimental conditions. These crystals contain 2-methylimidazolate (ZIF-8 linker) and benzimidazolate (ZIF-7 linker). It was observed that the PFG NMR attenuation curves measured for ethane in ZIF-7-8 exhibit deviations from the monoexponential behaviour, thereby indicating that the ethane self-diffusivity in different crystals of a crystal bed can be different. Measurements of the ethane uptake curves performed by IRM under the same conditions in different ZIF-7-8 crystals of the bed yield different transport diffusivities thus confirming that the rate of ethane diffusion is different in different ZIF-7-8 crystals. The IRM observation that the fractions of ZIF-8 and ZIF-7 linkers are different in different ZIF-7-8 crystals allowed attributing the observed heterogeneity in diffusivities to the heterogeneity in the linker fraction. The quantitative comparison of the average ethane self-diffusivities measured by PFG NMR in ZIF-7-8 with the corresponding data on corrected diffusivities from IRM measurements revealed a good agreement between the results obtained by the two techniques. In agreement with the expectation of smaller aperture sizes in ZIF-7-8 than in ZIF-8, the average ethane self-diffusivities in ZIF-7-8 were found to be significantly lower than the corresponding self-diffusivities in ZIF-8.
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Affiliation(s)
- Samuel Berens
- Department of Chemical Engineering, University of Florida, Gainesville, FL 32611, USA.
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Dvoyashkin M, Wilde N, Haase J, Gläser R. Diffusion of methyl oleate in hierarchical micro-/mesoporous TS-1-based catalysts probed by PFG NMR spectroscopy. RSC Adv 2018; 8:38941-38944. [PMID: 35558297 PMCID: PMC9090670 DOI: 10.1039/c8ra07434h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 11/30/2018] [Accepted: 11/07/2018] [Indexed: 11/23/2022] Open
Abstract
Pulsed field gradient (PFG) NMR is successfully applied to trace the diffusion of methyl oleate (MO) inside the mesopores of hierarchically structured titanium silicalite-1 (TS-1)-based catalysts. Introduction of mesoporosity by post-synthetic treatment of initially microporous TS-1 provides additional active surface to improve catalytic activity in the epoxidation of MO. The present study provides experimental evidence of the accessibility of mesopores for MO resulting from alkaline treatment of TS-1. The self-diffusion coefficients of MO inside the pores of hierarchically structured TS-1 catalysts are up to two orders of magnitude lower compared to the values in the bulk liquid phase. Additionally, the methodological capability of PFG NMR for measuring self-diffusion coefficients of long-chain hydrocarbons (up to C19) confined to narrow mesopores of catalytically active is demonstrated for the first time. Direct assessment of methyl oleate diffusion confined to nanopores of TS-1-based catalysts by means of pulsed field gradient NMR.![]()
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Affiliation(s)
- Muslim Dvoyashkin
- Institute of Chemical Technology
- Universität Leipzig
- 04103 Leipzig
- Germany
| | - Nicole Wilde
- Institute of Chemical Technology
- Universität Leipzig
- 04103 Leipzig
- Germany
| | - Jürgen Haase
- Felix-Bloch-Institut
- Universität Leipzig
- 04103 Leipzig
- Germany
| | - Roger Gläser
- Institute of Chemical Technology
- Universität Leipzig
- 04103 Leipzig
- Germany
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Friebe S, Geppert B, Steinbach F, Caro J. Metal-Organic Framework UiO-66 Layer: A Highly Oriented Membrane with Good Selectivity and Hydrogen Permeance. ACS Appl Mater Interfaces 2017; 9:12878-12885. [PMID: 28319660 DOI: 10.1021/acsami.7b02105] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The 3D metal-organic framework (MOF) structure UiO-66 [Zr6O4(OH)4(bdc)6], featuring triangular pores of approximately 6 Å, has been successfully prepared as a thin supported membrane layer with high crystallographic orientation on ceramic α-Al2O3 supports. The adhesion of the MOF layer to the ceramic support was investigated in different taxing conditions. Furthermore, by coating this UiO-66 membrane with a thin polyimide (Matrimid) top layer, we prepared a multilayer composite. Said membranes have been evaluated in the separation of hydrogen (H2) from different binary mixtures at room temperature. H2 as the smallest molecule (2.9 Å) should pass the UiO-66 membrane preferably since the kinetic diameters of all the other gases under study are larger. The gas mixture separation factors for the neat UiO-66 membrane were indeed found to be H2/CO2 = 5.1, H2/N2 = 4.7, H2/CH4 = 12.9, H2/C2H6 = 22.4, and H2/C3H8 = 28.5. The coating with Matrimid led to a sharp cutoff for gases with kinetic diameters greater than 3.7 Å, resulting in increased separation performance.
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Affiliation(s)
- Sebastian Friebe
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover , Callinstraße 3A, D-30167 Hannover, Germany
| | - Benjamin Geppert
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover , Callinstraße 3A, D-30167 Hannover, Germany
| | - Frank Steinbach
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover , Callinstraße 3A, D-30167 Hannover, Germany
| | - Jürgen Caro
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover , Callinstraße 3A, D-30167 Hannover, Germany
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Mueller R, Hariharan V, Zhang C, Lively R, Vasenkov S. Relationship between mixed and pure gas self-diffusion for ethane and ethene in ZIF-8/6FDA-DAM mixed-matrix membrane by pulsed field gradient NMR. J Memb Sci 2016. [DOI: 10.1016/j.memsci.2015.10.036] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
The increasing complexity of nanoporous catalysts and adsorbents presents a challenge to both the experimental measurement and theoretical modeling of transport behavior.
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Affiliation(s)
- Jörg Kärger
- Faculty of Physics and Earth Sciences
- University of Leipzig
- 04103 Leipzig
- Germany
| | - Douglas M. Ruthven
- Department of Chemical and Biological Engineering
- University of Maine
- Orono
- USA
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Abstract
This work provides an overview of different experimental techniques of diffusion measurements in porous materials and discusses transport properties of several classes of hierarchically organized micro-mesoporous materials.
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Affiliation(s)
- Daniel Schneider
- Faculty of Physics and Earth Sciences
- University of Leipzig
- Leipzig
- Germany
| | - Dirk Mehlhorn
- Faculty of Physics and Earth Sciences
- University of Leipzig
- Leipzig
- Germany
| | - Philipp Zeigermann
- Faculty of Physics and Earth Sciences
- University of Leipzig
- Leipzig
- Germany
| | - Jörg Kärger
- Faculty of Physics and Earth Sciences
- University of Leipzig
- Leipzig
- Germany
| | - Rustem Valiullin
- Faculty of Physics and Earth Sciences
- University of Leipzig
- Leipzig
- Germany
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Abstract
ZIFs are a unique class of porous solids topologically associated with zeolites, but dramatically different in components. Current research on ZIF-enabled membranes is highly imbalanced. Despite a large selection of available ZIF materials, seven out of ten published papers discuss ZIF-8-based membranes. This is partially due to insufficient knowledge on ZIFs' structure-transport property relationships as well as lack of capability to tailor their transport properties for particular separations. This Perspective will provide an account of recent progress in ZIF-enabled membranes and analyze the barriers that must be overcome to advance ZIF-enabled membranes beyond fundamental characterizations.
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Affiliation(s)
- Chen Zhang
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive NW, Atlanta, Georgia 30332-0100, United States
| | - William J Koros
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive NW, Atlanta, Georgia 30332-0100, United States
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Dutta AR, Sekar P, Dvoyashkin M, Bowers CR, Ziegler KJ, Vasenkov S. Relationship between single-file diffusion of mixed and pure gases in dipeptide nanochannels by high field diffusion NMR. Chem Commun (Camb) 2015; 51:13346-9. [DOI: 10.1039/c5cc04960a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Under single-file confinement, the relationship between diffusion rates of mixed and pure gases is studied experimentally for the first time and observed to differ from that for normal diffusion.
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Affiliation(s)
- Akshita R. Dutta
- Department of Chemical Engineering
- University of Florida
- Gainesville
- USA
| | - Poorvajan Sekar
- Department of Chemical Engineering
- University of Florida
- Gainesville
- USA
| | | | | | - Kirk J. Ziegler
- Department of Chemical Engineering
- University of Florida
- Gainesville
- USA
| | - Sergey Vasenkov
- Department of Chemical Engineering
- University of Florida
- Gainesville
- USA
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Mueller R, Zhang S, Klink M, Bäumer M, Vasenkov S. The origin of a large apparent tortuosity factor for the Knudsen diffusion inside monoliths of a samaria–alumina aerogel catalyst: a diffusion NMR study. Phys Chem Chem Phys 2015; 17:27481-7. [DOI: 10.1039/c5cp04609b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The contribution from surface diffusion into the apparent tortuosity factor can be separated for light gases in a porous catalyst.
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Affiliation(s)
- R. Mueller
- Department of Chemical Engineering
- University of Florida
- Gainesvlle
- USA
| | - S. Zhang
- Department of Chemical Engineering
- University of Florida
- Gainesvlle
- USA
| | - M. Klink
- Institute for Applied and Physical Chemistry
- University of Bremen
- Bremen
- Germany
| | - M. Bäumer
- Institute for Applied and Physical Chemistry
- University of Bremen
- Bremen
- Germany
| | - S. Vasenkov
- Department of Chemical Engineering
- University of Florida
- Gainesvlle
- USA
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