Ideal and mixture permeation selectivity of flexible prototypical zeolitic imidazolate framework – 8 Membranes

Sitprasert, Chatcharin; Wang, F.Y.; Rudolph, Victor; Zhu, Zhonghua

doi:10.1016/j.ces.2013.12.041

Cited by 9 publications

(6 citation statements)

References 25 publications

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“…In the case of ZIF-8, for instance, the assumption of a rigid framework leads to consistent predictions for adsorption, but a flexible framework is required for consistent predictions of diffusion. 359 To address these issues, refined algorithms 360 and new FFs 361−364 that account for flexibility have been developed. More broadly, in simulations, intermolecular van der Waals interactions are often described by a Lennard-Jones (LJ) potential, with parameters that depend upon the FF adopted.…”

Section: Computational Studiesmentioning

confidence: 99%

“…While the assumption of rigidity gives sensible agreement with experiments for MOFs and zeolites, − it discounts breathing mechanisms and bond stretching, which may affect performance predictions. In the case of ZIF-8, for instance, the assumption of a rigid framework leads to consistent predictions for adsorption, but a flexible framework is required for consistent predictions of diffusion . To address these issues, refined algorithms and new FFs − that account for flexibility have been developed.…”

Section: Advanced Metrologiesmentioning

confidence: 99%

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MOF-Based Membranes for Gas Separations

et al. 2020

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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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Section: Computational Studiesmentioning

confidence: 99%

Section: Advanced Metrologiesmentioning

confidence: 99%

MOF-Based Membranes for Gas Separations

et al. 2020

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“…For the same reason as with Cu 3 (BTC) 2 , the first step toward predicting the gas‐permeation properties of the ZIF‐8/polymer MMMs was to consult references about pure ZIF‐8 membranes. The gas‐permeation properties of all of the ZIF‐8 membranes in the literature were on the same level and much higher than those of the polyimide matrix; for instance, the CO 2 permeability was in the range 1560‐2670 barrer. The gas‐permeation properties of the ZIF‐8 membranes from Bux et al .…”

Section: Resultsmentioning

confidence: 94%

Gas‐permeation performance of metal organic framework/polyimide mixed‐matrix membranes and additional explanation from the particle size angle

Duan

Xiao

Zhu

et al. 2017

J of Applied Polymer Sci

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With MOFs of Cu3(BTC)2 and ZIF‐8 as the dispersed phases and four polyimides with CO2 permeabilities ranging from 1.36 to 564 barrer as the continuous phase, the influence of metal organic frameworks on the gas‐separation properties of mixed‐matrix membranes (MMMs) was investigated. The results show that the gas permeabilities of all of the prepared MMMs greatly increased and even largely exceeded the predicted value of the Bruggeman model; for example, with the same Cu3(BTC)2 loading of 21.3 vol %, the O2 permeability increase rate of our prepared Cu3(BTC)2/Matrimide 5218‐20 MMMs was 2.26 times, whereas that predicted by the Bruggeman model was only 1.05 times. In addition, when the gas permeability of the polymeric phase was far lower than the dispersed phase of ZIF‐8 or Cu3(BTC)2 compared with ZIF‐8, which had a particle size (R) around 150 nm, Cu3(BTC)2 of 5–15 µm showed a little better enhancing effect on the gas‐permeation performance of the MMMs. In addition to the properties of the dispersed and continuous phases, we speculated that the ratio between R of the dispersed phase to the membrane thickness (L) played an important role for MMMs; the larger R/L was, the greater the gas permeability of the MMMs was. This speculation was initially evidenced by the ZIF‐8/ODPA/TMPDA‐20 MMMs with different Ls. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45728.

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“…The RASPA 2.0 package was employed to perform the GCMC simulations with a simulation cell consisting of 8 (2 × 2 × 2) unit cells of a ZIF-8 polymorph. The atoms of ZIFs were frozen in the simulation, agreeing with a wide range of recent GCMC studies. ,,,, In the XYZ direction, periodic boundary conditions were used for simulation, and the LJ interactions were cut off at 12 Å with long-range correction applied. In single-component (there was only one type of adsorbate molecule, ethane or ethene) GCMC simulations, 100,000 cycles were employed to equilibrate the system, followed by the other 100,000 cycles to produce simulation data.…”

Section: Methodsmentioning

confidence: 99%

Identical Composition and Distinct Performance: How ZIF-8 Polymorphs’ Structures Affect the Adsorption/Separation of Ethane and Ethene

Duan

et al. 2021

J. Chem. Eng. Data

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Zeolitic imidazolate frameworks (ZIFs) can separate olefins from paraffin with very little energy consumption, which is critical for the chemical industry. They can form a large diversity of polymorphs, which show identical chemical formulas but distinct olefin/paraffin separation performance. The adsorption and separation of ethane/ethene on several ZIF-8 polymorphs, some recently synthesized in experiments, were studied by grand canonical Monte Carlo and ideal adsorbed solution theory simulations in this work. These two methods yielded consistent results, which also agree with experiments. The adsorption mechanism, especially the relationship between the spatial arrangement of the metal and ligand in these polymorphs and the adsorption of olefins/paraffin, was revealed via in-depth investigation of the simulation data. The adsorption of ethane/ethene and propane/propene was compared to further elucidate that the low pressure uptake well correlates with ZIF–gas interaction, for example, the heat of adsorption and Henry coefficient, while high pressure uptake correlates with the ZIFs’ geometrical structures, such as porosity or accessible surface area. The adsorption competition between ethane and ethene in the mixture and the separation performance of the ZIF polymorphs were also investigated. Our work could help understand how ZIFs’ structures affect their olefin/paraffin adsorption behavior and develop nanoporous materials with improved separation performance.

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Ideal and mixture permeation selectivity of flexible prototypical zeolitic imidazolate framework – 8 Membranes

Cited by 9 publications

References 25 publications

MOF-Based Membranes for Gas Separations

MOF-Based Membranes for Gas Separations

Gas‐permeation performance of metal organic framework/polyimide mixed‐matrix membranes and additional explanation from the particle size angle

Identical Composition and Distinct Performance: How ZIF-8 Polymorphs’ Structures Affect the Adsorption/Separation of Ethane and Ethene

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