The Experts below are selected from a list of 4938 Experts worldwide ranked by ideXlab platform
Dan Zhao - One of the best experts on this subject based on the ideXlab platform.
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reversed thermo switchable Molecular Sieving membranes composed of two dimensional metal organic nanosheets for gas separation
Elements, 2020Co-Authors: Xuerui Wang, Chenglong Chi, Kang Zhang, Yuhong Qian, Krishna M Gupta, Zixi Kang, Jianwen Jiang, Dan ZhaoAbstract:It is highly desirable to reduce the membrane thickness in order to maximize the throughput and break the trade-off limitation for membrane-based gas separation. Two-dimensional membranes composed of atomic-thick graphene or graphene oxide nanosheets have gas transport pathways that are at least three orders of magnitude higher than the membrane thickness, leading to reduced gas permeation flux and impaired separation throughput. Here we present nm-thick Molecular Sieving membranes composed of porous two-dimensional metal-organic nanosheets. These membranes possess pore openings parallel to gas concentration gradient allowing high gas permeation flux and high selectivity, which are proven by both experiment and Molecular dynamics simulation. Furthermore, the gas transport pathways of these membranes exhibit a reversed thermo-switchable feature, which is attributed to the Molecular flexibility of the building metal-organic nanosheets.
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beyond equilibrium metal organic frameworks for Molecular Sieving and kinetic gas separation
Crystal Growth & Design, 2017Co-Authors: Yuxiang Wang, Dan ZhaoAbstract:Metal–organic frameworks (MOFs) are a class of crystalline inorganic–organic hybrid materials that have demonstrated huge potential in gas separation due to their ultrahigh porosity, boundless chemical tunability, as well as surface functionality. Most gas separations realized in MOFs are under an equilibrium state and are dependent on the difference in thermodynamic affinities of gases to MOFs, whereas nonequilibrium separation such as kinetic and Molecular Sieving separation attracting growing attention in the past decade is achieved based on the difference in the size and diffusivity of gas molecules. In this perspective, we first discuss the pore size, temperature, and pressure effect on gas diffusion as well as nonequilibrium gas separation in MOFs. Second, we introduce current techniques reported to measure intracrystalline gas diffusivity. Third, we review recent progress in MOF-based nonequilibrium N2/O2 separation, CO2 capture, and hydrocarbon separation. In addition, we describe the hydrogen iso...
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reversed thermo switchable Molecular Sieving membranes composed of two dimensional metal organic nanosheets for gas separation
Nature Communications, 2017Co-Authors: Xuerui Wang, Chenglong Chi, Kang Zhang, Yuhong Qian, Krishna M Gupta, Zixi Kang, Jianwen Jiang, Dan ZhaoAbstract:It is highly desirable to reduce the membrane thickness in order to maximize the throughput and break the trade-off limitation for membrane-based gas separation. Two-dimensional membranes composed of atomic-thick graphene or graphene oxide nanosheets have gas transport pathways that are at least three orders of magnitude higher than the membrane thickness, leading to reduced gas permeation flux and impaired separation throughput. Here we present nm-thick Molecular Sieving membranes composed of porous two-dimensional metal-organic nanosheets. These membranes possess pore openings parallel to gas concentration gradient allowing high gas permeation flux and high selectivity, which are proven by both experiment and Molecular dynamics simulation. Furthermore, the gas transport pathways of these membranes exhibit a reversed thermo-switchable feature, which is attributed to the Molecular flexibility of the building metal-organic nanosheets. Reducing membrane thickness to nanometre scale should increase the throughput of gas separation sieves. Here, the authors report a Sieving membrane composed of two-dimensional metal-organic framework nanosheets, exhibiting both high permeation flux and thermally switchable behaviour.
William J Koros - One of the best experts on this subject based on the ideXlab platform.
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mixed matrix formulations with mof Molecular Sieving for key energy intensive separations
Nature Materials, 2018Co-Authors: Chen Zhang, Mohamed Eddaoudi, Gongping Liu, Valeriya Chernikova, Yang Liu, Kuang Zhang, Youssef Belmabkhout, Osama Shekhah, William J KorosAbstract:Membrane-based separations can improve energy efficiency and reduce the environmental impacts associated with traditional approaches. Nevertheless, many challenges must be overcome to design membranes that can replace conventional gas separation processes. Here, we report on the incorporation of engineered submicrometre-sized metal-organic framework (MOF) crystals into polymers to form hybrid materials that successfully translate the excellent Molecular Sieving properties of face-centred cubic (fcu)-MOFs into the resultant membranes. We demonstrate, simultaneously, exceptionally enhanced separation performance in hybrid membranes for two challenging and economically important applications: the removal of CO2 and H2S from natural gas and the separation of butane isomers. Notably, the membrane Molecular Sieving properties demonstrate that the deliberately regulated and contracted MOF pore-aperture size can discriminate between Molecular pairs. The improved performance results from precise control of the linkers delimiting the triangular window, which is the sole entrance to the fcu-MOF pore. This rational-design hybrid approach provides a general toolbox for enhancing the transport properties of advanced membranes bearing Molecular sieve fillers with sub-nanometre-sized pore-apertures.
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mixed matrix formulations with mof Molecular Sieving for key energy intensive separations
Nature Materials, 2018Co-Authors: Chen Zhang, Mohamed Eddaoudi, Gongping Liu, Valeriya Chernikova, Yang Liu, Kuang Zhang, Youssef Belmabkhout, Osama Shekhah, William J KorosAbstract:Membrane-based separations can improve energy efficiency and reduce the environmental impacts associated with traditional approaches. Nevertheless, many challenges must be overcome to design membranes that can replace conventional gas separation processes. Here, we report on the incorporation of engineered submicrometre-sized metal–organic framework (MOF) crystals into polymers to form hybrid materials that successfully translate the excellent Molecular Sieving properties of face-centred cubic (fcu)-MOFs into the resultant membranes. We demonstrate, simultaneously, exceptionally enhanced separation performance in hybrid membranes for two challenging and economically important applications: the removal of CO2 and H2S from natural gas and the separation of butane isomers. Notably, the membrane Molecular Sieving properties demonstrate that the deliberately regulated and contracted MOF pore-aperture size can discriminate between Molecular pairs. The improved performance results from precise control of the linkers delimiting the triangular window, which is the sole entrance to the fcu-MOF pore. This rational-design hybrid approach provides a general toolbox for enhancing the transport properties of advanced membranes bearing Molecular sieve fillers with sub-nanometre-sized pore-apertures. Sub-micrometre MOF particles are incorporated into polymers to form mixed matrix membranes. Molecular Sieving enables performance far beyond current limits for two applications, butane isomer separation and combined CO2/H2S removal from natural gas.
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unexpected Molecular Sieving properties of zeolitic imidazolate framework 8
Journal of Physical Chemistry Letters, 2012Co-Authors: Chen Zhang, Ryan P Lively, Ke Zhang, Justin R Johnson, Oguz Karvan, William J KorosAbstract:We studied Molecular Sieving properties of zeolitic imidazolate framework-8 (ZIF-8) by estimating the thermodynamically corrected diffusivities of probe molecules at 35 °C. From helium (2.6 A) to iso-C4H10 (5.0 A), the corrected diffusivity drops 14 orders of magnitude. Our results further suggest that the effective aperture size of ZIF-8 for Molecular Sieving is in the range of 4.0 to 4.2 A, which is significantly larger than the XRD-derived value (3.4 A) and between the well-known aperture size of zeolite 4A (3.8 A) and 5A (4.3 A). Interestingly, because of aperture flexibility, the studied C4 hydrocarbon molecules that are larger than this effective aperture size still adsorb in the micropores of ZIF-8 with kinetic selectivities for iso-C4H8/iso-C4H10 of 180 and n-C4H10/iso-C4H10 of 2.5 × 10(6). These unexpected Molecular Sieving properties open up new opportunities for ZIF materials for separations that cannot be economically achieved by traditional microporous adsorbents such as synthetic zeolites.
Gongping Liu - One of the best experts on this subject based on the ideXlab platform.
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mixed matrix formulations with mof Molecular Sieving for key energy intensive separations
Nature Materials, 2018Co-Authors: Chen Zhang, Mohamed Eddaoudi, Gongping Liu, Valeriya Chernikova, Yang Liu, Kuang Zhang, Youssef Belmabkhout, Osama Shekhah, William J KorosAbstract:Membrane-based separations can improve energy efficiency and reduce the environmental impacts associated with traditional approaches. Nevertheless, many challenges must be overcome to design membranes that can replace conventional gas separation processes. Here, we report on the incorporation of engineered submicrometre-sized metal–organic framework (MOF) crystals into polymers to form hybrid materials that successfully translate the excellent Molecular Sieving properties of face-centred cubic (fcu)-MOFs into the resultant membranes. We demonstrate, simultaneously, exceptionally enhanced separation performance in hybrid membranes for two challenging and economically important applications: the removal of CO2 and H2S from natural gas and the separation of butane isomers. Notably, the membrane Molecular Sieving properties demonstrate that the deliberately regulated and contracted MOF pore-aperture size can discriminate between Molecular pairs. The improved performance results from precise control of the linkers delimiting the triangular window, which is the sole entrance to the fcu-MOF pore. This rational-design hybrid approach provides a general toolbox for enhancing the transport properties of advanced membranes bearing Molecular sieve fillers with sub-nanometre-sized pore-apertures. Sub-micrometre MOF particles are incorporated into polymers to form mixed matrix membranes. Molecular Sieving enables performance far beyond current limits for two applications, butane isomer separation and combined CO2/H2S removal from natural gas.
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mixed matrix formulations with mof Molecular Sieving for key energy intensive separations
Nature Materials, 2018Co-Authors: Chen Zhang, Mohamed Eddaoudi, Gongping Liu, Valeriya Chernikova, Yang Liu, Kuang Zhang, Youssef Belmabkhout, Osama Shekhah, William J KorosAbstract:Membrane-based separations can improve energy efficiency and reduce the environmental impacts associated with traditional approaches. Nevertheless, many challenges must be overcome to design membranes that can replace conventional gas separation processes. Here, we report on the incorporation of engineered submicrometre-sized metal-organic framework (MOF) crystals into polymers to form hybrid materials that successfully translate the excellent Molecular Sieving properties of face-centred cubic (fcu)-MOFs into the resultant membranes. We demonstrate, simultaneously, exceptionally enhanced separation performance in hybrid membranes for two challenging and economically important applications: the removal of CO2 and H2S from natural gas and the separation of butane isomers. Notably, the membrane Molecular Sieving properties demonstrate that the deliberately regulated and contracted MOF pore-aperture size can discriminate between Molecular pairs. The improved performance results from precise control of the linkers delimiting the triangular window, which is the sole entrance to the fcu-MOF pore. This rational-design hybrid approach provides a general toolbox for enhancing the transport properties of advanced membranes bearing Molecular sieve fillers with sub-nanometre-sized pore-apertures.
Jürgen Caro - One of the best experts on this subject based on the ideXlab platform.
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mof in cof Molecular Sieving membrane for selective hydrogen separation
Nature Communications, 2021Co-Authors: Hongwei Fan, Jürgen Caro, Manhua Peng, Ina Strauss, Alexander Mundstock, Hong MengAbstract:Covalent organic frameworks (COFs) are promising materials for advanced Molecular-separation membranes, but their wide nanometer-sized pores prevent selective gas separation through Molecular Sieving. Herein, we propose a MOF-in-COF concept for the confined growth of metal-organic framework (MOFs) inside a supported COF layer to prepare MOF-in-COF membranes. These membranes feature a unique MOF-in-COF micro/nanopore network, presumably due to the formation of MOFs as a pearl string-like chain of unit cells in the 1D channel of 2D COFs. The MOF-in-COF membranes exhibit an excellent hydrogen permeance (>3000 GPU) together with a significant enhancement of separation selectivity of hydrogen over other gases. The superior separation performance for H2/CO2 and H2/CH4 surpasses the Robeson upper bounds, benefiting from the synergy combining precise size Sieving and fast Molecular transport through the MOF-in-COF channels. The synthesis of different combinations of MOFs and COFs in robust MOF-in-COF membranes demonstrates the versatility of our design strategy.
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photo switchable smart metal organic framework membranes with tunable and enhanced Molecular Sieving performance
Journal of Materials Chemistry, 2018Co-Authors: Jürgen Caro, Chuanyao Liu, Yunzhe Jiang, Chen Zhou, Aisheng HuangAbstract:Developing a novel MOF membrane material with switchable separation performance is an exciting and challenging research project. In the present work, we report preparation of a new kind of light induced smart MOF membrane, i.e., Cu(AzDC)(4,4′-BPE)0.5 membrane, which shows (i) enhanced Molecular Sieving performance, and (ii) is able to respond quickly to external light stimuli. Two photo-switchable moieties are addressed in the Cu(AzDC)(4,4′-BPE)0.5 membrane: azobenzene and bis(4-pyridyl)ethylene. When the Cu(AzDC)(4,4′-BPE)0.5 membrane is in situ irradiated with Vis and UV light, the separation factor of a H2/CO2 mixture can be switched reversibly between 21.3 and 43.7. This switching effect is mainly caused by reduced CO2 adsorption in the UV-cis state as proven by independent adsorption studies. For a steric reason, adsorption of CO2 is limited for the UV-cis state. In full agreement with this model, the adsorption of other gases H2, CH4 and N2 as well as their permeation behaviour is not observably influenced by the trans–cis switching.
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MXene Molecular Sieving membranes for highly efficient gas separation
Nature Communications, 2018Co-Authors: Li Ding, Yanying Wei, Libo Li, Tao Zhang, Haihui Wang, Jian Xue, Liang-xin Ding, Suqing Wang, Jürgen Caro, Yury GogotsiAbstract:Molecular Sieving membranes with sufficient and uniform nanochannels that break the permeability-selectivity trade-off are desirable for energy-efficient gas separation, and the arising two-dimensional (2D) materials provide new routes for membrane development. However, for 2D lamellar membranes, disordered interlayer nanochannels for mass transport are usually formed between randomly stacked neighboring nanosheets, which is obstructive for highly efficient separation. Therefore, manufacturing lamellar membranes with highly ordered nanochannel structures for fast and precise Molecular Sieving is still challenging. Here, we report on lamellar stacked MXene membranes with aligned and regular subnanometer channels, taking advantage of the abundant surface-terminating groups on the MXene nanosheets, which exhibit excellent gas separation performance with H2 permeability >2200 Barrer and H2/CO2 selectivity >160, superior to the state-of-the-art membranes. The results of Molecular dynamics simulations quantitatively support the experiments, confirming the subnanometer interlayer spacing between the neighboring MXene nanosheets as Molecular Sieving channels for gas separation. Two-dimensional materials show great potential for membrane technologies, but their disordered channels hinder their Molecular Sieving performance. Here, Wang, Gogotsi and colleagues design a MXene membrane with ordered nanochannels that exhibits an excellent H2/CO2 gas separation performance.
Zhuonan Song - One of the best experts on this subject based on the ideXlab platform.
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dual channel Molecular Sieving core shell zif mof architectures as engineered fillers in hybrid membranes for highly selective co2 separation
Nano Letters, 2017Co-Authors: Zhuonan Song, Fen Qiu, Edmond W. Zaia, Zhongying Wang, Martin Kunz, Jinghua Guo, Michael A Brady, Jeffrey J. UrbanAbstract:A novel core/shell porous crystalline structure was prepared using a large pore metal organic framework (MOF, UiO-66-NH2, pore size, ∼ 0.6 nm) as core surrounded by a small pore zeolitic imidazolate framework (ZIF, ZIF-8, pore size, ∼ 0.4 nm) through a layer-by-layer deposition method and subsequently used as an engineered filler to construct hybrid polysulfone (PSF) membranes for CO2 capture. Compared to traditional fillers utilizing only one type of porous material with rigid channels (either large or small), our custom designed core/shell fillers possess clear advantages via pore engineering: the large internal channels of the UiO-66-NH2 MOFs create Molecular highways to accelerate Molecular transport through the membrane, while the thin shells with small pores (ZIF-8) or even smaller pores generated at the interface by the imperfect registry between the overlapping pores of ZIF and MOF enhance Molecular Sieving thus serving to distinguish slightly larger N2 molecules (kinetic diameter, 0.364 nm) from ...
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Dual-Channel, Molecular-Sieving Core/Shell ZIF@MOF Architectures as Engineered Fillers in Hybrid Membranes for Highly Selective CO2 Separation
2017Co-Authors: Zhuonan Song, Fen Qiu, Edmond W. Zaia, Zhongying Wang, Martin Kunz, Jinghua Guo, Michael Brady, Jeffrey J. UrbanAbstract:A novel core/shell porous crystalline structure was prepared using a large pore metal organic framework (MOF, UiO-66-NH2, pore size, ∼ 0.6 nm) as core surrounded by a small pore zeolitic imidazolate framework (ZIF, ZIF-8, pore size, ∼ 0.4 nm) through a layer-by-layer deposition method and subsequently used as an engineered filler to construct hybrid polysulfone (PSF) membranes for CO2 capture. Compared to traditional fillers utilizing only one type of porous material with rigid channels (either large or small), our custom designed core/shell fillers possess clear advantages via pore engineering: the large internal channels of the UiO-66-NH2 MOFs create Molecular highways to accelerate Molecular transport through the membrane, while the thin shells with small pores (ZIF-8) or even smaller pores generated at the interface by the imperfect registry between the overlapping pores of ZIF and MOF enhance Molecular Sieving thus serving to distinguish slightly larger N2 molecules (kinetic diameter, 0.364 nm) from smaller CO2 molecules (kinetic diameter, 0.33 nm). The resultant core/shell ZIF@MOF and as-prepared hybrid PSF membranes were characterized by transmission electron microscopy, X-ray diffraction, wide-angle X-ray scattering, scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis, differential scanning calorimetry, and contact angle tests. The dependence of the separation performance of the membranes on the MOF/ZIF ratio was also studied by varying the number of layers of ZIF coatings. The integrated PSF-ZIF@MOF hybrid membrane (40 wt % loading) with optimized ZIF coating cycles showed improved hydrophobicity and excellent CO2 separation performance by simultaneously increasing CO2 permeability (CO2 permeability of 45.2 barrer, 710% higher than PSF membrane) and CO2/N2 selectivity (CO2/N2 selectivity of 39, 50% higher than PSF membrane), which is superior to most reported hybrid PSF membranes. The strategy of using dual-channel Molecular Sieving core/shell porous crystals in hybrid membranes thus provides a promising means for CO2 capture from flue gas
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continuously adjustable Molecular Sieving gate on 5a zeolite for distinguishing small organic molecules by size
Scientific Reports, 2015Co-Authors: Zhuonan Song, Yi Huang, Lei Wang, Yu BaoAbstract:Zeolites/Molecular sieves with uniform, Molecular-sized pores are important for many adsorption-based separation processes. Pore size gaps, however, exist in the current zeolite family. This leads to a great challenge of separating molecules with size differences at ~0.01 nm level. Here, we report a novel concept, pore misalignment, to form a continuously adjustable, Molecular-Sieving “gate” at the 5A zeolite pore entrance without sacrificing the internal capacity. Misalignment of the micropores of the alumina coating with the 5A zeolite pores was related with and facilely adjusted by the coating thickness. For the first time, organic molecules with sub-0.01 nm size differences were effectively distinguished via appropriate misalignment. This novel concept may have great potential to fill the pore size gaps of the zeolite family and realize size-selective adsorption separation.
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ultrathin Molecular Sieving graphene oxide membranes for selective hydrogen separation
Science, 2013Co-Authors: Zhuonan Song, Xiaojie Zhang, Yi Huang, Yating Mao, Harry J Ploehn, Yu BaoAbstract:Ultrathin, Molecular-Sieving membranes have great potential to realize high-flux, high-selectivity mixture separation at low energy cost. Current microporous membranes [pore size 2 /CO 2 and H 2 /N 2 mixtures, respectively, through selective structural defects on GO.
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ultrathin Molecular Sieving graphene oxide membranes for selective hydrogen separation
Science, 2013Co-Authors: Zhuonan Song, Xiaojie Zhang, Yi Huang, Yating Mao, Harry J Ploehn, Yu BaoAbstract:Ultrathin, Molecular-Sieving membranes have great potential to realize high-flux, high-selectivity mixture separation at low energy cost. Current microporous membranes [pore size < 1 nanometer (nm)], however, are usually relatively thick. With the use of current membrane materials and techniques, it is difficult to prepare microporous membranes thinner than 20 nm without introducing extra defects. Here, we report ultrathin graphene oxide (GO) membranes, with thickness approaching 1.8 nm, prepared by a facile filtration process. These membranes showed mixture separation selectivities as high as 3400 and 900 for H2/CO2 and H2/N2 mixtures, respectively, through selective structural defects on GO.