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The purification of p‐xylene (pX) from its xylene isomers represents a challenging but important industrial process. Herein, we report the efficient separation of pX from its ortho‐ and meta‐ isomers by a microporous calcium‐based metal–organic framework material (HIAM‐203) with a flexible skeleton. At 30 °C, all three isomers are accommodated but the adsorption kinetics of o‐xylene (oX) and m‐xylene (mX) are substantially slower than that of pX, and at an elevated temperature of 120 °C, oX and mX are fully excluded while pX can be adsorbed. Multicomponent column breakthrough measurements and vapor‐phase/liquid‐phase adsorption experiments have demonstrated the capability of HIAM‐203 for efficient separation of xylene isomers. Ab initio calculations have provided useful information for understanding the adsorption mechanism. [ABSTRACT FROM AUTHOR]

The purification of p‐xylene (pX) from its xylene isomers represents a challenging but important industrial process. Herein, we report the efficient separation of pX from its ortho‐ and meta‐ isomers by a microporous calcium‐based metal–organic framework material (HIAM‐203) with a flexible skeleton. At 30 °C, all three isomers are accommodated but the adsorption kinetics of o‐xylene (oX) and m‐xylene (mX) are substantially slower than that of pX, and at an elevated temperature of 120 °C, oX and mX are fully excluded while pX can be adsorbed. Multicomponent column breakthrough measurements and vapor‐phase/liquid‐phase adsorption experiments have demonstrated the capability of HIAM‐203 for efficient separation of xylene isomers. Ab initio calculations have provided useful information for understanding the adsorption mechanism. [ABSTRACT FROM AUTHOR]

The separation of alkane isomers is an important yet challenging process in the petrochemical industry. Being a crucial step to produce premium gasoline components as well as optimum ethylene feed, the current industrial separation by distillation is extremely energy intensive. Adsorptive separation based on zeolite is limited by insufficient adsorption capacity. Metal‐organic frameworks (MOFs) hold enormous promise as alternative adsorbents due to their diverse structural tunability and exceptional porosity. Precise control of their pore geometry/dimensions has led to superior performance. In this minireview, we highlight the recent progresses in developing MOFs for the separation of C6 alkane isomers. Representative MOFs are reviewed based on their separation mechanisms. Emphasis is put on the material design rationale for achieving optimal separation capability. Finally, we briefly discuss the existing challenges, possible solutions, and future directions of this important field. [ABSTRACT FROM AUTHOR]

The separation of alkane isomers is an important yet challenging process in the petrochemical industry. Being a crucial step to produce premium gasoline components as well as optimum ethylene feed, the current industrial separation by distillation is extremely energy intensive. Adsorptive separation based on zeolite is limited by insufficient adsorption capacity. Metal‐organic frameworks (MOFs) hold enormous promise as alternative adsorbents due to their diverse structural tunability and exceptional porosity. Precise control of their pore geometry/dimensions has led to superior performance. In this minireview, we highlight the recent progresses in developing MOFs for the separation of C6 alkane isomers. Representative MOFs are reviewed based on their separation mechanisms. Emphasis is put on the material design rationale for achieving optimal separation capability. Finally, we briefly discuss the existing challenges, possible solutions, and future directions of this important field. [ABSTRACT FROM AUTHOR]

The full separation of alkane isomers as a function of different degrees of branching remains a daunting challenge due to its stringent requirement with respect to pore dimensions of the adsorbents. In this work, we report a novel microporous coordination network built on calcium (II) and chloranilate. The compound has a flexible framework and exhibits temperature‐dependent adsorption behavior toward hexane isomers. At 30 °C, it accommodates substantial amounts of linear and monobranched hexanes but fully excludes their dibranched isomer, and at elevated temperatures such as 150 °C, it acts as a splitter for linear and branched alkanes. Its capability of efficient discrimination of hexane isomers as a function of branching is verified by experimental breakthrough measurements. Ab initio calculations have uncovered the underlying selective size‐exclusion separation mechanism. [ABSTRACT FROM AUTHOR]

The full separation of alkane isomers as a function of different degrees of branching remains a daunting challenge due to its stringent requirement with respect to pore dimensions of the adsorbents. In this work, we report a novel microporous coordination network built on calcium (II) and chloranilate. The compound has a flexible framework and exhibits temperature‐dependent adsorption behavior toward hexane isomers. At 30 °C, it accommodates substantial amounts of linear and monobranched hexanes but fully excludes their dibranched isomer, and at elevated temperatures such as 150 °C, it acts as a splitter for linear and branched alkanes. Its capability of efficient discrimination of hexane isomers as a function of branching is verified by experimental breakthrough measurements. Ab initio calculations have uncovered the underlying selective size‐exclusion separation mechanism. [ABSTRACT FROM AUTHOR]

High‐efficiency separation of C6 alkanes, particularly the mono‐ and dibranched isomers by using porous solids, is of paramount significance in the petrochemical industry and, remains a daunting challenge. In this work, we report the complete separation of linear/monobranched hexanes from their dibranched isomers through selective size‐exclusion by a microporous MOF, Zn‐tcpt (H3tcpt=2,4,6‐tris(4‐carboxyphenoxy)‐1,3,5‐triazine), with a two‐fold interpenetrated structure of hms nets. Importantly, its adsorption capacity and selectivity are notably higher than those of the previously reported adsorbents that can split mono‐ and dibranched alkane isomers. Dynamic breakthrough measurements verify the excellent separation of C6 alkane isomers by Zn‐tcpt, and the size‐exclusion based separation mechanism has been confirmed by ab initio materials modeling. The high‐efficiency separation of alkane isomers by Zn‐tcpt can be attributed to its optimal pore dimensions as well as high porosity. [ABSTRACT FROM AUTHOR]

High‐efficiency separation of C6 alkanes, particularly the mono‐ and dibranched isomers by using porous solids, is of paramount significance in the petrochemical industry and, remains a daunting challenge. In this work, we report the complete separation of linear/monobranched hexanes from their dibranched isomers through selective size‐exclusion by a microporous MOF, Zn‐tcpt (H3tcpt=2,4,6‐tris(4‐carboxyphenoxy)‐1,3,5‐triazine), with a two‐fold interpenetrated structure of hms nets. Importantly, its adsorption capacity and selectivity are notably higher than those of the previously reported adsorbents that can split mono‐ and dibranched alkane isomers. Dynamic breakthrough measurements verify the excellent separation of C6 alkane isomers by Zn‐tcpt, and the size‐exclusion based separation mechanism has been confirmed by ab initio materials modeling. The high‐efficiency separation of alkane isomers by Zn‐tcpt can be attributed to its optimal pore dimensions as well as high porosity. [ABSTRACT FROM AUTHOR]

Lithium sulfur batteries (LSBs) have attracted tremendous attention owing to their high theoretical specific capacity and specific energy. However, their practical applications are hindered by poor cyclic life, mainly caused by polysulfide shuttling. The development of advanced materials to mitigate the polysulfide shuttling effect is urgently demanded. Metal‐organic frameworks (MOFs) have been exploited as multifunctional materials for the decoration of separators owing to their high surface area, structural diversity, tunable pore size, and easy tailor ability. In this review, we aim to present the state‐of‐the‐art MOF‐based separators for LSBs. Particular attention is paid to the rational design (pore aperture, metal node, functionality, and dimension) of MOFs with enhanced ability for anchoring polysulfides and facilitating Li+ transportation. Finally, the challenges and perspectives are provided regarding to the future design MOF‐based separators for high‐performance LSBs. [ABSTRACT FROM AUTHOR]

The compounding of polyoxometalates (POMs) with structurally well-defined and porous metal–organic frameworks (MOFs) has become a hot research topic. Here, a core–shell type hybrid, {Ag5BW12O40}@[Ag3(μ-Hbtc)(μ-H2btc)]n (called {Ag5BW12O40}@Ag-BTC-2, where BTC = 1,3,5-benzyl carboxylic acid), was successfully prepared via a simple grinding method. IR, XRD, SEM, TEM, and XPS analysis was used to confirm the structure. The specific capacitance is 179.1 F g−1 when the current density is 1 A g−1, using nickel foam as the collector, and the capacitance retention is 97.4% after 5000 cycles. The resulting aqueous-based symmetric supercapacitor has a power density of 496 W kg−1 and an energy density of 12.4 W h kg−1. In addition, the degradation rates using {Ag5BW12O40}@Ag-BTC-2 toward methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) exceeded 90% in 140 min and remained essentially unchanged over five replicate experiments, showing high photocatalytic activity. Meanwhile, when {Ag5BW12O40}@Ag-BTC-2 acts as a H2O2 biosensor, it has a low detection limit (0.19 μM), a wide linear range (0.4 μM–0.27 mM) and high anti-interference properties. This shows that the synthesis of POMOFs via a grinding method is an effective strategy to improve the performance. [ABSTRACT FROM AUTHOR]

Proton exchange membrane (PEM) is one of the core materials which were widely used in the field of fuel cells (FCs). In recent years, the metal organic frameworks (MOFs) and polymer composite membranes as tunable proton-conducting materials have showed great potential in this field. Herein, a Cu(II)-based metal organic framework (Cu-MOF) with acid/base stability was introduced into poly(vinylpyrrolidone)/poly(vinylidene fluoride) (PVP/PVDF, PP) to fabricate hybrid membranes(Cu-MOF@PP-X, where X is the % Cu-MOF content). The effects of Cu-MOF loading amounts on the conductive behavior of Cu-MOF@PP-X composites have been documented. It is worth noting that Cu-MOF@PP-50 exhibited the proton conductivity up to 4.36 ​× ​10−4 ​S ​cm−1 at 353 ​K and 98% relative humidity (RH). In addition, the value of proton conduction is about two orders of magnitude higher than that of the parent Cu-MOF (1.91 ​× ​10−6 ​S ​cm−1). This work contributes to driving further advances of MOF/polymer composites in proton-conducting apparatus. [Display omitted] • A Cu-MOF with acid/base stability was introduced into polymers (PVP/PVDF, PP) to fabricate hybrid membranes. • The effects of Cu-MOF loading amounts on the conductive behavior of Cu-MOF@PP-X composites have been documented. • Cu-MOF@PP-50 exhibited a super protonic conductivity up to 4.36 ​× ​10−4 ​S ​cm−1 at 353 ​K and 98% relative humidity (RH). • The value of proton conduction of Cu-MOF@PP-50 is about two orders of magnitude higher than that of the parent Cu-MOF. [ABSTRACT FROM AUTHOR]

[Display omitted] • Downsizing a benchmark MOF into uniform nanosized materials. • Enhanced gas adsorption rate and capacity. • High-performance separation of propane and propylene. The separation of propane/propylene mixtures to produce polymer-grade propylene represents an important yet challenging task in the petrochemical industry. Metal-organic frameworks (MOFs) hold particular promise for the energy-efficient adsorptive separation of propane/propylene, in light of their structural diversity as well as highly tunable pore dimensions. MOFs exhibiting selective molecular exclusion for propylene over propane render exceptionally high adsorption selectivity. However, the relatively low adsorption capacity and/or slow diffusion kinetics have largely limited their separation efficiency. Here we report the fabrication of nano-sized crystals of a MOF-based splitter for propane and propylene. Compared to the micro-sized MOF samples, the nanocrystals display enhanced adsorption kinetics as well as notably improved adsorption capacity, making a new record with the highest efficiency for the separation of propane/propylene among all reported MOF-based splitters. Our study may shed light on the development of MOF-based adsorbents with optimal efficiency for industrially challenging gas separations. [ABSTRACT FROM AUTHOR]

[Display omitted] • C 2 H 4 /C 2 H 6 separation was studied using highly permeable ZIF-8 membranes. • The membrane temperatures were varied from −30 to 100 °C for separation. • A high C 2 H 4 permeance of 8.1 × 10−7 mol/(m2·s·Pa) was observed at −30 °C. Ethylene/ethane separation is a critical and energy-consuming process in the chemical industry due to the similar properties of the compounds and the great need of ethylene for e.g., polymer production. Many materials have been studied for their implementation as membranes as an energetically favorable alternative to conventional distillation and adsorption processes. Metal-organic frameworks (MOF) have revealed promising properties as highly permeable and selective membranes. Among the most studied and promising MOF candidates is ZIF-8, known for its thermal stability and small pores connected by narrow-sized windows. In this work, we present an analysis of the influence of parameters such as temperature, feed pressure and feed flowrate on the separation of ethylene/ethane through a thin ZIF-8/alumina disc membrane. We observed that the temperature has a significant effect on the separation. The ethylene permeance increased with decreased temperature and reached 8.1 × 10−7 mol/(m2·s·Pa) at −30 °C. At this temperature, the ethylene/ethane selectivity was 2.5. The study concluded with a considerable enhancement of the permeance of ZIF-8 membranes for ethylene/ethane separations, while maintaining a good selectivity compared to the reported values in the literature. The results have important implications for the development of more cost-effective and energy-efficient membrane-based separation technologies for ethylene purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • M(AIP)(BPY) 0.5 (M = Co, Ni, and Zn) showed efficient C 3 H 6 /C 3 H 8 separation. • The separation mechanism was based on the thermodynamic-kinetic synergetic effect. • Ni(AIP)(BPY) 0.5 had the highest C 3 H 6 /C 3 H 8 uptake ratio of 4.26 at 298 K and 1 bar. Efficient adsorption separation of propylene (C 3 H 6) and propane (C 3 H 8) can largely lower the energy consumption compared to the current energy-intensive cryogenic distillation. Herein, we report an isoreticular family of pillar-layer metal–organic frameworks (MOFs), M(AIP)(BPY) 0.5 (M = Co, Ni, and Zn), for efficient C 3 H 6 /C 3 H 8 separation by simultaneously exploiting thermodynamic and kinetic effects, circumventing disadvantages of each separation mechanism. The three MOFs feature an open metal site for each metal node and uniform but narrow one-dimensional (1D) channels, offering strong binding sites toward C 3 H 6 via π-complexations while obstructing the diffusion of bulkier C 3 H 8. The Ni-MOF shows the best separation performance based on the highest thermodynamic and kinetic C 3 H 6 /C 3 H 8 selectivities, further verified by computational simulations. Ni(AIP)(BPY) 0.5 has a moderate C 3 H 6 uptake of 1.94 mmol/g but a remarkably high C 3 H 6 /C 3 H 8 uptake ratio of 4.26 at 298 K and 1 bar. Efficient C 3 H 6 /C 3 H 8 separation, good recyclability, moisture and water stability of Ni(AIP)(BPY) 0.5 are confirmed. [ABSTRACT FROM AUTHOR]

• The large-scale synthesis of H 4 abtc (180 g scale) and Y-abtc (100 g scale) in high yields. • Breakthrough experiments on binary mixtures of propane/propylene at the 100 g scale. • Polymer grade propylene purity achieved using Y-abtc at 100 g scale. • Retained performance of Y-abtc at large scale demonstrating its potential for real world applications. Olefin/Paraffin separation, especially propylene purification from propane, is of extreme commercial importance as it produces chemical feedstock for synthetic plastics such as polypropylene. As an alternative to cryogenic distillation commonly used to purify these mixtures, the use of solid porous materials for adsorptive separation offers a more energetically efficient route. Metal-Organic Frameworks (MOFs) have shown great promise as adsorptive separation candidates in recent years. However, reports of these materials for the purification of C3 hydrocarbons exclusively provide insight of their performance in small scale laboratory settings. Single component isotherms and breakthrough curves are typically tested in the milligrams to gram scale. Herein, we present a scale-up, one-pot synthesis of a robust MOF with high propylene/propane selectivity. The organic linker 3,3′,5,5′-azobenzene-tetracarboxylic acid (H 4 abtc) and its yttrium-based MOF, Y-abtc, are both synthesized at the hundred-gram scale. Furthermore, we perform large-scale breakthrough experiments at the same scale. Our results show that Y-abtc samples synthesized from the one-pot 100 g scale reactions retain high crystallinity and size-exclusion based mechanism for the separation of propane/propylene mixtures. The same polymer-grade purity of propylene (>99.5%) is achieved as in the case of small scale (∼1 g) experiments. [ABSTRACT FROM AUTHOR]

The separation of alkanes, particularly monobranched and dibranched isomers, is of paramount importance in the petrochemical industry for optimizing the feedstock of ethylene production as well as for upgrading the octane number of gasoline. Here, we report the full separation of linear/monobranched alkanes from their dibranched isomers by a robust and easily scalable metal‐organic framework material, Co3(HCOO)6. The compound completely excludes dibranched alkanes but adsorbs their linear and monobranched isomers, as evidenced by single‐component and multicomponent adsorption measurements. More importantly, the material exhibits excellent performance in separating naphtha and is capable of providing high quality feedstock for the production of ethylene and gasoline components with high octane number, making it a promising candidate for naphtha separation in petrochemical industry. [ABSTRACT FROM AUTHOR]

A new 3D anionic metal-organic framework material, namely, [Me 2 NH 2 ] 2 [Cd 3 (L)]·2H 2 O (1 , H 4 L ​= ​2,5′-di(3′,5′-dicarboxylphenyl)pyridine) has been synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction, PXRD, thermogravimetric analysis and proton conduction investigation. In 1 , the adjacent Cd(II) ions are joined to form a trinuclear [Cd 3 (COO) 8 ] secondary building unit (SBU) by eight bridging carboxylate groups of L4− ligands. The trinuclear [Cd 3 (COO) 8 ] SBUs are connected by L4− ligands into a 3D (4,8)-connected framework with 1D channels. Most interestingly, due to the guest [Me 2 NH 2 ]+ cations, water molecules and carboxylates sites are lined the pore channels, 1 possesses a remarkable proton conductivity of 1.12 ​× ​10−1 ​S ​cm−1 ​at 60 ​°C and 98% RH, which is comparable to commercially available Nafion. The mechanism of proton conduction was also well discussed. A new 3D anionic metal-organic framework material, namely, [Me 2 NH 2 ] 2 [Cd 3 (L)]·2H 2 O (1 , H 4 L ​= ​2,5′-di(3′,5′-dicarboxylphenyl)pyridine) has been synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction, PXRD, thermogravimetric analysis and proton conduction investigation. Compound 1 exhibits a (4,8)-connected 3D network based on trinuclear [Cd 3 (COO) 8 ] cluster units with excellent water stability. It's worth noting that the value of proton conductivity of 1 reaches 1.12 ​× ​10−1 ​S ​cm−1 ​at 60 ​°C and 98% RH which is comparable to most of the dramatic proton conducting MOFs materials. The activation energy (E a) of 1 is 0.376 ​eV estimated by Arrhenius equation. [Display omitted] • A trinuclear Cd-based 3D (4,8)-connected anionic metal-organic framework were synthesized. • The [Me 2 NH 2 ]+ ​cations, H 2 O and host carboxylates could construct continuous proton-conducting pathways. • The MOF exhibited a remarkable proton conductivity of 1.12×10-1 ​S cm-1 ​at 60°C and 98% RH. [ABSTRACT FROM AUTHOR]

Developing new techniques and materials for ethylene (C 2 H 4) and ethane (C 2 H 6) separation is an industrially significant but challenging task. Here we report two isoreticular pillar-layer metal-organic frameworks, Co(aip)(bpy) 0.5 and Co(aip)(pyz) 0.5 , for the separation of C 2 H 4 /C 2 H 6. The pore apertures of the pillar-layer metal-organic frameworks are rationally controlled by changing the length of the pillar ligands. Significantly, Co(aip)(pyz) 0.5 with a shorter pillar ligand shows reduced pore size and molecular sieving separation of C 2 H 4 from C 2 H 6. Co(aip)(pyz) 0.5 has a moderate C 2 H 4 capacity of 1.78 mmol/g but ultrahigh C 2 H 4 /C 2 H 6 selectivity exceeding 2000 at ambient conditions. The molecular simulation revealed that large torsion angle between the organic linker plane and Co–O bond leads to the high energy barrier for C 2 H 6 to enter into the pore, which results in the molecular sieving separation of C 2 H 4 /C 2 H 6. Dynamic breakthrough experiments confirmed the high selectivity of Co(aip)(pyz) 0.5 for C 2 H 4. And high-purity C 2 H 4 (>97%) with a C 2 H 4 productivity of 19.1 l/kg can be obtained through the desorption process. Meanwhile, the excellent reusability and moisture stability endow it great potential for applications in adsorptive separation. [Display omitted] • The pore apertures of the pillar-layer MOFs are rationally controlled. • Co(aip)(pyz) 0.5 showed the molecular sieving separation of C 2 H 4 /C 2 H 6. [ABSTRACT FROM AUTHOR]

[Display omitted] • MOF-11 breaks the trade-off between uptake and selectivity for Xe/Kr separation. • MOF-11 has the highest Xe uptake of 4.05 mmol/g at 0.2 bar and 298 K. • MOF-11 has high Xe/Kr Henry and IAST selectivity of 13.6 and 16.1 at 298 K. • Xe/Kr separation is achieved by the synergy between optimal pore size and OMSs. Efficient separation of Xenon (Xe) and krypton (Kr) is important in the gas industries but remains challenging. Adsorptive separation affords an energy-efficient method to isolate the two noble gases, yet developing selective adsorbents with high uptake and excellent selectivity remains difficult, limited by a trade-off between uptake and selectivity. We report MOF-11 with optimal pore size and accessible open metal sites (OMSs) for separation of Xe over Kr via the discriminable difference in van der Waals interactions. MOF-11 affords a new benchmark for Xe/Kr separation with high Xe uptakes of 4.05 and 4.95 mmol/g (at 0.2 and 1 bar), high Xe/Kr Henry and IAST selectivity (13.6 and 16.1) at 298 K. Evidenced by Xe-loaded structure, multiple Xe···H interactions between Xe and the terminal H atoms allow Xe atoms firmly packed within the framework. This work demonstrates a strategy for balancing uptake and selectivity in Xe/Kr separation by capitalizing on the synergy between optimal pore size and OMSs. [ABSTRACT FROM AUTHOR]

Alkane isomers, hydrocarbon separation, metal-organic frameworks, naphtha, octane number Keywords: alkane isomers; hydrocarbon separation; metal-organic frameworks; naphtha; octane number EN alkane isomers hydrocarbon separation metal-organic frameworks naphtha octane number 11748 11748 1 08/19/21 20210816 NES 210816 B Naphtha was separated b by using a easily attainable metal-organic framework, Co SB 3 sb (HCOO) SB 6 sb , through selective molecular exclusion of alkane isomers with different degrees of branching. Cover Feature: Upgrading Octane Number of Naphtha by a Robust and Easily Attainable Metal-Organic Framework through Selective Molecular Sieving of Alkane Isomers (Chem. Eur. J. 46/2021). [Extracted from the article]