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[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]

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]