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Supramolecular metal–organic frameworks (SMOFs) are emerging as a new family of porous materials. In this work, a SMOF, [Cu2(ade)4(H2O)2](SiF6)2(SMOF-SIFSIX-1, ade = adenine) was successfully synthesized from the cationic complex of copper and adenine and hexafluorosilicate anions by a slow diffusion method and was demonstrated for trapping carbon dioxide in preference to methane and nitrogen. With one-dimensional pores of about 3.6 × 3.6 Å to induce their distinguishing interactions with the three components, SMOF-SIFSIX-1 exhibited excellent selective gas sorption behaviors for CO2/CH4(50:50) and CO2/N2(15:85) gas mixtures with ideal adsorbed solution theory selectivities of 21.1 and 131.7 at 273 K and 100 kPa pressure, respectively, outperforming most of reported hydrogen-bonded organic frameworks so far. Neutron powder diffraction and DFT-D calculations were also carried out to investigate the CO2adsorption configuration on SMOF-SIFSIX-1a, which suggested that this framework catch CO2due to “C···F” and “O···H” supramolecular interactions between CO2molecules and SMOF-SIFSIX-1a. This study demonstrates that the rarely studied SMOF material shows promising potential in gas adsorption separation.

Efficiently obtaining both high-purity gas-phase and adsorbed-phase products in a single physisorption process presents the challenge of simultaneously achieving high selectivity and uptake and rapid diffusion in adsorbents. With a focus on natural gas purification and high-purity acetylene production, we report for the first time that the synergistic ligand/anion binding mode and multiple diffusion pathways in a robust 2D layered ultramicroporous framework (ZUL-100) enable unprecedented carbon dioxide/methane and acetylene/methane separation performance. Taking advantage of its rich anion, functional ligand ,and rigid 3D interpenetrated ultramicroporous channels, ZUL-100 achieved record IAST selectivities for equimolar carbon dioxide/methane (3.2 × 105) and acetylene/methane (1.7 × 1010) mixtures, accompanied by record dynamic uptakes of carbon dioxide (3.10 mmol/g) and acetylene (4.79 mmol/g), respectively. The strong affinity and fast mass transfer of carbon dioxide and acetylene on ZUL-100 were systematically elucidated by a combination of in situ FTIR, single-crystal XRD, kinetic tests, and DFT-D adsorption/diffusion modeling. In particular, high-purity (≥99.999%) methane and carbon dioxide (acetylene) can both be obtained on ZUL-100 through a single adsorption–desorption cycle, with exceptional productivity (2.81–4.22 mmol/g of methane, 2.96 mmol/g of carbon dioxide, and 4.31 mmol/g of acetylene) and high yield (95.5% for carbon dioxide and 90.0% for acetylene).

The efficient separation of 4-methyl-1-pentene (4MP1) from its structural isomers is crucial for industrial applications but remains challenging due to the similar physicochemical properties of these compounds. This study introduces a novel strategy using metal–organic frameworks (MOFs), specifically an engineered variant of ZIF-108, which demonstrates remarkable improvements in the thermodynamic and kinetic properties for 4MP1 separation. By substituting the methyl groups in ZIF-8 with planar nitro groups, we achieved a strategic resizing of the pore windows and cavity dimensions in ZIF-108. This adjustment not only enhanced the molecular affinity and selectivity toward 4MP1 but also facilitated a diffusion rate that is 164 times faster than that observed in ZIF-8. These properties significantly elevated the performance of ZIF-108 in simulated moving bed (SMB) processes, achieving up to 96.5% recovery of high-purity 4MP1, outperforming traditional adsorbents. Comprehensive characterization, including density functional theory (DFT) calculations and molecular dynamics (MD) simulations, provided insights into the interactions and the stability of the adsorption process. The findings suggest that the strategic modification of the pore architecture in MOFs holds significant potential for optimizing the separation processes of industrially relevant mixtures.

Separation of the ethane/ethylene mixture is one of the most important but challenging processes in the petrochemical industry owing to their closely resembling physical and chemical characteristics. The remarkable characteristics of customized pore aperture and functionality endow metal–organic frameworks (MOFs) with great prospects in the adsorption separation of an ethane/ethylene mixture. However, large fixed-bed pressure drops, dustiness, transportation, and handling challenges of the powdered MOFs have largely restricted their large-scale industrial applications. Herein, we successfully prepared a silver-functionalized MOF pellet adsorbent using renewable carboxymethyl cellulose (CMC) as the binder and explored its feasibility for adsorptive separation of C2H4/C2H6in the industry via both single-component adsorption isotherms and breakthrough experiments. Scanning electron microscopy and N2adsorption isotherms revealed the “solid bridge” formed by CMC between MIL-101-SO3Ag@CMC pellets that tightly hold MOF crystals together while minimizing pore blockage. In addition, the pellets also attained excellent mechanical strength and stability sufficient to meet industrial application standards. Due to the formation of π-complexation between Ag(I) ions and the ethylene, MIL-101-SO3Ag@CMC pellets demonstrated a moderate-high ethylene adsorption capacity of 2.23 mmol/g at 298 K and 1 bar and an excellent separation performance for ethylene/ethane. Significantly, the ideal adsorbed solution theory selectivity of the ethylene/ethane (50:50, v/v) mixture for pellets was 25.2 at 298 K and 10 kPa, far exceeding most reported adsorbents. Furthermore, breakthrough experiments and humid adsorption experiments verified that MIL-101-SO3Ag@CMC can achieve high-purity ethylene (>99.9%) from the binary ethane/ethylene (50:50, v/v) mixture, indicating that MIL-101-SO3Ag@CMC is a promising adsorbent with both efficient C2H4/C2H6selectivity and excellent stability.

The selective splitting of hexane isomers without the use of energy-intensive phase-change processes is essential for the low-carbon production of clean fuels and also very challenging. Here, we demonstrate a strategy to achieve a complete splitting of the high-RON dibranched isomer from the monobranched and linear isomers, by using a nonlinear 3D ligand to form pillar-layered MOFs with delicate pore architecture and chemistry. Compared with its isoreticular MOFs with the same ted pillar but different linear 3D or linear 2D in-layer ligands, the new MOF constructed in this work, Cu(bhdc)(ted)0.5(ZUL-C5), exhibited an interesting “channel switch” effect which creates pore space with reduced window size and channel dimensionality together with unevenly distributed alkyl-rich adsorption sites, contributing to a greatly enhanced ability to discriminate between mono- and dibranched isomers. Evidenced by a series of studies including adsorption equilibrium/kinetics/breakthrough tests, guest-loaded single-crystal/powder XRD measurement, and DFT-D modeling, a thermodynamic–kinetic synergistic mechanism in the separation was proposed, resulting in a record production time for high-purity 2,2-dimethylbutane along with a high yield.

The simultaneous capture of trace propyne and propadiene from propylene is one of the important but energy demanding industrial processes because of their similar physicochemical properties as well as the ultralow concentration in the mixtures. Herein, a highly stable Ca-based MOF, constructed from an inexpensive precursor (CaCO3) and rigid squaric acid, is capable of preferentially capturing trace propyne and propadiene with record-high uptake capacities of 2.44 and 2.64 mmol/g at pressures as low as 5 mbar, respectively. Direct multicomponent breakthrough experiments confirm that Ca-based MOF exhibits an excellent performance for simultaneous removal of trace propyne and propadiene from propylene. DFT simulation and in situsingle-crystal X-ray diffraction of propadiene- and propyne-adsorbed Ca-based MOFs reveal that the strong affinity of the framework toward two species is ascribed to the multiple types of cooperative binding including π–π stacking and C–H···O interactions. The calcium squarate framework sets a new benchmark for adsorptive purification of propylene, showing great potential in the practical application.

Metal–organic frameworks (MOFs) packed in the column have been a promising candidate as the stationary phase for high performance liquid chromatography (HPLC). However, the direct packing of irregular MOF powder could raise some problems like high back pressure and low column efficiency in the HPLC separation. In this work, UiO-66 capable of separating xylenes was supported effectively on the surface of the monodisperse spherical silica microspheres by one-pot method. The hybridization of UiO-66 and silica microspheres (termed UiO-66@SiO2shell–core composite) was prepared by stirring the suspension of the precursors of UiO-66 and COOH terminated silica in the N,N-dimethylformamide with heating. The shell–core composite material UiO66@SiO2was characterized by SEM, TEM, PXRD and FTIR. Then, it was used as a packing material for the chromatographic separation of xylene isomers. Xylene isomers including o-xylene, m-xylene and p-xylene were efficiently separated on the column with high resolution and good reproducibility. Moreover, the UiO-66@SiO2shell–core composites packed column still remained reverse shape selectivity as UiO-66 possessed, and the retention of xylenes was probably ascribed to the hydrophobic effect between analytes and the aromatic rings of the UiO-66 shell. The UiO-66@SiO2shell–core composites obtained in this study have some potential for the separation of structural isomers in HPLC.

The demand for CO2/C2H2separation, especially the removal of CO2impurity, continues to grow because of the high-purity C2H2required for various industrial applications. The adsorption separation of C2H2and CO2via porous materials is gaining a considerable attention as it is more energy-efficient compared with cryogenic distillation. The ideal porous materials are those that preferentially adsorb CO2over C2H2; however, very few adsorbents meet such requirement. Herein, two isostructural cyclodextrin-based CD-MOFs (CD-MOF-1 and CD-MOF-2) were demonstrated to have an inverse ability to selectively capture CO2from C2H2by single-component adsorption isotherms and dynamic breakthrough experiments. These two MOFs showed excellent adsorption capacity and benchmark selectivity (118.7) for CO2/C2H2mixture at room temperature, enabling the pure C2H2to be obtained in only one step. This work revealed that these materials were promising adsorbents for obtaining high-purity C2H2via selectively capturing CO2from C2H2.