The diversity of metal–organic frameworks enables the design of highly efficient adsorbents and membranes towards hydrocarbon separations for energy consumption mitigation.

The efficient capture of SO is of great significance in gas-purification processes including flue-gas desulfurization and natural-gas purification, but the design of porous materials with high adsorption capacity and selectivity of SO remains very challenging. Herein, the selective recognition and dense packing of SO clusters through multiple synergistic host-guest and guest-guest interactions by controlling the pore chemistry and size in inorganic anion (SiF , SIFSIX) pillared metal-organic frameworks is reported. The binding sites of anions and aromatic rings in SIFSIX materials grasp every atom of SO firmly via S ···F electrostatic interactions and O ···H dipole-dipole interactions, while the guest-guest interactions between SO molecules further promote gas trapping within the pore space, which is elucidated by first-principles density functional theory calculations and powder X-ray diffraction experiments. These interactions afford new benchmarks for the highly efficient removal of SO from other gases, even if at a very low SO concentration. Exceptionally high SO capacity of 11.01 mmol g is achieved at atmosphere pressure by SIFSIX-1-Cu, and unprecedented low-pressure SO capacity is obtained in SIFSIX-2-Cu-i (4.16 mmol g SO at 0.01 bar and 2.31 mmol g at 0.002 bar). More importantly, record SO /CO selectivity (86-89) and excellent SO /N selectivity (1285-3145) are also achieved. Experimental breakthrough curves further demonstrate the excellent performance of these hybrid porous materials in removing low-concentration SO .

Propyne/propylene (C H /C H ) separation is a critical process for the production of polymer-grade C H . However, optimization of the structure of porous materials for the highly efficient removal of C H from C H remains challenging due to their similar structures and ultralow C H concentration. Here, it is first reported that hybrid ultramicroporous materials with pillared inorganic anions (SiF = SIFSIX, NbOF = NbOFFIVE) can serve as highly selective C H traps for the removal of trace C H from C H . Especially, it is revealed that the pyrazine-based ultramicroporous material with square grid structure for which the pore shape and functional site disposition can be varied in 0.1-0.5 Å scale to match both the shape and interacting sites of guest molecule is an interesting single-molecule trap for C H molecule. The pyrazine-based single-molecule trap enables extremely high C H uptake under ultralow concentration (2.65 mmol g at 3000 ppm, one C H per unit cell) and record selectivity over C H at 298 K (>250). The single-molecule binding mode for C H within ultramicroporous material is validated by X-ray diffraction experiments and modeling studies. The breakthrough experiments confirm that anion-pillared ultramicroporous materials set new benchmarks for the removal of ultralow concentration C H (1000 ppm on SIFSIX-3-Ni, and 10 000 ppm on SIFSIX-2-Cu-i) from C H .

Highly selective capture of methane from nitrogen is considered to be a feasible approach to improve the heating value of methane and mitigate the effects of global warming. In this work, an ultramicroporous squarate‐based metal‐organic framework (MOF), [Co3(C4O4)2(OH)2] (C4O42− = squarate), with enhanced negative oxygen binding sites was synthesized for the first time and used as adsorbent for efficient separation of methane and nitrogen. Adsorption performance of this material was evaluated by single‐component adsorption isotherms and breakthrough experiments. Furthermore, density functional theory calculation was performed to gain the deep insight into the adsorption binding sites. Compared with the other state‐of‐the‐art materials, this material exhibited the highest adsorption selectivity (8.5–12.5) of methane over nitrogen as well as the moderate volumetric uptake of methane (19.81 cm3/cm3) under ambient condition. The unprecedented selectivity and chemical stability guaranteed this MOF as a candidate adsorbent to capture CH4 from N2, especially for the unconventional natural gas upgrading. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3681–3689, 2018

MQDs-SnO2-modulated perovskite crystallization processes visualized by in situ 2D GIXRD technique.