In comparison with the fast development of binary mixture separations, ternary mixture separations are significantly more difficult and have rarely been realized by a single material. Herein, a new strategy of tuning the gate‐opening pressure of flexible MOFs is developed to tackle such a challenge. As demonstrated by a flexible framework NTU‐65, the gate‐opening pressure of ethylene (C2H4), acetylene (C2H2), and carbon dioxide (CO2) can be regulated by temperature. Therefore, efficient sieving separation of this ternary mixture was realized. Under optimized temperature, NTU‐65 adsorbed a large amount of C2H2 and CO2 through gate‐opening and only negligible amount of C2H4. Breakthrough experiments demonstrated that this material can simultaneously capture C2H2 and CO2, yielding polymer‐grade (>99.99 %) C2H4 from single breakthrough separation.

Selective elimination of sulfur dioxide is significant in flue gas desulfurization and natural gas purification, yet developing adsorbents with high capture capacity especially at low partial pressure as well as excellent cycling stability remains a challenge. Herein, a family of isostructural gallate-based MOFs with abundant hydrogen bond donors decorating the pore channel was reported for selective recognition and dense packing of sulfur dioxide via multiple hydrogen bonding interactions. Multiple O···H–O hydrogen bonds and O···H–C hydrogen bonds guarantee SO2 molecules are firmly grasped within the framework, and appropriate pore apertures afford dense packing of SO2 with high uptake and density up to 1.86 g cm–3, which is evidenced by dispersion-corrected density functional theory calculations and X-ray diffraction resolution of a SO2-loaded single crystal. Ultrahigh adsorption uptake of SO2 at extremely low pressure (0.002 bar) was achieved on Co-gallate (6.13 mmol cm–3), outperforming all reported state-of-the-art MOFs. Record-high IAST selectivity of SO2/CO2 (325 for Mg-gallate) and ultrahigh selectivity of SO2/N2 (>1.0 × 104) and SO2/CH4 (>1.0 × 104) were also realized. Breakthrough experiments further demonstrate the excellent removal performance of trace amounts of SO2 in a deep desulfurization process. More importantly, M-gallate shows almost unchanged breakthrough performance after five cycles, indicating the robust cycling stability of these MOFs.

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The prototype three-dimensional metal−organic framework Zn2(BDC)2(Dabco)·4DMF·0.5H2O (MOF-1) and two-dimensional Zn2(BDC)2(H2O)2·(DMF) (MOF-2) can be reversibly transformed with each other in which the activated MOF-2 exhibits high selective gas adsorption with respect to C2H2/CO2 at room temperature.

A new three-dimensional microporous metal-organic framework Cu(BDC-OH)(4,4'-bipy)·G(x) (UTSA-15; H(2)BDC-OH = 2-hydroxy-benzenedicarboxylic acid, 4,4'-bipy =4,4'-bipyridine, G = guest molecules) with functional -OH groups on the pore surfaces was solvothermally synthesized and structurally characterized. UTSA-15 features a three-dimensional structure having 2D intercrossed channels of about 4.1 × 7.8 and 3.7 × 5.1 Å(2), respectively. The small pores and the functional -OH groups on the pore surfaces within the activated UTSA-15a have enabled their strong interactions with CO(2) and C(2)H(2) which have been revealed in their large adsorption enthalpies of 39.5 and 40.6 kJ/mol, respectively, highlighting UTSA-15a as the highly selective microporous metal-organic framework for the CO(2)/CH(4) and C(2)H(2)/CH(4) gas separation with separation selectivity of 24.2 and 55.6, respectively, at 296 K.