Efficient adsorptive separation of acetylene (C2H2) from carbon dioxide (CO2) or ethylene (C2H4) is industrially important but challenging due to the identical dynamic diameter or the trace amount. Here we show an electrostatic potential compatible strategy in a nitroprusside-based Hofmann-type metal-organic framework, Cu(bpy)NP (NP = nitroprusside, bpy = 4,4’-bipyridine), for efficient C2H2 separation. The intruding cyanide and nitrosyl groups in undulating one-dimensional channels induce negative electrostatic potentials for preferential C2H2 recognition instead of open metal sites in traditional Hofmann-type MOFs. As a result, Cu(bpy)NP exhibits a 50/50 C2H2/CO2 selectivity of 47.2, outperforming most rigid MOFs. The dynamic breakthrough experiment demonstrates a 99.9% purity C2H4 productivity of 20.57 mmol g−1 from C2H2/C2H4 (1/99, v/v) gas-mixture. Meanwhile, C2H2 can also be captured and recognized from ternary C2H2/CO2/C2H4 (25/25/50, v/v/v) gas-mixture. Furthermore, computational studies and in-situ infrared spectroscopy reveal that the selective C2H2 binding arises from the compatible pore electro-environment generated by the electron-rich N and O atoms from nitroprusside anions.

Engineering pore environments exhibit great potential in improving gas adsorption and separation performances but require specific means for acetylene/carbon dioxide (C2H2/CO2) separation due to their identical dynamic diameters and similar properties. Herein, a novel sulfate‐pillared MOF adsorbent (SOFOUR‐TEPE‐Zn) using 1,1,2,2‐tetra(pyridin‐4‐yl) ethene (TEPE) ligand with dense electronegative pore surfaces is reported. Compared to the prototype SOFOUR‐1‐Zn, SOFOUR‐TEPE‐Zn exhibits a higher C2H2 uptake (89.1 cm3 g−1), meanwhile the CO2 uptake reduces to 14.1 cm3 g−1, only 17.4% of that on SOFOUR‐1‐Zn (81.0 cm3 g−1). The high affinity toward C2H2 than CO2 is demonstrated by the benchmark C2H2/CO2 selectivity (16 833). Furthermore, dynamic breakthrough experiments confirm its application feasibility and good cyclability at various flow rates. During the desorption cycle, 60.1 cm3 g−1 C2H2 of 99.5% purity or 33.2 cm3 g−1 C2H2 of 99.99% purity can be recovered by stepped purging and mild heating. The simulated pressure swing adsorption processes reveal that 75.5 cm3 g−1 C2H2 of 99.5+% purity with a high gas recovery of 99.82% can be produced in a counter‐current blowdown process. Modeling studies disclose four favorable adsorption sites and dense packing for C2H2.

Adsorbents executing molecular sieving mechanisms for the efficient separation of n‐hexane (C6) alkane isomers require delicate pore size control, but afford unsatisfactory single‐component separations according to their branch degrees. Herein, we report a novel oxygenate‐pillared microporous adsorbent, MoOFOUR‐Co‐tpb, ([Co(tpb)2MoO4], tpb = 1,2,4,5‐tetra(pyridin‐4‐yl) benzene), with three gourd‐shaped channels for dual pore‐size sieving of C6 isomers. In particular, MoOFOUR‐Co‐tpb excludes 2,2‐dimethylbutane, while 3‐methylpentane (3MP) can enter one channel showing a high uptake of 82.6 mg g−1, contrasting to the n‐hexane (nHEX) adsorption by two channels (136 mg g−1). This dual pore‐size control strategy renders a record high equilibrium–kinetic combined selectivity for nHEX/3MP (30.2). Moreover, three‐ and five‐component breakthrough experiments confirm the practical separation performances and cycling stability. Multiple theoretical simulations reveal the separation mechanism and adsorption sites.

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