A Water-Stable Ultramicroporous Metal-Organic Framework with Aromatic Pore Walls for Coal-Mine Methane Capture.

Selective separation of methane (CH4) from nitrogen-rich coal-mine methane remains challenging owing to their similar physicochemical properties. Here we report a water-stable ultramicroporous metal-organic framework, Ni(Hbzza)2, featuring densely packed aromatic pore walls that create a π-enriched confined environment for CH4 adsorption. The 3-fold interpenetrated architecture generates narrow channels that may strengthen London dispersion interactions with CH4, affording an uptake of 40 cm3 g-1 at 298 K and a CH4/N2 selectivity of 5.6 (IAST). Breakthrough experiments demonstrate efficient dynamic separation under both dilute and humid conditions.