LAUSR

The development of efficient methane (CH4) purification technology from natural gas is crucial to its utilization. Adsorptive separation using porous metal-organic frameworks (MOFs) offers a promising and energy-efficient strategy. Herein, a novel carborane hybrid MOF, Cu-CB-DMTPA, was solvothermally synthesized by using Cu2+, p-C2B10H10-(COOH)2, and 2,6-dimethyl-N,N-di(pyridin-4-yl)pyridin-4-amine (DMTPA). This material features electronegative pore surfaces rich in B-Hδ- groups and unique one-dimensional (1D) channels with dual pore sizes (large: 6.5 × 4.3 Å2; small: 3.4 × 2.8 Å2). Gas adsorption studies revealed significantly higher uptake of C3H8 (29.9 cm3 g-1) and C2H6 (31.3 cm3 g-1) over CH4 (9.9 cm3 g-1) at 298 K and 1.0 bar. Ideal adsorbed solution theory (IAST) selectivity calculations demonstrated outstanding performance for equimolar C3H8/CH4 (61.2) and C2H6/CH4 (14.4) separations, outperforming many popular materials. The separation mechanism, probed via in situ single-crystal X-ray diffraction (SCXRD) and Grand Canonical Monte Carlo (GCMC) simulations, is attributed to multiple cooperative weak interactions between the framework and hydrocarbons, with stronger binding affinity for larger and more polarizable molecules. Dynamic breakthrough experiments confirmed efficient one-step purification of CH4 (>99.99% purity) from a CH4/C2H6/C3H8 (85:10:5) mixture at 298 K, achieving a high CH4 productivity of 81.53 L kg-1. Cu-CB-DMTPA also maintains excellent recyclability and humidity resistance, highlighting its potential for industrial natural gas upgrading.