Rational Design of a <i>π</i> ‐Electron Rich Co‐MOF Enabling Benchmark C ₂ H ₆ /CH ₄ Selectivity in Natural Gas Purification

Abstract The growing demand for energy‐efficient natural gas purification necessitates advanced porous adsorbents that enable molecular precision in separating higher hydrocarbons C 2 H 6 /C 3 H 8 from CH ₄ while maintaining methane purity. Through rational π ‐electron engineering of the framework structure, a microporous Co‐MOF is reported, constructed from pyridine carboxylic acid‐based aromatic ligands that achieve a benchmark C₂H₆/CH₄ selectivity of 83.8, ranking among the highest reported for MOF materials. The framework also demonstrates an exceptional IAST selectivity of 715.6 for C 2 H 6 /C 3 H 8 (5/5) mixtures, coupled with high uptake capacities of 65.5 cm 3 ·g⁻¹ for C₂H₆ and 65.8 cm 3 ·g⁻¹ for C₃H₈ at 298 K and 100 kPa. This remarkable separation performance stems from the strategic incorporation of π ‐electron aromatic ligands, which enhance the C‐H··· π interactions with hydrocarbon molecules. Breakthrough experiments demonstrate practical viability, achieving 99.97% methane purity in the effluent stream. Molecular simulations confirm that the selective adsorption originates from optimized C‐H··· π interactions and van der Waals forces between the framework and guest molecules, validating the rational design approach for high‐performance MOFs in industrial gas separation.