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The highly efficient separation of CH 4 /N 2 remains a great challenge, but it is vital to make the most of diverse natural gas resources and contributes to mitigating global warming. In this work, two isostructural metal−organic frameworks (MOFs), M-MA-BPY where M is Co and Ni, were elaborately selected and synthesized to serve the purpose. These MOFs were thoroughly characterized and found to have favorable framework flexibility, endowing them with narrow and uniform pore networks suitable for the adsorptive separation of CH 4 /N 2 . Further studies revealed the M-MA-BPY MOFs' excellent stability toward water and moist air. Pure gas adsorption experiments suggested they have decent CH 4 capacities (0.92 and 1.01 mmol•g −1 for Co-and Ni-MA-BPY), prominent CH 4 /N 2 selectivities (7.2 and 7.4 for Co-and Ni-MA-BPY, IAST selectivity with equimolar CH 4 /N 2 gas mixture) at 298 K and 1 bar, and desirable heats of adsorption for CH 4 (22.8 and 23.5 kJ•mol −1 for Co-and Ni-MA-BPY). Dynamic breakthrough experiments and multiple adsorption−desorption cycling tests for CH 4 /N 2 binary mixtures with different gas ratios of 5:95, 15:85, 30:70, and 50:50 (v/v) confirmed the high separation performance of M-MA-BPY MOFs. Together with their relatively simple synthesis and cheap raw reagents, this work demonstrates M-MA-BPY MOFs are very promising adsorbents for the capture of methane from low-quality natural gas resources in ambient conditions.

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