Copper-based metal–organic framework with two methane traps for efficient CH4/N2 separation

Unconventional natural gas has become an important supplement to conventional energy sources, and the process of enrichment and purification of methane from low concentration coalbed methane is crucial. To this end, we report a copper-based metal–organic framework (MOF), ZJNU-119Cu, featuring two methane traps constructed with uncoordinated carboxylic acid oxygens and open metal sites. ZJNU-119Cu exhibits a high methane adsorption capacity (58.2 cm 3 ·g –1 ) at 298 K and 0.1 MPa and excellent CH 4 /N 2 separation performance under dynamic conditions. Density-functional theory calculations combined with grand canonical Monte Carlo simulation theory reveal the interaction mechanism for the uncoordinated carboxylic acid oxygen atoms and open metal sites in ZJNU-119Cu with CH 4 . The gas adsorption isotherms, heat of adsorption calculations, and breakthrough separation experiments indicate that this MOF is a very promising adsorbent for CH 4 /N 2 separation.