Exceptional capture of methane at low pressure by an iron‐based metal‐organic framework

Abstract

The selective capture of methane (CH4) at low concentrations and its separation from N2 are extremely challenging owing to the weak host‐guest interactions between CH4 molecules and any sorbent material. Here, we report the exceptional adsorption of CH4 at low pressure and efficient separation of CH4/N2 by MFM‐300(Fe). MFM‐300(Fe) shows a very high uptake for CH4 of 0.85 mmol g−1 at 1 mbar and 298 K and a record CH4/N2 selectivity of 45 for porous solids, representing a new benchmark for CH4 capture and CH4/N2 separation. The excellent separation of CH4/N2 by MFM‐300(Fe) has been confirmed by dynamic breakthrough experiments. In situ neutron powder diffraction, and solid‐state nuclear magnetic resonance and diffuse reflectance infrared Fourier transform spectroscopies, coupled with modelling, reveal a unique and strong binding of CH4 molecules involving Fe‐OH···CH4 and C···phenyl ring interactions within the pores of MFM‐300(Fe), thus promoting the exceptional adsorption of CH4 at low pressure.