Separation of <scp>CH₄</scp>/<scp>N₂</scp> by an ultra‐stable metal–organic framework with the highest breakthrough selectivity

Abstract

Abstract Selectively separating CH 4 from N 2 in natural gas purification is extremely important, but challenging. Herein, a copper‐based metal–organic framework (MOF) NKMOF‐8‐Me with inert pore environment was reported for efficient CH 4 /N 2 separation. Adsorption results show that this material owns the highest CH 4 uptake (1.76 mmol/g) and initial adsorption heat ( Q st 0 ) of CH 4 (28.0 kJ/mol) as well as difference in Q st 0 (9.1 kJ/mol) among all materials with good water stability. Breakthrough experiments confirm that this MOF can completely separate the CH 4 /N 2 mixture with the highest CH 4 /N 2 breakthrough selectivity (7.8) reported so far. Theoretical calculations reveal the separation mechanism is the short average distance between CH 4 and pore wall, resulting in a stronger adsorption affinity for CH 4 . In addition, this MOF exhibits highly structural stability and regeneration. These results guarantee this MOF as a promising adsorbent for the recovery of CH 4 from coalbed methane.