One Scalable and Stable Metal-Organic Framework for Efficient Separation of CH 4 /N 2 Mixture.

Separating CH 4 from coal bed methane is of great importance but challenging. Adsorption-based separation often suffers from low selectivity, poor stability, and difficulty to scale up. Herein, a stable and scalable metal-organic framework [MOF, CoNi(pyz-NH 2 )] with multiple CH 4 binding sites was reported to efficiently separate the CH 4 /N 2 mixture. Due to its suitable pore size and multiple CH 4 binding sites, it exhibits excellent CH 4 /N 2 selectivity (16.5) and CH 4 uptake (35.9 cm 3 /g) at 273 K and 1 bar, which is comparable to that of the state-of-the-art MOFs. Theoretical calculations reveal that the high density of open metal sites and polar functional groups in the pores provide strong affinity to CH 4 than to N 2 . Moreover, CoNi(pyz-NH 2 ) displays excellent structural stability and can be scale-up synthesized (22.7 g). This work not only provides an excellent adsorbent but also provides important inspiration for the future design and preparation of porous adsorbents for separations.