For CH4-N2 separation with high-efficiency

several typical MOFs based on different ligands with high surface areas were synthesized in large scale via the simple solvothermal method

and their CH4/N2 separation performance was investigated experimentally by pure gas adsorption and binary gas breakthrough experiments. The results show that the adsorptive separation selectivity of most MOFs is much higher than that of Si/Al zeolites owing to their lower polarity

and the selectivity of MOFs with multidentate ligands are similar with that of high-quality activated carbon because their wide pore sizes resulted from the long linkers are not good for the separation of CH4/N2. In addition

the open metal sites in MOFs increase channel polarity

which is not conducive to improving the separation selectivity of CH4/N2 mixtures. Fortunately

the ultra-microporous adsorbent (0.5 nm) based on monodentate ligand

namely [Ni3(HCOO)6] synthesized by the short linker of HCOO- and Ni2+

has a much higher selectivity up to 7.0

twice that of conventional adsorbents

such as Si/Al zeolites and actvited carbons. In a word

the knowledge obtained in this work provides a foundation for the design of new nanoporous materials towards the CH4/N2 separation with high-efficiency.