A robust calcium-based microporous metal-organic framework for efficient CH4/N2 separation

Abstract Efficient CH4/N2 separation is of importance for natural gas purification, which is however a great challenge due to their very close kinetic diameters and thermodynamic properties. Herein, a robust microporous calcium-based metal-organic framework (MOF) named SBMOF-1 was prepared to separate CH4/N2 for the first time, in consideration of the biocompatible, low cost, low toxicity and natural abundance feature of Ca metal. With the help of the organic ligand containing multiple-aromatic rings with low polarity, this Ca-MOF exhibits a high CH4/N2 selectivity (11.5), which is comparable to the best materials reported so far while with relatively high CH4 adsorption capacity (about 20.7 cm3 (STP)/g). The results of GCMC simulations and DFT calculations indicate that pore centers are the most energetically-favorable binding sites, and the stronger adsorption affinity of CH4 can be attributed to its shorter average distance with the pore wall of the material. Breakthrough experiment results in combination of good stability and regenerability suggest the promising application of this MOF in natural gas purification.