Enhanced adsorption selectivity of hydrogen/methane mixtures in metal-organic frameworks with interpenetration: A molecular simulation study

In this work a systematic molecular simulation study was performed to study the effect of interpenetration on gas mixture separation in metal-organic frameworks (MOFs). To do this, three pairs of isoreticular MOFs (IRMOFs) with and without interpenetration were adopted to compare their adsorption separation selectivity for CH4/H-2 mixtures at room temperature. The results show that methane selectivity is greatly enhanced in the interpenetrated IRMOFs compared with their noninterpenetrated counterparts, due to the formation of additional small pores and adsorption sites by the interpenetration of frameworks. Furthermore, this work shows methane selectivity behavior is more complex in the former and selectivity differs largely in the different areas of the pores, attributed to the existence of various small pores of different sizes. In addition, the present work shows the ideal adsorbed solution theory is likely to be applicable to interpenetrated MOFs with complex structures.