Simulation study on functional group-modified Ni-MOF-74 for CH 4 /N 2 adsorption separation.

This study employs grand canonical Monte Carlo (GCMC) simulations to investigate the impact of functional group modifications (CH3 , OH, NH2 , and OLi) on the adsorption performance of CH4 /N2 on Ni-MOF-74. The results revealed that functional group modifications significantly increased the adsorption capacity of Ni-MOF-74 for both CH4 and N2 . The packed methyl groups in CH3 -Ni-MOF-74 create an environment conducive to CH4 , leading to the highest CH4 adsorption capacity. The electrostatic potential distribution indicates that the strong electron-donating effect introduced by the alkali metal Li results in the highest electrostatic potential gradient in Li-O-Ni-MOF-74, leading to the strongest adsorption of N2 , this is unfavorable for CH4 /N2 separation. At 1500 kPa the selectivity order of adsorbents for mixed gases was as follows: CH3 -Ni-MOF-74 > NH2 -Ni-MOF-74 > OH-Ni-MOF-74 > Ni-MOF-74 > Li-O-Ni-MOF-74. This study highlights that CH3 -Ni-MOF-74 possesses optimal CH4 selectivity and adsorption performance. Given the current lack of research on functionalized MOF-74 for the separation of CH4 and N2 , the findings of this study will serve as a theoretical guide and provide references for the applications of CH4 adsorption and CH4 /N2 separation.