Ethylenediamine (ED) treated ZIF-8 nanoparticles enhanced the selectivity of CO2/CH4 by 37% compared to untreated ZIF-8 . It can remove H2S and CO2 from natural gas . The use of nanoparticles such as carboxylated carbon nanotubes (CNTs) composite prevented the aggregation of ZIF-8 in the membrane, increased the free volume of the MMM, and enhanced the CO2 adsorption performance and CO2/N2 separation performance . ZIF-8-PEI@IL (15 wt.%) increased the CO2 permeability of MMMs by 123%, and the selectivity of CO2/N2 and CO2/CH4 from 17 and 12 to 76 and 25, respectively .