New Type ZMOFs for the Separation of CO2 in Natural Gas

We reported a molecular simulation study for the separation of industrially gas mixtures in different ion-exchanged(Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Al3+) usf zeolite-like metal-organic framework (usf-ZMOF). The selectivities of the three systems (CO2/CH4, CO2/N-2, CO2/H-2) are higher than the average. For the different ion-exchanged usf-ZMOF, the selectivity enhances when the ion valences go up from positive one to three. In the same main group, the selectivity decreased with the atom number increasing. In our research, the highest one is Al-usf-ZMOF, in which at ambient temperature and pressure, the CO2 adsorption selectivity is 290 for the CO2/CH4 mixture, 1.68x10(4) for the CO2/H-2 mixture, and 1.7x10(3) for the CO2/N-2 mixture. We find that the much higher selectivity is due to the strong interaction between CO2 and ions. CO2 assemble clusters around the ions to make the density even higher than liquid density in the nearest areas.