Molecular simulation of CO2 Adsorption, Separation, and Permeability of MFI and FAU zeolites, and Cu-BTC in the presence of CH4, N2

Adsorption and separation of CO2 gaseous compounds with N2 and CH4 are investigated in FAU and MFI zeolites, and metal organic framework Cu-BTC by Monte-Carlo method. PCFF force field is used for the adsorption isotherms simulation of CH4 and CO2 in pure zeolites and DREIDING force field is applied for Cu-BTC. Simulation results have an acceptable and good consistency with experimental data. Pure adsorption isotherms and the mixture of CH4 and CO2 are studied in three structures. Moreover, the effects of pressure, temperature, and concentration of CO2 on adsorption, selectivity, and permeability of CO2 relative to CH4 and N2 are analyzed. The outcomes of simulation show that whenever temperature increases and pressure decreases, adsorption is reduced. This behavior is a function of molecular structure of adsorbent. In terms of porosity and voids accessible to gas molecules, we have Cu-BTC>FAU>MFI. In addition to pressure and feed concentration, evaluation of selectivity results illustrates that the selectivity of CO2 is dependent to molecular structure of zeolite in comparison to other gases. Comparing the findings of CO2 permeability coefficient in all three structures demonstrates that maximum permeability coefficient happens with MFI and the minimum one occurs in Cu-BTC.