Grand canonical Monte Carlo (GCMC) study on adsorption performance of metal organic frameworks (MOFs) for carbon capture

Abstract

Metal-Organic Frameworks (MOFs) have been proved to be promising materials for CO2 capture due to their high specific surface area. In this work, molecular models of MOF-5, Mg-MOF-74, ZIF-8, CO2 and N2 were established. Adsorption and separation behaviors of pure CO2 and CO2/N2 in the three MOFs were studied using Grand Canonical Monte Carlo (GCMC) simulations. The simulated single component isotherms and corresponding isosteric heat of adsorption implied underlying adsorption mechanisms of different MOFs. MOF-5 was found to have the highest saturation adsorption capacity for pure CO2 (35 mmol/g) at room temperature while Mg-MOF-74 has the highest CO2 uptake (11 mmol/g) under 10 bar. Meanwhile, the results also indicated that the existence of coordinated unsaturated metal sites enhanced the CO2 adsorption capacity of MOFs. In addition, their selectivity to CO2 over that of N2 have also been studied. In the case of CO2/N2 adsorption and separation, Mg-MOF-74 has the highest CO2 selectivity of 38 because of its strongest binding force with CO2. Moreover, industrial application potential of MOFs in swing adsorption processes for carbon capture and separation was analyzed combining with their current prices. This work is beneficial to the selection of MOFs in post-combustion CO2 capture.