A classical simulation study for carbon dioxide adsorption and separation capacity of MIL-53(Cr)

Abstract

Carbon dioxide (CO₂) concentrations are increasing, threatening global warming limits and leading to an alarming impact on the environment and human health. Therefore, reducing or converting CO₂ into high-value chemicals is necessary. In recent decades, CO₂ capture and separation based on the adsorption of highly porous materials, especially metal-organic framework (MOF) materials, has become very attractive. Among MOFs, MIL material, notably MIL-53(Cr), has been a top concern for its noteworthy adsorption and separation capacity due to its thermal stability, ultra-high specific surface, open metal sites, and more. Therefore, this work mainly uses grand canonical Monte Carlo simulation, a classical molecular simulation method, to calculate the amount of gas adsorbed in MIL-53(Cr) and study CO₂ adsorption and CO₂/H₂ separation capacity in the mixture of hydrogen (H₂) and CO₂ at room temperatures and low pressures below 50 bar via adsorption isotherms. This research explored the high CO₂ adsorption capacity and the impressive CO₂/H₂ selectivity of MIL-53(Cr). For pure CO₂, the absolute CO₂ uptake in MIL-53(Cr) is 9.18 mmol/g at 298 K and 50 bar. Besides, the maximum CO₂/H₂ selectivity of MIL-53(Cr) is 116 at 298 K. Remarkably, the CO₂/H₂ mole fraction has almost no effect on the value of the maximum SO₂/H₂ separation, , but leads to the change of pressure reaching . Furthermore, reducing the temperature significantly increases the separation capacity of CO₂/H₂; specifically, 245 when the temperature drops to 273 K.