Ionic liquid/metal-organic framework composite for CO2 capture: A computational investigation

Abstract

A composite of ionic liquid [BMIM][PF6] supported on metal-organic framework IRMOF-1 is investigated for CO2 capture by molecular computation. Due to the confinement effect, IL in the composite exhibits an ordered structure as observed from radial distribution functions. The bulky [BMIM]+ cation resides in the open pore of IRMOF-1, whereas the small [PF6]- anion prefers to locate in the metal cluster corner and possesses a strong interaction with the framework. [BMIM]+ exhibits a greater mobility than [PF6] -, which is also observed in simulation and experimental studies for imidazolium-based ILs in the bulk phase. With increasing IL ratio in the composite and thus enhancing confinement effect, the mobility of [BMIM] + and [PF6]- is reduced. Ions in the composite interact strongly with CO2; in particular, the [PF6] - anion is the most favorable site for CO2 adsorption. The composite selectively adsorbs CO2 from the CO2/N 2 mixture, with selectivity significantly higher than many other supported ILs. Furthermore, the selectivity increases with increasing IL ratio in the composite. This computational study, for the first time, demonstrates that IL/MOF composite might be potentially useful for CO2 capture. © 2011 American Chemical Society.