Molecular screening of ionic liquids for CO2 absorption and molecular dynamic simulation

Abstract

Abstract Though ionic liquids (ILs) are considered potential materials for CO2 capture because of their unique properties, it is time-consuming and costly to choose task-specific and suitable IL using the traditional “try-and-error” method. From the point of molecular design view, 25 cations and 20 anions are combined and screened using COSMOtherm to predict CO2 solubility at 298 K and 100 kPa. The prediction result showed that ILs with bFAP(tris(nonafluorobutyl)trifluorophosphate) anion could dissolve more CO2 than any others. To further understand the absorption performance of CO2 in ILs, molecular dynamic simulations are carried out to explore the interactions between CO2 and the four selected ILs, namely, [EMPyr][bFAP](1-ethyl-2-methylpyrazolium tris(nonafluorobutyl)trifluorophosphate), [B(Hex)3P][bFAP](butyl-trihexyl-phosphonium tris(nonafluorobutyl) trif-luorobutyl trifluorophosphate), [(Me)5isobuGua][bFAP](n,n,n,n,n-pentamethyl-n-isopropylguanidinium tris(nona-fluorobutyl)-trifluorophosphate), and [BEIM][bFAP] (1-butyl-3-ethyl-imidazolium tris(nonafluorobutyl)trifluo-rophosphate), at the atomic and molecular levels.