Solubility of CO2 and CH4 in Protic Amidium Bis (trifluoromethanesulfonyl)amide Ionic Liquids at 313.15 K

In this study, we investigated the CO2/CH4selectivity of protic amidium ionic liquids (ILs) comprisingbis(trifluoromethanesulfonyl)amide,N,N-dimethylformamidium([DMFH][TFSA]),N,N-dimethylacetamidium ([DMAH]-[TFSA]), andN,N-dimethylpropionamidium ([DMPH][TFSA]).CO2solubility was measured at a temperature of 313.15 K andpressures up to 8.3 MPa using a static circulation-type apparatus,whereas CH4solubility was measured at a temperature of 313.15 Kand pressures up to 8.0 MPa using a magnetic suspension balance.The CO2and CH4solubility in the ILs exhibited typical pressuredependence as observed for physical absorbents. [DMFH][TFSA]exhibited a higher CO2solubility and a lower CH4solubility than[DMAH][TFSA] and [DMPH][TFSA]. CO2/CH4selectivity was derived from the experimental solubility data. The proticamidium ILs presented herein exhibited higher CO2/CH4selectivity than conventional physical absorbents such as Selexol and Rectisol.