Cuprous‐based composite ionic liquids for the selective absorption of CO: Experimental study and thermodynamic analysis

Abstract Three cuprous‐based composite ionic liquids (ILs) [EimH][OAc]– x CuOAc ( x = 0.5, 0.6, 0.7) were prepared and employed for efficient absorption of CO. It is shown that the cuprous composite IL [EimH][OAc]–0.6CuOAc exhibited the largest absorption capacity for CO (0.031 g/g at 293.15 K and 1 bar) and had a record CO/N 2 selectivity of 967, which is better than most of common ILs and solvents reported in the literature. The results of Fourier transform infrared (FTIR) spectra, electrospray ionization mass spectrometry (ESI‐MS) analysis, and theoretical calculations reveal that such superior CO capacity mainly resulted from two kinds of chemical interaction between CO and the active anionic species [Cu(OAc) 2 ] − in [EimH][OAc]–0.6CuOAc. Furthermore, a “deactivated IL model” was further proposed to accurately describe the absorption behavior of CO in [EimH][OAc]–0.6CuOAc, in which the thermodynamic parameters including Henry's law constants, reaction equilibrium constants, and absorption enthalpies were estimated by the correlation of the experimental solubilities of CO.