Three cuprous-based composite ionic liquids (ILs) [EimH][OAc]-xCuOAc (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 ] À 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.

HCl regularly yields as a byproduct in the tail gas of pharmaceutical and chemical processes mainly including chlorination and dechlorination reactions. It is very challenging to obtain value-added pure HCl...

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Because of inefficient π-complexation of Cu+ sites, the CO solubilities of current available cuprous-based liquid absorbents are still unsatisfied and far away from equimolar CO capture. Herein, a novel cuprous-based quaternary deep eutectic solvent (DES) was prepared and employed as a superior absorbent for equimolar CO capture. It is found that the cuprous-based quaternary DES [Emim]Cl-CuCl-ZnCl2-EG showed a record CO uptake capacity (0.934 mol/mol, almost equimolar CO capture) and good ideal selectivities for CO/N2, CO/CO2, and CO/H2 at 1.0 bar and 298.2 K, which is by far the best liquid absorbent for efficient absorption of CO. The results of spectroscopic characterizations reveal that ZnCl2 and EG could weaken the Cu–Cl bond to have a significant red-shift, contributing to strengthen the Cu+ species interacting with more CO and thereby boosting CO capacity. Additionally, the CO absorption process was completely reversible, further demonstrating the good reusability of [Emim]Cl-CuCl-ZnCl2-EG. The cuprous-based quaternary DES thus shows good potential for efficient and selective absorption of CO.

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