Solubilities of CO2 in aqueous solutions of ionic liquids (ILs) and monoethanolamine (MEA) at pressures from 100 to 1600 kPa

Two ionic liquids (ILs) namely bis(2-hydroxyethyl)ammonium acetate (bheea) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) were mixed with water/aqueous solutions of monoethanolamine to form new hybrid solvents for the absorption of CO2. The uptake of CO2 in the aqueous mixtures of ILs + MEA were determined for a wide range of compositions at pressures between 100 and 1600 kPa and at three different temperatures (298.15, 303.15 and 313.15 K). For the case of aqueous (bheea) + MEA system, MEA acts as a supporting solvent whereas in the other case, ([bmim][BF4]) will acts as a supporting solvent for CO2 capture. The effect of pressure and temperature on CO2 loading for the aqueous solutions of bheea + MEA and ([bmim][BF4]) + MEA are discussed in detail.

► New hybrid solvents involving two ionic liquids and MEA were prepared and tested for CO2 capture. ► The results proved the tunability of such mixed hybrid solvents for maximum CO2 loading. ► The results showed the ionic liquids can be used either as base solvent or promoter for CO2 capture.