Investigation of the absorption performance and viscosity for CO2 capture process using [Bmim][Gly] promoted MDEA (N-methyldiethanolamine) aqueous solution

• MDEA-[Bmim][Gly] aqueous solution has good application prospect in CO2 removal.
• An appropriate addition of [Bmim][Gly] significantly increases the absorption rate.
• The viscosities of CO2-MDEA-[Bmim][Gly] solutions were measured and calculated.
• Effects of temperature, mass fraction and CO2 loading on viscosity were demonstrated.
• Good absorption performance and appropriate viscosity were simultaneously achieved.

The absorption performance of CO2 in 1-butyl-3-methylimidazolium glycinate ([Bmim][Gly]) promoted MDEA (N-methyldiethanolamine) aqueous solution was investigated. The influences of temperature and mass fraction on CO2 solubility were determined. The time dependence of CO2 solubility demonstrated that the absorption rate of CO2 significantly increased when MDEA aqueous solution was promoted by small amount of [Bmim][Gly]. The viscosities of both CO2-unloaded and CO2-loaded MDEA-[Bmim][Gly] aqueous solutions were measured at temperatures ranging from 303.2 K to 323.2 K and calculated by using the Weiland equation. The effects of temperature, mass fraction of MDEA and [Bmim][Gly], and CO2 loading on viscosities were demonstrated on the basis of experiments and calculations. Our work showed that when the mass fraction of [Bmim][Gly] ranged from 0.10 to 0.15 and the total mass fraction of MDEA and [Bmim][Gly] was around 0.5, high absorption rate, large absorption capacity and appropriate viscosity can be simultaneously achieved.