Performance and reaction kinetics of CO2 absorption into AMP solution with [Hmim][Gly] activator

• [Hmim][Gly] accelerated the absorption of CO2 in AMP aqueous solution.
• The [Hmim][Gly]-AMP solution could be regenerated efficiently after three cycles.
• CO2 reacted with [Hmim][Gly]-AMP solution conformed to zwitterionic mechanism.
• [Hmim][Gly]-AMP solution absorbing CO2 was the fast pseudo-first order reaction.
• k2 and E of CO2 absorption into [Hmim][Gly]-AMP solution were obtained.

Absorption and regeneration of a new aqueous blend of 1-hexyl-3-methylimidazolium glycinate ([Hmim][Gly]) and 2-amino-2-methyl-1-propanol (AMP) were investigated. The physicochemical properties of [Hmim][Gly]-AMP mixed solution with varying molar ratios were obtained at different temperature, and the results demonstrated that the mixed solution had a low viscosity with a high solubility of CO2. It was found that the reactivity of AMP was significantly enhanced with the addition of [Hmim][Gly], and the absorption of CO2 into the mixed solution was independent of temperature within a range of 298–323 K. The optimal regeneration temperature and time were 333 K and 60 min, respectively. The mixed solution could be regenerated efficiently after three cycles. Furthermore, the study of 13C NMR spectrum indicated that the reaction between CO2 and the [Hmim][Gly]-AMP solution was zwitterionic mechanism. Based on zwitterionic mechanism and two-film model, the kinetics of CO2 absorption into the mixed solution was investigated in the temperature range of 298–323 K by employing a double stirred-cell absorber. The kinetics region was considered to be a fast pseudo-first order, and the second order reaction rate constant was calculated as follows: k2,[Hmim][Gly]−AMP = 1.57 × 107exp(− 3088.92/T).