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

Abstract

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 298–323K. The optimal regeneration temperature and time were 333K and 60min, 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 298–323K 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).