Mass transfer and kinetics of CO2 absorption into aqueous monoethanolamine/1-hydroxyethy-3-methyl imidazolium glycinate solution

Abstract

The aqueous blend of monoethanolamine (MEA) and 1-hydroxyethy-3-methyl imidazolium glycinate ([C2OHmim][Gly]) was considered as a promising CO2-capturing solvent because of the advantages of fast absorption rate, high absorption capacity, great thermal stability and good resistance to O2. In the present work, kinetics of the reaction of CO2 and MEA/[C2OHmim][Gly] in aqueous solutions had been investigated using a double stirred-cell absorber with a defined gas/liquid interface. The zwitterion mechanism was used as the kinetic model to describe the absorption of CO2 in the mixed solution. The kinetic and mass transfer parameters, e.g., the reaction rate constant (k2,mix), the overall reaction rate constant (kov) and the enhancement factor (E), were evaluated at different absorbent concentrations and temperature. At 303.15K, the values of k2 into MEA/[C2OHmim][Gly] and [C2OHmim][Gly] solution were respectively calculated as 6506.4 and 8980.6m3kmol−1s−1. The relationship between k2 and the reaction temperature was determined by the Arrhenius Equation, and was presented as:k2,mix=7.12×106exp-2126.3T.