文摘
A novel ionic liquid (1-aminoethyl-3-methylimidazolium lysinate, [C2NH2MIm][Lys]) functionalized with three amino groups had been developed for carbon dioxide (CO2) capture in this work. The CO2 absorption loading of [C2NH2MIm][Lys] solution was found to be 1.59 mol CO2/mol IL with a concentration of 0.5 mol/L at 313.15 K, which was much higher than that of the most existing dual functionalized ILs. Besides, [C2NH2MIm][Lys] also owned a good regenerability even after 6 regeneration cycles. According to the results of 13C nuclear magnetic resonance (13C NMR), CO2 absorption into [C2NH2MIm][Lys] solution could be divided into two stages, which began with the formation of carbamate, and followed by the hydration of CO2 to form carbonate/bicarbonate. Meanwhile, the desorption of the saturated [C2NH2MIm][Lys] was proven to be a reverse process of the adsorption. Based on the mechanism results, the kinetics of CO2 capture into [C2NH2MIm][Lys] solution was investigated by using a double stirred-cell absorber at temperatures ranging from 303 to 333 K. Under the pseudo-first-order regime, the overall reaction rate constants (kov) and the forward second-order rate constants (k2) under different concentrations and temperature were obtained, which were both increased considerably as temperature increased. Moreover, the values of enhancement factor (E) were linear with CRNH2 and temperature. The Arrhenius equation of CO2 absorption was also estimated, and the activation energy was calculated to be 25.5 kJ·mol–1.