A novel ionic liquid absorbent with polyamidoamine dendrimer as cations for efficient CO2 absorption

Abstract

To achieve excellent absorptive loading and low viscosity, a novel amino-functionalized ionic liquid [G1.0 PAMAM] [2-MI] combined with water for CO2 capture is proposed in this work. The concentration of [G1.0 PAMAM] [2-MI], absorption temperature, and aeration rate were optimized by using Response Surface Methodology based on Box-Behnken design, and the model predictions were in good agreement with the experimental data. The results illustrated that the absorption loading of 42.71 wt% [G1.0 PAMAM] [2-MI]/H2O was 6.81 mol CO2/mol ILs (38.5°C, 100 mL/min), which was much higher than that of MEA /H2O, and the regeneration efficiency was maintained at 89.5 % after the eighth regeneration cycle. With the combined effect of 2-MI and water, the viscosities of the solution before and after absorption at 40°C were 35.3 and 53.8 mPa·s, respectively, which were significantly lower than those of the majority of ionic liquid absorbents. The reaction mechanism of [G1.0 PAMAM] [2-MI] with CO2 was demonstrated by 13C NMR to be a synergistic combination of a zwitterionic mechanism and a base-catalyzed hydration mechanism to produce carbamate and carbonate/bicarbonate (CO32–/HCO3–).