Performance and mechanism of CO2 absorption in 2-ethylhexan-1-amine + glyme non-aqueous solutions

In this work, novel non-aqueous absorbents composed of 2-ethylhexan-1-amine (EHA) and glyme were proposed for CO2 capture. The absorption performance of CO2 in EHA + diglyme, EHA + triglyme and EHA + tetraglyme non-aqueous solutions was investigated and the viscosities (η) of the CO2-saturated absorbents were measured. Besides the experiments, kinetic models were applied to correlate the CO2 absorption. The activation energy (Ea) was obtained from Arrhenius equation, and the absorption mechanism was deduced. The results showed that both Lagergren model and Avrami model can accurately correlate and predict the time-dependent absorption amount, thus an optimized composition under which excellent absorption performance and relatively low η and Ea can be simultaneously achieved was determined. Compared to water-based absorbents like MEA, the optimized non-aqueous absorbents take the advantages of better absorption performance and lower activation energy. Moreover, the glyme solvents have about 50% lower specific heat capacities and much higher boiling points (≥435 K) than water, which is expected to greatly reduce the sensible heat and the latent heat of the solvent during regeneration. Therefore, the proposed novel absorbents have promising industrial application potential in the CO2 capture process. •Non-aqueous 2-ethylhexan-1-amine + glyme were proposed as CO2 absorbents.•Two kinetic models well correlate and predict the CO2 absorption behaviors.•System concentration was optimized and the best glyme was determined.•Absorption performance is remarkably better than that of water-based absorbent.•Mechanism of CO2 absorption in non-aqueous absorbents was deduced.