Energy-Saving CO₂ Absorption Using Mixed Amine Absorbent DA2MP/AEP/MDEA: Performance, Mechanism, and Pilot-Scale Experiment

In order to address the limitations of traditional organic amine absorbent, such as the limited CO2 absorption loading, difficulties in CO2 product regeneration, and high regeneration energy consumption during regeneration, a mixed amine absorbent consisting of 7.5 wt % 1,5-diamino-2-methylpentane (DA2MP) + 7.5 wt % N-aminoethylpiperazin (AEP) + 15 wt % N-methyldiethanolamine (MDEA) (D-A-M) has been developed. This formulation employed linear amine DA2MP as the primary absorbent, while cyclic amine AEP and tertiary amine MDEA served as the auxiliary absorbents. The development was achieved through a rigorous screening process. The D-A-M absorbent demonstrated a CO2 absorption capacity of 0.78 mol CO2·mol–1 and a regeneration efficiency of 80.38%. Additionally, it exhibited excellent cycling stabilities over five absorption–desorption cycles with the regeneration efficiency consistently exceeding 70%. The reaction mechanism between the absorbent and CO2, as revealed by 13C NMR analysis, involves the sequential reaction of primary, secondary, and tertiary amine groups. Electrochemical corrosion tests indicated that the CO2-saturated D-A-M absorbent showed significantly reduced corrosivity compared to the saturated 30 wt % MEA absorbent. In the pilot-scale experiment, the D-A-M absorbent achieved a CO2 capture rate of 97.5% and corrected regeneration energy consumption of 3.27 GJ·ton CO2–1, highlighting its considerable potential for industrial application.