Engineering bicarbonate pathways through amine synergy: Mechanistic insights into high-efficiency CO2 capture with a tailored ternary blend

Chemical absorption using amine blends is a viable strategy for energy-efficient post-combustion CO 2 capture. Conventional amines suffer from high regeneration energy due to carbamate formation, whereas bicarbonate pathways offer thermodynamic benefits yet remain mechanistically unresolved. Herein, we developed a novel aqueous ternary amine blend, APH (7.5 wt% 2-amino-2-methyl-1-propanol, AMP/7.5 wt% piperazine, PZ/15 wt% 4-hydroxy-1-methylpiperidine, HMPD) that leverages molecular synergy to shift CO 2 absorption toward bicarbonate dominance. APH achieved absorption rate of 30 wt% MEA (0.00206 mol⋅min −1 ) while exhibiting a 175 % higher stabilized cyclic capacity (0.553 mol⋅mol −1 ) over five regeneration cycles. Combined 13 C NMR and DFT analyses revealed three synergistic bicarbonate-forming pathways: steric hindrance-induced carbamate hydrolysis, promoter-derived stepwise carbamate hydrolysis, and tertiary amine-catalyzed CO 2 hydration. Optimized AMP/PZ/HMPD ratios delivered 41 % lower regeneration energy (2.32 GJ⋅t −1 CO 2 ), low corrosion (0.0358 mmpy), and enhanced oxidative stability (88 % retention after 14 days). These advances stem from a molecular design approach correlating structural features with intermolecular synergies for pathway modulation. The APH blend thus emerges as a promising candidate for industrial applications.