The Energy-Saving Strategy for CO₂ Capture in Ionic Liquid Reinforced Amine Absorbents with a Potentiometric Method

The type and concentration of captured products in carbon dioxide capture processes significantly influence the energy consumption during regeneration, which can be minimized by optimizing the product composition. Therefore, the rapid evaluation of the product is critical. This study investigates the product regulation in CO2 absorption and regeneration using an ionic liquid-enhanced mixed amine solution composed of glycine tetramethylammonium ([N1111][Gly]), piperazine (PZ), and N-methyldiethanolamine (MDEA), employing a potentiometric method. The results show that the CO2 absorbent maintains an exceptionally high absorption capacity of 1.84 mol/kg with a bicarbonate content of up to 67.96% throughout the absorption process. These properties contribute to a 30% reduction in regeneration energy compared to a 30% monoethanolamine (MEA) aqueous solution. The absorption mechanism is characterized by the shuttling behavior of the ionic liquid and PZ at the gas–liquid interface, which enhances MDEA utilization and facilitates the formation of more easily regenerable components. Pilot test results further confirm a circulation capacity of 1.215 mol/L, with regeneration energy consumption consistent with laboratory findings. This study offers a comprehensive evaluation of product composition through potentiometric titration, providing valuable insights for identifying optimal CO2 absorbents and presenting significant potential for industrial energy savings.