Amino-Functionalized Ionic Liquid Phase Change Absorbents for Efficient CO2 Capture

Abstract Considering the escalating severity of global climate warming, reducing CO2 emissions has gained widespread recognition among the international community. Post-combustion capture is one of the most widely adopted technologies in this field. Chemical absorption, though mature, suffers from inherent drawbacks such as high regeneration energy consumption and significant solvent loss. Therefore, novel high-efficiency absorbents are urgently needed. In this study, an amino dual-functionalized ionic liquid [TEPAH][ATA] was synthesized via a one-step method and then mixed with NPA and water to construct a ternary phase-change absorption system, [TEPAH][ATA]/NPA/H2O. The CO2 absorption-desorption performance, phase-change behavior, and reaction mechanism of this system were systematically investigated. Results showed that the CO2 absorption loading reached 1.79 mol CO2 mol–1 IL. Upon saturation, the system spontaneously separated into two liquid phases, where the rich phase accounted for only 28% of the total volume yet contained over 96% of the absorbed CO2, and its viscosity was 6.59 mPa s. After five absorption-desorption cycles, the regeneration efficiency remained at 88.6%, demonstrating good cyclic stability. This study provides a reference for the application of ionic liquids in CO2 capture.