CO₂ Capture Performance and Preliminary Mechanistic Analysis of a Phase Change Absorbent

Phase change absorbents are deemed a promising alternative for CO₂ capture due to their excellent CO₂ absorption performance, good stability, and low renewable energy consumption. To address the issues of insufficient loading capacity, low regeneration efficiency, and high energy consumption during regeneration in current chemical absorbents, a novel phase change absorbent was developed. As an amino acid ionic liquid phase change absorbent with tetraethylenepentamine as the cation, imidazole as the anion, and n-propanol as the phase separation agent, this absorbent offers a potential solution. The highest absorption capacity of the [TEPAH][Im]/NPA/H₂O system at the optimal n-propanol-H₂O ratio (1:1) reaches 1.34 mol·mol^-1, and the viscosity of the CO₂-rich phase amounts to a mere 3.58 mPa·s. Additionally, the desorption efficiency reached 91.1% at 363.15 K, while the loading capacity in the fifth cycle remained over 1.16 mol·mol^-1. As n-propanol is present in the [TEPAH][Im]/NPA/H₂O system, the rich phase makes up roughly 30% of the total volume. The energy consumption for regeneration of the [TEPAH][Im]/NPA/H₂O phase change absorption system is 2.20 GJ·t^-1 CO₂. Under identical regeneration conditions, the system can reduce the regeneration energy consumption by 41.6%.