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

Abstract

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%.