Experimental study on CO₂ capture using 2-(2-aminoethylamino)ethanol/N,N-diethyl-ethanolamine/sulfolane phase-change absorbents

Chemical absorption is currently the most mature carbon capture technology, but it has high energy consumption. Phase change absorbents have great potential for reducing energy consumption. In this paper, an attempt is made to combine the commonly used organic phase splitter and physical phase splitter to explore the comprehensive performance of the absorber under the joint action of the two. Hydroxyethyl ethylenediamine (AEEA) was used as the active amine, N,N-diethylethanolamine (DEEA) as the organic phase splitter, and sulfolane as the physical phase splitter. Different molar ratios of the three reagents were carried out to screen out the combinations with superior split-phase effects, and the absorption and desorption characteristics of the combination of AEEA/DEEA/sulfolane were investigated in terms of absorption performance, desorption performance, cycling performance, and physical parameters. The results showed that the combination of 2 M AEEA/1 M DEEA/4 M sulfolane was the most advantageous, with an absorption load up to 2.17 mol/L, a volume of the rich phase accounting for about 64%, an initial absorption rate up to 0.1756 mol L-1 min(-1), a desorption rate of 75.5% at the desorption temperature of 393.15 K, and the rich-phase viscosity had a great advantage over the other molar ratio combinations. The changes of the components before and after phase separation were analyzed by C-13 NMR to investigate the phase separation mechanism, and the five repeated cycle tests showed that the absorption load was stable, the desorption capacity was strong, and the phase separation performance was good.