Development of novel amino acid salt-based liquid-liquid-solid absorbent for energy-efficient post-combustion CO2 capture

Water-lean phase change amino acid salt (AAS) has provided a promising solution to energy-efficient CO 2 capture. In this work, novel phase behaviors (liquid–liquid-solid and liquid–liquid) of potassium prolinate (ProK)-2-butoxyethanol (EGBE)-water system (P-E-H) were investigated to improve the CO 2 capture performance. Distribution of phase-forming compositions and CO 2 absorbed among the phases, regeneration efficiency of CO 2 -rich solutions and cyclic capacity were discussed in details, varying the ProK concentration and the mass ratio of EGBE to water (E to H). Phase splitting points were observed to be close to the saturated state under the absorption conditions. For liquid–liquid-solid systems, with decreasing the mass ratio of E to H, volume fraction of the solid phase and the captured CO 2 in ProH + –HCO 3 − species decreases. Desorption conditions were optimized for the CO 2 -rich slurry to form a homogenous liquid after blending with top liquid phase (MWTP) for absorbent reuse, where about 1.0–1.5 times higher desorption efficiency and cyclic capacity in comparison with aqueous 30 mass% MEA. Stability of capture performance and system compositions during eight runs of continuous absorption-phase separation-slurry desorption indicates the 40P-35E-25H absorbent excellent recyclability.