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Aqueous Potassium Lysinate for CO2 Capture: Evaluating at Desorber Conditions

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journal contribution
posted on 01.10.2019, 18:47 by Chenxu Li, Yue Zhao, Shufeng Shen
Potassium lysinate (LysK) has shown the advantages of reaction kinetics and absorption performance over conventional monoethanolamine (MEA) for CO2 capture. However, very little information is available about its desorption behaviors. In this work, CO2 solubility in aqueous 17.6, 33.5, and 40.8 mass % LysK was measured in an equilibrium reactor at temperatures of (363–393) K and CO2 partial pressures ranging from (2 to 400) kPa. Thermal degradation in the presence of CO2 and relative regeneration energy consumption for this absorbent were evaluated, and also compared with aqueous 30% MEA. An empirical model was proposed to correlate the solubility data and the calculated which are in good agreement with the experimental values with AARDs within 12%. CO2 desorption can be enhanced by overhead reflux of condensate water as a result of solvent vapor effect, which also results in the increasing evaporation heat. The aqueous LysK system was found to be less competitive than the MEA system in overall energy consumption of regeneration (kJ/mol CO2 released). Degradation of CO2-loaded LysK solutions in sealed reactors at 383 and 423 K for 5 and 15 days was qualitatively analyzed by total alkalinity and NMR spectroscopy. Compared with other absorbents, LysK has shown better resistance to thermal degradation in the presence of CO2.