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A Comparative Study of Aqueous Potassium Lysinate and Aqueous Monoethanolamine for Postcombustion CO2 Capture

Zhao, Yue, Bian, Yangyang, Li, Hui, Guo, Hui, Shen, Shufeng, Han, Jiangze, Guo, Dongfang
Energy & fuels 2017 v.31 no.12 pp. 14033-14044
absorbents, absorption, alkalinity, amino acids, calorimeters, carbon, carbon dioxide, desorption, energy, ethanolamine, fuels, heat, nitrogen, nuclear magnetic resonance spectroscopy, oxygen, potassium, salts, solubility, solvents, stable isotopes, toxicity
Aqueous monoethanolamine (MEA) is widely used for CO₂ capture and has been demonstrated as an effective absorbent in many postcombustion capture plants. However, several disadvantages such as toxicity, high volatility, solvent degradation, and high energy consumption were reported in the practical applications. Aqueous amino acid salts, particularly potassium lysinate (LysK), are considered as attractive alternatives to MEA. A comparative study of absorbent characteristics of aqueous LysK (2.0 M and 2.5 M) and aqueous MEA (5.0 M) was conducted in this study. The absorption and cyclic capacities, absorption and desorption rate, solubility of CO₂, and heat of absorption were measured using a stirred batch-type reactor and a CPA201 reaction calorimeter under similar postcombustion capture conditions. Thermal and oxidative degradation was also evaluated for aqueous 2.0 M LysK at 383 and 423 K under static N₂ and O₂ exposure conditions for 15 days. Samples were analyzed by total alkalinity and ¹³C and ¹H NMR spectra to provide insight into the degradation products. The advantages of the comparable CO₂ capture performance, high stability, and low solvent loss compared to the state-of-the-art solvent MEA, suggest LysK can be a potentially advantageous absorbent for industrial CO₂ capture processes.