Thermodynamic data for CO2 absorption in aqueous 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) solutions: CO2 solubility, N2O solubility, heat of absorption of CO2, pH and liquid speciation
2025
Diego Morlando | Ardi Hartono | Hanna K. Knuutila
New thermodynamic data for CO2 absorption in aqueous blends of 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) are measured in this work. The CO2 solubility in aqueous AMP/PZ solutions, including the CESAR1 blend, was measured at temperatures from 40 to 150 °C, extending the range of CO2 loading and temperature previously investigated.The heat of absorption of CO2 of aqueous AMP and AMP/PZ solutions was measured from 40 to 80 °C. The results indicate that the heat of absorption is constant with the temperature but it is affected by the AMP/PZ concentration ratio.The N2O solubility in the CESAR1 solvent was measured from 25 to 80 °C and up to CO2 loading of 0.52 molCO2/molamine. The N2O solubility decreases as a function of temperature and CO2 loading as a result of the salting-out effect.The effect of CO2, AMP and PZ concentration on the pH was experimentally determined. Liquid speciation for the CESAR1 blend and an aqueous solution of 1.5 M AMP + 0.75 M PZ was measured at CO2 loading from 0 to 0.80 molCO2/molamine. The results indicate that the CO2 dissolved exists mainly as PZ-carbamate at relatively low CO2 loading up to 0.40 molCO2/molamine, while at higher CO2 loading, the bicarbonate/carbonate and PZ-dicarbamate are the major products. The AMP carbamate is not a major product across the whole range of CO2 concentration investigated.The experimental data broaden the existing dataset and can support the development of rigorous thermodynamic models essential for evaluating energy requirements and environmental impacts of CO₂ capture using CESAR1 technology.
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