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

New thermodynamic data for CO 2 absorption in aqueous blends of 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) are measured in this work. The CO 2 solubility in aqueous AMP/PZ solutions, including the CESAR1 blend, was measured at temperatures from 40 to 150 °C, extending the range of CO 2 loading and temperature previously investigated. The heat of absorption of CO 2 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 N 2 O solubility in the CESAR1 solvent was measured from 25 to 80 °C and up to CO 2 loading of 0.52 mo l C O 2 / mo l amine . The N 2 O solubility decreases as a function of temperature and CO 2 loading as a result of the salting-out effect. The effect of CO 2 , 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 CO 2 loading from 0 to 0.80 mo l C O 2 / mo l amine . The results indicate that the CO 2 dissolved exists mainly as PZ-carbamate at relatively low CO 2 loading up to 0.40 mo l C O 2 / mo l amine , while at higher CO 2 loading, the bicarbonate/carbonate and PZ-dicarbamate are the major products. The AMP carbamate is not a major product across the whole range of CO 2 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.