Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

The major goal of this work was the prediction of the solubility of CO2 and H2S in aqueous methyldiethanolamine (MDEA ) reacting systems using the electrolyte equation of state ePC-SAFT with focus on weight fractions wMDEA greater than 0.3 (related to the binary water/MDEA system). Predictions in this work mean that no parameters were adjusted to the experimental gas solubility data in aqueous MDEA solutions. In order to obtain improved prediction results compared to state-of-the-art literature models, binary interaction parameters kij between water-MDEAH(+), water-HCO3(-), and water-HS(-) were introduced; these kij values were fitted to osmotic-coefficient data measured in this work and from literature. This new possibility to access these kij parameters allowed improved predictions of solubility, and the predictions were validated by new experimental CO2 solubility data at wMDEA = 0.6. Even more, the influence of the inert gas on solubility was predicted reasonably correct. Further, the solubility of in aqueous solutions was accurately predicted in the temperature range 298 K less than T less than 393 K at wMDEA = 0.32 and 0.48. In the final part of this work enthalpy of absorption was predicted for 353 K less than T less than 393 K at wMDEA = 0.3 for varying gas loadings. In summary, prediction results were satisfying considering the fact that ePC-SAFT parameters were fitted only to experimental data of pure fluids or binary systems.