Effect of the incorporation of speciation data in the modeling of CO2–DEA–H2O system

• An electrolyte equation of state is used for the modeling of the CO2 absorption in DEA solutions.
• The database includes speciation data.
• Models based on a data fitting of solubility data give a poor representation of the speciation.
• The model developed allows the simultaneous representation of solubility and speciation data.

An electrolyte equation of state based on Redlich Kwong Soave EOS is applied to the representation of the equilibrium properties of the water–CO2–diethanolamine system in the 298–366.5 K temperature range. In this work we have developed a model which is able to represent the liquid phase speciation as well as the CO2 solubility in the amine solutions. For this purpose the database used for the parameters determination consists of solubility data as well as Henry's constants and speciation data including experimental concentrations of molecular CO2 and of carbamate. The need of such speciation data is shown by a comparison of the speciation results obtained and those predicted using models from the literature based only on the data treatment of experimental VLE values.