A simplified semi-empirical model for modeling of CO2 solubilities in aqueous MDEA and MEA solutions

Abstract

A simplified semi-empirical model was developed for modeling of carbon dioxide (CO2) solubility in aqueous solutions of methyldiethanolamine (MDEA) and monoethanolamine (MEA) with a temperature range from 283.15 K to 393.15 K, and alkanolamine molarity (1–5) mol/L. This model accounts for chemical equilibria in the liquid phase and physical equilibria between the liquid and vapor phases, which can calculate the vapor liquid equilibria (VLE) of MDEA+H2O+CO2 system and MEA+H2O+CO2 system. This paper proposes a Simplified Kent-Eisenberg Model (SKEM) to describe the chemical equilibria in amine – acid system, which is built with the conception of ion pairs meets the like-ion repulsion assumption and the local electroneutrality assumption. In the physical equilibria, the Henley coefficient was refitted using a new correlation, which was built with the combinations of sines and cosines. Adjustable parameters of the SKEM model, representing chemical equilibrium constant including activity coefficients, were determined by data regression with 187 sets of data of MDEA+H2O+CO2 system and MEA+H2O+CO2 system. The SKEM model has a good predictive ability, the Absolute Average Relative Deviations (AARD) of predicted results of SKEM model in MDEA+H2O+CO2 system and MEA+H2O+CO2 systems are 13.66% and 8.33%, respectively.