Investigating the effect of blending of diamine and alkanolamine for CO2 capture: Experiment and thermodynamic modeling of CO2-AEEA-DEA-H2O system

Abstract

This study reports the experimental data on CO2 solubility in aqueous aminoethylethanolamine (AEEA) and diethanolamine (DEA) under different amine blending ratios (9:21, 15:15 and 21:9 wt% AEEA: DEA, respectively and remaining 70 wt% being the water), CO2 partial pressure up to 477.4 kPa and temperatures up to 393.15 K. The complex nature of AEEA diamine and DEA was thermodynamically modeled to evaluate the behavior of aqueous blend of AEEA and DEA for CO2 capture. The electrolyte nonrandom two liquid (electrolyte NRTL) activity coefficient model is used to incorporate the nonideality of the system. The system of blended aqueous AEEA and DEA contained twelve equilibrium equations, three mass balance equations, one charge balance equation and one hydronium ion-based polynomial. These equations were simultaneously solved by using an inhouse built MATLAB code to determine the CO2 loading, CO2 cyclic capacity, pH, heat of absorption, activity coefficients and concentration of seventeen species in the system. Model results have been compared with literature and inhouse experimental data, which are in a good agreement. Furthermore, study reports activity coefficients, mole fractions of seventeen species, dependence of CO2 loading on temperature, pressure and concentration of individual amine. The Absolute average deviation percent in the model and experimental data for AEEA, DEA and their blend are 9.90%, 7.61% and 8.55%, respectively for CO2 loading.