Thermodynamic modeling and new experimental CO2 solubility into aqueous EAE and AEEA blend, heat of absorption, cyclic absorption capacity and desorption study for post-combustion CO2 capture

Abstract

In the present study, carbon dioxide (CO2) solubility into aqueous blend of 2-(ethylamino) ethanol (EAE) and aminoehtylethanolamine (AEEA) was measured. The performance of CO2 capture by this amine blend was investigated in terms of CO2 solubility, heat of absorption, cyclic CO2 solubility, and initial rate of change of CO2 solubility. CO2 absorption study was carried out using bubble column reactor in the temperature range of 298.15 to 323.15 K, 8.11 to 20.27 kPa CO2 partial pressure, 0.10 to 0.30 wt fraction of AEEA in EAE and AEEA blend, and 10 to 30 wt% total concentration of blend solution. Desorption experiments were performed at 393.15 K. Maximum CO2 solubility was 1.033 mol CO2/mol amine at 298.15 K, 20.27 kPa, 0.30 wt fraction of AEEA in the blend, and 10 wt% of EAE and AEEA solution. A semi-empirical Kent-Eisenberg thermodynamic model and an empirical model were developed to calculate equilibrium CO2 solubility in the studied range of operating conditions with 2.56% and 0.45% average absolute deviation, respectively. At 313.15 K, 15.20 kPa CO2 partial pressure and total concentration of 30 wt% of EAE and AEEA blend, the equilibrium CO2 solubility was resulted as 0.748 mol CO2/mol amine and cyclic solubility of 0.503 mol CO2/mol amine was achieved. Heat of CO2 absorption was measured based on Gibbs Helmholtz equation and found as −72.25 kJ/mol for 30 wt% aqueous EAE and AEEA blend. Results of absorption capacity of EAE and AEEA solution and monoethylethanolamine (MEA) were compared at same operating conditions. This blend had higher CO2 solubility, lesser heat of absorption, more cyclic capacity and faster rate of change of initial CO2 solubility than MEA.