Post-combustion CO2 absorption-desorption performance of novel aqueous binary amine blend of Hexamethylenediamine (HMDA) and 2-Dimethylaminoethanol (DMAE)

In this investigation, a novel aqueous Hexamethylenediamine (HMDA) and 2-Dimethylaminoethanol (DMAE) amine blend was made to capture CO2, which would strongly contribute towards net-zero emission. The capability of the novel amine blend was investigated by conducting CO2 absorption and desorption experiments. The major research findings were equilibrium CO2 loading (α), cyclic capacity, heat duty, regeneration efficiency, CO2 absorption and desorption rate, pH, density, 13C NMR and FTIR characterization, process optimization, and toxicity assessment. CO2 absorption experimental operating conditions: temperature (T) = 298.15–333.15 K, CO2 partial pressure (PCO2) = 10.13–25.33 kPa, mole fraction of HMDA (mHMDA) = 0.05–0.20, and solution concentration (C) = 1–3 mol/L. The optimum equilibrium CO2 loading was found to be 1.2174 mol CO2/mol amine at T = 298.15 K, PCO2 = 25.33 kPa, mHMDA = 0.20, and C = 1 mol/L. Similarly, desorption experiments were performed at constant T = 393.15 K and PCO2 = 25.33 kPa. For C = 3 mol/L, cyclic capacity was 1.5951 mol CO2/L solution, which was 61.77 % higher than the benchmark 30 wt% monoethanolamine (MEA). The heat duty and regeneration efficiency for 3 mol/L solution were calculated to be 131.24 kJ/mol CO2 and 60.47 %, respectively. The novel amine blend's heat of CO2 absorption was calculated to be −75.50 kJ/mol. Response surface methodology (RSM) was used for modeling and optimization: αoptimum = 1.04583 mol CO2/mol amine at T = 306.90 K, PCO2 = 21.53 kPa, mHMDA = 0.16 and C = 1.5 mol/L.