Study on the Novel Blend of AHPD/HMDA/Triethylene Glycol for CO2 Absorption: Kinetics, CO2 Solubility, and Catalytic Desorption

The sterically hindered amine, 2‐amino‐2‐hydroxymethyl‐1,3‐propanediol (AHPD), is an efficient CO2 separation solvent. The addition of the activator 1,6‐hexamethyl diamine (HMDA) increases the reactivity of this solvent. The mixture of AHPD and HMDA in two co‐solvents, triethylene glycol (TEG) and water, is a candidate new blend with low volatility. In this work, the CO2 absorption kinetics of this blend was investigated using the stirred‐cell technique in the 308–318 K range. It was found that the second‐order rate constant for the reaction between CO2 and HMDA was 62,984 m3/(kmol s) at T = 308 K. The activation energy value was 34.9 kJ/mol. The effects of concentrations of HMDA and TEG on the absorption rate were studied. The loading capacity of this blend was measured, and its value was 0.86 mol/mol. The corresponding equilibrium CO2 partial pressure was 89.2 kPa. In a batch setup, desorption of the proposed blend was investigated. AHPD/HMDA/TEG mixture (1.5/0.5/2 kmol/m3) was regenerated, and its cyclic capacity at 368 K was 0.31 mol/mol. However, cyclic capacity improved to 0.46 mol/mol when γ‐Al2O3 catalyst was used. In this way, useful insights into the novel AHPD/HMDA/TEG blend were obtained.