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 CO 2 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 CO 2 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 CO 2 and HMDA was 62,984 m 3 /(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 CO 2 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/m 3 ) 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‐Al 2 O 3 catalyst was used. In this way, useful insights into the novel AHPD/HMDA/TEG blend were obtained.