Kinetics of CO2 Absorption into Aqueous AMP/HMDA/TEG Mixtures

Abstract

AbstractMixtures of 2‐amino‐2‐methyl‐1‐propanol (AMP), 1,6‐hexamethyl diamine (HMDA), triethylene glycol (TEG) and water, which merge the loading capacity of AMP, reactivity of HMDA and low volatility of TEG, are improved CO2‐capturing solvents. In the present study, kinetic aspects of the reaction of CO2 with the blend AMP+HMDA were investigated using co‐solvents TEG+Water. Kinetic data were experimentally obtained in a stirred cell at 303–318 K. The concentrations of AMP and HMDA in the mixtures were changed in the 2–3 and 0.1‐0.5 M range whereas TEG concentration was changed between 0.7 and 2 M. Pseudo‐first order rate constants were measured. Knowing the CO2 absorption rates in the aforesaid mixtures, the second‐order rate constant (65195 M−1 s−1) for the reaction between CO2 and HMDA at 308 K was found. The activation energy for the CO2‐HMDA system in aqueous solution was 33.1 kJ/mol. Equilibrium solubility of CO2 in AMP/HMDA/TEG/Water mixtures was measured. Finally, it was established that N,N’‐dimethyl‐1,6‐hexamethyl diamine (or HMDA−N,N’) – a dialkyl derivative of HMDA – is a further attractive promoter for AMP in TEG+Water mixtures.