Kinetics of CO2 absorption in aqueous hexamethylenediamine

In this work, kinetics of CO2 absorption in aqueous hexamethylenediamine (HMDA) has been investigated in the temperature range of 30-60 °C using a reaction calorimeter. Aqueous solutions of HMDA studied in this work are 5, 10, 20 and 30 mass%. Physicochemical and transport properties such as density, viscosity, physical solubility which are required to analyse the kinetics of CO2 absorption are measured. Pure component physical properties of HMDA are also measured. Mixed solvent physical properties are correlated with the pure component physical properties using suitable models. Under pseudo-first-order regime, second order rate constant for (HMDA + H2O + CO2) system is evaluated using zwitterions mechanism and correlated using Arrhenius power law expression. Reaction order is found to be unity with respect to both amine and CO2. Our work shows very high reaction kinetics for this system compared to conventional solvent monoethanolamine (MEA). Second order rate constant for the system studied is found to be 41,703 m3 kmol−1 s−1 at 30 °C (k2,MEA = 7560 m3 kmol−1 s−1 at 30 °C) with activation energy of 27.6 kJ/mol.