Enthalpy of Solution of CO2 in Aqueous Solutions of Primary Alkanolamines: A Comparative Study of Hindered and Nonhindered Amine-Based Solvents

Aqueous solutions of amines can be selective absorbents for the separation of carbon dioxide (CO2) from industrial effluents. Because of different chemical reactions, the mechanisms of CO2 absorption in 2-amino-2-methyl-1-propanol (hindered primary amine) or 2-aminoethanol (primary amine) will differ. These mechanisms are analyzed via the extents of reactions and enthalpies of solution, derived from a thermodynamic model representative of {CO2/amine/water} systems. The model was optimized to fit literature solubility data and tested by comparison of calculated and experimental enthalpy values. New experimental enthalpies of solution were collected for aqueous solutions of 2-amino-2-methyl-1-propanol (w(amine) = 0.1500, and w(amine) = 0.3000) at 372.9 K and pressures from 0.5 to 3.2 MPa.