Heat of Absorption of Carbon Dioxide (CO2) in Monoethanolamine (MEA) and 2-(Aminoethyl)ethanolamine (AEEA) Solutions

A method is proposed for measuring the enthalpy of absorption of CO2 (ΔH abs) that is differential in temperature and semi-differential in loading. A 2-L reaction calorimeter was used to measure the enthalpy of absorption of CO2 with aqueous solutions of monoethanolamine (MEA) and (2-aminoethyl)ethanolamine (AEEA) over the temperature range of 40−120 °C. By feeding CO2 in several steps and keeping the change in loading between each new equilibrium rather low (∼0.03−0.07 mol CO2/mol amine), it was possible to obtain values of ΔH abs that were semi-differential in loading. Experiments conducted at different temperature levels gave enthalpy values that were differential in temperature. Measured ΔH abs values were compared with integral values found in the literature and with differential values calculated from solubility measurements. The experimental results indicate that the use of the Gibbs−Helmholtz equation in an aggregate form does not necessarily give an accurate description of the ΔH abs values.