Calorimetric Measurements of CO2 Absorption into Aqueous -Methyldiethanolamine Solutions

A reaction calorimeter was used to study the rate and heat effects during CO2 absorption into aqueous solutions of N-methyldiethanolamine (MDEA). The experiments were carried out at constant pressure of 0.1 MPa and 0.3 MPa over a range of temperature from 293 K to 333 K. The amine content changed from 10 to 30 mass %. The experimental equipment and procedure were described with the emphasis on complexity originating from the difficulty of interpreting the chemical absorption data and measuring the enthalpy of absorption. The employed technique was also found to be useful in determining the CO2 solubility in aqueous MDEA. The enthalpy of absorption was found to be independent of pressure and amine concentration and it increased with temperature. A new method to estimate the chemical reaction rate from heat flow data has been developed and proved to be valid for the CO2—H2O—MDEA system. The present results show that the employed technique offers a big advantage of simultaneous monitoring of many data which are involved in the absorption process.