Determination of the liquid-phase speciation in the MDEA - H2O - CO2 system

Aqueous solutions of alkanolamines are commonly used in CO2 capture processes. To describe these complex processes rigorous mass transfer models are needed, in which all mass transfer, kinetics and thermodynamics are incorporated correctly. To improve the quality of the thermodynamic models, not only commonly used P-α (CO2 partial pressure versus CO2 liquid loading) experimental data, but also liquid phase speciation data are important. Speciation data of amine-H2O-CO2 data are very scarce in literature. In this work speciation data of MDEA-H2O-CO2 have been determined experimentally with a Fourier Transform Infra-Red spectrometer (FTIR) at ambient temperature. After several calibration lines were prepared, the speciation of this system was determined online in the FTIR. The experimental data presented in this work were well in line with speciation from open literature.