The aim of this Ph.D. thesis is the thermodynamic study of {amine – water} and {CO2 – amine – water} systems. The amines are demixing amines, which have the singularity to exhibit a liquid-liquid phase separation in aqueous solutions as a function of temperature, composition and CO2 loading charge. These compounds can be considerate as new absorbents for CO2 capture. The liquid-liquid phase separations for {amine – water} systems were detected by calorimetry and visual techniques using a microcalorimeter (microDSCIII, Setaram) and an equilibrium cell (SPM20, Thar Technologies). In order to help in the thermodynamic representation of {amine – water} systems, excess molar volumes, excess molar enthalpies and specific heat capacities were measured. The enthalpies of mixing were determined using a flow calorimetric technique. The calorimeter was a BT2.15 from Setaram equipped with a homemade mixing cell. Excess molar volumes were determined from densities measurement performed with a vibrating tube densitometer. The enthalpies of solution of CO2 with absorbent and limits of gas solubility were studied for selected systems of interest for CO2 capture using a flow calorimetric technique. Last part of this work concerns the development of thermodynamic models to correlate the experimental data. The Gibbs energies of studied {amine – water} systems were calculating using both extended UNIQUAC and NRTL models. However, two sets of parameters were necessary to describe on one side the liquid-liquid equilibrium of mixtures and on the other side excess molar enthalpies and specific heat capacities. For {CO2 – amine – water} systems, a gamma-phi model was used. Interactions parameters were adjusted with vapor-liquid data and are able to predict the enthalpy of solution of CO2 in aqueous amine solutions, solubility limits of gas and speciation of the system as a function of loading charge.
