The study of excess thermodynamic properties of liquid mixtures is very important for designing the thermal separation processes, developing solution theory models and to have a better understanding of molecular structure and interactions involved in the fluid mixtures. In particular, heat of mixing or excess molar enthalpy data of binary and ternary fluid mixtures have great industrial and theoretical significance. In this connection, the experimental excess molar enthalpies for seventeen binary and nine ternary systems involving hydrocarbons, ethers and alcohol have been measured at 298.15K and atmospheric conditions for a wide range of composition by means of a flow microcalorimeter (LKB 10700-1). The binary experimental excess molar enthalpy values are correlated by means of the Redlich-Kister polynomial equations and the Liebermann - Fried solution theory model. The ternary excess molar enthalpy values are represented by means of the Tsao-Smith equation with an added ternary term and the Liebermann-Fried model was used to predict ternary excess molar enthalpy values. The Liebermann-Fried solution theory model was able to closely represent the experimental excess enthalpy data for most of the binary and ternary systems with reasonable accuracy. The correlated and predicted excess molar enthalpy data for the ternary systems are plotted in Roozeboom diagrams

In modern separation design, an important part of many phase-equilibrium calculations is the mathematical representation of pure-component and mixture enthalpies. Mixture enthalpy data are important not only for determination of heat loads, but also for the design of distillation units. Further, mixture enthalpy data, when available, are useful for extending vapor-liquid equilibria to higher (or lower) temperatures, through the use of the Gibbs-Helmholtz equation. In this connection excess molar enthalpies for several binary and ternary mixtures involving ethers and hydrocarbons have been measured at the temperature 298.15 K and atmospheric pressure, over the whole mole fraction range. Values of the excess molar enthalpies were measured by means of a modified flow microcalorimeter (LKB 10700-1) and the systems show endothermic behavior. The Redlich-Kister equation has been used to correlate experimental excess molar enthalpy data of binary mixtures. Smooth representations of the excess molar enthalpy values of ternary mixtures are accomplished by means of the Tsao-Smith equation with an added ternary contribution term and are used to construct excess enthalpy contours on Roozeboom diagrams. The values of the standard deviations indicate good agreement between experimental results and those calculated from the smoothing equations. The experimental excess enthalpy data are also correlated and predicted by means of solution theories (Flory theory and Liebermann-Fried model) for binary and ternary mixtures, respectively. These solution theories correlate the binary heats of mixing data with reasonable accuracy. The prediction of ternary excess molar enthalpy by means of the solution theories are also presented on Roozeboom diagrams. The predictions of ternary excess enthalpy data by means of these theories are reasonably reliable.

In modern separation design, an important part of many phase-equilibrium calculations is the mathematical representation of pure-component and mixture enthalpies. Mixture enthalpy data are important not only for determination of heat loads, but also for the design of distillation units. Further, mixture enthalpy data, when available, are useful for extending vapor-liquid equilibria to higher (or lower) temperatures, through the use of the Gibbs-Helmholtz equation. In this connection excess molar enthalpies for several binary and ternary mixtures involving ethers and hydrocarbons have been measured at the temperature 298.15 K and atmospheric pressure, over the whole mole fraction range. Values of the excess molar enthalpies were measured by means of a modified flow microcalorimeter (LKB 10700-1) and the systems show endothermic behavior. The Redlich-Kister equation has been used to correlate experimental excess molar enthalpy data of binary mixtures. Smooth representations of the excess molar enthalpy values of ternary mixtures are accomplished by means of the Tsao-Smith equation with an added ternary contribution term and are used to construct excess enthalpy contours on Roozeboom diagrams. The values of the standard deviations indicate good agreement between experimental results and those calculated from the smoothing equations. The experimental excess enthalpy data are also correlated and predicted by means of solution theories (Flory theory and Liebermann-Fried model) for binary and ternary mixtures, respectively. These solution theories correlate the binary heats of mixing data with reasonable accuracy. The prediction of ternary excess molar enthalpy by means of the solution theories are also presented on Roozeboom diagrams. The predictions of ternary excess enthalpy data by means of these theories are reasonably reliable.

L'augmentation de la concentration de dioxyde de carbone (CO2) dans l'atmosphère depuis la révolution industrielle a conduit à l'augmentation de la température moyenne du globe. Pour limiter l’accroissement des températures atmosphériques moyennes, la quantité de dioxyde de carbone émise dans l'atmosphère doit être réduite. Une des solutions envisagée sur les sources fixes est le captage et le stockage du CO2. Ce procédé d’absorption/désorption, bien connu dans le traitement du gaz naturel, est onéreux et peu efficace pour le traitement du gaz des sources fixes et doit être optimisé. La solution proposée s’appuie sur l’utilisation de solvants démixants, présentant une séparation de phase équilibre liquide-liquide (LLE) en solution aqueuse en fonction de la température. Ce manuscrit présente une étude réalisée pour la famille des alkyl-pipéridines connues pour ses séparations de phase. Cette étude permettra d’évaluer l’influence de la taille, de la positionet du nombre de substituants sur les propriétés thermodynamiques d’intérêt pour le procédé. Pour étudier les LLE des solutions aqueuses démixantes, en particulier dans le cas des solutions chargées en gaz, deux instruments ont été mis au point. Il a été possible de démontrer que les changements opérés sur les diagrammes de phase des amines sont liés aux réactions chimiques mises en jeu lors de la dissolution du CO2. Pour les alkyl-pipéridines tertiaire on observe la température de démixtion diminue avec l’addition de CO2, allant avec la formation de carbonates. Avec les alkyl-pipéridines secondaires la température de démixtion augmente, ce qui est lié à la présence en solution de carbamates qui stabilisent la solution aqueuse. Le comportement des amines secondaires très encombrées, qui ne peuvent donc pas formées de carbamates, est similaire à celui des amines tertiaires, ce qui est cohérent avec les conclusions précédentes. Une étude approfondies des propriétés thermodynamiques d’excès (VE, CpE et HE) des alkyl-pipéridines en solution aqueuse a également permis de démontrer des relations structure - propriétés. La position du substituant sur le cycle pipéridine a une influence considérable et prévisible sur l’intensité des propriétés d’excès, alors que la nature de l’amine (secondaire ou tertiaire) va influencer la position de l’extremum de cette propriété. Enfin, une modélisation thermodynamique rigoureuses des solubilités et des enthalpies de dissolution du CO2 dans les solutions aqueuses de pipéridines a permis de déterminer les constantes de formation des carbamates dans les solutions aqueuses de 3- et 4-méthylpipéridines. / The increase of carbon dioxide (CO2) concentration in the atmosphere, since the industrial revolution has led to the rise in the average global climate temperature. To prevent the escalation of global climate temperatures the amount of CO2 emitted into the atmosphere must be reduced. One solution is carbon capture and sequestration which removes CO2 from fixed sources. The absorption/desorption cycle is well known for the treatment of acid gas, but is expensive and not as efficient for the treatment of gas from fixed/industrial sources. A solution to this problem is the use of aqueous demixing amine solvents which present a liquid-liquid phase equilibrium (LLE) as a function of temperature. This manuscript presents a study done to measure the LLE and thermodynamic properties of the alkyl piperidine family, which can be used for carbon capture processes. This work evaluates the effect of the size, position and number of alkyl substituents on the thermodynamic properties of interest in the carbon capture process. To study the LLE of aqueous demixing solutions, particularly gas loaded solutions, two novel apparatuses were developed. The results demonstrate that the changes in the amine phase diagrams are related to the chemical reactions involved with dissolution of CO2. The tertiary alkyl piperidines displayed reduced demixing temperature with the addition of CO2 due to the formation of carbonate species. The secondary alkyl piperidines display an increasing demixing temperature which is related to the formation of carbamate species which stabilizes the solution. Secondary alkyl piperidines that are severely sterically hindered, which cannot produce carbamates, behave similarly to the tertiary amine which is coherent with the preceding conclusion. The structure property relationship concerning the excess thermodynamic properties (VE, CpE et HE) of aqueous solutions were studied in depth. This revealed that the position of the substituents on the cyclic ring has a considerable and obvious influence on the intensity of the excess properties, along with the class of the amine, whether secondary or tertiary, will influence the positions of the extrema of the excess property. To conclude, a rigorous thermodynamic model based on the CO2 solubility and the enthalpy of solution for CO2 in aqueous solutions of alkyl piperidine, allowed for the determination of the carbamate formation constants of 3- and 4-methylpiperidine.