A predictive group-contribution framework for the thermodynamic modelling of CO2 absorption in cyclic amines, alkyl polyamines, alkanolamines and phase-change amines: New data and SAFT-γ

A significant effort is under way to identify improved solvents for carbon dioxide (CO 2 ) capture by chemisorption. We develop a predictive framework that is applicable to aqueous solvent + CO 2 mixtures containing cyclic amines, alkyl polyamines and alkanolamines. A number of the mixtures studied exhibit liquid-liquid phase separation, a behaviour that has shown promise in reducing the energetic cost of CO 2 capture. The proposed framework is based on the SAFT- γ Mie group-contribution (GC) approach, in which chemical reactions are described via physical association models that allow a simpler, implicit, treatment of the chemical speciation characteristic of these mixtures. We use previously optimized group interaction parameters between some amine groups and water (Perdomo et al., 2021) as well as develop new group interactions for the cNH, cN, NH 2 , NH, N, cCHNH, and cCHN groups with CO 2 ; a set of second-order group parameters are also developed to account for proximity effects in some alkanolamines. A combination of literature data and new experimental measurements of the absorption of CO 2 in aqueous cyclohexylamine systems obtained in this work, are used to develop and test the proposed models. The SAFT- γ Mie GC approach is used to predict the thermodynamics of selected mixtures, including ternary phase diagrams and mixing properties relevant in the context of CO 2 capture. The current work constitutes a substantial extension of the range of aqueous amine-based solvents that can be modelled and thus offers the most comprehensive thermodynamically consistent platform to date to screen novel candidate solvents for CO 2 capture.