(444e) Predicting the Phase Behavior of Highly Fluorinated Molecules Using the GC-SAFT-VR Equation of State

The statistical associating fluid theory (SAFT)¹ has been successful in predicting the phase behavior and thermodynamic properties for a wide range of fluids and their mixtures. The addition of the group contribution (GC) approach to SAFT has provided a set of transferable parameters that are able to be used to model a wide range of molecules. The GC-SAFT-VR^2–4approach models fluids as chains of tangentially bonded segments that represent functional groups. Parameters are obtained for each functional group by fitting to experimental data for a subset of a molecule class that contains that functional group. Once the parameters for that functional group are obtained, it can be utilized in other classes of molecules by only adjusting the cross interactions between that functional group and new functional groups in each molecule class. These functional group parameters can also be used to model properties of binary mixtures in addition to pure fluids. One such group of molecules, fluorinated molecules have been successfully modelled but the current models only have proven to be an adequate fit for simpler fluorinated molecules⁵, leaving out a wide range of more complex fluorinated molecules. Fluorinated molecules tend to possess highly desirable physical properties and have a wide range of possible physical applications. Although there is some data for properties of these molecules published, the data tends to focus on small, simple fluorinated molecules, yet the highly fluorinated complex molecules tend to have more applications, specifically in lowering industrial carbon emissions. In this work we will explore approaches to model highly fluorinated complex molecules, like hydrofluorinated ethers. This will allow for more accurate predictions of the properties of these molecules in addition to providing transferable parameters that can be used in a variety of similar molecules. Additionally, more accurate representation of these highly fluorinated complex molecules, will allow for the prediction of their properties in common binary mixtures such as with carbon dioxide, ethers, ketones, and alkanes.

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