This poster was presented at the 2020 Dow-MSU Professional Development Day, June 24, 2020. This demonstrates how we are using spectroscopy to determine the fraction of hydroxyls free and for butanol the model shows that most hydrogen bonds species are linear.
The challenge to accurately represent the non-ideal phase behavior of associating systems is a long-standing industrial need. Models frequently predict liquid-liquid phase splits that do not exist experimentally. Furthermore, existing models are unable to accurately model vapor-liquid and liquid-liquid equilibria using the same parameters. To address this need, our research group presents an activity coefficient approach to phase modeling, that features an explicit association term based on Wertheim’s perturbation theory. The association term is the averaged macroscopic manifestation of localized hydrogen bonding at the molecular level. Many different values for association constants are presented in the literature, resulting in significant uncertainty when applying models. Infrared spectroscopy can be used to probe these interactions at the molecular level; however, quantification of the entire hydroxyl band has remained elusive. In this work, we present an entirely new method of interpreting the spectra using an extinction coefficient that varies with wavenumber as inspired by quantum calculations, and we provide the first published quantification of the entire hydroxyl band using the Beer-Lambert law. The new method leads to increased confidence in curve fitting to determine the fraction of unbonded alcohol needed to parameterize the hydrogen bonding and to quantify the types of hydrogen bonds in solution. Finally, the association term is combined with the NRTL model and used to model the phase behavior of associating systems.
An overview presentation of the poster
References
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