(352m) Development of a COSMO-Based Thermodynamic Model with Wertheim’s Thermodynamic Perturbation Theory

With growing interest in biofuels, mixtures of organic acids, alcohols and water are being encountered more frequently in the chemical industry. These polar compounds hydrogen bond (or ‘associate’) and therefore exhibit large deviations from ideal behavior. Few models can accurately predict the thermodynamic properties of associating components. Even more theoretically rigorous models, such as those based on the COnductor-like Screening MOdel (COSMO) developed by Klamt et al.¹, which leverage quantum mechanical simulations to improve the representation of molecular interactions, are of limited use for associating components.

In previous work, Bala and Lira² developed a generalized expression for the association contribution to the activity coefficient, based on Wertheim’s Thermodynamic Perturbation Theory (TPT-1)^3,4. While TPT-1 has been integrated into several equations of state, including the SAFT⁵ and CPA⁶, it has not yet been combined with an ab initio model based on COSMO. In this work we develop an activity coefficient model that combines COSMO with TPT-1. The model is used to model binary systems, in which one of the component self-associates and the other is “inert” to hydrogen bonding, such as alcohol-alkane mixtures.

References

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