A PC-SAFT model for hydrocarbons I: Mapping aromatic π-π interactions onto a dipolar free energy

Aromaticity is an important property of many petroleum derived streams. Traditional thermodynamics tools (e.g., cubic equations of state) do not provide any special treatment to these aromatic hydrocarbons. A feature which discriminates aromatics from paraffins is that aromatic rings exhibit anisotropic pi-pi interactions. Accounting for this key difference between aromatic and non-aromatic hydrocarbons in an equation of state will allow for a level of predictability which is not possible with our current tools. By mapping the anisotropy of pi-pi attractions onto a dipolar free energy, we develop a simple and powerful treatment of aromatic hydrocarbons within the PC-SAFT equation state. We demonstrate that this approach provides a substantial increase in performance over the standard non-polar treatment of aromatic molecules. The methodology developed is used to develop a generalized hydrocarbon model in instalment II of this series. (C) 2019 Elsevier B.V. All rights reserved.