Excess Gibbs-energy models are the thermodynamic basis for the layout of thermal separation processes in the chemical and process industry, like distillation columns. Against the background of a change in resources towards biobased value chains, such models are being challenged by the need to describe more complex and/or oxygenated molecules. To contribute to this challenge, it is the scope of this research project to show new paths for the characterization of multi-component mixtures including complex molecules. Consequently, this project proposes to further develop a previously published excess Gibbs-energy model towards activity coefficients for chemical engineering applications.

The novelty of the approach is that it a priori accounts for geometrical information about the possible arrangements of molecules in condensed phases by considering clusters of molecules as modeling basis. In this way, in particular compared to most state of the art quasichemical-based approaches, the usual decoupling of interacting surface segments from geometric restrictions is avoided and only geometrically feasible arrangements of molecules are considered, which in particular enables the distinction between isomeric configurations.

The excess Gibbs-energy model as the starting point for this proposal was developed previously for clusters of dice-like molecules in a lattice. Its proposed further development comprises the improvement of the excess Gibbs-energy model itself by a different cluster construction, the combination of the model with a cluster sampling algorithm to provide cluster states for real molecules as model variables, and the application of the resulting model to Monte-Carlo data and a basic set of real two-component mixtures, to be compared to experimental data as well as established models