A computational approach to solvent selection
Systematic methods and tools for managing the complexity
Advances in Computational & Numerical Methods (T4-4)
Keywords: Solvent selection, thermodynamics, biphasic systems, COSMO-RS, biocatalysis
Multiphase reaction media are a promising strategy to push the approach of homogenous catalysts to an industrial scale. Important examples for industrial processes on ton-scale using the advantages of liquid/liquid biphasic metal-catalysis are the oligomerization in the Shell Higher Olefin Process (SHOP) [1] and the Ruhrchemie / Rhône-Poulenc process [2,3]. Biphasic systems also play an important role in separation processes in the chemical industry such as in the butadiene extraction [4].
To use the tool of biphasic reaction conditions effectively for engineering purposes, a distinct knowledge of the equilibrium thermodynamic boundaries is of great value. In order to obtain reliable data, a large number of time-consuming and expensive experiments is necessary. To minimize the amount of experimental work but also to reduce the environmental impact, a modern approach to solvent selection is straightforward.
A good starting point for such a project is an ideal system. For an ideal system, an analytical solution was derived to calculate and predict equilibrium conversion and product yield in biphasic reaction mixtures with only one reactive phase [5,6].
This mathematical expression was validated using a numerical model for the ideal case. In order to move on to non-ideal systems, a numerical model for the non-ideal case will set up. This non-ideal model will take the concentration dependence of the partition coefficients into account as well as activity coefficients. The activity coefficients will be modeled using COSMO-RS. Hence a link between the COSMOtherm software and the numerical simulation software gPROMS needs to be established.
For the collection of material data, partition coefficients were calculated using COSMO-RS. Furthermore, Gibbs free energies in solution were calculated. From the Gibbs free energies, the calculation of equilibrium constants is possible and thereby conversion.
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[5] M.F. Eckstein, M. Peters, J. Lembrecht, A.C. Spieß, L. Greiner, Adv. Synth. Catal., 2006, 348, 1591-1596.
[6] M.F. Eckstein, J. Lembrecht, J. Schumacher, M. Peters, C. Roosen, L. Greiner, W. Eberhard, A.C. Spiess, W. Leitner, U. Kragl, Adv. Synth. Catal., 2006, 348, 1597-1604.
Presented Tuesday 18, 16:40 to 17:00, in session Advances in Computational & Numerical Methods (T4-4).
