(341a) Molecular Design of Thermomorphic Solvents for the Hydroformylation of Dodecene

Molecular design of thermomorphic
solvents for the hydroformylation of dodecene

Kevin
McBride¹, Kai Sundmacher^1,2

¹Max
Planck Institute for Dynamics of Complex Technical Systems,
Magdeburg/DE

²Process
Systems Engineering, University of Magdeburg, Magdeburg/DE

The
use of thermomorphic multi-component solvent (TMS) systems is an
innovative concept to incorporate homogeneous reactions with
efficient catalyst separation via a temperature induced phase split.
In the rhodium catalyzed hydroformylation of long chain olefins, the
TMS is a promising prospect due to the requirement that the expensive
catalyst complex be recycled quantitatively. Thus, the key
characteristic of the TMS is its temperature sensitivity, meaning
that the phase behavior of these solvents can be tuned using
temperature as the control variable. We keep the temperature high
during the reaction, forming one phase, and then, with a reduction in
temperature, form two liquid phases where the catalyst is selectively
removed from the other components. Sought after properties are a
relatively wide miscibility gap and low distribution of the catalyst.
In this regard, selection of the solvent is a critical aspect of the
successful implementation of such a reaction.

Current
methods used to select candidate solvents for TMS do not contain
molecular information. The most current approach uses Hansen
parameters and temperature limitations; however, they do not contain
information about the liquid-liquid phase behavior. Hence, the
design space of the existing methods is limited. In addition, the
effect that the product has on the miscibility gap is not considered
in the preliminary evaluation. The effect of the TMS process-wide has
also not been investigated.

In
this work, we take both of these considerations into account. Using
other models such as modified UNIFAC or COSMO-RS, which contain
information about the solvents at the molecular level, solvent
screening is conducted. Using a geometric analysis of the
liquid-liquid equilibrium at various temperatures, candidate solvents
are identified. Upon further inspection for feasibility, reactivity
of the solvents, and influence of the product on the miscibility gap,
screened candidates are inserted into an optimizer that finds the
minimum cost of the selected process flowsheet. Here, we use the
hydroformylation of dodecene as an example reaction with the goal of
finding the optimal polar solvent for the TMS with decane as the
non-polar component.

By
using this procedure, we show that a rigorous TMS screening method
combined with process-wide optimization, allows us to consider the
overall effects of the TMS on cost during the initial process design.