M. Sc. Thomas Roth

Homogeneous transition metal catalysts offer many strengths over heterogeneous catalysts, including high catalyst activity and selectivity even at comparatively mild operating conditions. Despite these advantages, most industrial processes are catalyzed heterogeneously due to the easier and thus more cost-effective separation. Since recycling of the transition metals is indispensable for the economic and ecological sustainability of processes using homogeneous catalysts, the development of efficient separation and recycling concepts is required to make use of their strengths.

The immobilization of the catalyst in multiphase systems offers a promising approach in this respect, as the catalyst phase can be separated and recycled with relatively low effort. However, this approach also poses certain challenges, such as mass transport limitations across the phase interface. Therefore, this research will investigate and optimize different intensification strategies of continuous processes using aqueous multiphase systems for homogeneously catalyzed carbonylation reactions (Fig. 1). In each case, the product phase is separated from the catalyst phase in a decanter, allowing the latter to be recycled to the reactor (Fig. 2).

The first strategy is the improvement of the mixing and thus the enlargement of the phase interface by using the innovative jetloop reactor (Fig. 2, left). In the second strategy, cyclodextrins are used as phase transfer agents to improve the contacting of the catalyst with substrate molecules at the phase interface (Fig. 2, right).