Development of a continuous process for the hydroformylation of long-chain olefins in aqueous multiphase systems

The challenging task of homogeneous catalysis is the efficient combination of reaction and catalyst recycling. In the hydroformylation of long-chain olefins generally cobalt-based catalysts are used, but in our investigation we used rhodium-based catalysts, because of their higher activity in comparison to cobalt catalysts. In hydroformylation reactions, the recycling of the expensive rhodium catalyst as well as the selectivity to linear aldehydes are very challenging. Multiphase systems offer the possibility to increase the interfacial area during reaction on the one hand and to separate the metal–ligand complexes easily from the organic product phase after reaction, to recycle the expensive catalyst for further reactions, on the other hand. Solubilisers such as surfactants or polar solvents can be used to formulate such a tuneable solvent system. Upon cooling of the reaction mixture, phase separation is achieved. Based on that combination of reaction and phase separation for catalyst recycling, a novel process concept was developed for the hydroformylation of long-chain olefins. In order to show the applicability of that concept in a continuous process a fully automated miniplant was designed.