Selection of systems for catalyst recovery by micellar enhanced ultrafiltration

The most discussed problem of homogeneous catalysis, the recovery of expensive catalyst, may be solved with the application of a technology, already well established in other fields: micellar enhanced ultrafiltration (MEUF). Catalyst embedded in surfactant micelles is easy to recover from the reaction medium by an ultrafiltration process. In this contribution the selection of surfactants and membranes suitable for performing homogeneously catalyzed reactions in combination with a catalyst recovery by MEUF is described. For a group of representative anionic, cationic and non-ionic surfactants that are compatible with a homogeneous rhodium-based hydrogenation catalyst, membranes were selected that allow high catalyst recovery. For ionic surfactant micelles best performance is achieved with polyethersulfone membranes, while non-ionic systems are separated most efficiently using regenerated cellulose membranes.