title: Unlocking the potential of supported liquid phase catalysts with supercritical fluids: low temperature continuous flow catalysis with integrated product separation.
abstract: Solution-phase catalysis using molecular transition metal complexes is an extremely powerful tool for chemical synthesis and a key technology for sustainable manufacturing. However, as the reaction complexity and thermal sensitivity of the catalytic system increase, engineering challenges associated with product separation and catalyst recovery can override the value of the product. This persistent downstream issue often renders industrial exploitation of homogeneous catalysis uneconomical despite impressive batch performance of the catalyst. In this regard, continuous-flow systems that allow steady-state homogeneous turnover in a stationary liquid phase while at the same time effecting integrated product separation at mild process temperatures represent a particularly attractive scenario. While continuous-flow processing is a standard procedure for large volume manufacturing, capitalizing on its potential in the realm of the molecular complexity of organic synthesis is still an emerging area that requires innovative solutions. Here we highlight some recent developments which have succeeded in realizing such systems by the combination of near- and supercritical fluids with homogeneous catalysts in supported liquid phases. The cases discussed exemplify how all three levels of continuous-flow homogeneous catalysis (catalyst system, separation strategy, process scheme) must be matched to locate viable process conditions.
authors.affiliation: Institut für Technische Chemie und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, Aachen 52074, Germany.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Franciò
authors.affiliation: Centre for Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, UK u.hintermair@bath.ac.uk.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hintermair
authors.affiliation: Institut für Technische Chemie und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, Aachen 52074, Germany Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany leitner@itmc.rwth-aachen.de.
authors.forename: Walter
authors.initials: W
authors.lastname: Leitner
keywords: catalyst recycling; continuous-flow processing; homogeneous catalysis; ionic liquids; supercritical CO2; supported liquid phases