No abstract

Over the past 20 years, thermomorphic multiphase systems (TMS) have been used as a versatile and elegant strategy for the recovery and recycling of homogeneous transition‐metal catalysts, in both batch‐scale experiments and continuously operated processes. TMS ensure a homogeneous reaction in a monophasic reaction mixture at reaction temperature and the recovery of the homogeneous transition‐metal catalyst through liquid–liquid separation at a lower separation temperature. This is achieved by using at least two solvents, which have a highly temperature‐sensitive miscibility gap. The suitability of commercially available solvents makes this approach highly interesting from an industrial point of view. For the first time, herein, all studies in the area of TMS are reviewed, with the aim of providing a concise and integral representation of this approach for homogeneous catalyst recovery. In addition to the discussion of examples from the literature, the thermodynamic fundamentals of the temperature‐dependent miscibility of solvents are also presented. This review also gives key indicators to compare different TMS approaches, for instance. In this way, new solvent combinations and in‐depth research, as well as improvements to existing approaches, can be addressed and promoted.

The application of thermomorphic solvent systems offers the combination of homogeneous catalysis in a single phase and catalyst recovery via phase separation. To increase economic feasibility the minimization of waste streams and side reactions is desired. For this, a continuous process for the hydroformylation of 1‐dodecene in the solvent system DMF/n‐decane is shown. While the Rh/Biphephos catalyst is recycled in DMF in a first loop, the n‐decane and remaining olefins are separated from the product via distillation to form the second loop. In this process the need for additional solvent supply and the isomerization reaction of 1‐dodecene is reduced significantly. The reaction toward internal olefins decreases from initially 15 to 3%. The stable hydroformylation process with a yield of the linear hydroformylation product of 55% and l/b‐ratio of 95/5 is shown for 120 h. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4377–4383, 2016

A new process concept has been developed for recycling transition-metal catalysts in the synthesis of moderately polar products via aqueous thermomorphic multicomponent solvent systems. This work focuses on the use of "green" solvents (1-butanol and water) in the hydroformylation of the bio-based substrate methyl 10-undecenoate. Following the successful development of a biphasic reaction system on the laboratory scale, the reaction was transferred to a continuously operated miniplant to demonstrate the robustness of this innovative recycling concept for homogenous catalysts.

Die Anwendung thermomorpher Mehrkomponenten‐Lösungsmittelsysteme in chemischen Prozessen kann die Effektivität und Wirtschaftlichkeit homogen katalysierter Verfahren erheblich steigern. Die Ausnutzung einer stark temperaturabhängigen Mischungslücke von ausgewählten Lösungsmittelkombinationen ermöglicht eine einphasige Reaktionsführung und eine anschließende Katalysatorabtrennung mittels Flüssig/Flüssig‐Zweiphasentechnik. Dieses elegante Katalyseprinzip wurde am Beispiel der rhodiumkatalysierten Hydroformylierung von 1‐Dodecen in einer kontinuierlich betriebenen Miniplant im Langzeitbetrieb untersucht.