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Recycling Strategies

Schaubild Recycling Concepts for Homogeneous Catalysts: TMS, MWE/Membrane, Biphasic Immobilization, Crytallization

Thermomorphic Multiphase Systems (TMS)

A strategy for separating catalyst and product as well as overcoming mass transport limitations is the use of thermomorphic multicomponent solvent systems (TMS) which have some decisive advantages over other process variants:

  • Thermomorphic phase behaviour: Reaction control takes place without mass transport limitations between catalyst and substrate
  • The catalyst and product are separated by simple decantation after the reaction
  • Cheap and commercially available solvents can be used without additional surfactants, etc.

The technic of the TMS system uses the temperature dependence of the mixing gap between two solvents: a polar, catalyst-containing solvent and a nonpolar substrate phase. This system is two-phase at room temperature and forms a single-phase system when heated. This minimizes the mass transport limitation.

Angew. Chem. Int. 2016, Int. 55, 2924-2928 DOI: 10.1002/anie.201510738

Schaubild thermomorphic multiphase systems

Biphasic Immobilisation

The core of the process is the separation of the catalyst from the reaction products by generating two practically immiscible liquid phases which can be separated by simple phase separation. The phases consist of an aqueous phase in which the catalyst is dissolved and an organic phase formed from the reaction products n- and iso-Butanal. This concept of two-phase immobilization is transferred to other reactions in our working group in order to separate the catalyst from the product.

Appl.Cat. A Gen. 2017, 539, 90-96, DOI: 10.1016/j.apcata.2017.03.037.

Schaubild Membrane Seperation

MWE / Membrane

The basic principle of membrane se­pa­ra­tion is quite simple (see figure): A feed containing substrates, products and the catalyst flows over a membrane. Ideally, only the small products can pass through the membrane into the permeate stream, the rest remains in the retentate, which is returned to the reactor. Membrane separation processes operate without heating and therefore use less energy than conventional thermal separation processes such as distillation or crystallization.

Schaubild MWE/ Membrane


  • No restrictions due to phase equilibria and thermal treatment
  • Recycling of the catalyst is possible without thermal load
  • Low energy consumption and simple numbering-up of the membranes to the desired process specification

At our chair we work with different types of membranes such as ceramic or polymer membranes in different reactor structures to investigate their behaviour.

Chem. Eng. Process 2016, 99, 124 –131, DOI: 10.1016/j.cep.2015.07.019


One catalyst recycling strategy is product crystallization for the selective and easy separation of the catalyst and the product. During product crystallization, the reaction solution is slowly cooled down in temperature intervals by means of a crystallizer and a cryostat. By crystallizing the product, it is possible to filter off the reaction solution and recover the product. This process is a gentle process for the product and for the catalyst and the ligands used.

ChemCatChem 2017, 9 (23), 4319-4323, DOI: 10.1002/cctc.201700965

Schaubild Crystallization

Location & approach

The campus of TU Dort­mund University is located close to interstate junction Dort­mund West, where the Sauerlandlinie A 45 (Frankfurt-Dort­mund) crosses the Ruhrschnellweg B 1 / A 40. The best interstate exit to take from A 45 is “Dort­mund-Eichlinghofen” (closer to South Campus), and from B 1 / A 40 “Dort­mund-Dorstfeld” (closer to North Campus). Signs for the uni­ver­si­ty are located at both exits. Also, there is a new exit before you pass over the B 1-bridge leading into Dort­mund.

To get from North Campus to South Campus by car, there is the connection via Vogelpothsweg/Baroper Straße. We recommend you leave your car on one of the parking lots at North Campus and use the H-Bahn (suspended monorail system), which conveniently connects the two campuses.

TU Dort­mund University has its own train station (“Dort­mund Uni­ver­si­tät”). From there, suburban trains (S-Bahn) leave for Dort­mund main station (“Dort­mund Hauptbahnhof”) and Düsseldorf main station via the “Düsseldorf Airport Train Station” (take S-Bahn number 1, which leaves every 20 or 30 minutes). The uni­ver­si­ty is easily reached from Bochum, Essen, Mülheim an der Ruhr and Duisburg.

You can also take the bus or subway train from Dort­mund city to the uni­ver­si­ty: From Dort­mund main station, you can take any train bound for the Station “Stadtgarten”, usually lines U41, U45, U 47 and U49. At “Stadtgarten” you switch trains and get on line U42 towards “Hombruch”. Look out for the Station “An der Palmweide”. From the bus stop just across the road, busses bound for TU Dort­mund University leave every ten minutes (445, 447 and 462). Another option is to take the subway routes U41, U45, U47 and U49 from Dort­mund main station to the stop “Dort­mund Kampstraße”. From there, take U43 or U44 to the stop “Dort­mund Wittener Straße”. Switch to bus line 447 and get off at “Dort­mund Uni­ver­si­tät S”.

The AirportExpress is a fast and convenient means of transport from Dortmund Airport (DTM) to Dortmund Central Station, taking you there in little more than 20 minutes. From Dortmund Central Station, you can continue to the university campus by interurban railway (S-Bahn). A larger range of international flight connections is offered at Düsseldorf Airport (DUS), which is about 60 kilometres away and can be directly reached by S-Bahn from the university station.

The H-Bahn is one of the hallmarks of TU Dort­mund University. There are two stations on North Campus. One (“Dort­mund Uni­ver­si­tät S”) is directly located at the suburban train stop, which connects the uni­ver­si­ty directly with the city of Dort­mund and the rest of the Ruhr Area. Also from this station, there are connections to the “Technologiepark” and (via South Campus) Eichlinghofen. The other station is located at the dining hall at North Campus and offers a direct connection to South Campus every five minutes.

The facilities of TU Dortmund University are spread over two campuses, the larger Campus North and the smaller Campus South. Additionally, some areas of the university are located in the adjacent “Technologiepark”.

Site Map of TU Dortmund University (Second Page in English).