Nanofiltration coupled catalysis

Even if not really new, the concept of a membrane reactor has not been applied so intensively in homogeneous catalysis as in heterogeneous catalysis [20]. Nevertheless, the application of this concept in this area seems to be an exciting new topic, which opens up enormous possibilities of research and development. 

The reaction takes place in a continuously stirred tank reactor, thus reaching the activity and selectivity found in homogeneous reactions. The liquid is contacted with a nanofiltration (NF)-membrane that allows products to permeate but rejects the dissolved catalyst. This set-up is made possible by the development of solvent resistant NF-membranes having a molecular weight cut-off (MWCO) in the range 200-700 Da and working conditions below 40 °C and 35 bar. 

The continuous enantioselective hydrogenations of dimethyl itaconate (DMI) with Ru-BINAP (MW = 929 Da) and of methyl 2-acetamidoacrylate (MAA) with 

Rh-EtDUPHOS (MW = 723 Da) were selected as model systems because of the excellent performance of these catalysts and their industrial relevance. 

Supercritical Fluid-Assisted Membrane Separation and/or Reaction 

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K. DeSmet, S. Aerts, E. Ceulemans, l.F.J. Vankelecom, and P.A. Jacobs, Nanofiltration-coupled catalysis to combine the advantages of homogeneous and heterogeneous catalysis, Chem. Commun. 7 (2001) 597-598. 

Under carefully adjusted experimental conditions unmodified catalysts can be used in nanofiltration coupled homogeneous catalysis. Also non-dendritic but nanosized rigid catalytic systems can be retained by nanofiltration membranes. In this section, unmodified catalysts and rigid non-dendritic systems applied in continuous catalysis will be discussed. 

A. Datta, K. Ebert, H. Plenio, Nanofiltration for homogeneous catalysis separation Soluble polymer-supported palladium catalysts for Heck, Sonogashira, and Suzuki coupling of aryl halides, OrganometaUics 22 (2003) 4685-4691. 

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