Catalyst Separation by Size Exclusion Membranes

3 Catalyst Immobilization in Liquid-Liquid Biphasic Reaction Systems using Fluorous Phases, Supercritical CO2 or Ionic Liquids 

Liquid-liquid biphasic systems where the catalyst is designed to stay immobilized in one of the two immiscible phases is obviously a very elegant solution to the problem of product separation in homogeneous catalysis. Moreover, the concept has been demonstrated to work on an industrial scale in the aqueous hydroformylation Ruhrchemie/Rhbne-Poulenc process as described in detail above. 

In answer to these limitations, research and development efforts of the last 20 years have tried to develop advanced liquid-liquid biphasic hydroformylation catalysis by replacing water by another catalyst solvent. As the number of organic-organic, biphasic systems with a sufficient miscibility gap in the presence of hydroformylation products is very limited, these efforts led to the application of so-called advanced fluids or green solvents in hydroformylation catalysis. Given the restricted scope of this textbook, it will be only possible to describe briefly the most important approaches and their scopes and limitations. The reader interested in the details of these dynamic research fields is referred to a series of recently published monographs (Mathison et al., 2006 Leitner and Jessop, 2010, and Stark and Wasserscheid, 2010). 

Unfortunately, detailed investigation of this concept has revealed several serious drawbacks that so far could not be solved in a way that would allow commercial 

Given the fact that IL research in general - and catalysis in ILs in particular - is a very young research field it is too early to conclude from the Ust in Table 6.14.4 whether IL based, liquid-liquid biphasic hydroformylation technologies will make their way into industrial practice. However, every new development that helps to overcome one of the weak points will help to make industrial success more likely. 

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