Rhodium Catalysed Hydroformylation Using Supported Ionic Liquid Phase SILP Catalysis

3 Rhodium Catalysed Hydroformylation Using Supported Ionic Liquid Phase SILP) Catalysis 

The basic idea of immobilising a catalytically active solution on a solid support to obtain a solid catalyst with homogeneous type selectivity and efficiency is not new. In the late seventies, Scholten [69] and Hjortkjaer [70] described supported liquid phase 

To our knowledge, none of the developed SLP and SAP catalysts made their way into a technical process. Obviously, the possibility of using a supported liquid catalyst in a continuous liquid phase reaction is generally very restricted. The reason is that a very low solubility of the liquid in the feedstock/product mixture is enough to remove the catalyst from the surface over time (due to the very small amounts of liquid on the support). Even worse, the immobilised liquid film can be removed from the support physically by the mechanical forces of the continuous flow even in the case of complete immiscibility. 

Therefore, the most promising area of application for a supported liquid catalyst is a continuous gas phase process. In this context, the SILP concept offers very important advantages that make a reinvestigation of supported liquid catalysis with these unique liquids highly promising. 

Two ways of ionic liquid immobilisation have been applied so far a) the approach in which part of the ionic liquid phase is fixed to a support by chemical bonds between either the cation or the anion of the ionic liquid and the support and b) the impregnation approach in which physisorption fixes the ionic liquid onto the support. 

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