Immobilization of Homogeneous Hydroformylation Catalysts on Solid Surfaces by Covalent Anchoring

1 Immobilization of Homogeneous Hydroformylation Catalysts on Solid Surfaces by Covalent Anchoring 

An obvious way to combine the advantages of homogeneous and heterogeneous catalysis for optimized hydroformylation catalysis is to covalently anchor the molecular catalyst complex to a solid surface. Such an immobilized catalyst could be used in fixed bed or slurry type reactors and product separation would be as straightforward as for any heterogeneous catalyst. Indeed, this approach has been most widely studied as evidenced by numerous academic papers and patents, reviews, and books (Keim and Driessen-Hoelscher, 1999 and Reek et cd., 2006). 

Despite the obvious beauty of this approach and the enormous research work dedicated to its technical realization there is no example of a covalently surface bonded hydroformylation catalyst in industry so far. The main difficulty that has been encountered is unacceptably high metal leaching from the support, mainly due to unfavorable ligand-metal complexation equilibria. Therefore, the best results have been reported for bidentate, covalently anchored ligands, with Rh leaching in the range 100-1000 ppb. Other drawbacks of the approach in 

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New concepts are under intense academic and industrial development that allow facile product/catalyst separation (i) immobilization of homogeneous hydroformylation catalysts on solid surfaces by covalent anchoring ... 

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