Hierarchically Organized Metal Organic Catalysts f.. (HiCat)
Hierarchically Organized Metal Organic Catalysts for Continuous and Multi-batch Processes
Start date: Sep 1, 2008,
End date: Aug 31, 2011
Hierarchically organised metal organic catalysts shall be developed which can be easily recycled in multi-batch processes or which can be used in continuous processes without loosing the original advantages of the corresponding homogeneous soluble metal organic catalysts - high selectivity, activity and stability. The catalysts will be constructed using components at the nano-scale in a bottom-up approach. Hereby, catalytically active metal complexes will be linked with nanoparticles such as polymeric microgels, hyperbranched polymers or hybrid systems consisting of silsesquioxanes attached to hyperbranched polymers. Further hierarchical organisation of HiCat catalysts will be accomplished by interconnected networks formed from the assemblies of catalytic nanoparticles using end-functional T-responsive polymers that can interact with functionalities on the surface of the nanoparticles as binding agents. Recycling of the catalyst-nanoparticle entities in multi-batch operation will be studied utilizing the change of solubility of the polymer supported catalysts by external stimuli. Based on polymer-nanoparticles linked by T-responsive polymers, new types of films and membranes with graded porosity can be prepared by varying the size of the nanoparticles and the length of T-sensitive polymers. This opens new opportunities for integration of catalytic steps and separation within the hierarchically structured system and, hence for continuous reactor operation. The proposal combines the superiority of homogeneous metal-organic catalysts often possessing nearly 100 % selectivity with the advantage of efficient separation by grabbing a new concept for building up hierarchically organised catalytic systems. Structural principles of tailor-made ligands will be transferred into tailor-made functional surfaces of nanoparticles. For proof of principle of the concept, three types of reactions will be studied: olefin metathesis, CX coupling and enantioselective hydrogenation.
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