Supported ionic liquid phase (SILP) catalysis

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In the last years, ionic liquids have attracted significant attention as an alternative reaction medium for transition metal homogeneous catalysis. Besides the engineering advantage of their non-volatile nature, the great potential to develop new liquid-liquid biphasic reaction systems has been demonstrated by many research groups. However, in some cases when the chemical kinetics are fast the reaction may take place at the surface or in the diffusion layer of the ionic liquid rather than in the bulk solvent. In these cases, the ordinary liquid-liquid biphasic catalysis may therefore not be the ideal way to realise a catalytic reaction with an ionic catalyst layer, since only a minor part of the - relatively expensive - ionic liquid and of the catalyst dissolved therein is effectively used in the reaction. In this project, the immobilisation of a thin layer of a neutral, weakly-coordinating ionic liquid containing an active transition metal catalyst on the surface of a porous support will be investigated. While the transition metal catalyst is coordinated by dissolved ligands, the ionic liquid is distributed by physisorption on the support. This concept will be evaluated for at least two continuous gas phase processes: The Rh-catalysed hydroformylation of olefins and the Ni-catalyzed oligomerization of ethylene. For both reactions the catalytic performance of the new "supported ionic liquid phase (SILP) catalysts" will be compared to results for liquid-liquid biphasic catalysis. Detailed spectroscopic investigations of the active catalytic species on the support and in model systems will be an integral part of our studies to understand differences in activity, selectivity and lifetime. The proposed project aims to create improved catalytic systems in bridging the traditional gap between homogeneous and heterogeneous catalysis in a new, exciting manner. Both groups involved will bring their complementary expertise into the joint project: The Erlangen group is well-known for its expertise in homogeneous catalysis using ionic liquids, while the Copenhagen group has a long experience in continuous supported liquid phase (SLP) and heterogeneous catalysis and catalyst characterization by spectroscopic methods. The collaboration between the groups creates a scientific synergy with a great potential for innovative and efficient research in this multidisciplinary field.