(184d) Supported Ionic Liquid Phase (SILP) Catalysts for Ambient Pressure and Low Temperature Water-Gas-Shift Reaction

Supported Ionic Liquid Phase (SILP) catalysts are new materials consisting of an ionic liquid, a metal catalyst and a porous support.[1] The catalyst is dissolved in the ionic liquid which itself is dispersed as a thin film on the inorganic support. This application combines both the advantages of homogeneous and heterogeneous catalysis and thus bridges the gap between traditional homogeneous and heterogeneous catalysis.[2] Especially continuous, gas-phase reactions are highly suited for this novel and innovative technology. An industrially important example is the water gas shift (WGS) reaction, by which hydrogen can be generated from carbon monoxide and water. Homogeneous WGS catalysts operate at milder temperatures than commercial heterogeneous systems. This can open new fields of applications such as distributed hydrogen production or fuel reforming. Since hydrogen production via WGS is an exothermic reaction, lower temperatures result in higher equilibrium conversions.[3] In this contribution we present investigations of homogeneous metal complexes active in the water gas shift reaction which have been immobilized by the SILP technique. In a first set of experiments known homogeneous systems and newly developed complexes were screened in a continuous rig at temperatures of 100 to 160°C and 1 to 10bar. The most active complexes were investigated in detailed kinetic studies including variation of reaction temperature, partial pressures of CO and H2O, residence time, variation of the ionic liquid, support and catalyst loading. The investigated SILP systems exhibit activities and stabilities exceeding those of homogenous systems reported in literature.[4] Even commercially available WGS catalysts are outperformed by the newly developed catalysts under the applied temperature conditions. The results indicate that SILP derived WGS catalysts may become a promising alternative to conventional heterogeneous systems, especially in distributed fuel cell setups or decentralized biogas applications.

References:

[1] Riisager, A.; Fehrmann, R.; Flicker, S.; van Hal, R.; Haumann, M.; Wasserscheid, P. Angew. Chem. Int. Ed. 2005, 44, 185.

[2] Riisager, A.; Fehrmann, R.; Haumann, M.; Wasserscheid, P. Eur. J. Inorg. Chem. 2006, 695.

[3] Laine, R.M.; Crawford, E.J.; J. Mol. Cat. 1988, 44, 357.

[4] Jacob, G.; Davis, B.H.; Catalysis, 2007, 20, 122?285.

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