Department of Chemistry and Applied Biosciences

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Catalyst Design and Novel Catalytic Materials

The Baiker group has advanced the use of special techniques of solid state chemistry, particularly the application of molecular design concepts for developing novel catalytic materials. Several novel catalysts originated from this research. Baiker has pioneered the field of catalysis on glassy metals [1.a] by demonstrating how these amorphous materials can be beneficially used as model catalysts as well as precursors of highly active catalysts. Supported metal catalysts with unique structural and chemical properties were prepared from glassy metal alloys for various reactions. The Baiker group has developed useful methods for the controlled deposition of heavy metal atoms [1.b] on supported noble metal catalyst using underpotential deposition. The developed method provides a powerful tool for optimizing the active metal ensemble size and thereby the selectivity of supported metal catalysts. Efforts towards the synthesis of ultrafine metal particles [1.c] suitable for catalysis afforded an efficient chemical route to gold clusters with mean diameter 1.5 nm. The group has significantly contributed to the development of novel layer-type metal oxide catalysts prepared by selective grafting [1.d] of suitable metal organic precursors, from liquid and gas phases, onto functionalized support materials. Various novel xero- and aerogels [1.e], oxides, mixed oxides as well as metal/oxide systems with interesting catalytic potential have been synthesized and characterized. Basic studies using NMR and vibrational spectroscopy have provided new insight in the relationship between sol-gel and supercritical drying parameters and the structure of the resulting aerogels.

Perovskites [1.f] are another group of oxides investigated in Baiker's laboratory. Chiral heterogeneous catalysts [1.g] are in the focus of the group since several years. Systematic studies on the platinum-cinchona system used for the enantioselective hydrogenation of α-ketoesters have uncovered many important features of this complex catalytic system. The knowledge gained on the mechanism of enantio-differentiation has led to the exciting opportunities of utilizing molecularly engineered chiral modifiers and the originally narrow range of substrates which could be transformed enantioselectively on solid catalysts has greatly been extended. More recently, flame-derived catalytic materials [1.h] have been in the focus of the group. In cooperation with the group of S.E. Pratsinis a variety of flame-made materials with interesting catalytic properties were synthesized and structurally characterized, including mixed oxides, oxide-supported noble metals and hydroxyapatite.