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.
[1.a] Oxidation of Carbon Monoxide over Palladium on Zirconia Prepared from Amorphous Pd1Zr2 Alloy: I. Bulk Structural, Morphological and Catalytic Properties, A. Baiker, D. Gasser, J. Lenzner, A. Reller, and R. Schlögl, J. Catal., 126, 555 (1990).
Glassy Metals in Catalysis", by A. Baiker, in Topics in Applied Physics, Vol. 72, (Eds. H. Beck and H.J. Güntherodt), Springer Verlag, Berlin, Heidelberg, 1994, pp. 121-162.
[1.b] Preparation of Promoted Platinum Catalysts of Designed Geometry and Role of Promotors in the Liquid Phase Oxidation of 1-Methoxy-2-Propanol, T. Mallat, Z. Bodnar, A. Baiker, O. Greis, H. Strübig and A. Reller, J. Catal., 142, 237 (1993).
Oxidation of Alcohols on Platinum Metal Catalysts in the Aqueous Phase, T. Mallat and A. Baiker, Catal. Today, 19 , 247 (1994).
[1.c] A New Hydrosol of Gold Clusters. I. Formation and Particle Size Variation", D. G. Duff, A. Baiker and P.P. Edwards, Langmuir, 9, 2301(1993).
Preparation of Supported Gold Catalysts for Low Temperature CO Oxidation via Size-Controlled Gold Colloids, J. D. Grunwaldt, Ch. Kiener, C. Wögerbauer and A. Baiker, J. Catal., 181, 223 (1999).
[1.d] Monolayers and Double Layers of Vanadium Pentoxide on Different Carriers: Preparation, Characterization and Catalytic Activities, J. Kijenski, A. Baiker, M. Glinski, P. Dollenmeier and A. Wokaun, J. Catal., 101, 1 (1986).
Selective Catalytic Reduction of Nitric Oxide with Ammonia. Part 1: Monolayer and Multilayers of Vanadia Supported on Titania, A. Baiker, P. Dollenmeier, M. Glinski and A. Reller, Appl. Catal., 35, 351 (1987).
[1.e] Influence of the A-Site Cation in ACoO (A = La, Pr, Nd and Gd) Perovskite-Type Oxides on the Catalytic Activity for the Methane Combustion, A. Baiker, P.E. Marti, P. Keusch, E. Fritsch and A. Reller, J. Catal., 146, 268 (1994).
Methane Combustion over La0.8Sr0.2MnO3-x Supported on MAl2O4 (M = Mg, Ni and Co) Spinels, P.E. Marti, M. Maciejewski and A. Baiker, Appl. Catal. B: Environmental, 4, 225 (1994).
[1.f] Titania-Silica Mixed Oxides. I. Influence of Sol-Gel and Drying Conditions on Structural Properties, D. Dutoit, M. Schneider and A. Baiker, J. Catal., 153, 165 (1995).
Vanadia-Titania Aerogels. I. Preparation, Morphological Properties and Activity for the Selective Catalytic Reduction of Nitric Oxide by Ammonia, by M. Schneider, M. Maciejewski, S. Tschudin, A. Wokaun and A. Baiker, J. Catal., 149, 326 (1994).
[1.g] Progress in Asymmetric Heterogeneous Catalysis: Design of Novel Chirally Modified Platinum Metal Catalysts, A. Baiker, J. Mol. Catal. A: Chemical, 115 (3), 473 (1997).
Transition State Analogues – A Guide for the Rational Design of Enantioselective Heterogeneous Hydrogenation Catalysts", by A. Baiker, J. Mol. Catal. A: Chemical, 163, 203 (2000).
[1.h] Flame Aerosol Synthesis of Vanadia-Titania Nanoparticles: Stuctural and Catalytic Properties in the Selective Catalytic Reduction of NO by NH3, W. J. Stark, K. Wegner, S. E. Pratsinis, and A. Baiker, J. Catal., 197, 182 (2001)
Flame-made Pt/Ceria/Zirconia for Low-Temperature Oxygen Exchange, W. J. Stark, J-D. Grunwaldt, M. Maciejewski, S. E. Pratsinis, and A. Baiker, Chem. Mater., 17, 3352 (2005).