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Associate Professor JAENICKE, STEPHAN
B.Sc. (Vordiplom), 1973, University of Cologne; Dr rer. nat., 1981, University of Karlsruhe
Contact Information
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Department of Chemistry, NUS
3 Science Drive 3
Singapore 117543
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Office: S5-04-08
Tel: (65)-6516-2918
Fax: (65)-6779-1691
Email: chmsj@nus.edu.sg |
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Research Interests
Surface Chemistry and Catalysis
In the Surface Chemistry and Catalysis group, we address problems related to catalytic technologies and catalyst engineering. On a commercial scale, reactions are best conducted with heterogeneous catalyst systems because these offer advantages in catalyst-product separation after reaction. We explore novel methods to heterogenize catalysts, for example by dissolving the catalytically active species in an ionic liquid, which is itself immobilized as a thin film on a solid catalyst carrier.
Chiral Catalysis
Chiral compounds are at the center of the interest in the design of pharmacologically active molecules. We are evaluating several approaches to induce chirality:
- Homogeneous catalysts based on ligand-modified noble metals.
- Heterogenized systems, using chiral modifiers with a solid catalyst, or based on the principle of immobilizing or entrapping intrinsically homogeneous catalysts in a heterogeneous system.
- Enzymatic catalysis and whole cell fermentation. Enzymes are bio-catalysts which have evolved over millions of years to reach unrivalled selectivity and efficiency for chemical transformations. They are able to operate in aqueous systems. By harnessing the benefits of enzymes, it is frequently possible to save many steps spent on protecting and unprotecting functional sites in a conventional chemical synthesis. Enzymes usually act in concert with other enzymes in multi-step reactions. All these enzymes are produced on demand inside a viable cell. Use of whole cells as miniature bioreactors has therefore big advantages, and is frequently cost-effective compared with the use of isolated enzymes or chemical catalysts. However, the required fermentation technique poses its own challenges, which we address and overcome in our work.
Process Intensification
In another project, we study the improved mass transfer in gas-liquid-solid systems under Taylor flow conditions in micro-reactors or monolith reactors. In Taylor flow, the mass transfer coefficient can be increased by a factor 5 over that possible with conventional stirring, showing a big potential for process intensification. Another approach to process intensification is the use of phase transfer catalysts which accelerate reactions in biphasic systems, typically in two phase liquid-liquid systems.
Our group collaborates in these projects with Dr Th. Muller, TU Munich and Prof. Y. Sasson, Hebrew University of Jerusalem, Israel.
Representative Publications
 X. Wang, J.L.C. Lee, Y. Nie, S. Jaenicke. Evaluation of Multiphase Microreactors for the Direct Formation of Hydrogen Peroxide. Applied Catalysis A: General, (2007) in print.
Y.Z. Zhu, K.L. Fow, G.K. Chuah, S. Jaenicke. Dynamic Resolution of Secondary Alcohols Combining Enzyme-catalyzed Transesterification and Zeolite-catalyzed Racemization, Chem. Eur. J. 13 541-547 (2007).
N. Qafisheh, S. Mukhopahdyay. A.V. Joshi, Y. Sasson, G.K. Chuah, S. Jaenicke. Potassium Phosphate as a High Performance Solid Base in Phase Transfer Catalyzed Alkylation Reactions. Ind. Eng. Chem Res. (2007) in press.
K.L. Fow, S. Jaenicke, T.E. Muller and C. Sievers. Enhanced Enantioselectivity of Chiral Hydrogenation Catalysts after Immobilisation in Thin Films of Ionic Liquid. Journal of Molecular Catalysis A: Chemical, In Press, Available online 3 December 2006.
Y. Zhu, G.K. Chuah, S. Jaenicke. Selective Meerwein-Ponndorf-Verley reduction of a,b-unsaturated aldehydes over Zr-zeolite beta. J. Catalysis 241 25-33 (2006).
S. Jaenicke. Characterization of Heterogeneous Catalysts by Use of Model Reactions. Catalysis Surveys from Asia 9 173-185 (2005).
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