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| Dissertation / PhD Thesis/Book | PreJuSER-51182 |
2002
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/118
Report No.: Juel-4041
Abstract: Immobilisation of catalysts makes it possible to decouple the residence time of reactants and catalysts. That way, the total turnover number of the catalyst can be increased, the product specific catalyst costs can be reduced and the down stream process can be simplified. However, most common used immobilization methods like for example heterogenization techniques Buffer from diffusion limitations and low catalyst activities. Such difficulties can be overcome by the application of homogeneously soluble polymer-bound catalysts (Chemzymes) which can be retained by nano- and ultrafiltration, e.g. in a continuously operated membrane reactor. In this context, we investigated the reaction system for asymmetric transfer hydrogenation pictured below: [Abb.] We addressed the following tasks in the thesis: $\bullet$ Development of a 12-step convergent catalyst synthesis for the preparation of the polymer-bound transfer hydrogenation catalyst. $\bullet$ Kinetic investigation of the free and the polymer-bound catalyst. $\bullet$ Development of a random bi-bi-model including thermodynamic aspects allowing the prediction of yield and enantioselectivity of the catalyst. $\bullet$ Computer based optimisation of the process parameters regarding the total turnover number, space-time yield and enantioselectivity. $\bullet$ Performing of membrane reactor experiments based on the optimization and resulting in the production of (S)-phenylethanol with an enantiomeric excess up to 96 % and space-time yield up to 560 g/(L*d). Compared to the reaction systems mentioned above, the free catalyst increased the total turnover number by a factor of 48.
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