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978-3-8439-0314-1, Reihe Thermodynamik
Downstream processing in biphasic biocatalysis by means of scCO2
164 Seiten, Dissertation Technische Universität Dortmund (2011), Softcover, A5
The use of biocatalytic processes to replace common chemical pathways for the production of bulk and fine chemicals has gained considerable industrial interest over the last decades. Within several biocatalytic reactions shown to be of high interest, stereoselective epoxidations carried out in biphasic whole-cell biotransformations have been shown to be highly efficient and promising to produce apolar products on an industrial scale.
The use of a biphasic system, with whole-cells as the active biocatalyst, circumvents problems associated to low final product concentrations or co-factor addition formerly known to limit the industrial feasibility of biocatalytic processes. However these highly efficient reactions suffer from the formation of stable emulsions which cannot be processed efficiently using conventionally available unit operations such as centrifugation.
Based on previously gained results, the use of supercritical carbon dioxide for downstream processing purposes of these reactions is investigated and applied. Causes for the enhanced emulsion stability as well as the applicability of the concept of phase separation by supercritical carbon dioxide were determined and a mechanism leading to the complete phase separation by means of supercritical carbon dioxide is proposed. In order to further enhance product purification, a supercritical fluid extraction of the products where investigated. To enable a simulation of the complete downstream processing sequence by means of supercritical carbon dioxide, the phase behavior was simulated using the PC-SAFT equation of state. Based on the so defined pure component parameters different downstream processing alternatives were defined and simulated with Aspen Plus®. After a detailed optimization of all alternatives, as well as the analysis of the heat integration potential by the Pinch-point method, a detailed calculation of the total downstream processing cost for all alternatives is presented. Based on these results an efficient, cost – effective alternative is presented.