This review focuses on the kinetics of several modes of immobilization of lipases, on the mechanisms of reactions of activation of immobilized lipases, and on the kinetics and mechanisms of reactions catalyzed by immobilized lipases. A comprehensive overview of the state of the art pertaining to structural features of lipases is provided as an aid to understand immobilization, interfacial activation, and catalytic performance. General rate expressions are duly derived; more frequent simplifying assumptions are stated and the results thereof listed. Physicochemical and statistical significance of parameters in rate expressions fitted to experimental data are also discussed whenever possible.
Integration of reaction and separation steps in processes involving lipases is currently undergoing fast progress because it provides a convenient way to alleviate limiting kinetic factors that are common in biological reactions, viz. decreased product inhibition, increased product solubility, shifted chemical equilibria, increased selectivity, and reduced number of downstream unit operations and process streams (with concomitant increases in the efficiency of separation). It is the aim of this work to briefly review the processes that have been developed to achieve integration of lipase-catalytic action with separation. These processes fall within one of the following categories: solid/liquid systems (e.g. membrane reactors for microencapsulated lipases in reversed micelles), solid/j&d systems (e.g. supercritical reaction/extraction processes). solid/liquid/uapour systems (e.g. reactive distillation), and solid/Lupour systems (e.g. evaporative esterification).
This paper reports experimental work pertaining to alcoholysis between butanol and ethyl butanoate, catalyzed by an immobilized lipase in a liquid-vapor system where chemical reaction and physical separation are simultaneously carried out. The processing setup was tested for various compositions of the starting feedstock and operated under reduced pressure. Samples were withdrawn both from the boiler and the condenser, and they were chromatographically assayed for butyl butyrate. The integrated configuration tested is quite effective toward improvement of the final yield of the desired product.
This paper reports experimental and modeling work concerning alcoholysis reactions between butanol and ethyl butanoate, catalyzed by Lipozymee in n-hexane, using a batch stirred system at 608C. Description of the reaction kinetics was based on a postulated multisubstrate Ping Pong Bi Bi mechanism, and appropriate rate expressions were derived for all components in the reaction medium. Simplified models were fitted by nonlinear multiresponse regression analysis to data (experimental or calculated from mass balances, as appropriate) encompassing the concentrations of free butanol, ethyl butanoate, ethanol and butyl butanoate. Finally, incremental F-tests were performed to assess the simplest model form that was able to provide a statistically good fit throughout the entire reaction time frame.
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