from first principles PP-I-1

PP-V-6Supercritical Fluids as Solvents for Enzyme Catalyzed ReactionsKnez Z., Habulin M.University of Maribor, Faculty of Chem. and Chem. Engineering, Maribor, Sloveniazeljko.knez@uni-mb.siA “green” revolution as a part of necessary sustainable development, use also high pressure asa tool. The main impetus for this conversion is on one way driven by a concern to theenvironment to reduce the usage of solvents and energy and on the other hand high pressure isa tool to design and produce the products with completely new characteristics.Supercritical fluids and dense gasses are a unique class of non-aqueous media with manyfeatures (due to their physico-chemical properties) that make their use as a solvent forbiocatalysis and separation particularly desirable. The advantages of supercritical fluids assolvents fall into four general categories of benefits: environmental, process, chemical andhealth/safety. Other attractive features of supercritical fluids as solvents for biocatalyticprocesses include their high diffusivities, low toxicity and environmental impact; easedownstream processing and recyclability. Lipases have been used as versatile and veryefficient biocatalysts for a wide variety of chemical reactions such as esterifications,transesterification, interesterification and ester hydrolysis. Because of their high activity andselectivity they have a great potential for the use as biocatalysts in industrial applications.Lipases are endowed with exceptional substrate specificity. They can be employed in theproduction of pharmaceuticals, cosmetics, foods, medical diagnostics and other organicsynthetic materials. Application of high pressure lipase esterification technology is currentlymainly restricted to those operations where the cost of the product is high, but the enzymecost is relatively low in relation; i.e. this technology is applicable to high value finechemicals. Lipases may also be attractive in processes that involve thermolabilesubstrates/products or that may entail a number of side reactions and in processes where highenantio- and/or regio-selectivity is required. Another opportunity for applications is in aromaand flavours industries, such as foods or dairy perfumes; the production of various ingredientsby natural processes assumes great significance in this field. Using enzymes in high-pressurebatch system may cause changes in biocatalysts activity due to pressurization/depressurizationinfluence. Continuous reactors for SCFs have the advantage over batch reactors that they donot require depressurization to feed in the reactions or to recover the products.An overview of fundamental data, design of the processes, application of various types ofrectors, economics of the processes will be presented.315