Méthode alternative de préparation des Esters d’Huile Végétale par voie enzymatique – BIOCARMAT

First we have prepared porous supports with specific and controlled properties for the enzyme immobilization. The enzyme is incorporated in the porous material by physisorption or chemisorption. The obtained systems are named supported biocatalyst or bioreactor. The obtained bioreactor are characterize by various techniques such as x-ray scattering, nitrogen adsorption-desorption analysis, infrared spectroscopy Afterwards, the different components required for the biodiesel synthesis are added to the bioreactor in order that the transesterification reaction takes place. This reaction is followed by gas chromatography coupled with a mass spectrometer. A mathematical method, named experimental design methodology has been used to limit the number of experiences required to optimize the synthesis conditions of the biodiesel synthesis.

This project has led to the development at the laboratory scale of a device allowing the synthesis of an alternative and renewable carburant, named biodiesel. The biodiesel is obtained by the methanolysis of the colza oil. The reaction is performed in bioreactor. Different devices have been tested and from the point of view of the reaction kinetic and on its reuse the bioreactor for which the enzyme is chemically linked to the porous support is the more promising.

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This project has led to the publications of two articles in journals, specialist in the biotechnology domain; two other papers are still in writing phase. Results have also been shared with others scientists during six international or national conferences.

The predicted shortage of fossil fuel encouraged the search for substitutes for petroleum derivatives. This search resulted in an alternative fuel called biodiesel. The most popular method of producing biodiesel is the transesterification, which refers to a catalyzed chemical reaction involving vegetable oil and an alcohol to yield fatty acid esters (i.e. biodiesel) and glycerol. Sodium and potassium hydroxides are commonly used as industrial catalysts, since they are relatively cheap and also very active. On the other hand, their utilization in vegetable oil transesterification produces soaps by neutralizing the free fatty acids in the oil and by triglyceride saponification. The soap formation is an undesirable side-reaction, because it partially consumes the catalyst, decreases the biodiesel yield and complicates the separation and purification steps. The removal of these catalysts is technically difficult and brings extra cost to the final product. The obtained biodiesel can be polluted by sodium or potassium. Moreover, the difficulty for recycling and the generation of large waste amounts make the traditional catalysts less favourable. Recently, enzymatic conversion by lipase of triglycerides has been suggested as a realistic alternative to the conventional process. In addition, the enzymatic transesterification of triglycerides offers an environmentally more attractive process than the conventional one. However, the high cost of enzymes often makes the enzymatic processes economically unattractive. Therefore, the reuse of lipase is essential from the economic point of view and the key step in enzymatic processes lies in successful immobilization of the enzyme which will allow its recovery and reuse. The aim of this proposal is to use both ordered mesoporous and hierarchical materials to immobilize the Mucor miehei recombinant lipase in order to develop at the laboratory scale new heterogeneous catalysts for the synthesis of biodiesel through the transesterification of vegetable oil by ethanol. The team is constituted of researchers from three laboratories of the molecular physic and chemistry Institute ''Jean Barriol'' :