Biodiesel synthesis in a solvent-free system by recombinant Rhizopus oryzae: comparative study between a stirred tank and a packed-bed batch reactor

Abstract

A simultaneous synthesis of biodiesel, as fatty acid methyl esters, and monoacylglycerols catalysed by the recombinant Rhizopus oryzae lipase immobilized by adsorption on Relizyme OD/403M is presented. The use of this 1(3)-positional specific lipase prevents the formation of glycerol as a by-product, thus avoiding its drawbacks. The synthesis was carried out in a solvent-free system and it has been studied in two different reactor systems: stirred tank and packed-bed reactor. Stirred tank reactor presented a high-initial reaction rate and achieved a 33.6% yield, which corresponds to a value of 50.4% of the maximum yield that can be achieved with a 1(3)-positional specific lipase. In packed-bed reactor there was a smaller initial reaction rate, but it was achieved a 49.1% yield, which corresponds to a 73.6% of the maximum yield. When a second batch is performed, the yield decreased only 4% when packed-bed reactor is employed whereas a drastic decrease is observed in a stirred tank operation. Therefore, packed-bed reactor showed a best performance and minor damage to the biocatalyst.

Keywords:

• Rhizopus oryzae lipase
• biodiesel
• transesterification
• packed-bed reactor

Acknowledgements

This work was supported by the project CTQ2013-42391-R of the Spanish Ministry of Economy and Competitiveness. The group is member of 2014-SGR-452 and the Reference Network in Biotechnology (XRB) (Generalitat de Catalunya).

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

This work was supported by the project CTQ2013-42391-R of the Spanish Ministry of Economy and Competitiveness. The group is member of 2014-SGR-452 and the Reference Network in Biotechnology (XRB) (Generalitat de Catalunya).