Lipase-catalysed transesterification in ionic liquid/supercritical carbon dioxide biphasic systems using a recirculating enzymatic membrane reactor
Special Symposium - EPIC-1: European Process Intensification Conference - 1
EPIC-1: Poster Session (EPIC - Poster) - P1
Keywords: membrane reactor, ionic liquids, supercritical fluids, proccess integration, transesterification reactions
Lipase-catalysed transesterification in ionic liquid/supercritical carbon dioxide biphasic systems using a recirculating enzymatic membrane reactor
F. J. Hernández-Fernández*, A. P. de los Ríos, D. Gómez, F. Tomás-Alonso, M. Rubio and G. Víllora
Department of Chemical Engineering, Faculty of Chemistry, University of Murcia, P.O. Box 4021, Campus de Espinardo, E-30100, Murcia, Spain
E-mail: fjhernan@um.es
Supercritical carbon dioxide (scCO2) and room temperature ionic liquids (ILs) have recently been revealed as interesting clean alternatives to classical organic solvents [1] to be used in biocatalysis. Recent researches have demonstrated the possibility of carrying out integral green biocatalytic processes by combining these two different neoteric solvents [2]. The success of this biphasic system is based on the high solubility of the scCO2 in the RTIL phase, while the same RTIL shows non-detectable solubility in the scCO2 phase. Moreover, it was found that scCO2 can be used to extract organic substances from RTILs without any cross-contamination of the extract with the RTILs [3].
This work presents a synthetic biocatalytic process combining scCO2, ILs and membrane technology. The use of membrane reactors represent an attempt to integrate catalytic conversion, product separation and catalyst recovery into a single operation. Butyl propionate synthesis from vinyl propionate and 1-butanol catalyzed by Candida antarctica lipase B (CaLB) has been chosen as reaction model. Firstly, the synthetic activity of CaLB, covalently attached to a polymer layer previously adsorbed on a-alumina tubular membranes, in supercritical carbon dioxide, was tested into a tangential-flow reactor. According to the initial rates, a model based on the Ping Pong Bi-Bi mechanism with competitive alcohol inhibition was proposed.
Then, the immobilized enzyme was coated with three different RTILs (i) 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim+][PF6-]), (ii) 1-butyl-2,3-dimethyl imidazolium hexafluorophosphate ([bdimim+][PF6-]), (iii) 1-octyl-3-methylimidazolium hexafluorophosphate ([omim+][PF6-]) and (iv) 1-butyl-3–methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim+][NTf2-]), in order to study the influence of these media on both the activity and selectivity of CaLB. It was observed that when room temperature ionic liquid/supercritical carbon dioxide biphasic systems were used the selectivity showed an increase (reaching 99.5%) compared with supercritical carbon dioxide assayed in absence of ILs.
Acknowledgements:
This work was partially supported by the CICYT CTQ2005-09238/PPQ. The authors are thankful to Mr. R. Martínez from Novo España S.A. for the generous gift of enzymes.
References:
[1] S.V. Dzyuba, R.A. Bartsch, Angew. Chem. Int. Ed. 42 (2003), 148.
[2] F.J. Hernández, A.P. de los Ríos, D. Gómez, M. Rubio, G. Víllora. Appl. Catal. B: Environmental 67 (2006), 121.
[3] L. A. Blanchard, J. F. Brennecke, Ind. Eng. Chem. Res. 40 (2001) 287.
Presented Wednesday 19, 13:30 to 14:40, in session EPIC-1 Poster Session (EPIC - Poster) - P1.
