News & Press: Technical News

Continuous Catalyst-Free Esterification of Oleic Acid in Compressed Ethanol

Tuesday, January 6, 2015  
Posted by: Lee Gomez
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 Caroline Portilho Trentini,3 Lúcio Cardozo Filho,4 Edson Antonio da Silva,1
and Camila da Silva3,4 1 Program of Post-Graduation in Bioenergy,West Paran´a State University, Faculdade Street 645, Jardim La Salle, 85903-000 Toledo, PR, Brazil 2Department of Food Engineering, College of Animal Science and Food Engineering, University of S˜ao Paulo, R. Duque de Caxias Norte 225, 13635-900 Pirassununga, SP, Brazil 3 Department of Technology,Maring´a State University, Avenue Dr. ˆA ngeloMoreira da Fonseca 1800, 87506-370 Umuarama, PR, Brazil
4Department of Chemical Engineering, Maringa State University, Avenue Colombo 5790, 87020-900 Maringa, PR, Brazil Correspondence should be addressed to Camila da Silva; Received 5 October 2013; Revised 30 October 2013; Accepted 6 November 2013; Published 19 January 2014 Academic Editor: Dmitry Murzin Copyright © 2014 Ana Carolina de Araujo Abdala et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The esterification of oleic acid in a continuous catalyst-free process using compressed ethanol was investigated in the present study.
Experiments were performed in a tubular reactor and variables investigated were temperature, pressure, and oleic acid to ethanol molar ratio for different residence time. Results demonstrated that temperature, in the range of 473K to 573 K, and pressure had a positive effect on fatty acid ethyl esters (FAEE) production. In the experimental range investigated, high conversions can be obtained at low ethanol concentrations in the reaction medium and it was observed that oleic acid to ethanol molar ratios greater than 1 : 6 show no significant increase in conversion. Nonnegligible reaction conversions (>90%) were achieved at 573 K, 20MPa, oleic acid to ethanol molar ratio of 1 : 6, and 20 minutes of residence time. 1. Introduction Fatty acid, methyl or ethyl, esters can be usually obtained from free fatty acid (FFA) esterification reaction, through vegetable oils hydrolysis followed by the fatty acid esterification or from direct vegetable oils transesterification [1].The importance of examining the esterification reaction in amore detailed manner is justified by the huge amount and variety of vegetable oils worldwide available for biodiesel production which may have a high percentage of FFA making the conventional alkali-catalyzed transesterification
impracticable, since for this process the percentage of FFA needs to be less than 0.5% [2]. Recent studies propose to obtain esters in two reaction steps of substrates with high acidity, consisting of two approaches: (a) esterification of FFA and subsequent transesterification of triglycerides [3–5] or
(b) hydrolysis of triglycerides, followed by esterification of fatty acids obtained [6–8]. 

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