Acid-Catalyzed Homogeneous Esterification Reaction for Biodiesel Production from Palm Fatty Acids
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Acid-Catalyzed Homogeneous Esterification Reaction for Biodiesel Production from Palm Fatty Acids Donato A. G. Aranda Æ Rafael T. P. Santos Æ Neyda C. O. Tapanes Æ Andre´ Luis Dantas Ramos Æ Octavio Auqusto C. Antunes
Received: 10 September 2007 / Accepted: 16 October 2007 / Published online: 1 November 2007 Ó Springer Science+Business Media, LLC 2007
Abstract This work deals with esterification of palm fatty acids to produce biodiesel in a batch reactor, using homogeneous acid catalysts, evaluating the effect of the alcohol used, presence of water, type and concentration of catalysts. Methanesulfonic and sulfuric acid were the best catalysts. Reaction with methanol showed greater yields. It was showed very clearly that the presence of water in the reaction medium showed a negative effect in the reaction velocity. Kinetic parameters were estimated and molecular modeling was performed. Protonation of the carboxylic moiety of the fatty acid were defined as rate determinant step for the reaction. Keywords Esterification Biodiesel Fatty acid Homogeneous catalysis
D. A. G. Aranda (&) R. T. P. Santos N. C. O. Tapanes Greentec, Laborato´rio de Tecnologias Verdes, Escola de Quı´mica, Universidade Federal do Rio de Janeiro—UFRJ, Centro de Tecnologia, Bloco E, Sala 211, Cidade Universita´ria, Ilha do Funda˜o, CEP 21945-970, Rio de Janeiro, RJ, Brazil e-mail: [email protected] A. L. D. Ramos LCAT/ITP, Laborato´rio de Cata´lise, Instituto de Tecnologia e Pesquisa, Av. Murilo Dantas, 300—Pre´dio do ITP, Farolaˆndia, CEP 49032-490, Aracaju, Sergipe, Brazil A. L. D. Ramos PEP/UNIT, Programa de Po´s-Graduac¸a˜o em Engenharia de Processos, Universidade Tiradentes, Av. Murilo Dantas, 300, Farolaˆndia, CEP 49032-490, Aracaju, Sergipe, Brazil O. A. C. Antunes Instituto de Quı´mica, Universidade Federal do Rio de Janeiro, CT Bloco A, Sala 641, Cidade Universita´ria, Ilha do Funda˜o, CEP 21949-900, Rio de Janeiro, RJ, Brazil
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1 Introduction Biodiesel is a fuel comprised of alkyl esters of long chain fatty acids [1]. It is an alternative to petroleum diesel for reducing emissions of gaseous pollutants such as CO, SOx, particulate matter and organic compounds [2, 3]. Considering that it is made from renewable resources, its production provides a mean to recycle CO2 [4, 5]. Its properties are similar to petroleum-based diesel, allowing its use either as a substitute for diesel fuel or more commonly in fuel blends [3, 6, 7]. Besides, this fuel has an important social impact in countries with agricultural vocation like Brazil, the fifth oil crops producer in the world, responsible for 8.2% of oil crops production in 2006 [8]. There are several routes to obtain biodiesel using oilseeds, edible oils, animal fats and waste oils and greases as feedstock. Transesterification of triglycerides with low molecular weight alcohols catalyzed by homogeneous catalysts is the most used one [9–13]. This route has some advantages, like low cost and mild reaction conditions. Since alkali-catalyzed transesterification is much faster—about 4,00
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