Esterification of Oleic Acid for Biodiesel Production Catalyzed by SnCl 2: A Kinetic Investigation

Abiney L. Cardoso, Soraia Cristina Gonzaga Neves and Marcio J. Da Silva
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Abiney L. Cardoso: Departament of Chemistry, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil
Soraia Cristina Gonzaga Neves: Departament of Chemistry, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil
Marcio J. Da Silva: Departament of Chemistry, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil

Energies, 2008, vol. 1, issue 2, 1-14

Abstract: The production of biodiesel from low-cost raw materials which generally contain high amounts of free fatty acids (FFAs) is a valuable alternative that would make their production costs more competitive than petroleum-derived fuel. Currently, the production of biodiesel from this kind of raw materials comprises a two-stage process, which requires an initial acid-catalyzed esterification of the FFA, followed by a basecatalyzed transesterification of the triglycerides. Commonly, the acid H 2 SO 4 is the catalyst on the first step of this process. It must be said, however, that major drawbacks such as substantial reactor corrosion and the great generation of wastes, including the salts formed due to neutralization of the mineral acid, are negative and virtually unsurmountable aspects of this protocol. In this paper, tin(II) chloride dihydrate (SnCl 2 ·2H 2 O), an inexpensive Lewis acid, was evaluated as catalyst on the ethanolysis of oleic acid, which is the major component of several fat and vegetable oils feedstocks. Tin chloride efficiently promoted the conversion of oleic acid into ethyl oleate in ethanol solution and in soybean oil samples, under mild reaction conditions. The SnCl 2 catalyst was shown to be as active as the mineral acid H 2 SO 4 . Its use has relevant advantages in comparison to mineral acids catalysts, such as less corrosion of the reactors and as well as avoiding the unnecessary neutralization of products. Herein, the effect of the principal parameters of reaction on the yield and rate of ethyl oleate production has been investigated. Kinetic measurements revealed that the esterification of oleic acid catalyzed by SnCl 2 ·2H 2 O is first-order in relation to both FFAs and catalyst concentration. Experimentally, it was verified that the energy of activation of the esterification reaction of oleic acid catalyzed by SnCl 2 was very close those reported for H 2 SO 4 .

Keywords: Tin chloride catalyst; Biodiesel; free fatty acids; ethanolysis (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2008
References: View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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