Zinc Monoglycerolate as Highly Active and Reusable Catalyst in the Methyl Transesterification of Refined Soybean Oil

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Zinc Monoglycerolate as Highly Active and Reusable Catalyst in the Methyl Transesterification of Refined Soybean Oil Fa´bio da Silva Lisboa • Fabiano Rosa da Silva Luiz Pereira Ramos • Fernando Wypych



Received: 16 April 2013 / Accepted: 17 June 2013 Ó Springer Science+Business Media New York 2013

Abstract Layered zinc monoglycerolate was synthesized and investigated in the methyl transesterification of soybean oil. Conversions up to 98 % were obtained at 120 °C and after the fourth cycle of use under the same conditions, the solid preserved its structure, attesting the possibility to apply this material in industrial processes. Keywords Layered zinc monoglycerolates  Soybean oil  Methyl esters  Transesterification  Biodiesel

1 Introduction Recently many calcium derivatives have been investigated in a search for efficient catalysts for the transesterification of oils and fats to generate fatty acid alkyl esters [1–8]. Several compounds were found to be active like calcium oxide [1, 2], calcium ethoxide [3, 4], calcium binary oxides like titanates, zirconates and manganates [5] and more recently, calcium glycerolates also known as glyceroxides [6–9]. Beyond calcium, zinc compounds have been also frequently used in model reactions for biodiesel production, such as in the methyl esterification of lauric acid [10]. As recently reported for calcium [6–9] and also for zinc

compounds [10], the structure of these original compounds are not usually preserved during the reaction course. Especially for calcium oxide, the formation of catalytically active calcium glycerolates is still controversial but as glycerol is a co-product of transesterification, the coordination of the glycerol conjugated anion (glycerolate) with the metallic center is highly expected. Many other zinc compounds were also used in vegetable oil methyl transesterification, the most common are pure or doped oxides, pure or heat treated layered double hydroxides [11–15]. Zinc monoglycerolate, a potential product formed in situ in the transesterification of soybean oil can be synthesized by the coordination of glycerolate anions with zinc cations [16]. Zinc monoglycerolates have been utilized in pharmaceutical industries because of its non-toxicity and antiinflammatory activity [17] and very recently in the methyl transesterification of refined soybean oil [18]. Based on the previous data, we have investigated a detailed catalytic activity of zinc monoglycerolates in the methyl transesterification of refined soybean oil.

2 Experimental 2.1 Syntheses of Zinc Monoglycerolate

F. da Silva Lisboa  F. Wypych (&) Laborato´rio de Quı´mica de Materiais Avanc¸ados (LAQMA), Departamento de Quı´mica, Universidade Federal do Parana´, Caixa Postal 19081, Curitiba, PR 81531-980, Brazil e-mail: [email protected] F. R. da Silva  L. P. Ramos Centro de Pesquisa em Quı´mica Aplicada (CEPESQ), Departamento de Quı´mica, Universidade Federal do Parana´, Caixa Postal 19081, Curitiba, PR 81531-980, Brazil

Zinc monoglycerolate (ZnMG) was synthesized as recently reported [