Solid Acid Resin Amberlyst 45 as a Catalyst for the Transesterification of Vegetable Oil

Natalia Mariano Cabral; Juliana P Lorenti; Winfried Plass; Jean Marcel R Gallo

doi:10.3389/fchem.2020.00305

Solid Acid Resin Amberlyst 45 as a Catalyst for the Transesterification of Vegetable Oil

Front Chem. 2020 Apr 29:8:305. doi: 10.3389/fchem.2020.00305. eCollection 2020.

Authors

Natalia Mariano Cabral¹, Juliana P Lorenti¹, Winfried Plass², Jean Marcel R Gallo¹

Affiliations

¹ Group of Renewable Energy, Nanotechnology, and Catalysis (GreenCat), Department of Chemistry, Federal University of São Carlos, São Carlos, Brazil.
² Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Jena, Germany.

Abstract

Commercial transesterification of vegetable oil to biodiesel using alkaline hydroxides requires expensive refined vegetable oil and anhydrous alcohols to avoid saponification. These issues are not present in the acid-catalyzed process; however, the challenge still lies in developing stable and active solid acid catalysts. Herein, Amberlyst 45, a resin for high-temperature application, was efficiently used for biodiesel production by the methanolysis or ethanolysis of vegetable oil. Yields of up to 80 and 84% were obtained for the fatty acid methyl ester and the fatty acid ethyl ester, respectively. Two processes are proposed and showed to be efficient: (i) incremental addition of alcohol along with the reaction for both methanolysis and ethanolysis; or (ii) one-pot reaction for ethanolysis using oil/ethanol molar ratio of 1/18. The catalytic system used also showed to be compatible with used oil (2.48 ± 0.03 mg_NaOH ${g_{oil}}^{- 1}$ ) and to the presence of water (10-20 wt. % based on the alcohol), allowing the use of waste oil and hydrated alcohol.

Keywords: Amberlyst 45; acid catalysis; biodiesel; ethanolysis; transesterification.