Assessment of niobium phosphate as heterogeneous catalyst in esterification with methyl acetate

Abstract

Abstract BACKGROUND The aim of this work was to investigate the esterification reaction from oleic acid with methyl acetate (MeA) catalyzed by niobium phosphate to produce methyl esters. This catalyst has an amorphous structure and large surface area. Catalytic tests were performed according to an experimental design. The results were analyzed statistically and all of the variables were significant, especially the temperature. RESULTS A kinetic study of the reaction was carried out and the most suitable reaction conditions were 240 °C, 10% (m/m) of catalyst and MeA: oleic acid molar ratio 10:1. After 2 h, it was possible to obtain ≈80% (m/m) methyl oleate content. A noncatalytic test corroborated niobium phosphate activity in the reaction. A kinetic model fitted experimental data for the catalyzed and noncatalyzed reactions; kinetics parameters for Arrhenius equation were estimated. In a reuse test, the catalyst showed a gradual decrease in catalytic activity over five reaction cycles. CONCLUSION Niobium phosphate can be considered as a promising heterogeneous catalyst for biodiesel synthesis. © 2019 Society of Chemical Industry