DOI: https://doi.org/10.55373/mjchem.v28i4.184

Keywords: Lignin, magnetic acid catalysts, hydrothermal, esterification, Box-Behnken

Abstract

Two magnetic carbonaceous solid acid catalysts, commercial lignin-SO₃H@Fe₃O₄ and EFB lignin-SO₃H@Fe₃O₄, were prepared from commercial lignin and oil palm empty fruit bunch (EFB)-derived lignin, respectively, by simply hydrothermal carbonisation, calcination and sulfuric acid sulfonation steps. The catalysts exhibited high acid density (up to 2.40 mmol/g, including 2.21 mmol -SO₃H/g) and good performance in the esterification of oleic acid with methanol. High esterification rates of 82.6% and 95.6% were achieved at 60 oC within 2 h over EFB lignin-SO₃H@Fe₃O₄ and commercial lignin-SO₃H@Fe₃O₄, respectively, while the catalysts could be reused for at least five times. The catalyst preparation and esterification parameters were optimised by single-factor and Box-Behnken methodologies, respectively. The deacidification of Calophyllum inophyllum oil over EFB lignin-SO₃H@Fe₃O₄ was examined. The results of this study demonstrated the feasibility of utilising biomass-derived lignin for the production of magnetic solid acid, which can be used as a green, effective, and practical heterogeneous catalyst in biodiesel production.