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Esterification of oleic acid over solid acid catalysts prepared from Amazon flint kaolin

2010; Elsevier BV; Volume: 101; Issue: 3-4 Linguagem: Inglês

10.1016/j.apcatb.2010.10.021

1873-3883

Luís Adriano Santos do Nascimento, Laura M.Z. Tito, Rômulo Simões Angélica, Carlos Emmerson Ferreira da Costa, José Roberto Zamian, Geraldo Narciso da Rocha Filho,

Layered Double Hydroxides Synthesis and Applications

The esterification of free fatty acids (FFA) can be used to produce biodiesel from high FFA oils. In this work, a new eco-friendly catalyst for the esterification of oleic acid with methanol has been prepared from a waste material, Amazon flint kaolin, that was thermally treated (at 850 and 950 °C) and activated with sulfuric acid solutions (1 M and 4 M). The activated metakaolin samples were characterized by X-ray diffraction, scanning electron microscopy, N2 adsorption–desorption and adsorption studies of pyridine using TG/DTG and FTIR analysis. The leached metakaolin treated at 950 °C and activated with 4 M sulfuric acid solution showed the highest surface area (406 m2/g), the highest number of acid sites (237.7 μmol/g) and offered the maximum esterification activity (98.9%) at 160 °C, an acid:methanol molar ratio of 1:60 and 4 h reaction time. The influences of reaction parameters such as the molar ratio of the reactants, alcohol chain length, temperature and time have also been investigated. Based on the catalytic results, Amazon flint kaolin is found to be a promising raw material for the production of new solid acid catalysts for the esterification of FFAs.