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New heterogeneous catalyst for the esterification of fatty acid produced by surface aromatization/sulfonation of oilseed cake

2015; Elsevier BV; Volume: 150; Linguagem: Inglês

10.1016/j.fuel.2015.02.027

1873-7153

Eleonice Moreira Santos, Ana Paula C. Teixeira, Flávia Gontijo da Silva, Thérèse Cibaka, Maria H. Araújo, Willian X. C. Oliveira, Felipe Medeiros, Alex Nogueira Brasil, Leandro S. Oliveira, Rochel M. Lago,

Catalysis and Hydrodesulfurization Studies

In this work, an efficient heterogeneous acid catalyst for the esterification of oleic acid was prepared directly from oilseed cake by a simple sulfonation with concentrated H2SO4. Characterization by SEM/EDS, IR, Raman, TG, TG/MS, potentiometric titration showed that treatment with H2SO4 for 1, 2 and 4 h at 120 °C partially dehydrates the cake to form a carbon/cellulose composite which is sulfonated to produce strong SO3H acidic sites. These surface sites were active for the esterification of oleic acid with yields ca. 84%, 88% and 94% in the presence of 5, 10 and 20 wt% catalyst, respectively. These results are comparable to 98% yield obtained with 1 wt% H2SO4 and higher than 75% observed for a high surface area (880 m2 g−1) sulfonated activated carbon with similar number of SO3H active groups. These results are discussed in terms of two effects: (i) the number of sulfonic surface acidic groups and (ii) the presence of a hydrophilic cellulosic fraction in the catalyst that adsorbs/traps water formed in the reaction shifting the esterification equilibrium and improving the yield.