The present study aims at evaluating the efficiency of the HZSM-5 zeolite dealuminated with citric acid and modified with sulfated lanthanum oxide (SO42−/La2O3) as catalysts for the production of biodiesel via esterification. The effects of the treatments in the structural, textural and acid properties of produced catalysts were monitored by PXRD, adsorption/desorption of N2 and measurements of acidity by FTIR using pyridine and collidine as probe molecules. The catalysts were tested in the reaction of esterification using oleic acid and methanol as reactants. Different molar ratios (1:10, 1:20 and 1:45) and amounts of catalyst (2%, 5% and 10%) were tested and the conversion of oleic acid into methyl oleate analysed. Results show that the dealumination with citric acid and impregnation of SO42−/La2O3 over HZSM-5 produced catalysts more active for the conversion of oleic acid for the production of biodiesel, when compared to the parent HZSM-5 zeolite. The increase of external surface properties (acidity and area) was the main parameter influencing the activity of the catalysts for the considered reaction.
Bibliographical noteThe authors thank CAPES for granting the scholarship, FAPEMIG and CNPq for financial support, Laboratório de Gestão de Resíduos Químicos (LGRQ/UFLA) for chromatographic analyses, Instituto Superior Técnico (IST, Lisbon) for materials characterization and Zeochem by HZSM-5 sample.
- Acid properties