Biodiesel production by free fatty acid esterification using lanthanum (La3+) and HZSM-5 based catalysts

[Display omitted] ► Esterification of fatty acid was studied using lanthanum and HZSM-5 based catalyst. ► Sulfation process caused the formation of strong Brønsted acid sites in the catalysts. ► SLO/HZSM-5 had the lowest deactivation after the third reuse. ► Sulfated catalysts reached close to100% of conversion of oleic acid at 100°C. ► Sulfated catalysts are new eco-friendly catalyst for the esterification. In this work the use of the heterogeneous catalysts pure (LO) and sulfated (SLO) lanthanum oxide, pure HZSM-5 and SLO/HZSM-5 (HZSM-5 impregnated with sulfated lanthanum oxide (SO42−/La2O3)) was evaluated. The structural characterization of the materials (BET) showed that the sulfation process led to a reduction of the SLO and SLO/HZSM-5 surface area values. FTIR showed bands characteristic of the materials and, FTIR-pyridine indicated the presence of strong Brønsted sites on the sulfated material. In the catalytic tests the temperature was the parameter that most influenced the reactions. The best reaction conditions were: 10% catalyst, 100°C temperature and 1:5 mOA/mmeOH for LO, SLO, SLO/HZSM-5 and 10% catalyst, 100°C temperature and 1:20 mOA/mmeOH for HZSM-5. Under these conditions the conversions were: 67% and 96%, for LO and SLO, respectively and 80% and 100%, for HZSM-5 and SLO/HZSM-5, respectively. All catalysts deactivated after the first use, but the deactivation of SLO/HZSM-5 was smaller.