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

► 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.