In this work,biodiesel was obtained by the transesterification of jatropha oil with higher free fatty acids,using SO2-4/ TiO2-Al2O3 as a solid acid catalyst instead of traditional liquid acid and alkali catalysts.The effects of mixing speed,solid acid catalyst dosage,methanol/oil molar ratio,reaction temperature,co-solvent on the reaction were studied. The experimental results indicate that the solid acid catalyst of SO2-4/ TiO2-Al2O3 had a higher reactivity and stability on the transesterification of jatro...