Highly efficient synthesis of biodiesel catalyzed by CF3SO3H-functionalized ionic liquids: experimental design and study with response surface methodology

Five SO 3 H and CF 3 SO 3 H-functionalized ionic liquids (ILs) with different acidity were synthesized. The catalytic performances of various ILs were evaluated for producing biodiesel in the esterification reaction and the yield of biodiesel increased with the increase of ILs’ acid strength. [Bsmim]CF 3 SO 3 was found to be a highly-efficient catalyst for increasing the biodiesel yield due to its greatly enhanced Brønsted acidity, and it was also an environmental friendly solvent for its good recyclability and hydrophilicity. The experimental design and study were carried out by using the response surface methodology (RSM) for optimizing the production process. The optimum biodiesel yield of nearly 99% was achieved at the conditions that the catalyst amount of 11%, the molar ratio of methanol to oleic acid of 9:1, the reaction time of 3 h and the reaction temperature of 62 °C were used. In addition, the catalyst showed an excellent reusability.