Brönsted acid surfactant-combined dicationic ionic liquids as green catalysts for biodiesel synthesis from free fatty acids and alcohols

Quaternary ammonium Brönsted acid surfactant-combined dicationic ionic liquids (BASDILs) based on zwitterionic 1,2-bis[N-methyl-N-(3-sulfopropyl)-alkylammonium]ethane betaines and various anions were prepared and characterized. BASDILs possess properties similar to those of phase-separated catalysts and were applied to the catalytic synthesis of biodiesel from free fatty acids and alcohols. Several factors were investigated and the results indicated that [C12Sb][p-CH3C6H4SO3] was the optimal catalyst, with good catalytic performance and reusability under mild conditions.

Graphical AbstractBrönsted acid surfactant-combined dicationic ILs were synthesized and gave high activity for biodiesel synthesis from free fatty acids and alcohols. The structure of ILs influenced the activity.Figure optionsDownload full-size imageDownload as PowerPoint slide