Progress in Research of Brønsted Acid Ionic Liquid Catalysts for Synthesis of Biodiesel through Esterification of Fatty Acids

Abstract

Biodiesel has attracted considerable interest in recent years as an alternative, biodegradable and nonpolluting transportation fuel. Conventional alkaline process for biodiesel production are energy consuming and generate undesirable by-products such as soaps, that make difficult the separation and purification of biodiesel. Ionic liquids as environmentally benign chemical solvent, had been used in diverse chemical reactions. Especially, they could be applied in biodiesel production. Preparation of biodiesel catalyzed by ionic liquids have many merits, such as no corrosion to equipment, no pollution to environment, and reusability. Ionic liquids can improve the catalytic activity and they have wide utilization prospect in biodiesel preparation. In this paper, the advances in the Brønsted ionic liquids catalysts and their application in biodiesel production through esterification of fatty acids were reviewed. In addition, the prospect for the application of the ionic liquids to catalyze biodiesel production was also stated. Since the cost of ionic liquid may be an issue, there are some challenges to be faced, such as the production of ionic liquids with low cost, easy recovery and with the possibility of reutilization of the catalyst for several cycles.