Production of Biodiesel via Simultaneous Esterification and Transesterification

Abstract

Biodiesel is considered as a substitute for fossil-based diesel fuels because of its renewability and environmental friendliness. Biodiesel is generally produced by transesterification of oils or esterification of free fatty acids with methanol. In these production procedures, basic and acidic catalysts enhance biodiesel yields under mild conditions. Particularly, heterogeneous acids promote simultaneous (trans)esterification in a single pot for biodiesel production (free of soap formation) from cheap raw materials containing high contents of free fatty acids, which cannot only avoid complex separation processes involved in pre-esterification, but also simplify catalyst separation and reuse, thus greatly reducing the cost. This chapter reviews the synthesis of biodiesel via simultaneous (trans)esterification catalyzed by mixed metal oxides, acidic ionic liquids, carbon-based solid acids, magnetic solid acids and hybrid solid acids. Advantages of heterogeneous catalytic reaction systems are discussed. Guidance is given on improving the performance of heterogeneous acid catalysts for production of biodiesel.