ADVANCES IN BIODIESEL SYNTHESIS: THE ROLE OF VARIOUS CATALYSTS

Biodiesel is a renewable, clean-burning, and biodegradable fuel which can be synthesized from readily available domestic and natural sources, such as edible, non-edible and waste cooking oils, which may serve as a substitute to petro-diesel. It is produced by catalytic transesterification of fats and oils. A number of researches has been devoted to discovering a benign catalyst, especially heterogeneous acid catalyst that could convert non-edible and waste cooking oils with high free fatty acid into biodiesel, in an attempt to reduce the cost of production. The cost of production of biodiesel is still far higher than that of conventional petro-diesel, owing to the cost of edible oil currently being used, processes involved, and cost of conventional heterogeneous catalysts employed. This study assessed the role of various catalysts; homogeneous, heterogenous and enzyme-catalyzed transesterification reactions, in terms of their advantages and disadvantages in biodiesel production in order to establish very promising catalysts. Some methods of heterogeneous acid catalysts were also highlighted. Amongst the common heterogeneous catalyst, carbon-based solid acid catalysts were recommended as very promising solid acid catalyst that can utilize the non-edible oils in biodiesel production. The advantages of carbon-based solid acid catalysts include cheap readily available raw materials for their synthesis, easier production processes, relative stability, high reusability and potential for utilizing waste and nonedible oils for biodiesel production