Catalysts play a significant role in transesterification of vegetable oils. Currently, chemical and biological catalysts are being investigated, and both have their inherent merits and demerits. In large-scale applications, these catalysts are expected to be cost effective and environmentally friendly. If the catalyst is homogeneous in its physical form it is more effective than is the heterogeneous catalyst, but its separation from the mixture is a major issue. Some of the heterogeneous catalysts suffer leaching in harsh reaction conditions. Of late, nanocatalysts that demonstrate high efficiency are being studed. Nanoparticles are used in biological catalysts as solid carriers for lipase immobilization. Lipase immobilized on magnetic nanoparticles has proved to be a versatile biocatalyst for biodiesel production. This article reviews the role of various catalytic systems commonly used in the transesterification reaction of oils in biodiesel generation.

Due to the increasing awareness of the depletion of fossil fuel resources and environmental issues, biodiesel became more and more attractive in the recent years. Biodiesel production is a promising and important field of research because the relevance it gains from the rising petroleum price and its environmental advantages. This paper reviews the history and recent developments of Biodiesel, including the different types of biodiesel, the characteristics, processing and economics of Biodiesel industry. The application of biodiesel in automobile industry, the challenges of biodiesel industry development and the biodiesel policy are discussed as wel