Biodiesel synthesis and bioreactor design – An overview

Abstract

Biodiesel, an alternate, renewable, environment-friendly engine fuel, is making significant contribution to the world energy demand, particularly in the light of the diminishing petroleum reserves. In this paper, biodiesel synthesis from different feedstocks and use of different types of catalysts (both homogeneous and heterogeneous) has been reviewed. These feedstocks have been compared with respect to availability (yield of oil per unit area of cultivation), ease and fastness of transesterification, yield and purity of produced biodiesel. The comparison between homogeneous and heterogeneous catalysts including enzyme catalysts and relative superiority of each have been analysed and highlighted with respect to catalyst activity, formation of uncontaminated product and cost of downstream processing. The design features of different types of industrial bioreactors such as fluidised bed, semifluidised bed, diverging–converging fluidised bed and inverse fluidised bed reactors have been surveyed. Recommendations for future investigations have also been presented in this paper.