Abstract

Biodiesel production through heterogeneous catalyzed reaction has emerged as a preferred route as it is environmentally friendly, needs no water washing, product separation is much easier, hence reducing process stages. This review has discussed the advancement in research and development related with heterogeneous catalysts used for biodiesel production. The heterogeneous base catalysts have shown to be effective for biodiesel production, although have the limitation of being sensitive to high free fatty acid feedstocks and water content of feedstocks. Solid acid catalysts are capable of esterifying high free fatty acid feedstocks with the presence of acid catalytic active sites. However, heterogeneous acid-base (bifunctional) and strong solid acids catalysts are potential catalysts for biodiesel production as they show the ability to simultaneously catalyze esterification and transesterification reactions. Solid catalysts with presence of acid and base catalytic sites prove to be the best for production and the use of nanocatalyst is also encourage as it will boost the catalyst properties which is responsible for high yield of biodiesel. Furthermore, this review will help in the selection of suitable catalysts and optimum conditions for biodiesel production