The impact of heterogeneous catalyst on biodiesel production; a review

Energy is understood to be a fundamental requirement for humankind's daily existence. However, the researcher's interest has shifted to renewable energy sources in an effort to minimise the dependence on fossil fuels due to the continuously rising energy demand. Furthermore, the harmful effects of these fossil fuels on the ecosystem contribute to global warming. Biodiesels are the most practical form of green energy in that situation. The word bio stands for its natural origin, while diesel stands for its use as fuel, as the name implies. Traditionally, transesterification is used to create biodiesel. With the aid of a suitable heterogeneous or homogeneous catalyst, this reaction can take place, however amount of fatty acids it contains determines the best catalyst to use. Recently, heterogeneous catalysts have been preferred over homogenous catalysts as it can be reusable and can be easily separated. Moreover, homogeneous catalyst produces soap as a by-product and massive wastewater, further increasing allowable discharge costs. This paper reviews about biodiesel used as an alternative source of energy and its various prospects. This work reviews about the various heterogeneous catalyst and also analyses its effect on the thereafter biodiesel yield. This work also emphasis on the usage of waste or non-edible materials as a feedstock as it would help to lower the cost of production. This work reviews the advancements of heterogeneous catalysts in producing biodiesel. Various traits of heterogeneous catalysts (solid acid, solid-base, acid-base, and bio-catalyst) are also studied.