Bifunctional Heterogeneous Catalysts for Biodiesel Production Using Low-Cost Feedstocks: A Future Perspective

Biodiesel can be produced using domestic resources like straight vegetable oil, animal fats, and waste cooking oil. Its use, instead of conventional diesel, contributes to the reduction of CO2 emissions. The production of biodiesel through transesterification (TE) reactions requires adequate catalysts to speed up the reactions. The classical methods of biodiesel production were conducted using homogeneous catalysts, which have drawbacks such as high flammability, toxicity, corrosion, byproducts like soap and glycerol, and a high wastewater output. Recently, various types of heterogeneous catalysts and continuous reactors have been invented for the production of biodiesel. As a result, the initial choice of catalysts is crucial. However, it is also affected by the amount of free fatty acids in a given sample of oil. In addition, most of the catalysts are not suitable for large-scale industrial applications due to their high cost. Bifunctional heterogeneous catalysts are widely applicable and have a rich history of facilitating energy-efficient, selective molecular transformations, and contributing to chemical manufacturing processes like biodiesel. This chapter underlines the use of bifunctional heterogeneous catalysts for biodiesel production using low-cost feedstock. Furthermore, it examines the sustainability of catalysts and low-cost feedstock for large-scale biodiesel production. Finally, the chapter indicates a further perspective of biodiesel as an alternative fuel using low-cost feedstock and recommends a sustainable bifunctional heterogeneous catalyst for biodiesel production.