Developments in the utilization of heterogeneous catalysts for biodiesel generation: An update on recent advancements

• The role of heterogeneous catalyst has been discussed with respect to efficiency of transesterification. • Nano catalyst plays an important role in transesterification due to increased surface area. • The reuse capability makes heterogeneous catalyst less costly. Biodiesel is one of the ecofriendly energy sources that can be generated from edible, non-edible, waste, and algae feedstocks. Over time, the utilization of different kinds of heterogeneous catalysts has been proven critical in the manufacture of biodiesel from diverse feedstocks. They exhibit better reusability and easier separation compared to the homogenous catalysts. In this work, the advances in the use of heterogeneous catalysts for biodiesel production from 2018 to 2024 have been evaluated. The process parameters like alcohol to oil molar ratio (M/O), catalyst concentration (%), reaction time and reaction temperature (RT), reusability of the catalyst, etc. are evaluated. The catalysts derived from waste materials through the calcination process are an efficient and cost-effective substitute for conventional catalysts. Nanomaterials, due to their small size and higher aspect ratio, provide very high efficiency and reusability in catalytic reactions. The heterogeneous catalysts are also found to be highly reusable for multiple cycles and the leaching of active sites, clogging of pore spaces of catalyst, etc. are the major causes of catalyst deactivation. Magnetic heterogeneous catalysts have shown good biodiesel yields and high reusability. Also, naturally occurring calcium oxide and potassium compounds present in waste derived catalysts helped to give high biodiesel yields. The future direction in the path of development of heterogeneous catalysts from cheap, abundant, and environmentally benign materials. The synthesis of heterogeneous catalysts from waste materials addresses the issue of waste disposal and converting solid waste to value-added catalysts. The life cycle assessment studies, encompassing heterogeneous catalyst synthesis, feedstock oil extraction, biodiesel production, and fuel combustion may give valuable input on the environmental impact of the entire process.