A comprehensive review of biomass-derived heterogeneous catalysts for efficient biodiesel production

The transesterification process for biodiesel production relies on efficient catalysts to accelerate the chemical reactions involved. Choosing the appropriate catalyst is crucial and depends primarily on the free fatty acid content of the oil feedstock. Conventional biodiesel production processes typically employ homogeneous catalysts, which present several disadvantage, including toxicity, high flammability, corrosiveness, and significant effluent generation. Consequently, there is growing interest in biomass-derived heterogeneous catalysts and bio-waste, as these offer sustainable, recyclable, and environmentally friendly alternatives. These catalysts exhibit excellent stability and catalytic efficiency in both acidic and basic environments, as well as superior water resistance. This review provides an in-depth analysis of biomass-based heterogeneous catalysts, emphasizing their potential for sustainable biodiesel production. The primary focus is on the usage of biomass and bio-waste-derived catalysts for producing cost-effective biodiesel. This review offers an overview of present methods for synthesizing various types of catalysts, such as basic, acidic, bifunctional, and nanocatalysts, using a range of feedstocks. Furthermore, it explores the impact of different catalyst preparation techniques on biodiesel yield and evaluates the sustainability of these catalysts. This study also identifies gaps in the present literature on biomass-derived heterogeneous catalysts and other biocatalysts, offering suggestions for future research avenues.