The Role of Catalysts in Biodiesel Production as Green Energy Applications: A Review of Developments and Prospects

The present review focuses on the transesterification reaction for biodiesel production as green energy applications with three types of catalysts (i.e., basic, acidic, and enzymatic), with the acidic and basic catalysts further subdivided into heterogeneous and homogeneous categories. Heterogeneous catalysts excel in terms of activity, selectivity, water durability and managing free fatty acids (FFAs). Under normal operating circumstances, base catalysts outperform the alternatives and create an adequate amount of product. However, raw materials with a high concentration of free FAAs cannot be used with these catalysts. The amount and strength of the acidic or basic sites determine how well the catalysts will perform under various conditions. Furthermore, this paper discusses the benefits of some heterogeneous catalysts, including mesoporous silica-based catalysts, that can be modified to function as either basic or acidic catalysts. Recent studies have shown that mesoporous silica can achieve excellent catalytic efficiency even under normal operating conditions. This article provides a comprehensive overview of the current state of the art of catalyst categories, discusses the difficulties inherent in the transesterification process, and gives technological options for implementing catalysis in a sustainable manner.