Development and Stability Evaluation of a Heterogeneous Base Catalyst for Biodiesel Production

Fatty acid methyl ester (FAME, biodiesel) is gaining attention as a renewable alternative to conventional diesel fuel, with significant potential to reduce CO₂ emissions. However, current commercial FAME production predominantly relies on homogeneous base catalysts, such as sodium methoxide, which have notable limitations, including poor recyclability and significant wastewater generation. To address these challenges, this study focuses on the development and stability evaluation of a heterogeneous base catalyst for FAME production. The catalyst was prepared by loading sodium onto graphitic carbon nitride (GCN) synthesized from melamine and applied to the transesterification of triglycerides using soybean oil as a model feedstock. Catalyst stability, a key factor for commercial viability, was rigorously evaluated. The nitrogen groups in GCN effectively minimized sodium leaching, thereby enhancing stability. In batch reactor tests conducted at 120 ºC, the catalyst exhibited less than 10% activity loss after five reaction cycles. Bench-scale experiments in a continuous flow reactor further confirmed its durability, maintaining an average FAME yield of approximately 90% over at least 1,000 hours at 80 ºC. These results demonstrate the potential of heterogeneous catalysts to overcome the recyclability challenges associated with traditional homogeneous systems, providing a feasible pathway for commercial-scale FAME production.