Recent advances of biodiesel production enhanced by external field via heterogeneous catalytic transesterification system

With the depletion of traditional fossil fuel and the increasingly severe problem of carbon emissions, the world urgently seeks alternative energy sources. Biodiesel, with its clean and renewable characteristics, has become an ideal alternative to fossil fuel. The "temperature difference driven heating-mechanical stirring-heterogeneous catalytic transesterification" process is supposed to be an ideal technology for biodiesel production, but there is a large resistance to heat and mass transfer in this way, which leads to slow catalytic reaction rate and low biodiesel yield. To solve this process, researchers have innovatively introduced external field-enhanced technologies such as microwave and ultrasound, aiming to enhance heat and mass transfer processes, optimize reaction conditions and significantly improve biodiesel yield. This article deeply analyzes the principles of heterogeneously catalyzed transesterification reaction enhanced by external fields and their positive effect on reaction kinetics and thermodynamics. Furthermore, the performance of external field-enhanced technologies is comprehensively analyzed in terms of techno-economic, environmental and bibliometric mapping. Finally, the future application of external field-enhanced technologies in biodiesel production is prospectively discussed.