Biodiesel Production by Heterogeneous Catalysis and Eco-friendly Routes

Abstract

Biodiesel is produced on a large scale as an eco-friendly substitute and additive to fossil fuels. Catalytic homogeneous processes using strong acids, alkalis, and natural oils have been realized in industry. However, these traditional methods have several disadvantages, such as the generation of large volumes of waste, high water and reagent needs, use of hazardous reagents, high operation costs, and utilization of valuable feedstocks and catalysis, respectively. Different solutions have subsequently been investigated, such as cheap alternative feedstocks, co-solvents and catalysts, sustainable operational conditions, advanced reactor designs and scales, and advantageous pre- and post-reaction treatments. This review explores and analyzes the main aspects of current biodiesel technologies and opportunities. It also describes some advanced improvement strategies.