Sustainable Production of Biodiesel Using Ion-Exchange Resin Catalysts

The characteristics of various oils used as raw materials for fatty acid methyl esters, a biodiesel fuel, are introduced. Vegetable oils are biosynthesized in the form of triglycerides, but once the oils are pressed, their hydrolysis to free fatty acids (FFAs) by lipase enzymes begins. As industrial biodiesel production employs homogeneous alkali-catalyzed transesterification of triglycerides, only oils with a low FFA content (typically, <1wt%) can be used to reduce soap by-products. Ion-exchange resins have traditionally been used as separation materials in water treatment. To date, many studies have been conducted using ion-exchange resins as catalysts for fatty acid ester synthesis. About 80% of these are related to cation-exchange resins, while 16% are related to anion-exchange resins. In this chapter, the authors summarize the findings of various studies on each resin type and discuss their advantages and problems as catalysts.