ABSTRACT
Unmodified vegetable oils can be used as fuel in combustion engines. However, their high viscosity leads to poor atomization in the combustion chamber, and hence to operational problems such as engine deposits. Various strategies exist to convert vegetable oils into fuels, including hydrogenation (Pinto et al., 2013). The approach of transforming the oil to simple alkyl esters in a transesterification reaction with alcohols such as methanol or ethanol was recognized at an early point (Knothe, 2005). The term biodiesel most often refers to such fatty acid alkyl esters. In fact, the biodiesel standards (DIN 51606, EN 14214, and ASTM D6751) require or indirectly specify that biodiesel should be fatty acid methyl esters (FAME).Biodiesel is produced by reacting vegetable oils, animal fats and/or free fatty acids (FFA) with the alcohol to yield the fatty acid alkyl esters (Fig. 12.1).
