**2.4 Transesterification of vegetable oils**

In the transesterification of vegetable oils (see Fig.2), a triglyceride reacts with an alcohol in the presence of a strong acid or base, producing a mixture of fatty acids alkyl esters and glycerol (Wright et al., 1944 and Freedman, 1996). The stoichiometric reaction requires 1 mol of a triglyceride and 3 mol of the alcohol. However, an excess of the alcohol is used to increase the yields of the alkyl esters and to allow its phase separation from the glycerol formed. Several aspects, including the type of catalyst (alkaline or acid), alcohol/vegetable oil molar ratio, temperature, purity of the reactants (mainly water content) and free fatty acid content have an influence on the course of the transesterification (Schuchardta, 1998) based on the type of catalyst used.

Fig. 1. Basic transesterification process


#### Fig. 2. Transesterification of Vegetable Oils

The principal objective of this study is to produce quality biodiesel fuels using different oil feed stocks and test the performance and emissions of Diesel engine using different biodiesel fuel blends (B5, B10, B15 and B20). The combustion performance (torque and engine horsepoqer) and emissions (CO, CO2, HC's, and NOX) from the Diesel engine using a Bio-Diesel fuel blends and the conventional petroleum Diesel fuel will be compared.
