The process of making biodiesel is not very difficult. Biodiesel is made by mixing lye with methanol which causes the formation of methoxide. When methoxide and vegetable oil are mixed it creates glycerin and biodiesel. By separating the glycerin and biodiesel an alternative fuel is born.
The glycerin is not just a byproduct. It is useful, as well. Glycerin is a main ingredient in soap. So, the process of making biodiesel does not produce any harmful or useless byproducts such as traditional fuels do.
Chemically biodiesel is a mixture of methyl or ethyl ethers of fatty acids. The fats are the glycerin ethers of fatty acids. It is known that the molecules of fats consist of so called triglycerides: the connections of trivalent alcohol of glycerin with three fatty acids. Seven mass units of vegetable oil are added to one mass unit of methanol to receive the methyl ether. It is necessary to change glycerin to methanol in the glycerin ethers. This change (re-etherification) is carried out by means of the reaction between the fat and alcohol with the formation of methyl ether and precipitation of the dense glycerin that is insoluble in the methyl ether.
To receive a necessary speed of the reaction one may increase the temperature, add surplus alcohol and use the catalysts. Alkalis NAOH, KOH forming alcolates with alcohols, can be used as catalysts. The limited mutual solubility of alcohol and fat influences on the heterogeneous two-phase character of the reaction and significantly decreases the speed of the re-etherification process. This difficulty is easy to overcome by means of intensive mixing and dispersing. The quantity of the catalysts and the alcohol surplus are determined by the material characteristics and the results of the test reactions. The glycerin containing phase and ether phase received after the product separation needs to be cleaned from the unreacted alcohol and catalyst. The ether received has a high flammability provided with the high cetane number. If cetane number of a mineral fuel is 42-45, cetane number of biodisel is not less than 51. It causes the possibility of its application in the diesel engines without any other substances stimulating inflammation. Owing to this characteristic methyl ether was called biodiesel.