Biodiesel production. Comparison of several technologies

J.M. MARCHETTI

Handbook of Sustainable Energy

Novapublishers

Lugar: New York; Año: 2011; p. 467 - 485

Biofuel production has become one of the mayor research areas due to the need, by government decision and international agreements, of a reduction of carbon emission and the willing of being less dependent on fossil fuels. One of the mayor liquid renewable alternatives is biodiesel, defined by ASTM as the mono alkyl ester derivate from renewable lipid feedstock such as vegetable oils or animal fats. Being the mayor advantages that it is biodegradable, it has no CO or sulfur emissions, its produce a reduction in the CO2 emissions, prolongs the engines lives, etc. However, there are some disadvantages such as that it might increases the NOx emission and that could not be used in cold weather with out the supplement of additives since otherwise it might get frozen. Biodiesel is produced through the transesterification reaction of a triglyceride and an alcohol in the presence (not mandatory) of a catalyst. The regular alcohol employed is methanol due to its cost but ethanol it is a very often used alternative. The mayor vegetable oil used it is attach to the local production in order to have a cheap and sustain amount of raw material to carry on the reaction. The most common process employees a basic homogeneous catalyst, sodium or potassium hydroxide or their methoxide. This alternative is the simple’s one and the most studied so far; nevertheless, it has some disadvantages regarding the purity of the raw material that could be utilized. Other alternative catalysts, such as acid homogeneous ones (sulfuric acid) or heterogeneous ones such as solid resins, zeolites, support enzymes, monolithic catalysts or supercritical process are under research as well, in order to developed alternatives productions options.