Transesterification of Soybean Oil to Biodiesel by Using Heterogeneous Basic Catalysts

Biodiesel production has increased greatly in recent years, because of the less-detrimental effects of this fuel on the environment, compared to a conventional diesel obtained from petroleum. This work investigates the possibility of using MgO and calcined hydrotalcites as catalysts for the transesterification of soybean oil with methanol. The achieved experimental data show a correlation not only with the catalysts basicity, but also with its structural texture. However, the structural texture of the examined catalysts is dependent on both the precursor and the preparation method. At least four different types of basic sites have been individuated on the surface of MgO and calcined hydrotalcite catalysts. The strongest basic sites (super-basic) promote the transesterification reaction also at very low temperature (100 °C), while the basic sites of medium strength require higher temperatures to promote the same reaction. Ultimately, all the tested catalysts are resistant to the presence of moisture in the reaction environment.