EVALUATION OF THE NA/NB2O5 SYSTEM IN THE TRANSESTERIFICATION OF SOYBEAN OIL FOR BIODIESEL PRODUCTION

Biodiesel is considered an important substitute of diesel oil. Traditionally, it is obtained by the transesterification of vegetable oils with methanol or ethanol, catalyzed by NaOH or KOH. Heterogeneous catalysts have been studied with the aim at facilitating and diminishing costs with purification stages. In the present work, the Na/Nb2O5 system was evaluated on the reaction of soybean oil with ethanol. It was verified, by DRX and IR, that the niobia calcined at 500ºC and impregnated with sodium underwent greater structural alterations than that treated at 300°C. These modifications allowed the generation of basic properties on niobia surface (Hammett and CO2 adsorption /IR). This catalyst showed the highest conversion (30%) among the used materials. The method chosen for evaluating the catalysts yield was the 1H NMR spectroscopy.