Thermal stability evaluation of biodiesel derived from sunflower oil obtained through heterogeneous catalysis (KNO3/Al2O3) by thermogravimetry

Biofuel production is acquiring an important role as an energy alternative. Several research groups have proposed the use of heterogeneous catalysts in order to replace homogeneous catalysts. A new group of basic catalysts has been prepared with the aim of being used as heterogeneous catalysts in biodiesel production. The catalysts KNO 3 /Al 2 O 3 have been characterized and evaluated in the transesterification processes. They were characterized by X-ray diffraction and Scanning electron micrographs. The catalytic activity was evaluated in the transesterification of sunflower oil in biodiesel. The thermal stability of the biodiesel and the percentage of esters were evaluated. Through the TG curves, the samples of 2 and 4 % of KNO 3 /Al 2 O 3 have presented two mass loss and partial conversion of triglycerides in esters. Thus, the sample that contains 4 % KNO 3 /Al 2 O 3 has shown better catalytic activity in the transesterification reaction of sunflower oil, with a conversion rate of 60 % ethyl esters. On the other hand, the samples of 6 and 8 % of KNO 3 /Al 2 O 3 have revealed only mass loss.