Abstract
Biodiesel was produced from waste frying oil (WFO) by transesterification with ethanol and methanol, using supercritical carbon dioxide, as a reaction medium, and a spinel-like zinc aluminate heterogeneous catalyst. The reaction runs were carried out for 2 h taking samples every 30 min, using alcohol: oil molar ratio of 40:1, temperature range of 100 – 200 °C, catalyst dosage of 1- 10 %wt, under 700 rpm stirring. The biodiesel products were analyzed by gas chromatography according to DIN EN 14105. The influence of reaction parameters, such as temperature; catalyst dosage and reaction time in supercritical CO2, on the biodiesel yield was discussed. The results showed high yields (>96.5 %) of biodiesel for both ethanol and methanol at 200 °C after 30 min of reaction, showing that the heterogeneous catalyst used contributed to increase in the biodiesel yield in a short reaction time.
