Chiang Mai Journal of Science

Biodiesel preparation from the esterification of oleic acid with methanol catalyzed by Brønsted acid ionic liquid [H_NMP]CH₃SO₃ was investigated, and the and the effects of the amount of catalyst, molar ratio of methanol to oleic acid, reaction time and temperature on the esterification reaction were examined. The maximum oleic acid conversion was obtained by using a Box-Behnken experimental design. It was found that optimum response for oleic acid conversion was 97.35%, which can be obtained using methanol/oleic acid molar ratio of 11.23:1, catalyst dosage of 10.48%, reaction time at 2.81 h and reaction temperature at 52.86 °C. Oleic acid conversion at optimum conditions using recycled [H_NMP]CH₃SO₃ displayed few loss in catalytic activity after five runs.