| Summary: | 碩士 === 國立臺北科技大學 === 化學工程研究所 === 100 === The object of this study is to test the oxidation stability of biodiesels with various concentrations of metal contaminants including Cu, Mn, and Fe and evaluate the long time storage at ambient temperature. The oxidation stability of biodiesels was reduced with the addition of metal contaminants. The biodiesels include jatropha oil biodiesel, tung oil biodiesel, and jatropha oil biodiesel blending with diesel at various volumetric percentages. It was obvious that induction period (IP) was lower at high temperature or high concentration of metal contaminants. The IP obtained by EN 15751 was usually higher than that obtained by EN 14112. First-order reaction kinetics is adopted to invetigate the IP variation of the biodiesels. With higher concentration of metal contaminants, the decrase of IP and oxidation activation energy would approach to the constant. With higher blending ratio of diesel, the effect of metal contaminants on the decrease of activation energy becomes more remarkable. The IP predicted by the first-order reaction rate kinetics at 25 oC are 1.5-7.9 times than those predicted by the linear relationship between ln IP and T (oC). However, the IP of biodiesels in long time storage without aeration at ambient temperature is significantly longer than those predicted by first-order reaction rate kinetics and the linear relationship between ln IP and T. Furthermore, the increase time of acid value of tung oil and jatropha oil biodiesels contaminated with Cu would be close to those predicted by first-order reaction rate kinetics in long time storage under aeration condition. On the other hand, the increase time of acid value of original jatropha oil biodiesel is close to that predicted by the linear relationship between ln IP and T.
|
|---|
