| Biodiesel is a clean-burning substitute for petroleum-based diesel produced from virgin or waste vegetable oils and animal fats. One obstacle to the development of biodiesel is its high cost compared to petroleum diesel. Using waste frying oil instead of virgin oil can significantly reduce the high production cost. In our lab, promising preliminary results have indicated that transesterification of waste frying oil catalyzed by sulphuric acid has sufficient commercial feasibility to warrant further investigation.; In order to better understand the acid-catalyzed transesterification process and to optimize the process yield, an empirical study of the reaction kinetics was carried out. A mixture design for feed compositions at various temperatures was used to determine their effects on conversion rates and yields. Empirical models were built to describe the relationships of interest. Rate of mixing, feed composition and temperature were chosen as independent factors in this study. Intensity of mixing was found to have no significant effect on the yield over 100 rpm. The methanol to oil ratio and temperature were the most significant factors affecting the yield. Finally, a region of optimum operating conditions was determined from the models.; Analytical methods played an important role in our study. The extent of the reaction was followed off-line by gel permeation chromatography (GPC) and compared to results using an off-line infrared sensor based on attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The development, use and evaluation of the off-line method were discussed. The reproducibility of both methods was found to be excellent (≤1%); data obtained from both methods were found to be reliable. Finally, a comparison of the two methods showed good agreement (within 2%) in the monitoring of the transesterification reaction. |
