Production of Biodiesel from Soybean Oil Using a High-gravity Rotating Packed Bed

• Main Authors: Yu-hang Huang, 黃鈺航
• Other Authors: Yi-Hung Chen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/29735024608940261604

碩士 === 國立高雄應用科技大學 === 化學工程系碩士班 === 96 === This study investigates the new technology for the synthesis of biodiesel from the soybean oil with the high-gravity rotating packed bed (RPB). Biodiesel is used as alternative of diesel fuel because of its advantages in reducing the air pollution. However, the insoluble property of methanol in oil phase results in the slow reaction rate of transesterification. The biodiesel productivity in the continuous processes is usually limited due to the necessary retention time for the requirement of conversion degree. A RPB has been employed as the mass transfer device and micromixing reactor from 1980s. The flowing liquids in the RPB will form the thin liquid film on the packing materials due to the high centrifugal force. Here the RPB is applied as the transesterification reactor to transfer oil and methanol into biodiesel (Free acid methyl esters, FAME) and glycerol. The RPB, which provides high gravitational force by adjusting the rotational speed, is taken as a novel reactor owing to its high mixing efficiency. It has high potential to improve the biodiesel productivity or reduce the reactor volume by applying a RPB. The yield (YFAME) and productivity (PFAME) of fatty acid methyl esters are employed as the performance indexes of the biodiesel production. The effects of the operation conditions on the performance of the biodiesel production in the RPB system are examined. The value of YFAME significantly increases with the increase of temperature and catalyst dosage, while would be greatest at the certain values of the oil flow rate, rotating speed, and mole ratio of soybean to methanol. Furthermore, the highly potential of the RPB system for the continuous manufacture of biodiesel has been demonstrated in comparison of the results of YFAME and PFAME with the previous literatures. In the experimental conditions of the present work, the YFAME and PFAME can reach 96.3% and 0.695 mol/min, respectively. In the second part, the heterogeneous K2O/Al2O3 catalysts are prepared and packed in the circulating RPB reactor to proceed the transesterification reaction of the soybean oil. As a result, the time required to reach the equilibrium decreases with the increasing molar ratio of methanol to soybean oil from 6 to 24. The reaction rate of the transesterification increases with the packed amount of the K2O/Al2O3 catalysts from 59.2 to 118.4 g. However the amount of the K2O/Al2O3 catalysts increases to 177.6 g showing the slight enhancement on the transesterification conversion. On the other hand, the increase of temperature in the RPB reactor remarkably increases the transesterification rate. In the condition of molar ratio of the methanol to soybean oil of 24, reaction temperature of 60oC, catalyst amount of 177.6 g, rotating speed of 900 rpm, and circulating flow rate of 250 mL/min, the transesterification coversion can reach 96.4% at reaction time of 60 min.