Study On Microwave Reactor And Its Application In The Preparation Of Biodiesel

Biodiesel attracts much attention at home and abroad due to its renewable, environmental protection and non-toxic characteristics.Transesterification by acid or alkali is the common method of producing biodiesel, but the product is difficult to be separate. While transesterification by solid acid or alkali will make it easier to separate but the heat transfer is slowed down in the reaction, which lead to lower production efficiency. Microwave heating can greatly improve the reaction rate, but so far most studies of microwave assisted preparation of biodiesel in laboratory scale. It is not successfully applied in industry scale..According to the problems above, this paper focus on the following researches:(1)The best preparation conditions for K2O/Al2O3solid catalyst was obtained by single factor experiment. First put the Al2O3powder in the muffle furnace under550℃for1h; Second dissolved KNO3in water and dip the Al2O3powder in it; Then dried it under110℃for12h; Last roasted them in the muffle furnace under700℃for4h.(2)Research on the characteristics of K2O/Al2O3solid catalyst:the current prepared solid base catalyst was characterized by scanning electron microscopy (SEM), X-ray power diffraction (XRD), thermogravimetric analysis (TGA).(3) A novel experimental intelligent microwave reactor was designed and fabricated for the biodiesel preparation. Microwave power can be adjusted steplessly, and a mode stirrer was employed to distribute the microwave. These made microwave irradiation uniformity. The biodiesel was prepared by use of microwave heating and solid catalyst of K2O/Al2O3. t The optimum conditions of biodiesel preparation was:methanol and soybean oil mole ratio (131), catalyst mass fraction (3.0%), reaction temperature (70℃), reaction time (20min), microwave power density (4.5W/g). Under these conditions the reversion rate of biodiesel could reach more than90%.The physical and chemical properties of raw oil and biodiesel were checked and the result indicated that itl meet the requirements of national standard of biodiesel except density.(4)The pilot scale microwave reactor was also designed and fabricated, which solved the microwave irradiation nonuniformity and material temperature non-uniformity problem. The devices was used for the experiment and good effects was achieved.Current solid alkali catalyst and microwave radiation is an alternative method for biodiesel production.