Preparation Of Biodiesel By Using Solid Base Catalyst

Today, with the development of industry and transportation, more and more diesel is consumed. So people have met the air pollution problem caused by the diesel combustion and the problem caused by the absence of petroleum. Therefore, it's imminent to find an alternative energy which is renewable and has more environmental benefits. Biodiesel is such a kind of fuel which is made from renewable vegetable oil and animal fat, and it can also reduce the air pollutant and the emission of CO2. Now biodiesel attracts the attention of many countries which dive into the research and preparation. Although the biodiesel's development of China has just begun, the potentiality is great. There are varieties of technologies for biodiesel's preparation, and some new technologies for biodiesel appear everyday.In this paper, KNO₃/Al₂O₃ solid base catalyst was first prepared. The results show that the catalyst loaded KN03(mass fraction) of 35% on Al₂O₃, after being calcined at 700℃for 5 h, is the optimum catalyst. The catalysts were characterized by means of FTIR, XRD, and Hammett titration methods. The Al-O-K formed on the surface of Al₂O₃ by KNO₃ dispersion, together with the K₂O decomposed by KNO₃ at high temperature, provided the active basic sites for the reaction. The influence of calcination temperature and loading amount of KNO₃ on transesterification were researched. In this paper, the factors of microwave exit power, reaction time, catalyst mass fraction and mole ratio of methanol to soybean oil were studied for the transesterification in the presence of microwave. The transesterification using NaOH and KNO₃/Al₂O₃ solid base catalyst in the presence of microwave were also optimized respectively. When the KNO₃/Al₂O₃ solid base catalyst was employed as the catalyst, the optimized reaction parameters were: microwave exit power of 360 W, reaction time of 35 min, catalyst mass fraction of 6% and mole ratio of methanol to soybean oil of 13. Under the optimized reaction conditions, the conversion of soybean oil can reach 97.5 %. Compared with the method of conventional heating methods, the way using microwave irradiation and solid base catalyst is proved to be faster together with lower energy consumption.The biodiesel prepared had reached the American standards of ASTMPS 121-99.