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Energy is an important material base of human society to exist and develop.With the dual increasing pressures of environment and energy, the development of renewable, environmente-friendly fuels to replace fossil fuels has become a world consensus. Biodiesel,for its good performance bring the huge potential and broad market prospects, becomes gradually the focus of attention.There are many methods for preparation of biodiesel, direct mixing method, micro-emulsion method, high-temperature thermal cracking method and transesterification. currently,The base catalyzed transesterification,for its mild reaction conditions, low cost of catalyst, fast reaction rate, and high conversion ratio, is one of more widely used methods in industrial.Ionic liquid is liquid under the room temperature or near room temperature (<150℃) and entirely composed of the anion and cation. As a new type of environment-friendly solvent and liquid catalyst, Ionic liquid has many unique advantages. Because of unique and excellent performance, it is considered to be one of the most promising green solvent and catalyst in the 21st century.It has been used in catalytic reaction, organic synthesis, separation science and electrochemical and other areas.In this paper, using a laboratory-made alkaline ionic liquid [Bmim] OH as catalyst for transesterification of rapeseed oil and ultrasound-assisted transesterification of rapeseed oil.The raw material characteristics of rapeseed oil,and rapeseed oil fatty acids and rapeseed biodiesel component analysis and other related study.Through a single factor and orthogonal tests, The author seriously study of many factors which are effect on transesterification, such as molar ratio between methanol to rapeseed oil, reaction temperature, reaction time and amount of ionic liquids, and the ionic liquid stability. The results showed that the optimum reaction conditions were:n(methanol):n(rapeseed oil)=16:1, reaction temperature150℃, reaction time 4h, dosage of catalyst 6% of rapeseed oil weight. Yield of biodiesel was 96.2%. The ionic liquid is stable and without decreasing,which repeatedly used for 5 times.Reaction kinetics studies have shown that the reaction order was 0.7075, the activation energy was 43.94 kJ/mol, preexponential factor was 96,056.32. The reaction kinetic model was.-(dcA)/(dt)=96056.32e-(43.93)/(RT)C A0.7075.Rapeseed biodiesel preparation under the ultrasound-assisted alkaline ionic liquid [Bmim] OH, we get the optimal reaction conditions were:ultrasonic frequency 59KHz, ultrasonic power 200W, reaction temperature 90℃, reaction time 1h, n (methanol):n (rapeseed oil)=16:1 and the amount of catalyst for the quality of rapeseed oil 6%. Under these conditions, biodiesel yield was 90.8%.The main component of rapeseed oil biodiesel is grease containing C18, its molecular structure meets the requirements of diesel substitute, is an ideal substitute for diesel oil. After measuring rapeseed oil biodiesel with UPLC, its main components were flax acid methyl ester, linoleic acid methyl ester, oil acid methyl ester, and mustard methyl.
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