Preparation Of Biodiesel By Esterification

Biodiesel, an alternative diesel fuel, is made from renewable biological sources such as vegetable oils and animals fats. Just like the cracking of heavy oil, high viscous and high molecular weight fatty acid glycerides can be cracked to be lower molecular weight FAME (fatty acid methyl ester) through the transesterification of oils or fats with short carbon chain alcohol (Alcoholysis), However, in this reaction system, methanol partly dissolved in oils or fats. So the reaction is controlled by a blending condition, besides proper catalyst selection and reaction temperature. Usually strong mechanical stirring was used to improve the reactants interface area to achieve a rapid conversion.One batch ultrasonic enhanced reactor was designed and the effects of ultrasonic energy on the transesterification of soybean oil with methanol to prepare biodiesel (BD) were investigated primarily. It was found that with the help of low frequency ultrasonic (100W) the reaction time was much shorter than that of conventional mechanical agitation. As a result, by using ultrasonic (19.7 kHz, 100W) the equilibrium time of transesterification reaction was greatly reduced. Compared to the transesterification of mechanical stirring, the reaction time was shortened from 60 minutes to 10 minutes and the reaction conversion was increased from 94% to 99% under the reaction condition of 35℃ water bath, 6:1 methanol-oil molar ratio and lwt% catalyst. It's implied that emulsification and reaction enhancement of ultrasonic outfield cooperated well on improving the transesterification reaction. Furthermore the power of ultrasonic is quite important to emulsify immiscible oil-methanol system according to its higher viscosity. It's not enough to mix the reaction liquids well by the irradiation of 30W ultrasonic in this experiment, which resulted less conversion efficiency.Two processes to produce biodiesel by chemical method are introduced. The domestic and overseas developments of economic feasibility evaluation of biodiesel production are reviewed. Primary factors influencing on the cost of biodiesel production, such as raw materials cost, process selection, glycerin price and production scale, are discussed. According to above economic analysis and the situation of China, Several reasonable advices on developing biodiesel industry of China are given. Running mode and economic feasibility of community based biodiesel production are also discussed.