Study On The Preparation Of Biodiesel From Fried Oil With Supercritical Methanol

Biodiesel is a new kind of renewable energy resources. It is exploited recently and researched zealously by researchers both at home and abroad as the best candidate for diesel fuels.In this paper, biodiesel was prepared from fried oil (fried bean oil and fried salad oil) and methanol with supercritical transesterification reaction. The effects of the volume ratio of methanol to oil, reaction temperature and reaction time to the yield of glycerol during the transesterification reaction were investigated using simple factor experiment and orthogonal test. And then the optimal conditions for the transesterification reaction were obtained, which were 330℃, volume ratio of methanol to oil 25:5, 15min for the fried bean oil system and 350℃, volume ratio of methanol to oil 25:5, 15min for the fried salad oil system.The kinetics of transesterification with fried salad oil was investigated by analyzing the relationship between percent conversion of transesterification and reaction time, and the kinetic model was established finally. The results showed that reaction order was 2, activation energy was 52.46kJ/mol.The product of the transesterification reaction was detected by GC-MS and FTIR. The results showed that the constituents in the product were methyl ester with 12 carbon atoms to 24 carbon atoms, and the main constituents were methyl hexadecanoate and methyl linoleate.Some fuel performances of the biodiesel sample prepared from fried salad oil were test. The results showed that the volume heat value of this biodiesel sample was equivalent to that of 0# diesel oil, the kinematic viscosity of this sample was 6.38 mm2/s, density 0.899g/ml, higher completeness of combustion, acid value 0.51mgKOH per gram oil, total glycerol content 0.21wt%, sheet copper corrosion grade 1, and solidifying point at about 0℃.