Biodiesel Production Through3-in-1Process Of Extraction-transesterification-separation

With the aggravation of the petroleum crisis and environmental pollution in the word, more and more scientists had paid attention to biodiesel, i.e. an environmental friendly alternative fuel. Traditional process of biodiesel production was very complex. It contained extraction of raw oil, and recovery and separation of the catalyst after transesterification of oils with short-chain alcohols. The high cost of these steps restricted its use and commercialization. In this paper, in order to solve the above problems, production of biodiesel through3-in-1process of extraction, transesterification and separation was conducted, which provide some scientific guidances and technical supports for commercial production of biodieselFirstly, the transesterification reaction of soybean oil with methanol or ethanol using DBU as catalysts was studied. The preferable reaction conditions were determined as follows:10wt%DBU,7:1of molar ratio of methanol to oil,60℃of temperature, and2h of reaction time. The yield of biodiesel was99.01%. So DBU can be used as catalyst to produce biodiesel.Secondly, in situ extraction-transesterification reaction of Jatropha Curcas seed oil with methanol using DBU as catalyst was investigated and optimized. The preferable reaction conditions were determined as follows:the amount of DBU10wt%, weight ratio of methanol to oil6:1, reaction temperature60℃, and reaction time3h. The yield of biodiesel was98.96%. The extraction yield of Jatropha Curcas seed oil was99.13%. The characteristic of reverse switchable-polarity of DBU was used, in which DBU converts to an ionic liquid upon exposure to an atmosphere of carbon dioxide after the reaction, so that the solvent can be decanted from the oil. The preferable reaction conditions were determined as follows:the molar ratio of methanol to DBU2:1, reaction temperature25℃, and reaction time10min, the flow rate50mL/min. The conversion of DBU was99.79%. All of it could almost be decanted from the biodiesel. The oil&fat (triglycerides) was put into the phase of glycerine to make monoacylglycerols and diacylglycerols. The oil phase (monoacylglycerols and diacylglycerols) and DBU were separated using the previously method. The preferable conditions of the transesterification reaction of glycerine were determined as follows:molar ratio of triglycerides to glycerine3:1, reaction temperature40℃, and reaction time2h. TLC analysis proved that there was almost no residual glycerol after the reaction. Finally, the ionic liquid was converted to its non-ionic of DBU by bubbling N2using the characteristic of reverse switchable-polarity of DBU. And DBU was recovered and reused. The preferable reaction conditions were determined as follows:reaction temperature60℃, reaction time30min, and the flow rate of N250mL/min. The yield of DBU recovery was96.41%, which suggested that the catalyst was totally recovered. Then biodiesel was produced by the transesterification reaction of soybean oil with methanol using the recovered DBU as catalyst, and the yield was95.28%, The results showed that three steps of oil extraction, transesterification and separation could be made in one step in a system through using DBU. It could simplify the process of biodiesel production and reduce the cost of production.