Study On The Synthesis Factors Of Biodiesel

As the increase of the demand for and the decrease of the storage fuel, biodiesel has been paid increasing attention as one of the alternative fuels. Presently, biodiesel is mainly produced by transesterification of vegetable oils or animal fats with methanol using H2SO4 or NaOH as a catalyst. Although this is a mature technology, there are some shortcomings in the traditional homogeneous catalyst system, including high quality of the material, emulsion formation during the reaction, which results in the difficulty in separation the products and pollution. Solid acid catalyst is currently the popular subject of research.We proposed a method for the production of biodiesel, by which the transesterification was carried out at a high temperature with segregative solid acid catalyst. In this way, pretreatments can be avoided and the catalysts can be easily recovered, as well as the decrease of pollution. Following this idea; experiments had been conducted using the transesterification of methanol and triglycerides as a model reaction at the aid of a series of solid acid. The results indicate that NaHSO₄·H₂O and AlCl3·6H2O are active catalysts. The purpose of this thesis is to examine the reaction properties of transesterification of vegetable oils and methanol by suing the above catalysts under sub critical condition.We compared a series of catalysts such as chloride (Al, Cu, Fe, Sn), NaHSO₄·H₂O and the mixture of NaHSO₄·H₂O and AlCl3·6H2O. The contents of biodiesel have been studied at various mole ratio of methanol to oil, the category and dosage of catalyst, temperature and reaction time by cupric glycerinate colorimetry. The products were analyzed by infrared spectroscopy, using orthogonal analysis of parameters in a four– factor and there– level test to optimize the experiment. Catalyzed by NaHSO₄·H₂O, the optimum conditions were obtained: reaction temperature 90℃, reaction time 12h, the molar ratio of methanol to oil 40:1 and the dosage of catalyst 6%. Esterification rate can reach 85% and their influencing parameters are temperature, reaction time, the molar ratio of methanol to oil and the dosage of catalyst in sequence. Catalyzed by NaHSO₄·H₂O and AlCl3·6H2O, the optimum conditions were obtained: reaction temperature 80℃, reaction time 9h, the molar ratio of methanol to oil 40:1, n(NaHSO₄·H₂O):n(AlCl3·6H2O)= 1.5:1 and the dosage of catalyst 5%. Esterification rate can reach 90%. In this thesis, the most active catalyst is the mixed catalyst NaHSO₄·H₂O and AlCl₃·6H₂O.