【作者】 岳鹍；

【导师】 王兴国；

【作者基本信息】 江南大学 ， 粮食、油脂及植物蛋白工程， 2006， 硕士

【摘要】 酯交换合成生物柴油过程中,醇油混合物呈两相而不互溶,反应速率较慢,通过添加惰性共溶剂可使油/甲醇体系均相化,大幅提高反应速率,促进反应产率的提高。本文以废煎炸油为研究对象,通过均相酯交换法合成生物柴油,并对处理过程、转化机理以及反应动力学进行了研究。本文利用精炼菜籽油、大豆毛油及废煎炸油,与四氢呋喃和乙醚在常压20℃下进行溶解度实验,绘制了油/甲醇/醚的三元体系相图。在此基础上,对油脂脂肪酸组成、游离脂肪酸含量、醇油比和体系温度对形成油/甲醇/醚均相体系所需共溶剂添加量的影响进行研究,结果表明短碳链脂肪酸含量的增加、游离脂肪酸含量的增加及体系温度的升高都有利于降低形成均相体系所需共溶剂的加量。本文研究了合成工艺对生物柴油合成产率的影响,结果表明以四氢呋喃为共溶剂,使醇油两相互溶有助于反应速率的加快。影响均相酯交换合成工艺的主要因素有醇油比、催化剂加量、反应温度和反应时间。在单因素实验的基础上利用正交回归设计进行优化,确定均相合成工艺的最佳条件为:反应温度64℃、催化剂H2SO4用量3.95%、反应时间3.3h,在此条件下酯化反应产率可达98.1%。酯化动力学研究表明,均相酯交换反应在甲醇过量的情况下,呈拟一级反应,其宏观反应速率速率方程为:d[TG]/dt =-K1[TG],反应活化能Ea为55.83kJ/mol。相同条件下非均相反应宏观反应速率方程为:d[TG]/dt = -K1α/(1+ζ1Rv)[TG]。醇油两相溶解度低是造成非均相酯化反应速率慢的重要原因。更多还原

【Abstract】 Because triglycerides and alcohols are not totally miscible, the transesterification can occur only in the interfacial region and it is a very slow process. By adding cosolvent to effect formation of the single phase, the transesterification is rapid and proceeds essentially to completion. In this work, by homogeneous transesterification the waste frying oil of daily life was transformed to the substitute fuel - biodiesel. A kinetic model of conversion process of waste frying oil was established based on the studying of the process, transforming mechanism and the reacting kinetics.Several ternary phase diagrams comprising vegetable oils, methanol and ethers are obtained at ordinary pressure. The shorter chain length of the composing FFA ,the higher content of FFA and higher temperature of the ternary system could reduce the quantity of cosolvent , which is needed to achieve single phase.The transesterification in homogeneous phase to form methyl esters and glycerin are much faster than the traditional transesterification. The effects of reaction condition to the biodiesel yields are also discussed. The main factors affecting transesterification are the molar ratio of oil to alcohol, catalyst, reaction temperature and reaction time. By single factor test, a response surface analysis is designed to determine the optimum parameter of the transesterification. It was determined as follows: reaction temperature 64℃, the addition level of catalyst H2SO4 3.95%, reaction time 3.3h. In the condition, the fatty acids methyl ester yield was 98.1%.When putting excessive methanol, the transesterification presented for pseudo-first-order reaction, the reaction equation was d[TG]/dt =-K1[TG], and the activation energy was 55.83 kJ/mol on the study of transforming mechanism and the reacting kinetics. In the same condition, the traditional transesterification equation was d[TG]/dt = -K1α/(1+ζ1 Rv)[TG]. The immiscible of triglycerides and alcohols is the most important reason for the slowness of the traditional transesterification.更多还原