蓖麻油酯交换法制备生物柴油的研究
蓖麻油酯交换法制备生物柴油的研究
摘 要
本文通过滴定共沉法制备Mg/Al水滑石，并以其作为催化剂，研究了以蓖麻油为原料、通过酯交换法制备生物柴油的工艺条件。对水滑石制备过程中的Mg/Al摩尔比、沉淀终点溶液pH值、晶化温度、晶化时间、焙烧温度、焙烧时间等条件进行了单因素考察，以研究不同制备条件下Mg/Al水滑石的活性。同时又研究了酯交换反应过程中催化剂的用量、醇油摩尔比、反应时间、反应温度、搅拌强度等条件对生物柴油转化率的影响，通过对这些条件的单因素考察，得到了最佳的工艺合成条件。通过实验考察不同的洗涤方法对最终产品游离甘油含量的影响，以便找出适宜的洗涤方法。
水滑石的最佳制备条件为：Mg/Al物质的量比3:1、沉淀pH值11.5、晶化温度80℃、晶化时间46h、焙烧温度500℃、焙烧时间6h。
蓖麻油酯交换的最佳反应条件：醇油摩尔比9:1、催化剂用量为蓖麻油重的1.2%、反应温度65℃、反应时间165min、搅拌强度6档。
本文以自制的水滑石为催化剂，用优化的酯交换反应条件制备生物柴油，所得到的生物柴油的转化率为88.6%。
关键词：生物柴油，酯交换，Mg/Al水滑石
Study on the production of biodiesel from castor oil by transesterification
Abstract
In this work, Mg/Al hydrotalcites were prepared by titration coprecipitation and used as catalyst in the preparation of biodiesel. The synthesis conditions had been studied with castor oil as raw material through transesterification. The single factors, such as Mg/Al molar ratio, end point pH, crystallization temperature, crystallization time, baking temperature and baking time were investigated so as to study the activity of Mg/Al hydrotalcites.
At the same time, the influences of single factors on the biodiesel conversion rate during transesterification, such as molar ratio of methanol to oil, amount of catalyst, reaction time, reaction temperature and stirring intensity were investigated and the optimum conditions were obtained. Different wash methods were inspected, with the aim of discovering suitable wash method.
The best preparation conditions of Mg/Al hydrotalcites were obtained as follows: Mg/Al molar ratio 3:1, end point pH 11.5, crystallization temperature 80℃, crystallization time 46h, the baking temperature 500, baking time 6h.
The best tansesterification of castor oil were as follows: amount of catalyst 1.2%, molar ratio of methanol to oil 9:1, reaction time 165min, reaction temperature 65 ℃, stirring intensity 6 level.
The conversion rate of biodiesel was 88.6% under optimized transesterification conditions with self-prepared Mg/Al hydrotalcites as catalyst.
Key words: biodiesel, tansesterification, Mg/Al hydrotalcites
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