Transesterification of Vegetable Oils with Ethanol and Characterization of the Key Fuel Properties of Ethyl Esters
Transesterification of Vegetable Oils with Ethanol and Characterization of the Key Fuel Properties of Ethyl Esters
复制标题
植物油与乙醇的酯交换反应以及乙酯关键燃料特性的表征
DOI：
10.3390/en20200362
复制
发表时间：
2009
期刊：
影响因子：
3.2
通讯作者：
S. Kalligeros
中科院分区：
文献类型：
--
作者：
G. Anastopoulos;Y. Zannikou;S. Stournas;S. Kalligeros
以向日葵、菜籽油、橄榄油和煎炸废油为原料，在氢氧化钠催化下，与乙醇进行酯交换反应。酯的制备包括两步酯交换反应，然后进行纯化。考察了催化剂与油的质量比（0.25 ~ 1.5%）、乙醇与油的摩尔比（6：1 ~ 12：1）和反应温度（35 ~ 90 °C）对向日葵籽油转化率的影响，优化了两步反应的条件。其余的植物油在最佳反应参数下转化为乙酯。第一步酯交换反应的最佳条件为：醇油摩尔比为12：1，NaOH用量为1%wt/wt，反应温度为80 °C，而乙酯的最大产率为81.4%wt/wt。在第二步反应中，当催化剂浓度为0.75%，醇油摩尔比为6：1时，乙酯收率比第一步提高了16%。根据EN测试方法测量酯的燃料性质。基于实验结果，可以看出乙酯与甲酯没有显著差异。此外，结果表明，乙基酯的密度，粘度和高热值的值与汽车和重型发动机柴油的那些相似。然而，CFPP值较高，这可能导致冷启动的潜在困难。另一方面，从处理和储存的角度来看，闪点高于柴油的闪点，构成了安全保障。
The transesterification reactions of four different vegetable oils (sunflower, rapeseed, olive oil and used frying oil) with ethanol, using sodium hydroxide as catalyst, were studied. The ester preparation involved a two-step transesterification reaction, followed by purification. The effects of the mass ratio of catalyst to oil (0.25 – 1.5%), the molar ratio of ethanol to oil (6:1 – 12:1), and the reaction temperature (35 – 90 °C) were studied for the conversion of sunflower oil to optimize the reaction conditions in both stages. The rest of the vegetable oils were converted to ethyl esters under optimum reaction parameters. The optimal conditions for first stage transesterification were an ethanol/oil molar ratio of 12:1, NaOH amount (1% wt/wt), and 80 °C temperature, whereas the maximum yield of ethyl esters reached 81.4% wt/wt. In the second stage, the yield of ethyl esters was improved by 16% in relation with the one-stage transesterification, which was obtained under the following optimal conditions: catalyst concentration 0.75% and ethanol/oil molar ratio 6:1. The fuel properties of the esters were measured according to EN test methods. Based on the experimental results one can see that the ethyl esters do not differ significantly from methyl esters. Moreover, the results showed that the values of density, viscosity, and higher heating value of ethyl esters were similar to those of automotive and heavy duty engine diesel fuel. However, the CFPP values were higher, which may contribute to potential difficulties in cold starts. On the other hand, the flash points, which were higher than those of diesel fuel constituted a safety guarantee from the point of view of handling and storage.