Biodiesel Production by Ethanolysis of Various Vegetable Oils Using Calcium Ethoxide as a Solid Base Catalyst

What is it about?

In this study, fatty acid ethyl esters (FAEE) were produced from 4 different vegetable oils (sunflower, cotton seed, olive oil and used frying oil) using calcium ethoxide as a heterogeneous solid base catalyst. The ester preparation involved a two-step transesterification reaction, followed by purification. The effects of the mass ratio of catalyst to oil, the molar ratio of ethanol to oil, and the reaction temperature were studied on 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 transterification were an ethanol/oil molar ratio of 12:1, catalyst amount (3.5%), and 80 °C temperature, whereas the maximum yield of ethyl esters reached 80.5%. In the second stage, the yield of ethyl esters showed signs of improvement of 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. Property analysis of prepared ethyl ester samples was done, in order to examine their quality parameters. The results obtained showed that the density, viscosity and calorific value of the produced ethyl esters had values close to those of a no. 2 diesel. On the contrary, the cold filter plugging points were higher than the conventional diesel fuel.

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Why is it important?

In this study, ethanolysis of 4 different vegetable oils (sunflower, cotton seed, olive oil and used frying oil) using calcium ethoxide as heterogeneous catalyst was conducted, in order to characterize the ethyl esters obtained for their applications as fuels in internal combustion engines. The driving force for this study was that for one reason the reaction of ethanolysis for the production of biodiesel, has rarely been studied, especially in heterogeneous catalytic systems, compared to the intensive studies undertaken on the methanolysis reactions. The second and most important reason why this study was undertaken came about as a result of the European Renewable Energy Directive which bans biofuels with a GHG savings of less than 60% by 2018. One of the tools to improve the GHG savings from Biodiesel is to replace methanol with ethanol. Finally, a further reason that this study was conducted was the M/393 Mandate of the European Commission to European Committee for Standardization (CEN) for the development of a European Standard for Fatty Acid Ethyl Ester (FAEE) to be used as a fuel for diesel engines. To briefly outline what the mandate entails it should be noted that the European market is characterized by a significant and continuously growing demand for diesel fuel. Therefore the demand for diesel fuel type replacements is significant greater than that for gasoline. Bioethanol has been used in the European market mainly as ETBE (ethyl tert butyl ether) on the basis of the specifications of the Fuel Quality Directive 98/70/EC as it amended by the Directive 2009/30/EC. Although used in low blends (5%), as ETBE and E85, bioethanol still faces problems to penetrate the European market further.

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