What is it about?

The transesterification of tobacco seed oil and used frying oil to methyl esters biodiesel was studied using potassium bicarbonate loaded on alumina as heterogeneous catalyst. Reaction parameters such as catalyst concentration, methanol to oil ratio, reaction time, and agitation speed on the conversion of tobacco seed and used frying oil were investigated. The catalyst loaded KHCO3 of 30 % m/m on Al2O3, after being calcined at 700°C for 6 h, was found to be the optimum catalyst. The quality of the methyl esters was tested according to the European standard EN 14214. The two types of biodiesel produced seemed to meet all the parameters of the European standard except the oxidation stability. In the case of used frying oil biodiesel, not only the oxidation stability was not met, but this biodiesel did not also meet the acid value and water content specifications.

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Why is it important?

The heterogeneous catalysts that were developed in previous experimental studies could substitute those commonly used in industry for the transesterification of vegetable oils to biodiesel, most of them are activated in high pressures; whereas, they require high molar ratio of alcohol to oil, thus significantly increasing the production cost. Therefore, the solid base catalyst of potassium bicarbonate loaded on Al2O3 was synthesized and used for the production of biodiesel at atmospheric pressure so as to find an innovative catalyst for future use. The catalytic efficiency in methanolysis of tobacco seed oil and used frying oil was studied regarding the conversion of the oils to methyl esters.


The alumina loaded with potassium bicarbonate was demonstrated to be a strong solid base catalyst for the transesterification of vegetable oils with methanol. The catalyst with 30 % m/m KHCO3 loaded on Al2O3 and after calcinated at 700°C for 6 h was found to be the optimum catalyst, which can give the best catalytic activity. When the transesterification reactions of two vegetable oils were carried out at reflux of methanol, with a molar ratio of methanol to oil of 8:1, a reaction time of 2.5 h, a catalyst amount of 3 %, and an agitation speed of 600 r/min, the conversion of cottonseed oil was 97.1 %, while the conversion of used frying oil reached 96.6%. • The catalyst 30 % m/m KHCO3 /Al2O3 can be reused at least three times for the conversion of oils that have a small FFA and water content.

Associate Professor Stamatios S. Kalligeros
Hellenic Naval Academy

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This page is a summary of: Synthesis of Biodiesel from Tobacco and Waste Frying Oil Using Heterogeneous KHCO3/Al2O3 Catalyst, Journal of ASTM International, January 2010, ASTM International,
DOI: 10.1520/jai102574.
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