Transesterification of different vegetable oils to produce Biodiesel
Sustainable process-product development & green chemistry
Sustainable & Clean Technologies - IIa: Energy Production (T1-5a)
Keywords: biodiesel, vegetable oil, transesterification
Biodiesel, an alternative diesel fuel, is made from renewable biological sources such as vegetable oils and animal fats. Nowadays, most biodiesel is produced by the transesterification of triglycerides of refined/edible type oils using methanol and an alkaline catalyst. In the transesterification of vegetable oils, a triglyceride reacts with the alcohol, producing a mixture of fatty acids alkyl esters and glycerol. The overall process is a sequence of three consecutive and reversible reactions, in which di- and monoglycerides are formed as intermediates. The stoichiometric reaction requires 1 mol of a triglyceride and 3 mol of the alcohol. However, an excess of the alcohol is used to increase the yields of the alkyl esters and to allow its phase separation from the glycerol formed.
Often, the vegetable oils of choice for Biodiesel production are those which occur abundantly in the region of testing. In this work, several vegetable oils were tested so the influence of the raw material composition in the quality of biodiesel was studied. The used vegetable oils were: sunflower, soybean, rapeseed, palm, corn, peanut and grape seed oil. The transesterification process was carried out in a 500 ml spherical reactor provided with thermostat, a condensation system, and mechanical stirring. An alkaline catalyst (KOH) was used in the transesterification process. The reactor was immersed in a constant-temperature bath. Experimental conditions were as follows: reaction time, 1 h at atmospheric pressure; weight of catalyst, 1 % wt of initial oil weight; molar ratio methanol:oil, 6:1; reaction temperature 60 ºC and stirring rate, 600 rpm.
The following parameters: methyl ester, methyl ester of linolenic acid and methanol content, viscosity, acid value, flash point and oxidation stability, were used to characterize the biodiesel obtained. Also, the fatty acid content of vegetable oils was measured. In this work, the influence of the vegetable oils nature on the quality of biodiesel, according to standard EN 14214, was discussed.
Presented Wednesday 19, 16:15 to 16:30, in session Sustainable & Clean Technologies - IIa: Energy Production (T1-5a).
