The Factors Affecting the Rate of Preparation and the Content of Rapeseed Oil Methyl Esters by Using Sodium Methylate as a Catalyst
Kristaps Māliņš, Valdis Kampars, Jānis Brinks, Tatjana Rusakova, Zane Ābelniece

The most commonly used catalysts in the transesterification reaction for biodiesel production are alkali metal hydroxides or their alcoholates. The activity of alkali metal alcoholates in the transesterification process is higher than that of metal hydroxides of the same alkali. In addition, hydroxides form soap and water in reaction with the free fatty acids in vegetable oils, whereas alcoholates form soap and alcohol, which can further participate in the biodiesel formation reaction. The released water in case of hydroxide adversely affects the biodiesel extraction process by hydrolyzing the triglycerides. The study of the influence of concentration of triglyceride, alcohol and catalyst, as well as the temperature and the reaction time on the transesterification process and its optimization is a way to achieve the economic impact of biodiesel extraction. To determine suitable reaction conditions for the extraction of RME (rapeseed oil methyl esters) from rapeseed oil produced in Latvia, a series of experiments were conducted under conditions characteristic of industrial processes. It has been found that RME concentration in rapeseed oil layer is directly proportional to RME yield under experimental conditions at time interval to 180 minutes. Coherence is described by equation Y=1.00298×C-3.650 (r = 0.974), where Y – RME yield, but C – RME content in oil layer. By increasing molar ratio of methanol (from 3.2 to 7.0 moles against rapeseed oil), concentration of NaOCH3 (from 0.25 to 2.5 w% out of rapeseed oil) and reaction temperature (from 30 to 80 ºC), speed of equilibrium entrance and yield of RME increased approximately by 2, 11 and 3%, accordingly. For implementation of batch processes, the preferred reaction temperature is 40 – 50 ºC, the molar ratio of methanol/oil is 4/1 and the NaOCH3 concentration is 0.75%. However, when using continuous processes, the reaction would be more efficient at a higher temperature with lower quantities of catalyst and methanol.

rapeseed oil, methyl esters, transesterification, kinetics, ester content, optimization

Māliņš, K., Kampars, V., Brinks, J., Rusakova, T., Šustere, Z. The Factors Affecting the Rate of Preparation and the Content of Rapeseed Oil Methyl Esters by Using Sodium Methylate as a Catalyst. Materials Sciences and Applied Chemistry. Vol.25, 2012, pp.9-15. ISSN 1407-7353. e-ISSN 2255-8713.

Publication language
Latvian (lv)
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