Biodiesel Synthesis from Rapeseed Oil in the Presence of Sodium and Potassium Hydroxides

Abstract

Biodiesel is produced by methanolysis or ethanolysis
of triglycerides, and there are many factors affecting the
transesterification process. The most important variables of the
transesterification reaction are as follows: quality of the oil,
catalyst type, concentration of catalyst, molar ratio of alcohol to
oil, temperature and reaction time. The literature studies show
that there is not a generally accepted procedure for the
characterisation of transesterification reactions results and
catalyst formulation activity. Therefore, even the evaluation of
the usability of the most utilised industrial catalysts (sodium
hydroxide and potassium hydroxide) is inconsistent. The
experimental investigations of the transesterification reactions of
high quality rapeseed oil in the presence of the above mentioned
catalysts by change of all the variables allow us to regard two
different characteristics of each reaction (reaction yield and
process yield) that has to be determined. The comparison of these
two characteristics gives a new instrument for classification of
catalyst formulations. In the case of high quality rapeseed oil,
sodium hydroxide and potassium hydroxide have shown a similar
activity. Sodium hydroxide is more preferable when the
concentration area of the used catalysts is low, but potassium
hydroxide – at the high concentration area of catalysts.