LAUSR

An alternative method for the biodiesel or fatty acid alkyl ester (FAAE) synthesis has been proposed—rapeseed oil interesterification with methyl formate. Reaction with methyl formate proceeds at a relatively low temperature (28 °C) instead of 55–65 °C necessary for triglyceride reactions with methanol and other monoesters. Similarly to transesterification with methanol, the product of the reaction with methyl formate consists of two layers. The main product the fatty acid methyl ester (FAME) is located in the top layer, but the process by-product formins forms the bottom layer. In this work, solutions of potassium alkoxides (methoxide, ethoxide, isopropoxide, tert-butoxide) in appropriate alcohols as homogeneous catalysts were used, adhering to the catalyst to oil molar ratio (COMR) 0.1 and methyl formate to oil molar ratio (MFOMR) 18. The FAAE content in the biodiesel layer in presence of all catalysts was 77–81 wt.%, which is lower than the level required by the EN14214 but significantly higher than the FAME content in reactions with methyl acetate under the same conditions. Fuel properties such as flash point, carbon residue, density, viscosity, and cold flow properties were investigated. For samples with MFOMR equal to or higher than 36 FAAE exceed 93% and the main characteristics of samples correspond to the EN14214 limits even without product purification.