Properties of rapeseed oil fatty acid alkyl esters derived from different alcohols

Abstract

One of the ways to improve the cold flow properties of biodiesel is to derive it from other alcohols instead of methanol. In this research a three step synthesis of fatty acid alkyl esters (FAAE) in the presence of sulfuric acid was performed via transesterification of rapeseed oil using 11 different linear or branched alcohols (C1C6) – methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol, 2-methylbutan-1-ol, pentan-1-ol, 2,2-dimethylpropan-1-ol, 4-methylpentan-2-ol. Furthermore, a vacuum distillation was carried out to increase ester content over ⩾96.5wt.%. It was concluded that an increase of the length of FAAE hydrocarbon chain in alcohol moiety significantly helps to improve the cold flow properties of FAAE distillates. From linear alcohols the minimal values of (cold filter plugging point (CFPP) −17°C, cloud point (CP) −16°C and pour point (PP) −18°C were reached using FAAE derived from butan-1-ol. From branched alcohols the lowest CFPP −24°C, CP −28°C and PP −37°C were achieved by obtaining FAAE from 4-methylpentan-2-ol.