Influence of blending vegetable oil methyl esters on biodiesel fuel properties: Oxidative stability and cold flow properties

• Influence of the fatty acids structure on biodiesel properties was studied.
• Oxidative stability was correlated with polyunsaturated fatty acids content.
• CFPP (cold filter plugging point) resulted highly dependent on fatty acid chain length.
• Short chain fatty acids can enhance the cold flow performance of biodiesel.
• The commercial additive tested did not produce a significant reduction in CFPP.

Properties of biodiesel can be related to the chemical composition of the biomass source used in transesterification. Saturated fatty acids confer high oxidative stability, while unsaturated fatty acids improve the cold flow properties, which are also influenced by the chain length. In the present study, blends of biodiesel produced from different vegetable oils were evaluated in order to obtain the proper blend to fulfill the European Standard EN14214 in terms of oxidative stability and cold flow properties. Citric acid was used to purify the methyl ester phase. Oxidative stability resulted highly dependent on polyunsaturated fatty esters while fatty ester chain length is a determining factor in cold flow performance of the blends. A preliminary study of the effectiveness of a commercial additive (a Poly alkyl methacrylate) in improving methyl ester flow at low temperatures was done, but no significant changes were found.