Estimating and improving cold filter plugging points by blending biodiesels with different fatty acid contents

Abstract

Biodiesels are alkyl esters produced by transesterification of higher fatty acids (aliphatic chains composed of 14 to 22 carbon units) from animal fats and/or vegetable oils. The cold filter plugging points (CFPP) of biodiesels are not only higher than that of petro-diesel, but they also differ from the melting point of the raw (unesterified) materials. In this study, we empirically derived equations that estimated the CFPP of a biodiesel based on its fatty acid content, using various biodiesel blends containing four methyl esters with different fatty acid compositions: soybean (SME), palm (PME), rapeseed (RME), and lard (LME). These blending ratio experiments yielded three equations that described the correlation between CFPP and fatty acid content: Y (CFPP, °C) = −3.1X (blending ratio) − 12.7 (PME/SME); Y = 2.2X − 10.7 (LME/SME); and Y = −4.0X − 13.0 (PME/RME). We also obtained the correlation between CFPP and total saturated fatty acid methyl ester content in the biodiesels: Y (CFPP, °C) = 0.449X (total saturated fatty acid methyl ester content, wt%) − 9.198. These empirical equations accurately predicted CFPP values of biodiesel compounds with known fatty acid compositions, facilitating the use of diverse biodiesels in industrial fields.