Lubricity additives for diesel by amidation of vegetable oils

Abstract

The influence of the addition of fatty acid amides and esters on the lubrication properties of base diesel fuels is studied in this work. Nine fatty acid amides could be prepared by amidation of three vegetable oils such as coconut oil, palm oil, and rice bran oil with primary amines such as ethylamine, butylamine, and hexylamine. This method of preparation gave about 75-86% yield of products. Nine fatty acid esters were prepared from transesterification of vegetable oils with various alcohols such as ethanol, 1-butanol, and 1-hexanol in the presence of sulfuric acid, giving about 90-97% yield of products. Their structures were identified by FT-IR, MS, [superscript 1]H-, and [superscript 13]C-NMR. The synthesized lubricity additives were blended with base diesel fuel, and then were investigated the lubricity performances using High Frequency Reciprocating Rig machine. All samples at concentration of 0.2% by weight could provide satisfactory mean wear scar diameter of less than 460 micrometre. Considering the performances of fatty acid amides series, rice bran oil ethylamide was the best lubricity additive for diesel fuel, because it resulted in the lowest wear scar diameter value. For fatty acid esters series, rice bran oil hexyl ester were the best lubricity additive for diesel fuel. Moreover, all additives did not alter the physical properties of base diesel fuel.