Chapter 9: A Novel Application of Chemically Modified Eleostearic Acid Methyl Ester (EAME) for Improving Diesel Lubricity^†

Ultra-low-sulfur diesel (ULSD) fuels require addition of higher concentrations of additives or blending with another material of enough lubricity, thereby increasing the cost. Herein, a tung oil-based fatty acid methyl ester (eleostearic acid methyl ester, EAME) and a maleation compound (EAME/MA) were synthesized by reacting with maleic anhydride (MA) via the Diels–Alder reaction. EAME/MA further reacts with short chain alcohols by opening cyclic anhydride to form esters such as methanol and butanol, i.e., EAME/MA/ME and EAME/MA/BU. The EAMA/MA/ME and EAME/MA/BU compounds effectively enhanced the lubricity of ULSD. For example, the lubricity of ULSD at low additive levels (500–1000 ppm) resulted in great improvement in the high-frequency reciprocating rig (HFRR) lubricity tests. By adding a low additive level of 500 ppm to the ULSD fuel, the wear scar and friction of ULSD were reduced by 40% and 46–47%, respectively. The additive concentrations were 20 and 40 times lower than blending biodiesel at 1–2%. Also, by blending EAME/MA/BU at a level of 1000 ppm into petrodiesels, such as 0150H GP1 and Durasyn 166 PAO base oils, wear scar values were reduced by 25% and 26%, respectively.