Japanese Standards for Diesel Fuel Containing 5% FAME: Investigation of Acid Generation in FAME Blended Diesel Fuels and Its Impact on Corrosion

The Agency of Natural Resources and Energy, Ministry of Economy, Trade and Industry has conducted conformity tests of diesel fuel containing Fatty Acid Methyl Ester (FAME) to amend diesel fuel standards in Japan. The objective of the tests is to examine appropriate specifications of diesel fuel containing FAME for automotive use for existing vehicles in the Japanese market. The conformity testing includes verification of fuel system component compatibility, tail pipe emissions, and characterization of the reliability and durability of the engine system, including the fuel injection system. In designing the conformity tests, the maximum FAME concentration was 5%. Most of the new standards are essentially equivalent to EN14214, but the total acid number (TAN) of specific acids, and oxidation stability of the new standards for diesel fuel containing FAME, are different from EN14214. Results found here showed that TAN should be 0.13 mgKOH/g or less, and total formic, acetic and proprionic acids should be 30 wt. ppm or less. Oxidation stability was defined in a new test method here as an increase in TAN of under 0.12 mgKOH/g after 16 hours of heat load at 115°C.