Study of oxidation behavior of Jatropha oil methyl esters and Karanja oil methyl esters blends with EURO-IV high speed diesel

Poor oxidation stability of methyl esters is the major problem associated with its worldwide acceptance. As per the standards EN 14214 and prEN16091; and ASTM-D 7545-09 the oxidation stability limit should be 20 h for the blends and 8 h for neat methyl ester. One approach for increasing resistance of fatty acid methyl ester derivatives against autoxidation is to treat them with oxidation inhibitors known as antioxidants. This study examines the effectiveness of five such commercial antioxidants [viz. tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PrG) and pyrogallol (PY)] on the storage stability of Jatropha methyl ester (JOME), Karanja methyl ester (KOME), and their 5%, 10%, 20% and 40% blends with low sulphur EURO-IV High speed Diesel (HSD) using Petrotest PetrOxymeter. The impact of the antioxidants strongly depends on the feed-stock used for biodiesel production. PY was found to be the most effective antioxidant for JOME and its EURO-IV blends; however, PrG has shown maximum effectiveness with KOME and its EURO-IV HSD blends. 500 ppm was found to be the most optimum concentration for both the antioxidants.