Compatibility of metals and elastomers with ethyl butyrate and methyl butyrate blended gasoline

Abstract

Ethanol and methyl tertiary butyl ether (MTBE) are widely being used as octane number improver for gasoline fuel in the world. However, it is well known that they might cause corrosion of auto parts and phase separation from gasoline by water contamination owing to their high water solubility. Accordingly, many studies on ester type oxygenates with very low water solubility are being carried out to resolve the problems. This study aims at investigating experimentally the effects of ester type oxygenates blended gasoline on the compatibility with metallic and elastomeric auto parts and comparing with those of ethanol and MTBE. Four types of oxygenates blended gasoline mixtures were tested: each 10% of ethanol (E10), ethyl butyrate (EB10), methyl butyrate (MB10) and MTBE (MTBE10). Metallic and elastomeric specimens were immersed in each of four test fuels at ambient temperature for elastomers and at 100℃ for metals during the period of test. EB10 showed similar material compatibility of MTBE10. On the contrary, E10 and MB10 had bad influence on the elastomeric specimens in weight and length change due to swelling. E10 even made aluminum specimens show distinct pits on the surface by corrosion. The result of the compatibility tests indicated that ethyl butyrate can be recommended as one of the promising alternatives of oxygenate instead of ethanol and MTBE.