Physical properties of gasoline-ETBE-isobutanol (in comparison with ethanol) ternary blends and their impact on regulatory compliance

Abstract

Many developed countries promote biofuels to fight against climate change. The blend of ethanol and ethyl tert-butyl ether (ETBE) with gasoline is a common way to increase the renewable energy content of fuel. The use of bio-isobutanol instead of or in addition to ethanol can help solve some problems of ethanol.Eighty five gasoline-isobutanol-ETBE blends (up to 100/100/30%v/v respectively) were tested. For each blend, the density, vapour pressure (RVP) and distillation curve were measured. The impact that the addition of isobutanol-ETBE blends has on gasoline standards was analysed and also compared with that caused by the addition of ethanol-ETBE blends.Some chemical data of these fuels and the densities measured allow us to identify some advantageous properties for isobutanol blends in terms of oxygen content, energy density, stoichiometry, renewable energy content, etc. The excess of RVP for isobutanol ternary blends is lower than that of ethanol blends, being advantageous in terms of evaporative emissions. Apart from the oxygen content limit, the most restrictive parameters for isobutanol ternary blends are the evaporated percentages at 100 °C and 70 °C, and the RVP. Nevertheless, the different performance of ethanol and isobutanol blends could help to meet fuel standards by using both bio-alcohols at once.