Addition of an azeotropic ETBE/ethanol mixture in eurosuper-type gasolines

This study proposes an azeotropic ETBE/ethanol mixture as a possible oxygenated additive for the formulation of eurosuper-type gasolines. Two eurosuper gasolines with different chemical compositions and well defined characteristics of density, volatility and octane numbers are used. Gasoline formulations containing azeotropic mixtures display an intermediary behavior between that of ETBE (ethyl tert-butyl ether) and ethanol in gasoline blends. Formulations containing this additive offer advantages over ethanol (low volatility and low solubility in water) and ETBE (higher octane number and lower production cost). Gasolines with azeotropic additives show lower Reid vapor pressures (RVPs) than gasolines formulated with ethanol, and therefore low levels of volatile organic compounds, similarly to highly pure ETBE. The use of the azeotropic mixture containing ethanol (renewable, deriving from biomass) and ETBE (produced from ethanol and isobutene) in its formulation is environmentally attractive in industrialized countries due to the need to reduce carbon dioxide emissions.