Vapor Pressure and Octane Numbers of Ternary Gasoline-Ethanol-ETBE Blends

The objective of this study was to examine key gasoline properties, such as octane rating and volatility of ternary blends with ethanol and ethyl-tert-butyl-ether (ETBE). Ethanol and ETBE were added in various concentrations in specific refinery gasoline pool components, so a total of 30 gasoline-ethanol-ETBE samples were prepared and tested. Vapor pressure and octane numbers [research octane number (RON) and motor octane number (MON)] were determined for the mixtures containing 0.9-5.5% v/v ethanol and 2.0-9.8% v/v ETBE. Ethanol was always considered a valuable component for refinery gasoline pool due to its good antiknock characteristics. However, its azeotropic behavior in gasoline is considered as a drawback for the vapor pressure of the blend. On the other hand, the use of ETBE in gasoline increases the octane number and lowers the vapor pressure, thus allowing refinery blenders to use a higher vapor pressure base gasoline in the final fuel formulation. Experimental results indicated that ethanol concentration up to 5% v/v in the gasoline formulation increased the vapor pressure of the mixture. The addition of both ethanol and ETBE in the base gasoline resulted in ternary mixtures which smoothed the behavior of the vapor pressure while they acted as excellent octane improvers. (C) 2014 American Society of Civil Engineers.