VAPOR-LIQUID-EQUILIBRIUM OF (ETHERS PLUS HYDROCARBONS OR METHANOL OR WATER) FOR MOTOR GASOLINE MODELING

Modern environmentally beneficial methods of formulating motor gasolin e often use alcohols and/or ethers as octane improvers, Thus, the ther mophysical properties of these substances have become important in pro cess engineering design, the simulation of gasoline blending operation s, and engine operability. In all of these applications, phase equilib rium properties are represented by thermodynamic models, which are der ived from a combination of theory and experimental data. This work see ks to quantify these models from careful measurement of key thermodyna mic properties. Vapour-liquid equilibrium measurements on 2-ethoxy-2-m ethylpropane (ETBE), 2-methoxy-2-methylbutane (TAME) and 2-methoxy-2-m ethylpropane (MTBE) with various alkanes, aromatics and oxygenates hav e been made over a temperature range of 293 to 323 K using a static ex perimental method. These data are utilised in the development of a fle xible model for the thermodynamic properties of motor gasolines. The d ata are well correlated by the UNIQUAC excess Gibbs model for the liqu id phase and with the Hayden-O'Connell correlation for the virial equa tion for the gas phase. Prediction of the vapour phase composition abo ve a gasoline containing MTBE and methanol show maximum differences of 0.0353 in mass fraction. (C) 1997 Elsevier Science B.V.