Measurements of isothermal vapor-liquid equilibrium of binary methanol/dimethyl carbonate system under pressure

By a static total pressure method, an equilibrium still with a viewing window was employed to measured isothermal vapor-liquid equilibrium data for methanol (1)-dimethyl carbonate (2) binary system from 337.35 to 428.15 K, as well as the lotus of azeotrope changing with pressure. The static total pressure method requires no analysis of phase composition, while the influence of vapor phase quantity must be considered under pressure. The system quantity (nT) and composition (z1) of feedings and volume data (VG) of equilibrium vapor phase were taken directly from the experiments. The fugacity coefficients of vapor phase were calculated from the experimental p-VG-T data, and correlated by the modified Peng-Robinson equation of state, which can be applied for both vapor and liquid phases. The isothermal equilibrium vapor and liquid compositions were then directly computed based on mass balance and a model-free method of calculation y from T, p and feeding composition z1. The experimental data were also correlated with the modified Peng-Robinson equation of state and bubble point calculations. The correlated results showed that the maximum average relative deviation for experimental composition y1 was 0.0174, and for total pressure pcalc was 2.74%. The azeotrope of the binary system at different temperatures was also determined, which is consistent with the literature data.