Determination and modeling of binary solid-liquid equilibria of para-xylene/meta-xylene, para-xylene/ortho-xylene by DSC method

Solid-liquid equilibria of three binary mixtures consisting of para-xylene, ortho-xylene, meta-xylene and ethylbenzene were investigated in this study using differential scanning calorimetry (DSC) method, the mixtures were cooled to -120 °C and then heated to 20 °C at different heating rates, eutectic phase diagrams were observed for para-xylene/ortho-xylene and para-xylene/meta-xylene binary systems. The freezing point of pure ethylbenzene at atmospheric pressure is around -95 °C, but due to the effect of induction time, the observed freezing temperature is lower than -120 °C, the operation temperature of industrial xylene crystallization separation process is higher than -80 °C traditionally, therefore ethylbenzene will not crystallize in practical process, the phase diagram for para-xylene/ethylbenzene was not achieved. The experimental data were compared with data from other literatures and new features were found. The data were well correlated by Apelblat equation and λ H equation, it is significative to provide important engineering data for the separation and purification of xylene mixtures.