Solid-liquid phase equilibria of benzene + 2-methyl-2-propanol system under high pressures

Abstract

Solid-liquid phase equilibria of the benzene + 2-methyl-2-propanol system have been investigated at temperatures from 278 to 323 K and pressures up to 300 MPa using a high-pressure optical vessel. The uncertainties of the measurements of temperature, pressure and composition are within ±0.1 K, ±0.5 MPa, and ±0.001 mole fraction, respectively. The freezing pressure at a constant composition increases monotonously with pressure. The eutectic point shifts to a higher temperature and benzene-rich composition with increasing pressure. In order to describe the pressure-temperature-composition relation of high-pressure solid-liquid phase equilibria, a new simple equation has been proposed as follows:

$$In x_i (P,T) = - \frac{1}{{RT}}\{ C(T)[P - B(T)] + D(T)[P^2 - B(T)^2 ]\} $$

where B, C, and D are the temperature-dependent coefficients and are expressed by the polynomials of reciprocal of temperature. It is found that the solid-liquid coexistence curves of both eutectic systems and solid-solution systems can be correlated satisfactorily by this equation.