Volumetric properties of ethyl acetate + carbon dioxide binary fluid mixtures at high pressures

Volumetric properties of carbon dioxide, ethyl acetate and their binary mixtures containing 27.7, 42.6, 52.9 and 67.3% by mass CO2 have been determined over a temperature range from 295 to 380 K for pure components, and from 295 to 340 K for mixtures at pressures up to 32 MPa. measurement methodology was employed in which a pressure-generator is used to alter the position of a movable piston while continually monitoring its position, thus the internal volume, with a computer-interfaced linear variable differential transformer (LVDT). The real-time recording of the internal volume permits generation of continuous density–pressure data which are correlated by smooth functions and used to determine the isothermal compressibility, the isobaric expansivity, the thermal pressure coefficient, and the excess volumes. The densities were observed to vary in the range from 0.60 to 0.98 g/cm3 for carbon dioxide; from 0.80 to 0.92 g/cm3 for ethyl acetate, and from 0.75 to 0.98 g/cm3 for the mixtures. Depending upon the temperature and pressure, the compressibility values were in the range 0.002–0.04 MPa−1 for CO2, and 1.0–2.3 × 10−3 MPa−1 for ethyl acetate. The expansivity values were in the range 3.7–11 × 10−3 K−1 for CO2 and 1.0–1.4 × 10−3 K−1 for ethyl acetate. The thermal pressure coefficients were in the range 0.3–1.9 MPa/K for CO2 and 0.55–1.2 MPa/K for ethyl acetate. In the mixtures, the isothermal compressibility and isobaric expansivity were found to increase while the thermal pressure coefficients decreased in going from ethyl acetate to carbon dioxide. The mixtures displayed mostly negative excess volumes. The magnitude of the negative excess volume was observed to decrease with pressure at a given temperature, but increase with increasing temperature at a given pressure. The largest (negative) excess volume, approaching −16 cm3/mol, was observed at the higher experimental temperature (340 K) and the lower pressure (16 MPa).