Solid-liquid-vapor phase equilibria were measured for the binary systems carbon dioxide plus methane, carbon dioxide plus ethane, and carbon dioxide plus propane over the temperature region 204 to 216 K. Vapor-liquid phase equilibria were measured for carbon dioxide plus methane at 212 K, carbon dioxide plus ethane at 204, 209, and 212 K, and carbon dioxide plus propane at 216 K.

There were two major objectives for the work. The first objective was the experimental measurement and thermodynamic modeling of ternary vapor liquid equilibria of carbon dioxide systems of interest to the natural gas industry. The second objective was the measurement and thermodynamic modeling of solid-liquid-vapor phase behavior in binary carbon dixide systems.

Vapor-liquid equilibria were measured for the binary systems methane + carbon dioxide at 230, 250, and 270 K; methane + ethane at 210, 230, 270 K; and ethane + carbon dioxide at 210, 213, 230, 250 K. The ternary stystem methane + ethane + carbon dioxide was studied at 230 K over the pressure range 1.15 MPa to 6.59 MPa. The Peng-Robinson equation of state was used to model the experimental data with an accuracy sufficient for most engineering calculations Preliminary studies were made of the solid-liquid-vapor equilibria for the binary systems methane + carbon dioxide and ethane + carbon dioxide.