Solubilities of naphthalene in (CO 2 + C 2H 6) and (CO 2 + C 3H 8) up to 333 K and 17.7 MPa

Abstract

Solubilities of naphthalene in supercritical ethane and in two solvent mixtures (0.4 carbon dioxide + 0.6 ethane) and (0.85 carbon dioxide + 0.15 propane) were measured at temperatures between 307.9 and 338.0 K over the pressure range 6–26 MPa. The accuracy of the measurements was ±3%. The upper critical end point (UCEP) temperature for naphthalene with the (0.4 carbon dioxide + 0.6 ethane) solvent mixture was estimated from the intersection of the three-phase solid-liquid-gas line and the vapour-liquid mixture critical line to be 327.7 K at a pressure of 17.0 MPa. The UCEP temperature for naphthalene with the (0.85 carbon dioxide + 0.15 propane) solvent mixture is 327.6 K at a pressure of 15.0 MPa. The ( p, T) projections of both three-phase curves have a minimum in temperature below the UCEP. The Peng-Robinson equation of state was used to calculate the phase behaviour of these mixtures, and good agreement with the experimental solubilities and three-phase measurements was found.