HIGH-PRESSURE VAPOR-LIQUID AND SOLID-GAS EQUILIBRIA USING A PENG-ROBINSON GROUP-CONTRIBUTION METHOD

In this paper, the new excess Gibbs energy mixing rule, which coupled with the consistent form with the quadratic composition dependence of the second virial coefficient and the excess Gibbs energy (G(0)(E)) at standard zero pressure, has been developed. This proposed mixing rule , combining a Peng-Robinson equation of state with the analytical solu tions of groups (ASOG) group contribution method, provide a Peng-Robin son group contribution method (PRASOG). The PRASOG model has predicted the high-pressure vapor-liquid equilibria (VLE) for binary systems co ntaining alcohols, acetone, and water using the available ASOG group p air parameters determined at low pressure with good accuracy. The ASOG parameters have also been shown for 31 group pairs relating to two ga s groups, CO2 and CH4, which indicate potential for global warming, us ing binary experimental high-pressure VLE data in the temperature rang e 200-600 K. High-pressure VLE have then been correlated for 56 binary systems containing carbon dioxide and/or methane. These results are c ompared with those of the predicted Soave-Redlich-Kwong (PSRK) and lin ear combination of the Vidal and Michelsen (LCVM) models. Finally, usi ng the group pair parameters that have been determined from VLE data, solid-gas equilibria have been predicted with fairly good accuracy for eight binary and one ternary systems containing carbon dioxide.