ESTIMATION OF CHEMICAL-EQUILIBRIA IN HIGH-PRESSURE GASEOUS SYSTEMS BYA MODIFIED REDLICH-KWONG-SOAVE EQUATION OF STATE

This paper considers the calculation of homogeneous chemical equilibri a in high-pressure gaseous systems. A modified Redlich-Kwong-Soave equ ation of state, which represents satisfactorily single-phase fugacity coefficients of pure fluids, is extended to mixtures. Mixture paramete rs are derived from the corresponding pure-component ones by means of the classical mixing rules. Equilibrium compositions are predicted for the ammonia synthesis, the water-gas shift reaction, and the methanol synthesis. In the case of ammonia, extensive experimental data betwee n 10 and 80 MPa are reproduced with good accuracy; when the model is e xtrapolated up to 350 MPa, still satisfactory results can be calculate d. For the water-gas shift reaction, acceptable results are obtained w ith limited experimental data sets. As to methanol synthesis, an inter esting behavior is evidenced when operating near methanol's critical t emperature. The proposed model is shown to be superior to both the Lew is-Randall approach and the original Redlich-Kwong-Soave equation of s tate and can be used to predict equilibrium conversion of gas-phase re actions under high pressures.