| dc.description.abstract | Thermodynamic properties are important information for the design of chemical engineering processes. The Peng-Robinson+COSMOSAC equation of state, denoted as PR+COSMOSAC, has been shown to provide reasonable prediction for thermodynamic properties of pure substances and fluid phase behavior of mixtures without the issue of missing parameters. In COSMO-based models, the molecular interactions are determined from molecular surface charges obtained from the quantum mechanical and COSMO (QM/COSMO) calculations. It has been shown that the accuracy of the COSMOSAC model in predicting fluid phase equilibrium may be affected by the use of quantum chemical computation method in previous literature.
In this work, we investigate the accuracy of the PR+COSMOSAC in predicting thermodynamic properties of pure fluids, such as critical properties and vapor pressures, and fluid phase behavior of mixtures, such as vapor–liquid equilibria and solubility of solid solute in supercritical carbon dioxide, using different QM/COSMO results from different quantum chemical packages (ADF, DMol3, and Gaussian), computational methods (GGA-BP, VWN-BP, B3LYP, and PM6) and basis sets (TZP, DNP, and 6-31G(d,p)-cosmo). The values of parameters in the PR+COSMOSAC were re-optimized for each quantum chemical computation method. It is found that the prediction results of thermodynamic properties of pure fluids and vapor-liquid equilibria are very similar using different QM/COSMO results from different quantum chemical packages. Taking ADF(GGA-BP/TZP) as the example, vapor pressures of pure fluids (ALD-P = 0.194), sublimation pressures of pure fluids (ALD-P = 0.647), critical pressures of pure fluids (AARD = 8.00%), critical temperatures of pure fluids (AARD = 4.20%), critical volumes of pure fluids (AARD = 17.76%), boiling temperatures of pure fluids (AAD = 14.11K), vapor-liquid equilibria (AARD-P = 21.97% and AAD-y = 7.90%). However, the prediction results with ADF(GGA-BP/TZP) (ALD-x = 0.95) and Gaussian(B3LYP/6-31G(d,p)-cosmo) (ALD-x = 0.85) may be more accurate than the other quantum chemical computation methods in the solubility of solid solutes in supercritical carbon dioxide. | en_US |