Phase Equilibrium, Structure, and Transport Properties of Carbon-Dioxide Expanded Liquids: A Molecular Simulation Study

摘要

We review our recent work on phase equilibrium, transport properties and local structure in carbon-dioxide-expanded liquids (CXL's). In addition, we present new data on the effect of increasing CO_2 mole fraction on hydrogen bonding in CO_2- expanded methanol and acetic acid. Phase equilibrium and structure data were calculated using Gibbs Ensemble Monte Carlo techniques and transport properties were determined from molecular-dynamics simulation. We show, using existing force fields for pure CO_2 and a variety of pure organic solvents and standard Lorentz-Berthelot combination rules, that molecular simulation gives results for CXL vapor-liquid phase equilibria and transport properties that are in good agreement with experiment. Also, our phase equilibrium results were found to be at least as good as, and often superior to, predictions using the Peng-Robinson Equation of State (PREOS) and have the advantage over empirical PR-EOS predictions in that no experimental input data from the mixtures are required. Thus, molecular simulation is shown to be a potentially important tool in determining CXL properties required for design and optimization of CXL media in catalytic processes.