A novel approach to phase equilibria predictions using ab initio methods

Journal Article · Thu Jul 01 04:00:00 EDT 1999 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie9900263· OSTI ID:680086

Sum, A K; Sandler, S I ^[1]

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1. Univ. of Delaware, Newark, DE (United States). Center for Molecular and Engineering Thermodynamics

Molecular orbital ab initio calculations have been used to compute interaction energies between pairs of molecules in a large molecular cluster. These energies are then used as the interaction energy parameters in the widely used Wilson and UNIQUAC activity coefficient models. Low-pressure vapor-liquid equilibria predictions based on the calculated parameters have been computed for binary systems of water with methanol, ethanol, 1-propanol, 2-propanol, formic acid, acetic acid, acetone, acetonitrile, acetaldehyde, and m-methylformamide. Excellent predictions are obtained with the UNIQUAC model, whereas poor results are found with the Wilson model. In several cases, the authors` predictions are also superior to those obtained from UNIFAC. In addition, using the same parameters and the UNIQUAC model, high-pressure-vapor-liquid equilibria predictions were made using the Peng-Robinson-Stryjek-Vera equation of state and the Wong-Sandler mixing rule for methanol, ethanol, 2-propanol, and acetone separately with water. The low- and high-pressure results demonstrate that this unique approach can lead to accurate vapor-liquid equilibrium predictions for hydrogen-bonding mixtures based only on pure-component properties and the structure of the molecules.

• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
• DOE Contract Number: FG02-85ER13436
• OSTI ID: 680086
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 7 Vol. 38; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ACETALDEHYDE
ACETIC ACID
ACETONE
ACETONITRILE
AMIDES
BINARY MIXTURES
EQUATIONS OF STATE
EQUILIBRIUM
FORMIC ACID
METHANOL
MOLECULAR ORBITAL METHOD
PHASE STUDIES
PROPANOLS