Understanding the Differing Fluid Phase Behavior of Cyclohexane + Benzene and Their Hydroxylated or Aminated Forms
Y Mauricio Muñoz-Muñoz1, Chieh-Ming Hsieh2, Jadran Vrabec1
1Thermodynamics and Energy Technology, University of Paderborn , 33098 Paderborn, Germany.
The Journal of Physical Chemistry. B
|May 3, 2017
Summary
Different functional groups in binary mixtures explain unique phase behaviors. Hydrogen bonding and repulsive interactions dictate whether mixtures form azeotropes or remain zeotropic, impacting their vapor-liquid equilibrium.
Area of Science:
- Physical Chemistry
- Chemical Engineering
- Thermodynamics
Background:
- Binary mixtures exhibit diverse vapor-liquid phase behaviors, including azeotropy and zeotropy.
- Understanding these behaviors is crucial for chemical process design and separation technologies.
Purpose of the Study:
- To investigate the molecular origins of different vapor-liquid phase behaviors in three binary mixtures.
- To correlate phase equilibria and excess properties with microscopic interactions.
Main Methods:
- Utilized molecular modeling and simulation.
- Employed the COSMO-SAC model and a cubic equation of state.
- Analyzed phase equilibria, excess properties (volume, enthalpy, Gibbs energy), and microscopic structure.
Main Results:
- Cyclohexane + benzene mixture shows repulsive interactions, leading to pressure maximum azeotropy and positive excess Gibbs energy.
- Cyclohexylamine + aniline mixture, with amine groups, exhibits balanced interactions and zeotropic behavior.
- Cyclohexanol + phenol mixture, with hydroxyl groups, displays strong hydrogen bonding, resulting in pressure minimum azeotropy and negative excess Gibbs energy.
Conclusions:
- Repulsive interactions drive pressure maximum azeotropy.
- Strong hydrogen bonding interactions lead to pressure minimum azeotropy.
- Moderate hydrogen bonding and repulsive interactions result in zeotropic behavior.
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