Explicit consideration of spatial hydrogen bonding direction for activity coefficient prediction based on implicit...

Area of Science:

• Thermodynamics
• Physical Chemistry
• Computational Chemistry

Background:

• Activity coefficients are vital for understanding mixture non-ideality and thermodynamic properties.
• The COSMO-SAC model predicts activity coefficients but struggles with associating fluids.
• Current models neglect the spatial orientation crucial for hydrogen bond formation.

Purpose of the Study:

• To develop a more accurate model for predicting activity coefficients in associating fluids.
• To incorporate spatial orientational constraints into hydrogen bond descriptions.
• To improve the reliability of thermodynamic property predictions for complex mixtures.

Main Methods:

• Proposed a new directional hydrogen bond (DHB) approach within the COSMO-SAC framework.
• Utilized Valence Shell Electron Pair Repulsion (VSEPR) theory to define orientation-dependent interactions.
• Limited hydrogen bond interactions to specific spatial regions based on lone pair electron projections.

Main Results:

• The new COSMO-SAC(DHB) model shows significantly improved accuracy for predicting activity coefficients.
• The model demonstrates enhanced reliability for various properties, including vapor-liquid equilibria (VLE) and water-octanol partition coefficients (Kow).
• Fewer universal parameters are required compared to previous models.

Conclusions:

• The COSMO-SAC(DHB) model offers a more accurate and reliable method for predicting thermodynamic properties of associating fluids.
• Incorporating directional hydrogen bonding significantly advances the prediction capabilities for mixture non-ideality.
• This approach provides a more robust tool for chemical process design and analysis.