Date of Award

Spring 2005

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering - (Ph.D.)

Department

Chemical Engineering

First Advisor

Dana E. Knox

Second Advisor

Robert Benedict Barat

Third Advisor

Joseph W. Bozzelli

Fourth Advisor

Michael Chien-Yueh Huang

Fifth Advisor

Lev N. Krasnoperov

Abstract

A methodology to predict the thermodynamics of macroscopic fluid systems from quantum chemistry and statistical thermodynamics has been developed. This work extends the group-contribution concepts most utilized in chemical engineering. Computational chemistry software is used to define the geometries and electron density profiles of target molecules. Atoms in Molecules theory and associated software packages are used to calculate rigorous properties of the functional groups within molecules of interest. These properties are incorporated into an intermolecular potential energy function which describes interactions between entire molecules as a set of interactions between functional groups. This information is applied to a lattice-fluid model with the capability to predict volumetric properties of pure fluids and vapor/liquid equilibrium properties of mixture systems. This work develops a bridge from chemistry at the molecular level to the statistical mechanics at the macroscopic system level.

The rigorous properties of functional groups lead to the application of firstprinciples mathematical models that qualitatively agree with volumetric properties of pure fluids and predict vapor/liquid equilibrium behavior for near-ambient mixtures of alkanes, alcohols and ethers. The theoretical and computational efforts developed in this work offer engineers the ability to determine molecular-level modeling parameters within engineering models without the use of experiment.

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