A Size-Dependent Thermodynamic Model for Coke Crystallites: The Carbon-Sulfur System Up to 2500 K (2227 °C)

A model is presented for the development of the thermodynamic functions of enthalpy, entropy, and Gibbs energy for the elements carbon and sulfur in coke crystallites. The crystallites of various degrees of graphitization may be described by crystallite length L a and crystallite height L c . This c...

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Bibliographic Details
Published in:Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 2016-06, Vol.47 (3), p.1817-1831
Main Authors: Ouzilleau, Philippe, Gheribi, Aïmen E., Lindberg, Daniel K., Chartrand, Patrice
Format: Article
Language:English
Subjects:
Carbon
Characterization and Evaluation of Materials
Chemistry and Materials Science
Coke
Crystallites
Crystallization
Entropy
Hydrogen
Materials Science
Mathematical models
Metallic Materials
Metallurgy
Nanotechnology
Structural Materials
Sulfur
Surfaces and Interfaces
Thermodynamic models
Thermodynamics
Thin Films
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Summary:A model is presented for the development of the thermodynamic functions of enthalpy, entropy, and Gibbs energy for the elements carbon and sulfur in coke crystallites. The crystallites of various degrees of graphitization may be described by crystallite length L a and crystallite height L c . This carbon/sulfur model has been developed using concepts similar to those in the carbon/hydrogen model for coke crystallites. The major model parameters are derived from reported thermodynamic properties. Approximately 75 pct of the model parameters for the carbon/hydrogen and carbon/sulfur system are parameters common to both systems. The resulting crystallite size ( L a ) constrained in the carbon/sulfur phase diagram, computed by a Gibbs energy minimization technique, is presented for 1 atm and temperatures between 1500 K and 2500 K (1227 °C and 2227 °C). A very good agreement is obtained between the predicted thermal desulfurization of petroleum cokes and critically assessed experimental data. The removal of sulfur from coke crystallites is predicted to occur mostly between 1600 K and 1850 K (1327 °C and 1577 °C) at 1 atm, depending on the L a value. The precision in the predictive calculations and the transferability of the model parameters are two aspects that tend to support the usefulness and the theoretical basis of the entire approach.
ISSN:1073-5615
1543-1916
DOI:10.1007/s11663-016-0643-8