Reduction of Iron Oxide Catalysts: The Investigation of Kinetic Parameters Using Rate Perturbation and Linear Heating Thermoanalytical Techniques

Michael J. Tiernan, Philip A. Barnes, Gareth M B Parkes

Research output: Contribution to journalArticle

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Abstract

The mechanisms and kinetics of the reduction of powdered Fe2O3 and Fe3O4 samples have been investigated under nonisothermal conditions to provide a detailed insight into the processes occurring. Both conventional linear heating temperature-programmed reduction (TPR) and constant rate temperature-programmed reduction (CR-TPR) techniques were utilized. Fe2O3 was found to reduce to Fe in a two-step process via Fe3O4. The mechanism of the prereduction step of Fe2O3 to Fe3O4 was found to follow an nth order expression where nucleation or diffusion was not the rate-controlling factor while the main reduction step to metal was described by a model involving the random formation and growth of nuclei. A CR-TPR rate perturbation method, "rate-jump", was applied to the measurement of variations in apparent activation energy throughout the reduction processes, under near-equilibrium conditions and the activation energy measurements are compared with those obtained under conventional linear heating conditions.

Original languageEnglish
Pages (from-to)220-228
Number of pages9
JournalJournal of Physical Chemistry B
Volume105
Issue number1
DOIs
Publication statusPublished - 11 Jan 2001

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Iron oxides
Kinetic parameters
iron oxides
Heating
catalysts
perturbation
Catalysts
heating
kinetics
Activation energy
activation energy
Electric power measurement
Temperature
temperature
ferric oxide
Nucleation
Metals
nucleation
Kinetics
nuclei

Cite this

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abstract = "The mechanisms and kinetics of the reduction of powdered Fe2O3 and Fe3O4 samples have been investigated under nonisothermal conditions to provide a detailed insight into the processes occurring. Both conventional linear heating temperature-programmed reduction (TPR) and constant rate temperature-programmed reduction (CR-TPR) techniques were utilized. Fe2O3 was found to reduce to Fe in a two-step process via Fe3O4. The mechanism of the prereduction step of Fe2O3 to Fe3O4 was found to follow an nth order expression where nucleation or diffusion was not the rate-controlling factor while the main reduction step to metal was described by a model involving the random formation and growth of nuclei. A CR-TPR rate perturbation method, {"}rate-jump{"}, was applied to the measurement of variations in apparent activation energy throughout the reduction processes, under near-equilibrium conditions and the activation energy measurements are compared with those obtained under conventional linear heating conditions.",
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Reduction of Iron Oxide Catalysts : The Investigation of Kinetic Parameters Using Rate Perturbation and Linear Heating Thermoanalytical Techniques. / Tiernan, Michael J.; Barnes, Philip A.; Parkes, Gareth M B.

In: Journal of Physical Chemistry B, Vol. 105, No. 1, 11.01.2001, p. 220-228.

Research output: Contribution to journalArticle

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