Kinetics of Multi‐Step Redox Processes by Time‐Resolved In Situ X‐ray Diffraction |
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| Authors: | Lukas C Buelens Vladimir V Galvita Hilde Poelman Christophe Detavernier Guy B Marin |
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| Affiliation: | 1. Ghent University, Laboratory for Chemical Technology, Technologiepark 914, 9052 Ghent, Belgium;2. Ghent University, Department of Solid State Sciences, Krijgslaan 281, S1, 9000 Ghent, Belgium. |
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| Abstract: | The kinetics of redox reactions of iron oxide in oxygen carrier 50Fe2O3/MgAl2O4 are examined using different time‐resolved techniques. Reduction kinetics are studied by H2 temperature‐programmed reduction (H2‐TPR) monitored by time‐resolved in situ XRD. In contrast to conventional TPR, in situ XRD distinguishes the three‐stage reduction of Fe2O3 → Fe3O4 → FeO → Fe. It also shows that the oxidation of Fe → Fe3O4 by CO2 has no intermediate crystalline phases, explaining why its kinetics can easily be investigated by conventional CO2 temperature‐programmed oxidation (CO2‐TPO). A shrinking core model which takes into account solid state diffusion allows describing the experimental data. |
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| Keywords: | Chemical looping CO2 conversion Iron oxide Kinetics Oxidation Reduction Time‐resolved in situ XRD |
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