Thermodynamic modeling of the CeO2–CoO phase diagram

Kim, Sung S.

doi:10.1016/j.jallcom.2004.07.060

Cited by 10 publications

(8 citation statements)

References 52 publications

(15 reference statements)

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“…Such a result is expected due to the smaller ionic radius of Co 2+ (R IV = 0.75 Å) in comparison with that of cerium (R IV = 0.87 Å). The homogenous area of BaCe 0.9 − x Gd 0.1 Co x O 3 − δ system is wider compared to electrolytes based on CeO 2 , due to the fact that the maximum solubility of CoO in CeO 2 is 3 mol% at 1580°C [30]. The morphology of the samples was determined by the aid of scanning electron microscopy and the corresponding images are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Investigation of the structural and electrical properties of Co-doped BaCe0.9Gd0.1O3−δ

et al. 2011

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Section: Resultsmentioning

confidence: 99%

Investigation of the structural and electrical properties of Co-doped BaCe0.9Gd0.1O3−δ

et al. 2011

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“…No further characterizations were performed to identify the chemical composition of the species associated with the color change because the absence of NO activity did not justify further investigation and the N 2 O decomposition rates did not appear to be affected by this structure or composition change. Color changes were not observed for the ceria catalysts in either the NO or N 2 O decomposition experiments, although solid compounds of cobalt and ceria are reported as thermodynamically stable at these temperatures [16].…”

Section: No Decompositionmentioning

confidence: 84%

Supported, Alkali-Promoted Cobalt Oxide Catalysts for NOx Removal from Coal Combustion Flue Gases

Argyle¹

2005

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A series of cobalt oxide catalysts supported on alumina (γ-Al 2 O 3 ) were synthesized with varying contents of cobalt and of added alkali metals, including lithium, sodium, potassium, rubidium, and cesium. Unsupported cobalt oxide catalysts and several cobalt oxide catalysts supported ceria (CeO 2 ) with varying contents of cobalt with added potassium were also prepared.The catalysts were characterized with UV-visible spectroscopy and were examined for NO x decomposition activity. The CoO x /Al 2 O 3 catalysts and particularly the CoO x /CeO 2 catalysts show N 2 O decomposition activity, but none of the catalysts (unsupported Co 3 O 4 or those supported on ceria or alumina) displayed significant, sustained NO decomposition activity. For the Al 2 O 3 -supported catalysts, N 2 O decomposition activity was observed over a range of reaction temperatures beginning about 723 K, but significant (>50%) conversions of N 2 O were observed only for reaction temperatures >900 K, which are too high for practical commercial use.However, the CeO 2 -supported catalysts display N 2 O decomposition rates similar to the Al 2 O 3 -supported catalysts at much lower reaction temperatures, with activity beginning at ~573 K.Conversions of >90% were achieved at 773 K for the best catalysts. Catalytic rates per cobalt atom increased with decreasing cobalt content, which corresponds to increasing edge energies obtained from the UV-visible spectra. The decrease in edge energies suggests that the size and dimensionality of the cobalt oxide surface domains increase with increasing cobalt oxide content.The rate data normalized per mass of catalyst that shows the activity of the CeO 2 -supported catalysts increases with increasing cobalt oxide content. The combination of these data suggest that supported cobalt oxide species similar to bulk Co 3 O 4 are inherently more active than more dispersed cobalt oxide species, but this effect was only observed with the CeO 2 -supported catalysts.

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“…There was no evidence of the formation of intermediate phases. An assessment of the experimental data and thermodynamic modeling of the CeO 2 ‐CoO system were done by Kim . A simple regular solution model was used to describe the excess Gibbs energy for the solution phases.…”

Section: Literature Surveymentioning

confidence: 99%

“…A simple regular solution model was used to describe the excess Gibbs energy for the solution phases. Kim also calculated the liquidus, solidus, and solvus curves and estimated the thermodynamic lattice stabilities of the phases in the CeO 2 ‐CoO system.…”

Section: Literature Surveymentioning

confidence: 99%

“…The binary CeO 2 ‐CoO is a simple eutectic phase diagram with the small solid solubilities on both Ce and Co‐rich side. To the best of our knowledge, the CALPHAD assessment of this system is not published, although critical assessment of the thermodynamic data was already given by Kim . Figure summarizes the optimized phase diagram of CeO 2 ‐CoO together with experimental data from the literature .…”

Section: Thermodynamic Modelingmentioning

confidence: 99%

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Experimental Phase Diagram Determination and Thermodynamic Assessment of the CeO₂‐Gd₂O₃‐CoO System

Ivas

Povoden-Karadeniz

Grundy³

et al. 2012

J. Am. Ceram. Soc.

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New phase diagram data and a thermodynamic assessment of the CeO‐Gd2O3‐CoO system using the CALPHAD approach are presented. This information is needed to understand the surprisingly low sintering temperature (950°C–1050°C) of CeO2‐based materials doped with small amounts of transition metal oxide (e.g., CoO). Experimental phase equilibria between 1100°C and 1300°C are reported based on the analysis of annealed and molten samples. No isolated compound exists in the ternary. At 1300°C the Co solubility in the ternary compounds Ce1−x−yGdxCoyO2−x/2−y (fluorite) is 2.7 mol% and is less than 1 mol% in the Gd2−xCexO3+x/2 (bixbyite). The Ce solubility in the perovskite GdCoO3−δ was found to be 1 mol%. The lowest temperature eutectic melt in the ternary has a composition of 57.2 mol% Co and 41.1 mol% Gd melting at an onset temperature of 1303 ± 5°C, which is close to the binary eutectic in the Gd2O3‐CoO system at 60 ± 2 mol% Co and 1348 ± 1°C.

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Thermodynamic modeling of the CeO2–CoO phase diagram

Cited by 10 publications

References 52 publications

Investigation of the structural and electrical properties of Co-doped BaCe0.9Gd0.1O3−δ

Investigation of the structural and electrical properties of Co-doped BaCe0.9Gd0.1O3−δ

Supported, Alkali-Promoted Cobalt Oxide Catalysts for NOx Removal from Coal Combustion Flue Gases

Experimental Phase Diagram Determination and Thermodynamic Assessment of the CeO₂‐Gd₂O₃‐CoO System

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Thermodynamic modeling of the CeO2–CoO phase diagram

Cited by 10 publications

References 52 publications

Investigation of the structural and electrical properties of Co-doped BaCe0.9Gd0.1O3−δ

Investigation of the structural and electrical properties of Co-doped BaCe0.9Gd0.1O3−δ

Supported, Alkali-Promoted Cobalt Oxide Catalysts for NOx Removal from Coal Combustion Flue Gases

Experimental Phase Diagram Determination and Thermodynamic Assessment of the CeO2‐Gd2O3‐CoO System

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Experimental Phase Diagram Determination and Thermodynamic Assessment of the CeO₂‐Gd₂O₃‐CoO System