Cerium(III) oxide
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| Names | |
|---|---|
| IUPAC name
Cerium(III) oxide
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| Other names
Cerium sesquioxide
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| Identifiers | |
| ECHA InfoCard | 100.014.289 |
CompTox Dashboard (EPA)
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| Properties | |
| Ce2O3 | |
| Molar mass | 328.24 g/mol |
| Appearance | yellow/green pulver, |
| Density | 6.2 g/cm3 |
| Melting point | 2,177 °C (3,951 °F; 2,450 K) |
| Boiling point | 3,730 °C (6,750 °F; 4,000 K) |
| insoluble | |
| Solubility in sulfuric acid | soluble |
| Solubility in hydrochloric acid | insoluble |
| Structure | |
| Hexagonal, hP5 | |
| P-3m1, No. 164 | |
| Related compounds | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cerium(III) oxide is an oxide of the rare earth metal cerium. It has chemical formula Ce2O3, and is gold-yellow in color.
Applications
Exhaust catalysts
Cerium oxide is used as a catalytic converter for the minimisation of CO emissions in the exhaust gases from motor vehicles.
When there is a shortage of oxygen, cerium(IV) oxide is reduced by carbon monoxide to cerium(III) oxide:
- 2 CeO
2 + CO → Ce
2O
3 + CO
2
When there is an oxygen surplus, the process is reversed and cerium(III) oxide is oxidized to cerium(IV) oxide:
- 2 Ce
2O
3 + O
2 → 4 CeO
2
Water splitting
The cerium(IV) oxide-cerium(III) oxide cycle or CeO2/Ce2O3 cycle is a two step thermochemical water splitting process based on cerium(IV) oxide and cerium(III) oxide for hydrogen production.[1]
Illumination
Cerium(III) oxide combined with tin(II) oxide (SnO) in ceramic form is used for illumination with UV light. It absorbs light with a wavelength of 320 nm and emits light with a wavelength of 412 nm.[2] This combination of cerium(III) oxide and tin(II) oxide is rare, and obtained only with difficulty on a laboratory scale.
Production
Cerium(III) oxide is produced by the reduction of cerium(IV) oxide with hydrogen at approximately 1,400 °C (2,550 °F) to make air stable cerium(III) oxide. Production at other temperatures results in pyrophoric cerium(III) oxide.[3]
References
- ^ Hydrogen production from solar thermochemical water splitting cycles
- ^ Spectral Studies of New Luminophors for Dental Porcelain
- ^ Georg Brauer: Handbuch der Präparativen Anorganischen Chemie Band II, Seite 1090, Ferdinand Enke Verlag Stuttgart 1978, ISBN 3-432-87813-3