Cerium(III) oxide
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| IUPAC name
Cerium(III) oxide
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| Other names
Cerium sesquioxide
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.014.289 |
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PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| Ce2O3 | |
| Molar mass | 328.229 g·mol−1 |
| Appearance | yellow-green dust[citation needed] |
| 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 | |
| P3m1, No. 164 | |
| Hazards | |
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| Related compounds | |
Other anions
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Cerium(III) chloride |
Other cations
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Lanthanum(III) oxide, Praseodymium(III) oxide |
Related compounds
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Cerium(IV) oxide |
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, also known as cerium oxide, cerium trioxide, cerium sesquioxide, cerous oxide or dicerium trioxide, is an oxide of the rare-earth metal cerium. It has chemical formula Ce2O3 and is gold-yellow in color. According to X-ray crystallography, the Ce(III) ions are seven-coordinate, a motif typical for other trivalent lanthanide oxides.[1]
Applications
[edit]Cerium oxide is of commercial interest as a catalyst for oxidation of carbon monoxide and reduction of NOx. These applications exploit the facility of the Ce(III)/Ce(IV) redox couple.[2] It is used in catalytic converters ("three-way 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 oxidizes carbon monoxide to the benign dioxide:[3][4]
- 2 CeO2 + CO → Ce2O3 + CO2
When oxygen is in surplus, the process is reversed and cerium(III) oxide is oxidized to cerium(IV) oxide:
- 2 Ce2O3 + O2 → 4 CeO2
Cerium oxide-based catalysts have been intensively investigated for selective catalytic reduction (SCR)of NOx. Such technologies, which tend to use vanadium oxide-based catalysts rather than ceria, are associated with power plants, foundaries, cement factories and other energy-intensive facilities.[5]
Cerium oxide finds use as a fuel additive to diesel fuels,[clarification needed] which results in increased fuel efficiency and decreased hydrocarbon derived particulate matter emissions,[6] however the health effects of the cerium oxide bearing engine exhaust is a point of study and dispute.[7][8][9]
Other properties
[edit]Water splitting
[edit]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.[10][2]
Photoluminescence
[edit]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.[11] This combination of cerium(III) oxide and tin(II) oxide is rare, and obtained only with difficulty on a laboratory scale.[citation needed]
Production
[edit]Cerium(III) oxide is produced by the reduction of cerium(IV) oxide with hydrogen at approximately 1,400 °C (2,550 °F). Samples produced in this way are only slowly air-oxidized back to the dioxide at room temperature.[12]
References
[edit]- ^ Bärnighausen, H.; Schiller, G. (1985). "The Crystal Structure of A-Ce2O3". Journal of the Less Common Metals. 110 (1–2): 385–390. doi:10.1016/0022-5088(85)90347-9.
- ^ a b Montini, Tiziano; Melchionna, Michele; Monai, Matteo; Fornasiero, Paolo (2016). "Fundamentals and Catalytic Applications of CeO2-Based Materials". Chemical Reviews. 116 (10): 5987–6041. doi:10.1021/acs.chemrev.5b00603. hdl:11368/2890051. PMID 27120134.
- ^ Bleiwas, D.I. (2013). Potential for Recovery of Cerium Contained in Automotive Catalytic Converters. Reston, Va.: U.S. Department of the Interior, U.S. Geological Survey.
- ^ "Argonne's deNOx Catalyst Begins Extensive Diesel Engine Exhaust Testing". Archived from the original on 2015-09-07. Retrieved 2014-06-02.
- ^ Han, Lupeng; Cai, Sixiang; Gao, Min; Hasegawa, Jun-ya; Wang, Penglu; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong (2019). "Selective Catalytic Reduction of NO x with NH3 by Using Novel Catalysts: State of the Art and Future Prospects". Chemical Reviews. 119 (19): 10916–10976. doi:10.1021/acs.chemrev.9b00202. PMID 31415159.
- ^ "Exploring Nano-sized Fuel Additives EPA scientists examine nanoparticle impacts on vehicle emissions and air pollution".
- ^ "Nanoparticles used as additives in diesel fuels can travel from lungs to liver, November 18, 2011. Marshall University Research Corporation".
- ^ Park, B.; Donaldson, K.; Duffin, R.; Tran, L.; Kelly, F.; Mudway, I.; Morin, J. P.; Guest, R.; Jenkinson, P.; Samaras, Z.; Giannouli, M.; Kouridis, H.; Martin, P. (Apr 2008). "Hazard and risk assessment of a nanoparticulate cerium oxide-based diesel fuel additive - a case study". Inhal Toxicol. 20 (6): 547–66. Bibcode:2008InhTx..20..547P. doi:10.1080/08958370801915309. PMID 18444008.
- ^ "Exploring Nano-sized Fuel Additives EPA scientists examine nanoparticle impacts on vehicle emissions and air pollution".
- ^ Hydrogen production from solar thermochemical water splitting cycles Archived August 30, 2009, at the Wayback Machine
- ^ Peplinski, D.R.; Wozniak, W. T.; Moser, J. B. (1980). "Spectral Studies of New Luminophors for Dental Porcelain". Journal of Dental Research. 59 (9): 1501–1509. doi:10.1177/00220345800590090801. PMID 6931128.
- ^ Y. Wetzel (1963). "Scandium, Yttrium, Rare Earths". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY, NY: Academic Press. p. 1151.