Cerium(III) oxide

For the other compound also known as cerium oxide, see Cerium(IV) oxide.

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.

Cerium(III) oxide

Names
IUPAC name Cerium(III) oxide
Other names Cerium sesquioxide
Identifiers
CAS Number	1345-13-7 Y
3D model (JSmol)	Interactive image
ChemSpider	8081132
ECHA InfoCard	100.014.289
EC Number	234-374-3
PubChem CID	9905479
UNII	82Q2098IFG
CompTox Dashboard (EPA)	DTXSID60149580
InChI InChI=1S/2Ce.3O/q2*+3;3*-2 Key: DRVWBEJJZZTIGJ-UHFFFAOYSA-N
SMILES [O-2].[O-2].[O-2].[Ce+3].[Ce+3]
Properties
Chemical formula	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)
Solubility in water	insoluble
Solubility in sulfuric acid	soluble
Solubility in hydrochloric acid	insoluble
Structure
Crystal structure	Hexagonal, hP5
Space group	P3m1, No. 164
Hazards
GHS labelling:
Pictograms
Related compounds
Other anions	Cerium(III) chloride
Other cations	Lanthanum(III) oxide, Praseodymium(III) oxide
Related compounds	Cerium(IV) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Applications

Engine and 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 CeO₂ + CO → Ce₂O₃ + CO₂

When there is an oxygen surplus, the process is reversed and cerium(III) oxide is oxidized to cerium(IV) oxide:

2 Ce₂O₃ + O₂ → 4 CeO₂

Major automotive applications for cerium(III) oxide are as a catalytic converter for the oxidation of CO and NO_x emissions in the exhaust gases from motor vehicles,^[1][2] and secondly, cerium oxide finds use as a fuel additive to diesel fuels, which results in increased fuel efficiency and decreased hydrocarbon derived particulate matter emissions,^[3] however the health effects of the cerium oxide bearing engine exhaust is a point of study and dispute.^[4][5][6]

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.^[7]

Photoluminescence

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.^[8] This combination of cerium(III) oxide and tin(II) oxide is rare, and obtained only with difficulty on a laboratory scale.^{[citation needed]}

Production

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.^[9]

References

1. 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.
2. "Argonne's deNOx Catalyst Begins Extensive Diesel Engine Exhaust Testing". Archived from the original on 2015-09-07. Retrieved 2014-06-02.
3. "Exploring Nano-sized Fuel Additives EPA scientists examine nanoparticle impacts on vehicle emissions and air pollution".
4. "Nanoparticles used as additives in diesel fuels can travel from lungs to liver, November 18, 2011. Marshall University Research Corporation".
5. 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. doi:10.1080/08958370801915309. PMID 18444008.
6. "Exploring Nano-sized Fuel Additives EPA scientists examine nanoparticle impacts on vehicle emissions and air pollution".
7. Hydrogen production from solar thermochemical water splitting cycles Archived August 30, 2009, at the Wayback Machine
8. 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.
9. 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.

External links

• Transformation of CeO2(1 1 1) to Ce2O3(0 0 0 1) films