Cerium (III) oxide

Crystal structure
__ Ce 3+      __ O 2−
General
Surname	Cerium (III) oxide
other names	Dicertrioxide
Ratio formula	Ce 2 O 3
Brief description	yellowish green crystalline powder
External identifiers / databases
CAS number 1345-13-7 EC number 215-718-1 ECHA InfoCard 100.014.289 PubChem 9905479 Wikidata Q900883
properties
Molar mass	328.23 g mol −1
Physical state	firmly
density	6.2 g cm −3
Melting point	2210 ° C
boiling point	3730 ° C
solubility	almost insoluble in water, soluble in acids
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Cerium (III) oxide is an oxide of the metal cerium , which is a rare earth element.

In addition to cerium (III) oxide, there is also cerium oxide in the +4 oxidation state as cerium (IV) oxide (CeO ₂ ).

Manufacturing

Cerium (III) oxide Ce ₂ O ₃ is produced from cerium (IV) oxide CeO ₂ by reduction with carbon or hydrogen H ₂ at over 1000 ° C. It is stable in air if it was produced at temperatures above 1400 ° C.

${\displaystyle {\ce {2 CeO2 + H2 -> Ce2O3 + H2O}}}$

${\displaystyle {\ce {2 CeO2 + C -> Ce2O3 + CO}}}$

properties

Cerium (III) oxide is colored golden yellow. Greenish-yellow preparations are incompletely reduced. Powdery, non-stabilized cerium (III) oxide changes slowly in air, and quickly (sometimes with glowing) in the case of slow heating into cerium (IV) oxide. The compound is easily soluble in acids. In ceramic form together with tin (II) oxide SnO it luminesces when illuminated with UV light . It absorbs light with a wavelength of 320 nm and emits light with a wavelength of 412 nm.

Cerium (III) oxide has a hexagonal crystal structure of the lanthanoid A type.

use

Cerium oxides are used as a catalyst to reduce CO emissions in vehicle exhaust gases. If there is a lack of oxygen, cerium (IV ) oxide is reduced to cerium (III) oxide in the presence of carbon monoxide :

${\displaystyle {\ce {4 CeO2 + 2 CO -> 2 Ce2O3 + 2 CO2}}}$

Conversely, if there is an excess of oxygen, cerium (III) oxide is oxidized to cerium (IV) oxide:

${\displaystyle {\ce {2 Ce2O3 + O2 -> 4 CeO2}}}$

The cerium (IV) oxide-cerium (III) oxide process is being developed for the future production of hydrogen using solar energy .

Individual evidence

1. ↑ ^{a b c d e} David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Properties of the Elements and Inorganic Compounds, pp. 4-57. (WebElements: dicerium trioxide ).
2. ↑ Entry on cerium (III) oxide in the GESTIS substance database of the IFA , accessed on March 22, 2020(JavaScript required) .
3. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
4. ↑ ^{a b c} Georg Brauer (ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 1090.
5. ^ DR Peplinski, WT Wozniak, JB Moser: Spectral Studies of New Luminophors for Dental Porcelain . In: Journal of Dental Research . tape 59 , no. 9 , September 1980, p. 1501-1506 , doi : 10.1177 / 00220345800590090801 .