Cerium(III) oxide

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Cerium(III) oxide
La2O3structure.jpg
Names
IUPAC name
Cerium(III) oxide
Other names
Cerium sesquioxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.014.289 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 234-374-3
PubChem CID
UNII
  • InChI=1S/2Ce.3O/q2*+3;3*-2
    Key: DRVWBEJJZZTIGJ-UHFFFAOYSA-N
  • [O-2].[O-2].[O-2].[Ce+3].[Ce+3]
Properties
Ce2O3
Molar mass 328.229 g·mol−1
Appearanceyellow-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
GHS labelling:
GHS-pictogram-exclam.svg GHS-pictogram-pollu.svg
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).
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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.

Contents

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 NOx 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]

Related Research Articles

<span class="mw-page-title-main">Combustion</span> Chemical reaction

Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion does not always result in fire, because a flame is only visible when substances undergoing combustion vaporize, but when it does, a flame is a characteristic indicator of the reaction. While the activation energy must be overcome to initiate combustion, the heat from a flame may provide enough energy to make the reaction self-sustaining.

Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:

<span class="mw-page-title-main">Catalytic converter</span> Exhaust emission control device

A catalytic converter is an exhaust emission control device that converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalyzing a redox reaction. Catalytic converters are usually used with internal combustion engines fueled by gasoline or diesel, including lean-burn engines, and sometimes on kerosene heaters and stoves.

Vehicle emissions control is the study of reducing the emissions produced by motor vehicles, especially internal combustion engines.

<span class="mw-page-title-main">Vehicle emission standard</span> Legal requirements governing air pollutants released into the atmosphere

Emission standards are the legal requirements governing air pollutants released into the atmosphere. Emission standards set quantitative limits on the permissible amount of specific air pollutants that may be released from specific sources over specific timeframes. They are generally designed to achieve air quality standards and to protect human life. Different regions and countries have different standards for vehicle emissions.

<span class="mw-page-title-main">Exhaust gas</span> Gases emitted as a result of fuel reactions in combustion engines

Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack, or propelling nozzle. It often disperses downwind in a pattern called an exhaust plume.

<span class="mw-page-title-main">Diesel exhaust</span>

Diesel exhaust is the gaseous exhaust produced by a diesel type of internal combustion engine, plus any contained particulates. Its composition may vary with the fuel type or rate of consumption, or speed of engine operation, and whether the engine is in an on-road vehicle, farm vehicle, locomotive, marine vessel, or stationary generator or other application.

<span class="mw-page-title-main">Cerium(IV) oxide</span> Chemical compound

Cerium(IV) oxide, also known as ceric oxide, ceric dioxide, ceria, cerium oxide or cerium dioxide, is an oxide of the rare-earth metal cerium. It is a pale yellow-white powder with the chemical formula CeO2. It is an important commercial product and an intermediate in the purification of the element from the ores. The distinctive property of this material is its reversible conversion to a non-stoichiometric oxide.

Selective catalytic reduction (SCR) is a means of converting nitrogen oxides, also referred to as NO
x
with the aid of a catalyst into diatomic nitrogen, and water. A reductant, typically anhydrous ammonia, aqueous ammonia, or a urea solution, is added to a stream of flue or exhaust gas and is reacted onto a catalyst. As the reaction drives toward completion, nitrogen, and carbon dioxide, in the case of urea use, are produced.

<span class="mw-page-title-main">Diesel exhaust fluid</span> Standardized aqueous urea solution for exhaust aftertreatment

Diesel exhaust fluid is a liquid used to reduce the amount of air pollution created by a diesel engine. Specifically, DEF is an aqueous urea solution made with 32.5% urea and 67.5% deionized water. DEF is consumed in a selective catalytic reduction (SCR) that lowers the concentration of nitrogen oxides in the diesel exhaust emissions from a diesel engine.

In atmospheric chemistry, NOx is shorthand for nitric oxide and nitrogen dioxide, the nitrogen oxides that are most relevant for air pollution. These gases contribute to the formation of smog and acid rain, as well as affecting tropospheric ozone.

<span class="mw-page-title-main">Diesel particulate filter</span> Removes diesel particulate matter or soot from the exhaust gas of a diesel engine

A diesel particulate filter (DPF) is a device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine.

BlueTEC is Mercedes-Benz Group's marketing name for engines equipped with advanced NOx reducing technology for vehicle emissions control in diesel-powered vehicles. The technology in BlueTec vehicles includes a selective catalytic reduction (SCR) system that uses diesel exhaust fluid, and a system of NOx adsorbers the automaker calls DeNOx, which uses an oxidizing catalytic converter and diesel particulate filter combined with other NOx reducing systems.

A NOx adsorber or NOx trap (also called Lean NOx trap, abbr. LNT) is a device that is used to reduce oxides of nitrogen (NO and NO2) emissions from a lean burn internal combustion engine by means of adsorption.

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<span class="mw-page-title-main">Hydrogen internal combustion engine vehicle</span> Vehicle with hydrogen internal combustion engine

A hydrogen internal combustion engine vehicle (HICEV) is a type of hydrogen vehicle using an internal combustion engine. Hydrogen internal combustion engine vehicles are different from hydrogen fuel cell vehicles. Instead, the hydrogen internal combustion engine is simply a modified version of the traditional gasoline-powered internal combustion engine. The absence of carbon means that no CO2 is produced, which eliminates the main greenhouse gas emission of a conventional petroleum engine.

<span class="mw-page-title-main">Cerium(IV) oxide–cerium(III) oxide cycle</span> Chemical reaction

The cerium(IV) oxide–cerium(III) oxide cycle or CeO2/Ce2O3 cycle is a two-step thermochemical process that employs cerium(IV) oxide and cerium(III) oxide for hydrogen production. The cerium-based cycle allows the separation of H2 and O2 in two steps, making high-temperature gas separation redundant.

<span class="mw-page-title-main">Cerium</span> Chemical element, symbol Ce and atomic number 58

Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the oxidation state of +3 characteristic of the series, it also has a stable +4 state that does not oxidize water. It is also considered one of the rare-earth elements. Cerium has no known biological role in humans but is not particularly toxic, except with intense or continued exposure.

Bharat stage emission standards (BSES) are emission standards instituted by the Government of India to regulate the output of air pollutants from compression ignition engines and Spark-ignition engines equipment, including motor vehicles. The standards and the timeline for implementation are set by the Central Pollution Control Board under the Ministry of Environment, Forest and Climate Change.

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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.