Vanadium(V) oxide

Last updated
Vanadium(V) oxide
Vanadium-pentoxide-monolayer-3D-balls.png
Vanadium pentoxide powder.jpg
Names
IUPAC name
Divanadium pentaoxide
Other names
Vanadium pentoxide
Vanadic anhydride
Divanadium pentoxide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.013.855 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 215-239-8
KEGG
PubChem CID
RTECS number
  • YW2450000
UNII
UN number 2862
  • InChI=1S/5O.2V Yes check.svgY
    Key: GNTDGMZSJNCJKK-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/5O.2V/rO5V2/c1-6(2)5-7(3)4
    Key: GNTDGMZSJNCJKK-HHIHJEONAP
  • O=[V](=O)O[V](=O)=O
Properties [1]
V2O5
Molar mass 181.8800 g/mol
AppearanceYellow solid
Density 3.35 g/cm3 [2]
Melting point 681 °C (1,258 °F; 954 K) [2]
Boiling point 1,750 °C (3,180 °F; 2,020 K) [2] (decomposes)
0.7 g/L (20 °C) [2]
+128.0·10−6 cm3/mol [3]
Structure [4]
Orthorhombic
Pmmn, No. 59
a = 1151 pm, b = 355.9 pm, c = 437.1 pm
Distorted trigonal bipyramidal (V)
Thermochemistry [5]
127.7 J/(mol·K)
Std molar
entropy (S⦵298)
131.0 J/(mol·K)
-1550.6 kJ/mol
-1419.5 kJ/mol
Hazards
GHS labelling:
GHS-pictogram-silhouette.svg GHS-pictogram-skull.svg GHS-pictogram-pollu.svg
Danger
H302, H332, H335, H341, H361, H372, H411
NFPA 704 (fire diamond)
NFPA 704.svgHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
4
0
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
10 mg/kg (rat, oral)
23 mg/kg (mouse, oral) [6]
500 mg/m3 (cat, 23 min)
70 mg/m3 (rat, 2 hr) [6]
NIOSH (US health exposure limits):
PEL (Permissible)
C 0.5 mg V2O5/m3 (resp) (solid) [7]


C 0.1 mg V2O5/m3 (fume) [7]

Safety data sheet (SDS) ICSC 0596
Related compounds
Other anions
Vanadium oxytrichloride
Other cations
Niobium(V) oxide
Tantalum(V) oxide
Related vanadium oxides
Vanadium(II) oxide
Vanadium(III) oxide
Vanadium(IV) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Vanadium(V) oxide (vanadia) is the inorganic compound with the formula V 2 O 5. Commonly known as vanadium pentoxide, it is a brown/yellow solid, although when freshly precipitated from aqueous solution, its colour is deep orange. Because of its high oxidation state, it is both an amphoteric oxide and an oxidizing agent. From the industrial perspective, it is the most important compound of vanadium, being the principal precursor to alloys of vanadium and is a widely used industrial catalyst. [8]

Contents

The mineral form of this compound, shcherbinaite, is extremely rare, almost always found among fumaroles. A mineral trihydrate, V2O5·3H2O, is also known under the name of navajoite.

Chemical properties

Reduction to lower oxides

Upon heating a mixture of vanadium(V) oxide and vanadium(III) oxide, comproportionation occurs to give vanadium(IV) oxide, as a deep-blue solid: [9]

V2O5 + V2O3 → 4 VO2

The reduction can also be effected by oxalic acid, carbon monoxide, and sulfur dioxide. Further reduction using hydrogen or excess CO can lead to complex mixtures of oxides such as V4O7 and V5O9 before black V2O3 is reached.

Acid-base reactions

V2O5 is an amphoteric oxide. Unlike most transition metal oxides, it dissolves slightly in water to give a pale yellow, acidic solution. Thus V2O5 reacts with strong non-reducing acids to form solutions containing the pale yellow salts containing dioxovanadium(V) centers:

V2O5 + 2 HNO3 → 2 VO2(NO3) + H2O

It also reacts with strong alkali to form polyoxovanadates, which have a complex structure that depends on pH. [10] If excess aqueous sodium hydroxide is used, the product is a colourless salt, sodium orthovanadate, Na3VO4. If acid is slowly added to a solution of Na3VO4, the colour gradually deepens through orange to red before brown hydrated V2O5 precipitates around pH 2. These solutions contain mainly the ions HVO42− and V2O74− between pH 9 and pH 13, but below pH 9 more exotic species such as V4O124− and HV10O285− (decavanadate) predominate.

Upon treatment with thionyl chloride, it converts to the volatile liquid vanadium oxychloride, VOCl3: [11]

V2O5 + 3 SOCl2 → 2 VOCl3 + 3 SO2

Other redox reactions

Hydrochloric acid and hydrobromic acid are oxidised to the corresponding halogen, e.g.,

V2O5 + 6HCl + 7H2O → 2[VO(H2O)5]2+ + 4Cl− + Cl2

Vanadates or vanadyl compounds in acid solution are reduced by zinc amalgam through the colourful pathway:

VO2yellow - VOblue - Vgreen - Vpurple Vanadium oxidation states.jpg
VO2yellow → VOblue → Vgreen → Vpurple

The ions are all hydrated to varying degrees.

Preparation

The orange, partly hydrated form of V2O5 V2O5powder.jpg
The orange, partly hydrated form of V2O5
Precipitate of "red cake", which is hydrous V2O5 V2O5 hydrous.jpg
Precipitate of "red cake", which is hydrous V2O5

Technical grade V2O5 is produced as a black powder used for the production of vanadium metal and ferrovanadium. [10] A vanadium ore or vanadium-rich residue is treated with sodium carbonate and an ammonium salt to produce sodium metavanadate, NaVO3. This material is then acidified to pH 2–3 using H2SO4 to yield a precipitate of "red cake" (see above). The red cake is then melted at 690 °C to produce the crude V2O5.

Vanadium(V) oxide is produced when vanadium metal is heated with excess oxygen, but this product is contaminated with other, lower oxides. A more satisfactory laboratory preparation involves the decomposition of ammonium metavanadate at 500–550 °C: [13]

2 NH4VO3 → V2O5 + 2 NH3 + H2O

Uses

Ferrovanadium production

In terms of quantity, the dominant use for vanadium(V) oxide is in the production of ferrovanadium (see above). The oxide is heated with scrap iron and ferrosilicon, with lime added to form a calcium silicate slag. Aluminium may also be used, producing the iron-vanadium alloy along with alumina as a byproduct.

Sulfuric acid production

Another important use of vanadium(V) oxide is in the manufacture of sulfuric acid, an important industrial chemical with an annual worldwide production of 165 million tonnes in 2001, with an approximate value of US$8 billion. Vanadium(V) oxide serves the crucial purpose of catalysing the mildly exothermic oxidation of sulfur dioxide to sulfur trioxide by air in the contact process:

2 SO2 + O2⇌ 2 SO3

The discovery of this simple reaction, for which V2O5 is the most effective catalyst, allowed sulfuric acid to become the cheap commodity chemical it is today. The reaction is performed between 400 and 620 °C; below 400 °C the V2O5 is inactive as a catalyst, and above 620 °C it begins to break down. Since it is known that V2O5 can be reduced to VO2 by SO2, one likely catalytic cycle is as follows:

SO2 + V2O5 → SO3 + 2VO2

followed by

2VO2 +½O2 → V2O5

It is also used as catalyst in the selective catalytic reduction (SCR) of NOx emissions in some power plants and diesel engines. Due to its effectiveness in converting sulfur dioxide into sulfur trioxide, and thereby sulfuric acid, special care must be taken with the operating temperatures and placement of a power plant's SCR unit when firing sulfur-containing fuels.

Other oxidations

Proposed early steps in the vanadium-catalyzed oxidation of naphthalene to phthalic anhydride, with V2O5 represented as a molecule vs its true extended structure V2O5OxNaphth.svg
Proposed early steps in the vanadium-catalyzed oxidation of naphthalene to phthalic anhydride, with V2O5 represented as a molecule vs its true extended structure

Maleic anhydride is produced by the V2O5-catalysed oxidation of butane with air:

C4H10 + 4 O2 → C2H2(CO)2O + 8 H2O

Maleic anhydride is used for the production of polyester resins and alkyd resins. [15]

Phthalic anhydride is produced similarly by V2O5-catalysed oxidation of ortho-xylene or naphthalene at 350–400 °C. The equation for the vanadium oxide-catalysed oxidation of o-xylene to phthalic anhydride:

C6H4(CH3)2 + 3 O2 → C6H4(CO)2O + 3 H2O

The equation for the vanadium oxide-catalysed oxidation of naphthalene to phthalic anhydride: [16]

C10H8 + 4½ O2 → C6H4(CO)2O + 2CO2 + 2H2O

Phthalic anhydride is a precursor to plasticisers, used for conferring pliability to polymers.

A variety of other industrial compounds are produced similarly, including adipic acid, acrylic acid, oxalic acid, and anthraquinone. [8]

Other applications

Due to its high coefficient of thermal resistance, vanadium(V) oxide finds use as a detector material in bolometers and microbolometer arrays for thermal imaging. It also finds application as an ethanol sensor in ppm levels (up to 0.1 ppm).

Vanadium redox batteries are a type of flow battery used for energy storage, including large power facilities such as wind farms. [17] Vanadium oxide is also used as a cathode in lithium ion batteries. [18]

Biological activity

V2o5label.jpg

Vanadium(V) oxide exhibits very modest acute toxicity to humans, with an LD50 of about 470 mg/kg. The greater hazard is with inhalation of the dust, where the LD50 ranges from 4–11 mg/kg for a 14-day exposure. [8] Vanadate (VO3−
4), formed by hydrolysis of V2O5 at high pH, appears to inhibit enzymes that process phosphate (PO43−). However the mode of action remains elusive. [10] [ better source needed ]

Related Research Articles

<span class="mw-page-title-main">Oxide</span> Chemical compound where oxygen atoms are combined with atoms of other elements

An oxide is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al2O3 that protects the foil from further oxidation.

<span class="mw-page-title-main">Sulfuric acid</span> Chemical compound (H₂SO₄)

Sulfuric acid or sulphuric acid, known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, and hydrogen, with the molecular formula H2SO4. It is a colorless, odorless, and viscous liquid that is miscible with water.

<span class="mw-page-title-main">Vanadium</span> Chemical element, symbol V and atomic number 23

Vanadium is a chemical element; it has symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer (passivation) somewhat stabilizes the free metal against further oxidation.

<span class="mw-page-title-main">Naphthalene</span> Chemical compound

Naphthalene is an organic compound with formula C
10H
8. It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings. It is the main ingredient of traditional mothballs.

<span class="mw-page-title-main">Phthalic acid</span> Aromatic organic compound with formula C6H4(COOH)2

In organic chemistry, phthalic acid is an aromatic dicarboxylic acid, with formula C6H4(CO2H)2 and structure HO(O)C−C6H4−C(O)OH. Although phthalic acid is of modest commercial importance, the closely related derivative phthalic anhydride is a commodity chemical produced on a large scale. Phthalic acid is one of three isomers of benzenedicarboxylic acid, the others being isophthalic acid and terephthalic acid.

<span class="mw-page-title-main">Phthalic anhydride</span> Chemical compound

Phthalic anhydride is the organic compound with the formula C6H4(CO)2O. It is the anhydride of phthalic acid. Phthalic anhydride is a principal commercial form of phthalic acid. It was the first anhydride of a dicarboxylic acid to be used commercially. This white solid is an important industrial chemical, especially for the large-scale production of plasticizers for plastics. In 2000, the worldwide production volume was estimated to be about 3 million tonnes per year.

<span class="mw-page-title-main">Group 5 element</span> Group of elements in the periodic table

Group 5 is a group of elements in the periodic table. Group 5 contains vanadium (V), niobium (Nb), tantalum (Ta) and dubnium (Db). This group lies in the d-block of the periodic table. This group is sometimes called the vanadium group or vanadium family after its lightest member; however, the group itself has not acquired a trivial name because it belongs to the broader grouping of the transition metals.

Sulfur trioxide (alternative spelling sulphur trioxide, also known as nisso sulfan) is the chemical compound with the formula SO3. It has been described as "unquestionably the most [economically important]" sulfur oxide. It is prepared on an industrial scale as a precursor to sulfuric acid.

<span class="mw-page-title-main">Calcium sulfate</span> Laboratory and industrial chemical

Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water. Calcium sulfate causes permanent hardness in water.

An acidic oxide is an oxide that either produces an acidic solution upon addition to water, or acts as an acceptor of hydroxide ions effectively functioning as a Lewis acid. Acidic oxides will typically have a low pKa and may be inorganic or organic. A commonly encountered acidic oxide, carbon dioxide produces an acidic solution when dissolved.

The contact process is the current method of producing sulfuric acid in the high concentrations needed for industrial processes. Platinum was originally used as the catalyst for this reaction; however, as it is susceptible to reacting with arsenic impurities in the sulfur feedstock, vanadium(V) oxide (V2O5) is now preferred.

<span class="mw-page-title-main">Maleic anhydride</span> Chemical compound

Maleic anhydride is an organic compound with the formula C2H2(CO)2O. It is the acid anhydride of maleic acid. It is a colorless or white solid with an acrid odor. It is produced industrially on a large scale for applications in coatings and polymers.

<span class="mw-page-title-main">Vanadate</span> Coordination complex of vanadium

In chemistry, a vanadate is an anionic coordination complex of vanadium. Often vanadate refers to oxoanions of vanadium, most of which exist in its highest oxidation state of +5. The complexes [V(CN)6]3− and [V2Cl9]3− are referred to as hexacyanovanadate(III) and nonachlorodivanadate(III), respectively.

<span class="mw-page-title-main">Vanadium oxytrichloride</span> Chemical compound

Vanadium oxytrichloride is the inorganic compound with the formula VOCl3. This yellow distillable liquid hydrolyzes readily in air. It is an oxidizing agent. It is used as a reagent in organic synthesis. Samples often appear red or orange owing to an impurity of vanadium tetrachloride.

<span class="mw-page-title-main">Ammonium metavanadate</span> Chemical compound

Ammonium metavanadate is the inorganic compound with the formula NH4VO3. It is a white salt, although samples are often yellow owing to impurities of V2O5. It is an important intermediate in the purification of vanadium.

<span class="mw-page-title-main">Vanadium(III) chloride</span> Chemical compound

Vanadium(III) chloride describes the inorganic compound with the formula VCl3 and its hydrates. It forms a purple anhydrous form and a green hexahydrate [VCl2(H2O)4]Cl·2H2O. These hygroscopic salts are common precursors to other vanadium(III) complexes and is used as a mild reducing agent.

<span class="mw-page-title-main">Vanadium compounds</span>

Vanadium compounds are compounds formed by the element vanadium (V). The chemistry of vanadium is noteworthy for the accessibility of the four adjacent oxidation states 2–5, whereas the chemistry of the other group 5 elements, niobium and tantalum, are somewhat more limited to the +5 oxidation state. In aqueous solution, vanadium forms metal aquo complexes of which the colours are lilac [V(H2O)6]2+, green [V(H2O)6]3+, blue [VO(H2O)5]2+, yellow-orange oxides [VO(H2O)5]3+, the formula for which depends on pH. Vanadium(II) compounds are reducing agents, and vanadium(V) compounds are oxidizing agents. Vanadium(IV) compounds often exist as vanadyl derivatives, which contain the VO2+ center.

<span class="mw-page-title-main">Sodium decavanadate</span> Chemical compound

Sodium decavanadate describes any member of the family of inorganic compounds with the formula Na6[V10O28](H2O)n. These are sodium salts of the orange-colored decavanadate anion [V10O28]6−. Numerous other decavanadate salts have been isolated and studied since 1956 when it was first characterized.

<span class="mw-page-title-main">Vanadyl perchlorate</span> Chemical compound

Vanadyl perchlorate or vanadyl triperchlorate is a golden yellow coloured liquid or crystalline compound of vanadium, oxygen and perchlorate group. The substance consists of molecules covalently bound and is quite volatile; it ignites organic solvents on contact and explodes at temperatures above 80 °C.

<span class="mw-page-title-main">Pervanadyl</span> Chemical compound

Pervanadyl (VO+2) is a pale yellow oxycation of vanadium(V). It is the predominant vanadium(V) species in acidic solutions with pH between 0 and 2, and its salts are formed by protonation of vanadium(V) oxide in such solutions:

References

  1. ↑ Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. p. B-162. ISBN   0-8493-0462-8..
  2. 1 2 3 4 Haynes, p. 4.94
  3. ↑ Haynes, p. 4.131
  4. ↑ Shklover, V.; Haibach, T.; Ried, F.; Nesper, R.; Novak, P. (1996), "Crystal structure of the product of Mg2+ insertion into V2O5 single crystals", J. Solid State Chem., 123 (2): 317–23, Bibcode:1996JSSCh.123..317S, doi:10.1006/jssc.1996.0186 .
  5. ↑ Haynes, p. 5.41
  6. 1 2 "Vanadium dust". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  7. 1 2 NIOSH Pocket Guide to Chemical Hazards. "#0653". National Institute for Occupational Safety and Health (NIOSH).
  8. 1 2 3 Bauer, Günter; Güther, Volker; Hess, Hans; Otto, Andreas; Roidl, Oskar; Roller, Heinz; Sattelberger, Siegfried (2000). "Vanadium and Vanadium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a27_367. ISBN   3-527-30673-0.
  9. ↑ Brauer, p. 1267
  10. 1 2 3 Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. pp. 1140, 1144. ISBN   978-0-08-022057-4..
  11. ↑ Brauer, p. 1264
  12. ↑ "The oxidation states of vanadium". RSC Education. Retrieved 2019-10-04.
  13. ↑ Brauer, p. 1269
  14. ↑ "Gibbs-Wohl Naphthalene Oxidation". Comprehensive Organic Name Reactions and Reagents. 2010. pp. 1227–1229. doi:10.1002/9780470638859.conrr270. ISBN   978-0-470-63885-9.
  15. ↑ Tedder, J. M.; Nechvatal, A.; Tubb, A. H., eds. (1975), Basic Organic Chemistry: Part 5, Industrial Products, Chichester, UK: John Wiley & Sons.
  16. ↑ Conant, James; Blatt, Albert (1959). The Chemistry of Organic Compounds (5th ed.). New York, New York: The Macmillan Company. p. 511.
  17. ↑ REDT Energy Storage. "Using VRFB for Renewable applications".
  18. ↑ Sreejesh, M.; Shenoy, Sulakshana; Sridharan, Kishore; Kufian, D.; Arof, A. K.; Nagaraja, H. S. (2017). "Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications". Applied Surface Science. 410: 336–343. Bibcode:2017ApSS..410..336S. doi:10.1016/j.apsusc.2017.02.246.

Cited sources

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