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Vanadium(V) oxide (''vanadia'') is the
inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemis ...
with the
formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...
V2 O5. 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 In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
, it is both an
amphoteric In chemistry, an amphoteric compound () is a molecule or ion that can react both as an acid and as a base. What exactly this can mean depends on which definitions of acids and bases are being used. One type of amphoteric species are amphipro ...
oxide and an
oxidizing agent An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...
. From the industrial perspective, it is the most important compound of
vanadium Vanadium is a chemical element with the 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 ( pass ...
, being the principal precursor to alloys of vanadium and is a widely used industrial catalyst. The mineral form of this compound, shcherbinaite, is extremely rare, almost always found among
fumaroles A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcan ...
. 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 Vanadium(III) oxide is the inorganic compound with the formula V2O3. It is a black solid prepared by reduction of V2O5 with hydrogen or carbon monoxide. It is a basic oxide dissolving in acids to give solutions of vanadium (III) complexes. V2O3 ...
,
comproportionation Comproportionation or synproportionation is a chemical reaction where two reactants containing the same element but with different oxidation numbers, form a compound having an intermediate oxidation number. It is the opposite of disproportionation. ...
occurs to give
vanadium(IV) oxide Vanadium(IV) oxide or vanadium dioxide is an inorganic compound with the formula VO2. It is a dark blue solid. Vanadium(IV) dioxide is amphoteric, dissolving in non-oxidising acids to give the blue vanadyl ion, Osup>2+ and in alkali to give the b ...
, as a deep-blue solid: :V2O5 + V2O3 → 4 VO2 The reduction can also be effected by
oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early invest ...
,
carbon monoxide Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simpl ...
, and
sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic a ...
. Further reduction using
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...
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 In chemistry, an amphoteric compound () is a molecule or ion that can react both as an acid and as a base. What exactly this can mean depends on which definitions of acids and bases are being used. One type of amphoteric species are amphipro ...
oxide. Unlike most 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 In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...
to form polyoxovanadates, which have a complex structure that depends on pH.. If excess aqueous
sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and al ...
is used, the product is a colourless
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
,
sodium orthovanadate Sodium orthovanadate is the inorganic compound with the chemical formula . It forms a dihydrate . Sodium orthovanadate is a salt of the oxyanion. It is a colorless, water-soluble solid. Synthesis and structure Sodium orthovanadate is produced by ...
, 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 Sodium decavanadate describes any member of the family of inorganic compounds with the formula Na6 10O28H2O)n. These are sodium salts of the orange-colored decavanadate anion 10O28sup>6−. Numerous other decavanadate salts have been isolated and ...
) predominate. Upon treatment with
thionyl chloride Thionyl chloride is an inorganic compound with the chemical formula . It is a moderately volatile, colourless liquid with an unpleasant acrid odour. Thionyl chloride is primarily used as a chlorinating reagent, with approximately per year bein ...
, it converts to the volatile liquid
vanadium oxychloride 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 ...
, VOCl3: :V2O5 + 3 SOCl2 → 2 VOCl3 + 3 SO2


Other redox reactions

Hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dige ...
and
hydrobromic acid Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at and contains 47.6% HBr by mass, which is 8.77 mol/L. ...
are oxidised to the corresponding
halogen The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this grou ...
, e.g., :V2O5 + 6HCl + 7H2O → 2 O(H2O)5sup>2+ + 4Cl + Cl2
Vanadates Vanadates can refer to: * Ammonium vanadate (disambiguation) Ammonium vanadate may refer to: * Ammonium metavanadate (ammonium trioxovanadate(V)), NH4VO3 * Ammonium orthovanadate (ammonium tetraoxovanadate(V)), (NH4)3VO4, a compound related to ...
or vanadyl compounds in acid solution are reduced by zinc amalgam through the colourful pathway: The ions are all hydrated to varying degrees.


Preparation

Technical grade V2O5 is produced as a black powder used for the production of
vanadium Vanadium is a chemical element with the 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 ( pass ...
metal and
ferrovanadium Ferrovanadium (FeV) is an alloy formed by combining iron and vanadium with a vanadium content range of 35–85%. The production of this alloy results in a grayish silver crystalline solid that can be crushed into a powder called "ferrovanadium ...
. A vanadium ore or vanadium-rich residue is treated with
sodium carbonate Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...
and an
ammonium The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaterna ...
salt to produce
sodium metavanadate Sodium metavanadate is the inorganic compound with the formula NaVO3. It is a yellow, water-soluble salt. Sodium metavanadate is a common precursor to other vanadates. At low pH it converts to sodium decavanadate. It is also precursor to exoti ...
, 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 Vanadium is a chemical element with the 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 ( pass ...
metal is heated with excess
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
, but this product is contaminated with other, lower oxides. A more satisfactory laboratory preparation involves the decomposition of
ammonium metavanadate 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.Günter Bauer, Volker Gü ...
at 500–550 °C: :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 Ferrovanadium (FeV) is an alloy formed by combining iron and vanadium with a vanadium content range of 35–85%. The production of this alloy results in a grayish silver crystalline solid that can be crushed into a powder called "ferrovanadium ...
(see above). The oxide is heated with scrap
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
and
ferrosilicon Ferrosilicon is an alloy of iron and silicon with a typical silicon content by weight of 15–90%. It contains a high proportion of iron silicides. Production and reactions Ferrosilicon is produced by reduction of silica or sand with coke in t ...
, with lime added to form a
calcium silicate Calcium silicate is the chemical compound Ca2SiO4, also known as calcium orthosilicate and is sometimes formulated as 2CaO·SiO2. It is also referred to by the shortened trade name Cal-Sil or Calsil. It occurs naturally as the mineral larnite. ...
slag Slag is a by-product of smelting ( pyrometallurgical) ores and used metals. Broadly, it can be classified as ferrous (by-products of processing iron and steel), ferroalloy (by-product of ferroalloy production) or non-ferrous/base metals (by-p ...
.
Aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...
may also be used, producing the iron-vanadium alloy along with alumina as a


Sulfuric acid production

Another important use of vanadium(V) oxide is in the manufacture of
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
, 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 In thermodynamics, an exothermic process () is a thermodynamic process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity ...
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...
of sulfur dioxide to
sulfur trioxide 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 important economically" sulfur oxide. It is prepared on an ind ...
by air in the
contact process 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 ...
: :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 Selective catalytic reduction (SCR) is a means of converting nitrogen oxides, also referred to as with the aid of a catalyst into diatomic nitrogen (), and water (). A reductant, typically anhydrous ammonia (), aqueous ammonia (), or a urea () s ...
(SCR) of NO''x'' emissions in some
power plant A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many ...
s 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

Maleic anhydride 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 pol ...
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 Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natura ...
resins and alkyd resins.
Phthalic anhydride 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 commer ...
is produced similarly by V2O5-catalysed oxidation of ortho-xylene or
naphthalene Naphthalene is an organic compound with formula . 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 aromat ...
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: :C10H8 + 4½ O2 → C6H4(CO)2O + 2CO2 + 2H2O Phthalic anhydride is a precursor to
plasticiser A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticize ...
s, used for conferring pliability to polymers. A variety of other industrial compounds are produced similarly, including
adipic acid Adipic acid or hexanedioic acid is the organic compound with the formula (CH2)4(COOH)2. From an industrial perspective, it is the most important dicarboxylic acid: about 2.5 billion kilograms of this white crystalline powder are produced annuall ...
,
acrylic acid Acrylic acid (IUPAC: propenoic acid) is an organic compound with the formula CH2=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has a ...
,
oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early invest ...
, and
anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxoan ...
.


Other applications

Due to its high coefficient of
thermal resistance Thermal resistance is a heat property and a measurement of a temperature difference by which an object or material resists a heat flow. Thermal resistance is the reciprocal of thermal conductance. * (Absolute) thermal resistance ''R'' in kelvi ...
, vanadium(V) oxide finds use as a detector material in
bolometer A bolometer is a device for measuring radiant heat by means of a material having a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley. Principle of operation A bolometer ...
s and microbolometer arrays for
thermal imaging Infrared thermography (IRT), thermal video and/or thermal imaging, is a process where a thermal camera captures and creates an image of an object by using infrared radiation emitted from the object in a process, which are examples of infrared ...
. 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 A flow battery, or redox flow battery (after reduction–oxidation), is a type of electrochemical cell where chemical energy is provided by two chemical components dissolved in liquids that are pumped through the system on separate sides of a ...
used for
energy storage Energy storage is the capture of energy produced at one time for use at a later time to reduce imbalances between energy demand and energy production. A device that stores energy is generally called an accumulator or battery. Energy comes in ...
, including large power facilities such as
wind farm A wind farm or wind park, also called a wind power station or wind power plant, is a group of wind turbines in the same location used to produce electricity. Wind farms vary in size from a small number of turbines to several hundred wind turb ...
s. Vanadium oxide is also used as a cathode in lithium ion batteries.


Biological activity

Vanadium(V) oxide exhibits very modest acute toxicity to humans, with an
LD50 In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is the ...
of about 470 mg/kg. The greater hazard is with inhalation of the dust, where the
LD50 In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is the ...
ranges from 4–11 mg/kg for a 14-day exposure. Vanadate (), formed by hydrolysis of V2O5 at high pH, appears to inhibit enzymes that process phosphate (PO43−). However the mode of action remains elusive.


References


Cited sources

* *


Further reading

*. *.


External links


How Vanadium Oxide Is Used In Energy Storage
* * *

(
Concise International Chemical Assessment Document Concise International Chemical Assessment Documents (CICADs) are published by the World Health Organization within the framework of the International Programme on Chemical Safety (IPCS). They describe the toxicological properties of chemical compoun ...
29) * * {{DEFAULTSORT:Vanadium(V) Oxide Vanadium(V) compounds Catalysts Infrared sensor materials IARC Group 2B carcinogens Oxidizing agents Transition metal oxides