Vanadium(IV) oxide

Vanadium dioxide

Dark green black solid

Fixed

4.34 g · cm -3

1970 ° C

Insoluble in water

Attention

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Vanadium ( IV) oxide is one of several oxides of vanadium. It is a high-melting, black solid. Vanadium ( IV) oxide plays an important role in the catalytic conversion of sulfur dioxide to sulfur trioxide in the contact process for the production of sulfuric acid.

Production and representation

Vanadium (IV ) oxide can be produced from vanadium ( V) oxide win. This transforms itself when heated with weak reducing agents such as carbon monoxide, sulfur dioxide or oxalic acid in vanadium (IV ) oxide:

Properties

Physical Properties

Vanadium ( IV) oxide has two different modifications which are converted at 70 ° C each other. Below 70 ° C it has a distorted rutile structure in which two vanadium atoms are linked by a bond. Above 70 ° C to break these bonds. Here, an undistorted rutile structure is formed. Simultaneously, the electrical conductivity and the paramagnetic significantly increased.

Chemical Properties

Vanadium (IV) oxide, such as titanium (IV ) oxide, amphoteric, it dissolves both in strong acids, as well as strong bases. With acids it forms [VO (H2O ) 5] 2 ions, with bases [VO (OH ) 3] - ions.

Use

During the production of sulfuric acid by the contact method is produced by a oxygen ion transfer from vanadium ( V) oxide on the sulfur dioxide vanadium ( IV) oxide. The recovery of vanadium anhydride (V ) oxide is carried out by oxidation with oxygen.

Due to the conversion between the different phases can be used (IV ) oxide, vanadium as an optical switch. It converts at 68 ° C in a short time by a transparent and semiconducting in a reflective and conductive state to. By introducing small amounts of tungsten in vanadium dioxide, the transition temperature can be lowered to about 29 ° C, making it suitable for the oxide heat- resistant coating of glass surfaces.