Cobalt sulfide

Source: Wikipedia, the free encyclopedia.
Cobalt sulfide
Identifiers
RTECS number
  • GG332500
UNII
Properties
CoxSy
Molar mass 90.9982 g/mol
Appearance black solid (alpha)
grayish-red crystals (beta)
Density 5.45 g/cm3
Melting point 1195 °C
0.00038 g/100 mL (18 °C)
Solubility slightly soluble in acid
+225.0·10−6 cm3/mol
Structure
octahedral (beta)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cobalt sulfide is the name for

semiconducting, insoluble in water, and nonstoichiometric.[1]

Minerals and hydrometallurgy

Cobalt sulfides occur widely as minerals, comprising major sources of all cobalt compounds. Binary cobalt sulfide minerals include the cattierite (CoS2) and linnaeite (Co3S4). CoS2 (see image in table) is isostructural with iron pyrite, featuring disulfide groups, i.e. Co2+S22−. Linnaeite, also rare, adopts the spinel motif.[2] The Co9S8 compound is known as a very rare cobaltpentlandite (the Co analogue of pentlandite).[3] Mixed metal sulfide minerals include carrollite (CuCo2S4) and siegenite (Co3−xNixS4).

CoS is known as jaipurite. However, this species is questionable.[4][5]

Cobalt sulfide minerals are converted to cobalt via roasting and extraction into aqueous acid. In some processes, cobalt salts are purified by precipitation when aqueous solutions of cobalt(II) ions are treated with hydrogen sulfide. Not only is this reaction useful in the purification of cobalt from its ores, but also in qualitative inorganic analysis.[1]

Applications and research

In combination with molybdenum, the sulfides of cobalt are used as catalysts for the industrial process called hydrodesulfurization, which is implemented on a large scale in refineries. Synthetic cobalt sulfides are widely investigated as electrocatalysts.[6]

Selected literature

References