Cuprospinel
Encyclopedia
Cuprospinel, occurs naturally in Baie Verte
Baie Verte, Newfoundland and Labrador
Baie Verte is a town located on the northeast coast of the island portion of the Canadian province of Newfoundland and Labrador on the Baie Verte Peninsula.-Geography:...

, Newfoundland
Newfoundland and Labrador
Newfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400...

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

. The mineral was found in an exposed ore
Ore
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....

 dump, on the property of Consolidated Rambler Mines Limited near Baie Verte, Newfoundland. The mineral was first characterized by Ernest Henry Nickel, a mineralogist with the Department of Energy, Mines and Resources in Australia, in 1973.

Cuprospinel, is an inverse spinel
Spinel
Spinel is the magnesium aluminium member of the larger spinel group of minerals. It has the formula MgAl2O4. Balas ruby is an old name for a rose-tinted variety.-Spinel group:...

 with the formula CuFe2O4, where copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 substitutes some of the iron cations in the structure. Its structure is similar to that of magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...

, Fe3O4, yet with slightly different chemical and physical properties due to the presence of copper.

Structural properties

Cuprospinel, like many other spinels has the general formula AB2O4. Yet, cuprospinel is an inverse spinel in that its A element, in this case copper (Cu2+), only occupies octahedral sites
Octahedral molecular geometry
In chemistry, octahedral molecular geometry describes the shape of compounds where in six atoms or groups of atoms or ligands are symmetrically arranged around a central atom, defining the vertices of an octahedron...

 in the structure and the B element, iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 (Fe2+ and Fe3+), is split between the octahedral and tetrahedral sites
Tetrahedral molecular geometry
In a tetrahedral molecular geometry a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos−1 ≈ 109.5° when all four substituents are the same, as in CH4. This molecular geometry is common throughout the first...

 in the structure. The Fe2+ species will occupy some of the octahedral sites and there will only be Fe3+ at the tetrahedral sites. Cuprospinel adopts both cubic
Cubic crystal system
In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals....

 and tetragonal
Tetragonal crystal system
In crystallography, the tetragonal crystal system is one of the 7 lattice point groups. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a square base and height .There are two tetragonal Bravais...

 phases at room temperature
Room temperature
-Comfort levels:The American Society of Heating, Refrigerating and Air-Conditioning Engineers has listings for suggested temperatures and air flow rates in different types of buildings and different environmental circumstances. For example, a single office in a building has an occupancy ratio per...

, yet as temperature is elevated the cubic form is most stable.

Uses

Cuprospinel is used in various industrial processes as a catalyst. An example is the water gas shift reaction
Water gas shift reaction
The water-gas shift reaction is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen:The water-gas shift reaction is an important industrial reaction. It is often used in conjunction with steam reforming of methane or other hydrocarbons, which is...

:
H2O(v) + CO(g) → CO2(g) + H2(g)

This reaction is particularly important for hydrogen production
Hydrogen production
Hydrogen production is the family of industrial methods for generating hydrogen. Currently the dominant technology for direct production is steam reforming from hydrocarbons. Many other methods are known including electrolysis and thermolysis...

 and enrichment.

The interest of cuprospinel arises in that magnetite is a widely used catalyst for many industrial chemical reactions, such as the Fischer-Tropsch process
Fischer-Tropsch process
The Fischer–Tropsch process is a set of chemical reactions that convert a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. The process, a key component of gas to liquids technology, produces a petroleum substitute, typically from coal, natural gas, or biomass for use as synthetic...

, the Haber-Bosch process and the Water gas shift reaction
Water gas shift reaction
The water-gas shift reaction is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen:The water-gas shift reaction is an important industrial reaction. It is often used in conjunction with steam reforming of methane or other hydrocarbons, which is...

. It has been shown that doping magnetite with other elements gives it different chemical and physical properties, these different properties sometimes allow the catalyst to work more efficiently. As such, cuprospinel is essentially magnetite doped with copper and this enhances magnetite's water gas shift properties as a heterogeneous catalyst.
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