Strunz classification 4.BB.05 | Crystal system Isometric | |
Category Oxide mineral
Spinel group Formula
(repeating unit) CuFe2O4 or (Cu,Mg)Fe2O4 Crystal class Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m) Space group Cubic
Space group: Fd3m | ||
Cuprospinel, occurs naturally in Baie Verte, Newfoundland, Canada. The mineral was found in an exposed ore 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.
Contents
Cuprospinel, is an inverse spinel with the formula CuFe2O4, where copper substitutes some of the iron cations in the structure. Its structure is similar to that of magnetite, 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 in the structure and the B element, iron (Fe2+ and Fe3+), is split between the octahedral and tetrahedral sites 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 and tetragonal phases at room temperature, 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:
H2O(v) + CO(g) → CO2(g) + H2(g)This reaction is particularly important for hydrogen production 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, the Haber–Bosch process and the water-gas shift reaction. 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.