Copper chromite

Copper chromite is an inorganic compound with the formula Cu₂Cr₂O₅ which is used to catalyze reactions in organic synthesis.

The material was first described in 1908. The catalyst was developed in North America by Homer Burton Adkins and Wilbur Arthur Lazier partly based on interrogation of German chemists after World War II in relation to the Fischer-Tropsch process. For this reason it is sometimes referred to as the Adkins catalyst or the Lazier catalyst.

The compound commonly adopts a spinel structure. The oxidation states for the constituent metals are Cu(II) and Cr(III). A variety of compositions are recognized for the substance, including Cr₂CuO₄·CuO·BaCrO₄ (CAS# 99328-50-4) and Cr₂Cu₂O₅ (CAS# 12053-18-8). Commercial samples often contain barium oxide and other components.

Copper chromite is produced by thermal decomposition of one of three substances. The traditional method is by the uncatalyzed ignition of copper chromate:

Copper barium ammonium chromate is the most commonly used substance for production of copper chromite. The resulting copper chromite mixture produced by this method can only be used in procedures that contain materials inert to barium, as barium is a product of the decomposition of copper barium ammonium chromate, and is thus present in the resulting mixture. The by-product copper oxide is removed using an acetic acid extraction, consisting of washing with the acid, decantation and then heat drying of the remaining solid to yield isolated copper chromite. Copper chromite is produced by the exposure of copper barium ammonium chromate to temperatures of 350-450 °C, generally by a muffle furnace: