12018-10-9

fine brown to black powder

Grayish-black tetragonal crystals; density 5.4 g/cm³. When heated to elevated temperatures (above 900°C) copper(II) chromite decomposes to cupric chromate(II), CuCrO₂ and chromium (VI) oxide, CrO₃. Copper(II) chromite is insoluble in water and dilute acids.

Copper chromite is used as a hydrogenation catalyst.

Copper chromite is primarily used as a catalyst forhydrogenation reactions because of its ability to hydrogenate functional groupsin aliphatic and aromatic compounds selectively. Industrially, copper chromiteis used to reduce furfural to furfuryl alcohol and butyraldehyde to 1-butanol,partially reduce conjugated dienes to monoenes, and selectively reduce carbonylgroups in vegetable oils. This CuCr catalyst is studied for a variety ofcatalytic applications including converting the hydrogenolysis of cellulose.It is also used as a catalyst for combustion to help control burn rate and as alight-absorbing pigment.

Copper(II) chromite is obtained by heating copper chromate, CuCrO₄ at 400°C. The Adkin catalyst, a mixture of copper oxide and copper chromite, is prepared by mixing aqueous solutions of copper nitrate, sodium dichromate and ammonium hydroxide; the orange precipitate of copper ammonium chromate formed is dried and then heated below 400°C.

Copper chromite is a black powder and inorganic pigment thatadopts a spinel crystal structure. It can be made by the high-temperaturecalcination of copper(II) oxide and chromium(III) oxide or the thermaldecomposition of copper chromate, which evolves oxygen at higher temperaturesand decomposes to copper chromite.