Copper chromite often refers to

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

s with the formula . They are black solids. is a well-defined material. The other copper chromite often is described as . It is used to catalyze reactions in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

History

Copper chromite was first described in 1908. The catalyst was further developed by Homer Burton Adkins and Wilbur Arthur Lazier, partly based on interrogation of

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

chemists after

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

in relation to the

Fischer–Tropsch process The Fischer–Tropsch process (FT) is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons. These reactions occur in the presence of metal catalysts, typically at te ...

. For this reason it is sometimes referred to as the Adkins catalyst or the Lazier catalyst. Adkins was the first to incorporate barium into the structure, which prevents the catalyst from being reduced to an inactive form during hydrogenation reactions.

Chemical structures

The stoichiometry of the Laziar or Adkins catalyst is not well defined, thus the structure of their material is not defined either. The

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical Electrical charge, charge of an atom if all of its Chemical bond, bonds to other atoms are fully Ionic bond, ionic. It describes the degree of oxidation (loss of electrons ...

s for the constituent metals in Cu₂Cr₂O₄ are Cu(II) and Cr(III). A variety of compositions are recognized for the substance, including Cu₂CrO₄·CuO·BaCrO₄ ( CAS# 99328-50-4), Cu₂Cr₂O₅ (CAS# 12053-18-8), and Cr₂CuO₄. Commercial samples often contain barium oxide and other components.

Production

Copper chromites catalyst are produced by

thermal decomposition Thermal decomposition, or thermolysis, is a chemical decomposition of a substance caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic ...

of diverse precursors. The traditional method is by the

calcining Calcination is thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), generally fo ...

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 Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Th ...

, 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 Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...

extraction, consisting of washing with the acid,

decantation Decantation is a process for the separation of mixtures of miscible, immiscible liquids or of a liquid and a solid mixture such as a Suspension (chemistry), suspension. The layer closer to the top of the container—the less density, dense of th ...

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 A muffle furnace or muffle oven (sometimes retort furnace in historical usage) is a furnace in which the subject material is isolated from the fuel and all of the products of combustion, including gases and flying ash. After the development of ...

: : → + CuO + 2 Ba + 4 + 4 Cr + + 6 Copper ammonium chromate is also used for production of copper chromite. It is generally utilized as an alternative to the route of barium ammonium chromate for usage in chemicals reactive with barium. This can also be washed with acetic acid and dried to remove impurities. Copper chromite is produced through the exposure of copper ammonium chromate to temperatures of 350-450 °C: : → + CrO + 4 + An active copper chromite catalyst which includes

in its structure can be prepared from a solution containing

barium nitrate Barium nitrate is the inorganic compound with the chemical formula Ba( NO3)2. It, like most barium salts, is colorless, toxic, and water-soluble. It burns with a green flame and is an oxidizer; the compound is commonly used in pyrotechnics. Ma ...

copper(II) nitrate Copper(II) nitrate describes any member of the family of inorganic compounds with the formula Cu( NO3)2(H2O)x. The hydrates are hygroscopic blue solids. Anhydrous copper nitrate forms blue-green crystals and sublimes in a vacuum at 150-200 ° ...

, and ammonium chromate. When these compounds are mixed a resulting precipitate is formed. This solid product is then

calcine Calcination is thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), generally for ...

d at 350–400 °C to yield the catalyst: : Cu(NO₃)₂ + Ba(NO₃)₂ + (NH₄)₂CrO₄ → CuCr₂O₄·BaCr₂O₄

Illustrative reactions

Hydrogenolysis Hydrogenolysis is a chemical reaction whereby a carbon–carbon or carbon–heteroatom single bond is cleaved or undergoes lysis (breakdown) by hydrogen.Ralph Connor, Homer Adkins. Hydrogenolysis Of Oxygenated Organic Compounds. J. Am. Chem. Soc. ...

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

compounds to the corresponding

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

s. This approach is useful for conversion of fatty acid esters, such as

fatty acid methyl ester Fatty acid methyl esters (FAME) are a type of fatty acid ester that are derived by transesterification of fats with methanol. The molecules in biodiesel are primarily FAME, usually obtained from vegetable oils by transesterification. They are u ...

s (FAMEs) to

fatty alcohol Fatty alcohols (or long-chain alcohols) are usually high-molecular mass, straight-chain primary alcohols, but can also range from as few as 4–6 carbon atoms to as many as 22–26, derived from natural fats and oils. The precise chain length vari ...

s: : In some cases, alkene groups are hydrogenated. * Diethyl maleate can similarly be hydrogenated to either butyrolactone or 1,4-butanediol, depending on conditions. *Sebacoin, derived from the acyloin condensation of dimethyl sebacate, is hydrogenated to 1,2-cyclodecanediol in the presence of this catalyst. *

Phenanthrene Phenanthrene is a polycyclic aromatic hydrocarbon (PAH) with formula C14H10, consisting of three fused benzene rings. It is a colorless, crystal-like solid, but can also appear yellow. Phenanthrene is used to make dyes, plastics, pesticides, expl ...

is reduced at the 9,10 position. *

of tetrahydrofurfuryl alcohol to 1,5-pentanediol at 250–300 °C under 3300-6000 psi of H₂. *

Decarboxylation Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is ...

of α-phenylcinnamic acid to ''cis''-

stilbene Stilbene may refer to one of the two stereoisomers of 1,2-diphenylethene: * (''E'')-Stilbene (''trans'' isomer) * (''Z'')-Stilbene (''cis'' isomer) See also * Stilbenoid Stilbenoids are hydroxylated derivatives of stilbene. They have a C6–C ...

. Reactions involving hydrogen are conducted at relatively high gas pressure (135 atm) and high temperatures (150–300 °C) in a so-called hydrogenation bomb. More active catalysts, such as W-6 grade

Raney nickel Raney nickel , also called spongy nickel, is a fine-grained solid composed mostly of nickel derived from a nickel–aluminium alloy. Several grades are known, of which most are gray solids. Some are pyrophoric, but most are used as air-stable s ...

, also catalyze hydrogenations such as ester reductions. The latter catalyst benefits from requiring less vigorous conditions (i.e., it works at room temperature under similar hydrogenation pressures) but requires a higher ratio of catalyst to

reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

References

External links

* CAS registry 440-47-3& 317-38-0 {{Organic reactions Reagents for organic chemistry Copper(II) compounds Hydrogenation catalysts Chromium(III) compounds Chromium–oxygen compounds Substances discovered in the 1900s