Raney nickel
Overview
 
Raney nickel is a solid catalyst composed of fine grains of a nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

-aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

, used in many industrial processes. It was developed in 1926 by American]] engineer Murray Raney
Murray Raney
Murray Raney was an American mechanical engineer born in Carrollton, Kentucky. He was the developer of a nickel catalyst that became known as Raney nickel, which is often used in industrial processes and scientific research for the hydrogenation of multiple covalent bonds present in...

 as an alternative catalyst for the hydrogenation
Hydrogenation
Hydrogenation, to treat with hydrogen, also a form of chemical reduction, is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically...

 of vegetable oils in industrial processes. More recently it is used as a heterogeneous catalyst
Catalysis
Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 in a variety of organic syntheses
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

, most commonly for hydrogenation reactions.

Raney nickel is produced when a block of nickel-aluminium alloy is treated with concentrated sodium hydroxide.
Encyclopedia
Raney nickel is a solid catalyst composed of fine grains of a nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

-aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

, used in many industrial processes. It was developed in 1926 by American]] engineer Murray Raney
Murray Raney
Murray Raney was an American mechanical engineer born in Carrollton, Kentucky. He was the developer of a nickel catalyst that became known as Raney nickel, which is often used in industrial processes and scientific research for the hydrogenation of multiple covalent bonds present in...

 as an alternative catalyst for the hydrogenation
Hydrogenation
Hydrogenation, to treat with hydrogen, also a form of chemical reduction, is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically...

 of vegetable oils in industrial processes. More recently it is used as a heterogeneous catalyst
Catalysis
Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 in a variety of organic syntheses
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

, most commonly for hydrogenation reactions.

Raney nickel is produced when a block of nickel-aluminium alloy is treated with concentrated sodium hydroxide. This treatment, called "activation", dissolves most of the aluminium out of the alloy. The porous structure left behind has a large surface area, which gives high catalytic activity. The ratio of nickel to aluminium is around 1 for the original material used by Raney, and may vary from about 1 to 4.

Since Raney is a registered trademark of W. R. Grace and Company
W. R. Grace and Company
W. R. Grace and Company is a Columbia, Maryland, United States based chemical conglomerate.The company has two main divisions, Davison Chemicals and Performance Chemicals. The Davison unit makes chemical catalysts, refining catalysts, and silica-based products that let other companies make...

, only those products by its Grace Davison division are properly called "Raney nickel". The more generic terms "skeletal catalyst" or "sponge-metal catalyst" may be used to refer to catalysts that have physical and chemical properties similar to those of Raney nickel. However, since the Grace company itself does not use any generic names for the catalysts it is supplying, "Raney" may become generic under U. S. trademark law.

Alloy preparation

Alloys are prepared commercially by melting the active metal (nickel in this case, but iron and copper "Raney-type" catalysts can be prepared as well) and aluminium in a crucible
Crucible
A crucible is a container used for metal, glass, and pigment production as well as a number of modern laboratory processes, which can withstand temperatures high enough to melt or otherwise alter its contents...

 and quenching the resultant melt, which is then crushed into a fine powder. This powder may be screened for a specific particle size range, depending on the application for which the catalyst is required.

The initial alloy composition is important because the quenching process produces a number of different Ni/Al phases with different leaching properties. This may result in markedly different porosities in the end product. The most common starting alloy used in industry contains an equal amount per weight of nickel and aluminium (which is incidentally the same ratio Murray Raney used in his discovery of Raney nickel).

During the quenching procedure, small amounts of a third metal, such as zinc or chromium, may be added. This is done to enhance catalytic activity; as such, this third metal is called a "promoter". Note that the addition of a promoter changes the mixture from a binary alloy to a ternary alloy, which leads to different quenching and leaching properties during activation.

Activation

The porous structure of the catalyst arises from the selective removal of aluminium from alloy particles using concentrated sodium hydroxide solution. The simplified leaching reaction is given by the following chemical equation
Chemical equation
A chemical equation is the symbolic representation of a chemical reaction where the reactant entities are given on the left hand side and the product entities on the right hand side. The coefficients next to the symbols and formulae of entities are the absolute values of the stoichiometric numbers...

:
2 Al + 2 NaOH + 6 H2O → 2 Na[Al(OH)4] + 3 H2


The formation of sodium aluminate
Sodium aluminate
Sodium aluminate is an important commercial inorganic chemical. It works as an effective source of aluminium hydroxide for many industrial and technical applications. Pure sodium aluminate is a white crystalline solid having a formula variously given as NaAlO2, NaAl4 , Na2O·Al2O3, or Na2Al2O4...

 (Na[Al(OH)4]) requires that solutions of high concentration of sodium hydroxide be used in order to avoid the formation of aluminium hydroxide
Aluminium hydroxide
Aluminium hydroxide, Al3, ATH, sometimes erroneously called Hydrate of alumina, is found in nature as the mineral gibbsite and its three, much more rare forms, polymorphs: bayerite, doyleite and nordstrandite. Closely related are aluminium oxide hydroxide, AlO, and aluminium oxide, Al2O3,...

, which precipitates as bayerite. Hence sodium hydroxide solutions with concentrations of up to 5 molar are used. Bayerite may cause blocking of the pores formed during leaching, and with the subsequent loss of surface area, it can reduce the efficiency and activity of the catalyst.

The temperature used to leach the alloy has a marked effect on the surface properties of the catalyst. Commonly used temperatures range from 70 to 100 °C. The surface area of Raney nickel (and skeletal catalysts in general) tends to decrease with increasing leaching temperature. This is due to structural rearrangements within the alloy that may be considered analogous to sintering
Sintering
Sintering is a method used to create objects from powders. It is based on atomic diffusion. Diffusion occurs in any material above absolute zero, but it occurs much faster at higher temperatures. In most sintering processes, the powdered material is held in a mold and then heated to a temperature...

, where alloy ligaments would start adhering to each other at higher temperatures leading to the loss of the porous structure.

Before storage, the catalyst can be washed with distilled water at ambient temperature in order to remove any remaining traces of sodium aluminate. Oxygen-free (degassed) water is preferred for storage in order to prevent oxidation of the catalyst, which would accelerate its aging process and result in reduced catalytic activity.

Properties

Macroscopically, Raney nickel is a finely-divided gray powder. Microscopically, each particle of this powder is a three-dimensional mesh
Mesh
Mesh consists of semi-permeable barrier made of connected strands of metal, fiber, or other flexible/ductile material. Mesh is similar to web or net in that it has many attached or woven strands.-Types of mesh:...

, with pores of irregular size and shape of which the vast majority are created during the leaching process. Raney nickel is notable for being thermally and structurally stable as well has having a large BET
BET theory
BET theory aims to explain the physical adsorption of gas molecules on a solid surface and serves as the basis for an important analysis technique for the measurement of the specific surface area of a material...

 (Brunauer-Emmett-Teller
Edward Teller
Edward Teller was a Hungarian-American theoretical physicist, known colloquially as "the father of the hydrogen bomb," even though he did not care for the title. Teller made numerous contributions to nuclear and molecular physics, spectroscopy , and surface physics...

) surface area. These properties are a direct result of the activation process and contribute to a relatively high catalytic activity.

During the activation process, aluminium is leached out of the NiAl3 and Ni2Al3 phases that are present in the alloy, while most of the aluminium that remains does so in the form of NiAl. The removal of aluminium from some phases but not others is known as "selective leaching
Selective leaching
Selective leaching, also called dealloying, demetalification, parting and selective corrosion, is a corrosion type in some solid solution alloys, when in suitable conditions a component of the alloys is preferentially leached from the material. The less noble metal is removed from the alloy by...

". It has been shown that the NiAl phase provides the structural and thermal stability of the catalyst. As a result, the catalyst is quite resistant to decomposition ("breaking down", commonly known as "aging"). This resistance allows Raney nickel to be stored and reused for an extended period; however, fresh preparations are usually preferred for laboratory use. For this reason, commercial Raney nickel is available in both "active" and "inactive" forms.

The surface area is typically determined via a BET measurement using a gas that will be preferentially adsorbed on metallic surfaces, such as hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

. Using this type of measurement, it has been shown that almost all the exposed area in a particle of the catalyst has nickel on its surface. Since nickel is the active metal of the catalyst, a large nickel surface area implies that there is a large surface available for reactions to occur simultaneously, which is reflected in an increased catalyst activity. Commercially available Raney nickel has an average nickel surface area of 100 m2 per gram of catalyst.

A high catalytic activity, coupled with the fact that hydrogen is absorbed within the pores of the catalyst during activation, makes Raney nickel a useful catalyst for many hydrogenation
Hydrogenation
Hydrogenation, to treat with hydrogen, also a form of chemical reduction, is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically...

 reactions. Its structural and thermal stability (i.e., the fact that it does not decompose at high temperatures) allows its use under a wide range of reaction conditions. Additionally, the solubility
Solubility
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on...

 of Raney nickel is negligible in most common laboratory solvents, with the exception of mineral acid
Mineral acid
A mineral acid is an acid derived from one or more inorganic compounds. A mineral acid is not organic and all mineral acids release hydrogen ions when dissolved in water.-Characteristics:...

s such as hydrochloric acid, and its relatively high density (about 6.5 g/cm3) also facilitates its separation from a liquid phase after a reaction is completed.

Applications

Raney nickel is used in a large number of industrial processes and in organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

 because of its stability and high catalytic activity at room temperature.

Industrial applications

A practical example of the use of Raney nickel in industry is shown in the following reaction, where benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

 is reduced
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

 to cyclohexane
Cyclohexane
Cyclohexane is a cycloalkane with the molecular formula C6H12. Cyclohexane is used as a nonpolar solvent for the chemical industry, and also as a raw material for the industrial production of adipic acid and caprolactam, both of which being intermediates used in the production of nylon...

. Reduction of the benzene ring is very hard to achieve through other chemical means, but can be effected by using Raney nickel. Other heterogeneous catalysts, such as those using platinum group
Platinum group
The platinum group metals is a term used sometimes to collectively refer to six metallic elements clustered together in the periodic table.These elements are all transition metals, lying in the d-block .The six...

 element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...

s, may be used instead to similar effect, but these tend to be more expensive to produce than Raney nickel. The cyclohexane thus produced may be used in the synthesis of adipic acid
Adipic acid
Adipic acid is the organic compound with the formula 42. From the industrial perspective, it is the most important dicarboxylic acid: About 2.5 billion kilograms of this white crystalline powder are produced annually, mainly as a precursor for the production of nylon...

, a raw material used in the industrial production of polyamides such as nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...

.

Other industrial applications of Raney nickel include the conversion of:
  • Dextrose to Sorbitol
    Sorbitol
    Sorbitol, also known as glucitol, Sorbogem® and Sorbo®, is a sugar alcohol that the human body metabolizes slowly. It can be obtained by reduction of glucose, changing the aldehyde group to a hydroxyl group. Sorbitol is found in apples, pears, peaches, and prunes...

    ;
  • Nitro compounds to amines, for example, 2,4-dinitrotoluene
    Dinitrotoluene
    2,4-Dinitrotoluene or Dinitro is an organic compound with the formula C6H32. This pale yellow crystalline solid is well known as a precursor to trinitrotoluene but is mainly used in the polymer industry....

     to 2,4-toluenediamine;
  • Nitriles to amines, for example, stearonitrile to stearylamine and adiponitrile
    Adiponitrile
    Adiponitrile is the organic compound with the formula 42. This dinitrile, a viscous, colourless liquid, is an important precursor to the polymer nylon 66. In 2005, about one billion kilograms were produced annually.-Early routes:...

     to hexamethylenediamine
    Hexamethylenediamine
    Hexamethylenediamine is the organic compound with the formula H2N6NH2. The molecule is a diamine, consisting of a hexamethylene hydrocarbon chain terminated with amine functional groups. The colorless solid has a strong amine odor, similar to piperidine...

    ;
  • Olefins to paraffins, for example, sulfolene
    Sulfolene
    Sulfolene, or butadiene sulfone is a cyclic organic chemical with a sulfone functional group. It is the product of a cycloaddition between butadiene and sulfur dioxide....

     to sulfolane
    Sulfolane
    Sulfolane is a clear, colorless liquid commonly used in the chemical industry as an extractive distillation solvent or reaction solvent. Sulfolane was originally developed by the Shell Oil Company in the 1960s as a solvent to purify butadiene...

    ;
  • Acetylenes to paraffins, for example, 1,4-butynediol
    1,4-Butynediol
    1,4-Butynediol is an organic compound that is an alkyne and a diol. This yellow crystalline solid is soluble in water and ethanol.-Synthesis:1,4-Butynediol can be produced in the Reppe synthesis, where formaldehyde and acetylene are the reactants:...

     to 1,4-butanediol
    1,4-Butanediol
    1,4-Butanediol is the organic compound with the formula HOCH2CH2CH2CH2OH. This colorless viscous liquid is derived from butane by placement of alcohol groups at each end of the chain. It is one of four stable isomers of butanediol.-Synthesis:...

    .

Desulfurization

One application of Raney nickel in organic synthesis is desulfurization. For example, thioacetal
Thioacetal
Thioacetals are the sulfur analogue of acetals. They are prepared in a similar way to acetals: by reacting a thiol with an aldehyde:Dithioacetals are prepared similarly to thioacetals, which are intermediates:...

s will be reduced to hydrocarbons:

Thiol
Thiol
In organic chemistry, a thiol is an organosulfur compound that contains a carbon-bonded sulfhydryl group...

s, and sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...

s can be removed from aliphatic, aromatic, or heteroaromatic compounds. Likewise, Raney nickel will remove the sulfur of thiophene
Thiophene
Thiophene is a heterocyclic compound with the formula C4H4S. Consisting of a flat five-membered ring, it is aromatic as indicated by its extensive substitution reactions. Related to thiophene are benzothiophene and dibenzothiophene, containing the thiophene ring fused with one and two benzene...

 to give a saturated alkane
Alkane
Alkanes are chemical compounds that consist only of hydrogen and carbon atoms and are bonded exclusively by single bonds without any cycles...

.

Reduction of functional groups

It is typically used in the reduction
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

 of compounds that have multiple bonds
Molecular geometry
Molecular geometry or molecular structure is the three-dimensional arrangement of the atoms that constitute a molecule. It determines several properties of a substance including its reactivity, polarity, phase of matter, color, magnetism, and biological activity.- Molecular geometry determination...

, such as alkyne
Alkyne
Alkynes are hydrocarbons that have a triple bond between two carbon atoms, with the formula CnH2n-2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature...

s, alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s, nitrile
Nitrile
A nitrile is any organic compound that has a -C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, one example being super glue .Inorganic compounds containing the -C≡N group are not called...

s, diene
Diene
In organic chemistry a diene or diolefin is a hydrocarbon that contains two carbon double bonds.Conjugated dienes are functional groups, with a general formula of CnH2n-2. Dienes and alkynes are functional isomers...

s, aromatics and carbonyl
Carbonyl
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....

 containing compounds. Additionally, Raney nickel will reduce heteroatom-heteroatom bonds such as hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...

s, nitro
Nitro compound
Nitro compounds are organic compounds that contain one or more nitro functional groups . They are often highly explosive, especially when the compound contains more than one nitro group and is impure. The nitro group is one of the most common explosophores used globally...

 groups, and nitrosamines. It has also found use in the reductive alkylation
Alkylation
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbene . Alkylating agents are widely used in chemistry because the alkyl group is probably the most common group encountered in...

 of amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

s and the amination
Amination
Amination is the process by which an amine group is introduced into an organic molecule. Enzymes which catalyse this reaction, are termed aminases. This can occur in a number of ways including reaction with ammonia or another amine such as an alkylation, reductive amination and the Mannich reaction...

 of alcohols.

When reducing a carbon-carbon double bond, Raney nickel will add hydrogen in a syn
Syn addition
In organic chemistry, syn and anti addition are different ways in which two substituents can be added to a double bond or triple bond. This article will use alkenes as examples....

fashion.

Safety

Due to its large surface area and high volume of contained hydrogen gas, dry, activated Raney nickel is a pyrophoric material that should be handled under an inert atmosphere. Raney nickel is typically supplied as a 50% slurry
Slurry
A slurry is, in general, a thick suspension of solids in a liquid.-Examples of slurries:Examples of slurries include:* Lahars* A mixture of water and cement to form concrete* A mixture of water, gelling agent, and oxidizers used as an explosive...

 in water. Care should be taken never to expose Raney nickel to air. Even after reaction, Raney nickel contains significant amounts of hydrogen gas, and may spontaneously ignite when exposed to air.

Raney nickel will produce hazardous fumes when burning, and therefore the use of a gas mask is recommended when extinguishing fires caused by it. Additionally, acute exposure to Raney nickel may cause irritation of the respiratory tract, nasal cavities and causes pulmonary fibrosis
Pulmonary fibrosis
Pulmonary fibrosis is the formation or development of excess fibrous connective tissue in the lungs. It is also described as "scarring of the lung".-Symptoms:Symptoms of pulmonary fibrosis are mainly:...

 if inhaled. Ingestion may lead to convulsions and intestinal disorders. It can also cause eye and skin irritation. Chronic exposure may lead to pneumonitis
Pneumonitis
Pneumonitis or pulmonitis is a general term that refers to inflammation of lung tissue.Pneumonia is pneumonitis combined with consolidation and exudation...

 and other signs of sensitization
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...

 to nickel like skin rashes ("nickel itch").
Nickel is also rated as being a possible human carcinogen
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...

 by the IARC
International Agency for Research on Cancer
The International Agency for Research on Cancer is an intergovernmental agency forming part of the World Health Organisation of the United Nations....

 (Group 2B, EU category 3
Directive 67/548/EEC
The Dangerous Substances Directive is one of the main European Union laws concerning chemical safety. It was made under Article 100 of the Treaty of Rome...

) and teratogen, while the inhalation of fine aluminium oxide
Aluminium oxide
Aluminium oxide is an amphoteric oxide with the chemical formula 23. It is commonly referred to as alumina, or corundum in its crystalline form, as well as many other names, reflecting its widespread occurrence in nature and industry...

 particles is associated with Shaver's disease. Care should be taken when handling these raw materials during laboratory preparation of Raney nickel. Moreover, activation of Raney nickel produces large amounts of hydrogen gas as a by-product, which is also highly flammable.

Development

Murray Raney
Murray Raney
Murray Raney was an American mechanical engineer born in Carrollton, Kentucky. He was the developer of a nickel catalyst that became known as Raney nickel, which is often used in industrial processes and scientific research for the hydrogenation of multiple covalent bonds present in...

 graduated as a Mechanical Engineer from the University of Kentucky
University of Kentucky
The University of Kentucky, also known as UK, is a public co-educational university and is one of the state's two land-grant universities, located in Lexington, Kentucky...

 in 1909. In 1915 he joined the Lookout Oil and Refining Company in Tennessee and was responsible for the installation of electrolytic cell
Electrolytic cell
An electrolytic cell decomposes chemical compounds by means of electrical energy, in a process called electrolysis; the Greek word lysis means to break up. The result is that the chemical energy is increased...

s for the production of hydrogen which was used in the hydrogenation
Hydrogenation
Hydrogenation, to treat with hydrogen, also a form of chemical reduction, is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically...

 of vegetable oils. During that time the industry used a nickel catalyst prepared from nickel(II) oxide
Nickel(II) oxide
Nickel oxide is the chemical compound with the formula NiO. It is notable as being the only well characterized oxide of nickel . The mineralogical form of NiO, bunsenite, is very rare. It is classified as a basic metal oxide...

. Believing that better catalysts could be produced, around 1921 he started to perform independent research while still working for Lookout Oil. In 1924 a 1:1 ratio Ni/Si
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 alloy was produced, which after treatment with sodium hydroxide, was found to be five times more active than the best catalyst used in the hydrogenation of cottonseed oil. A patent for this discovery was issued in December 1925.

Subsequently, Raney produced a 1:1 Ni/Al alloy following a procedure similar to the one used for the nickel-silicon catalyst. He found that the resulting catalyst was even more active and filed a patent application in 1926. This is the preferred alloy composition for production of Raney nickel catalysts currently in use.

Following the development of Raney nickel, other alloy systems with aluminium were considered, of which the most notable include copper, ruthenium
Ruthenium
Ruthenium is a chemical element with symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most chemicals. The Russian scientist Karl Ernst Claus discovered the element...

 and cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....

. Further research showed that adding a small amount of a third metal to the binary alloy would promote the activity of the catalyst. Some widely used promoters are zinc, molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...

 and chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...

. An alternative way of preparing enantioselective Raney nickel has been devised by surface adsorption
Adsorption
Adsorption is the adhesion of atoms, ions, biomolecules or molecules of gas, liquid, or dissolved solids to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. It differs from absorption, in which a fluid permeates or is dissolved by a liquid or solid...

 of tartaric acid
Tartaric acid
Tartaric acid is a white crystalline diprotic organic acid. It occurs naturally in many plants, particularly grapes, bananas, and tamarinds; is commonly combined with baking soda to function as a leavening agent in recipes, and is one of the main acids found in wine. It is added to other foods to...

.

See also

  • Devarda's alloy
    Devarda's alloy
    Devarda's alloy , is an alloy of aluminium , copper and zinc ....

    : Al, Cu and Zn alloy, also used to produce nascent hydrogen
    Nascent hydrogen
    Atomic hydrogen is the species denoted by H , contrasted with dihydrogen, the usual 'hydrogen' commonly involved in chemical reactions. It is claimed to exist transiently but long enough to effect chemical reactions...

  • Nickel aluminide
    Nickel aluminide
    Nickel aluminide is an intermetallic material with properties similar to both a ceramic and a metal.There are three materials called nickel aluminide:* NiAl, CAS number 12003-78-0 * NiAl3, CAS number 12004-71-6* Ni3Al-Ni3Al:...


External links

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