Catalytic Properties and Uses of Transition Elements

Catalytic Properties and Uses of Transition Elements

Many transition metals and their compounds have catalytic properties that have found great uses on the chemical industry and in laboratories. Some of the more important catalytic properties and uses of transition elements are listed here:

TiCl3Used as the Ziegler – Natta catalyst in the production of polythene.
V2O5Converts SO2 to SO3 in the Contact process for making H2SO4
MnO2Used as a catalyst to decompose KCIO3 to give O2
FePromoted iron is used in the Haber – Bosch process for making NH3
FeCl3Used in the production of CCl4 from CS2 and Cl2
FeSO4 and H2O2

Used as Fenton’s reagent for oxiding alcohols to aldehydes

PdCl2Wacker process for converting C2H4 + H2O + PdCl2 to CH3CHO + 2HCl + Pd
PdUsed for hydrogenation (e.g. phenol to cyclohexanone)
Pt/PtoAdams catalyst, used for reductions
PtFormerly used for SO2 SO3 in the Contact process for making H2SO4
PtIs increasingly being used in three stage – convertors for cleaning car exhaust fumes
Pt/RhFormerly used in the Ostwald process for making HNO3 to oxidize NH3 to NO
CuIs used in the direct process for manufacture of (CH3)2SiCl2 used to make silicones
Cu/VOxidation of cyclohexanol/cyclohexanone mixtures to adipic acid which is used to make nylon-66
CuCl2Deacon process of making Cl2 from HCl.
NiRaney nickel, numerous reduction processes (e.g manufacture of hexamethylenediamine, production of H2 from NH3 reducing anthraquinone to anthraquinol in the production of H2O2)
Ni complexesReppe synthesis (polymerization of alkynes, e.g. to give benzene or cyclooctatetraene)

In some cases the transition metals with their variable valency may form unstable intermediate compounds. In other cases the transition metal provides a suitable reaction surface.

The catalytic properties and uses of transition elements can further be seen among enzymes. Enzymes are catalysts that enhance the rates of specific reactions. They are proteins and are produced by living cells from amino acids. They work under mild conditions often give 100% yields and may speed a reaction by 106 and 1012 times. Some enzymes require the presence of metal ions as cofactors and these are called metalloenzymes. Many (but not all) metalloenzymes contain a transition metal. Some metalloenzymes are listed in table below


A further feature of the transition elements is that they sometimes form nonstoichiometric compounds. These are compounds of indefinite structure and proportions. For example, iron(II) oxide FeO should be written with a bar over the formula FeO to indicate that the ratio of Fe and O atoms is not exactly 1 : 1 analysis shows that the formula varies between Fe0.94O and Fe0.84O. Vanadium and selenium form a series of compounds ranging from VSe0.98 to VSe2. These are given the formulae:

VSe (VSe0.98 VSe1.2)

V2Se3 (VSe1.2 VSe1.6)

V2Se4 (VSe1.6 VSe2)

Nonstoichiometry is shown particularly among transition metal compounds of the Group 16 elements (O, S, Se, Te). It is mostly due to the variable valency of transition elements. For example copper is precipitated from a solution containing Cu2+ by passing in H2S. The sulphide is completely insoluble, but this is not used as a gravimetric method for analyzing for Cu because the precipitate is a mixture of CuS and Cu2S. sometimes nonstoichiometry is caused by defects in the solid structures.

MetalloEnzymes and MetalloProteins(MetalloProteins are in Brackets)

MetalEnzymes/metalloproteinBiological function
MoXanthine oxidase

Nitrate reductase

Metabolism of purines

Utilization of nitrates



Urea formation

Adding or removing PO43-

FeII or FeIIIAldehyde oxidase






Succinic dehydrogenase

Oxidation of aldehydes

Decomposes H2O2

Decomposes H2O2

Electron transfer


O2 transport in higher animals

Aerobic oxidation of carbohydrates

Fe and MoNitrogenaseFixation of dinitrogen
CoGlutamic mutase Ribonucleotide reductaseMetabolism of amino acids

Biosynthesis of DNA

CuI or CuIIAmine oxidases

Ascorbate oxidase

Cytochrome oxidase

Galactose oxidase

Lysine oxidase

Dopamine hydroxylase





Oxidation of amines

Oxidation of ascorbic acid

Principal terminal oxidase

Oxidation of galactose

Elasticity of aortic walls

Producing noradrenaline to generate nerve impulses in the brain

Skin pigmentation

Utilization of Fe

O2 transport in invertebrates


ZnIIAlcohol dehydrogenase

Alkaline phosphatase

Carbonic anhydrase


Metabolism of alcohol

Releasing PO43-

Regulation of pH and CO2 formation

Digestion of proteins