1) In a chemical reaction, what does a catalyst do
2) Homogeneous catalyst example
|3) Heterogeneous catalyst example
4) Catalyst examples
5) Heterogeneous catalyst vs homogeneous catalyst
We will also learn :
- Catalyst in chemistry
- Types of catalyst
- Examples of catalysts in industry
|Catalyst In Chemistry|
TYPES OF CATALYSIS
Also, there is a third type of catalyst known as Enzyme catalysis which is largely used in the biological sector.
In homogenous catalysis, the catalyst is in the same phase as the reactants and is evenly distributed throughout. This type of catalysis can occur in the gas phase or the liquid (solution) phase.
Homogeneous catalyst example in Gas Phase:
a) Oxidation of sulphur dioxide to sulphur trioxide with nitric oxide as a catalyst,
Example of Homogenous Catalysis in Solution Phase:
Many reactions in solutions are catalyzed by acid and bases,
a) Hydrolysis of cane sugar in aqueous solution in the presence of mineral acid as catalyst,
b) Ester hydrolysis in the presence of acid or alkaline,
c) Decomposition of hydrogen peroxide in the presence of iodine ion as a catalyst,
The catalyst is called heterogeneous catalysis at a different physical stage than the reactants.
Heterogeneous catalyst example
Some example of heterogeneous catalysis with reactants in the gas, liquid or the solid phase is listed below.
1) Heterogeneous catalysis with gaseous reactant (Contact catalysis)
a) Combination of sulphur dioxide and oxygen in the presence of finely divided platinum or vanadium pentoxide, (Contact Process for Sulphuric acid)
b) In the presence of finely divided iron, nitrogen and hydrogen mixture to form ammonia, (Haber Process for Ammonia).
c) Oxidation of ammonia to nitric oxide in the presence of platinum gauze ( a stage in the manufacture of Nitric acid).
d) Hydrogenation reactions of unsaturated organic compounds are catalyzed by a finely divided nickel.
Vegetable oils are triesters of glycerol with higher unsaturated acid. When hydrogen is passed through the vegetable oils in the presence of nickel, the carbon-carbon double bonds of the acid portions are hydrogenated to yield solid fats (Vanaspati ghee).
2) Heterogeneous catalysis with liquid reactants
a) The decomposition of aqueous solutions of hydrogen peroxide is catalyzed by manganese dioxide or platinum in colloidal form,
b) Benzene and ethanol chloride react in the presence of anhydrous aluminium chloride to form phenyl methyl ketone,
3) Heterogeneous catalysis with the solid reactant
The decomposition of potassium chlorate is catalyzed by manganese dioxide.
2KClO3 + [MnO2] → 2KCl + 3O2 + [MnO2]
MECHANISM OF ENZYME CATALYSIS