7.3 Contact Process
Contact Process for the Manufacture of Sulphuric Acid
Sulphuric acid is a most important industrial chemical used for making a large number of compounds e.g. fertilizer, plastic, explosives, paints, leather, tanning, textiles, metallurgy etc. Sulphuric acid is used in almost all industries which is why it is called the King of Chemicals.
Sources:
This process is based on the catalytic oxidation of SO2 and SO3 in the presence of atmospheric oxygen. Sulphur dioxide is produced by burning sulphur or roasting sulphide ores.
This reaction is reversible and exothermic. Therefore the optimum conditions for the reaction are:
1) Concentration: A controlled amount of air is passed.
2) Temperature: The temperature of the reaction should be kept at 450 C
3) Pressure: Pressure is usually kept at 200kPa / 2 atm
4) Catalyst: Vanadium pentaoxide is an efficient catalyst
1) Burner: Sulphur is burnt in a Sulphur burner, SO2 gas produced and vapours of this gas are cooled by passing through a pipe cooler made up of iron.