Question

What are the conditions required to carry out the contact process?

Answer 1

1. Optimum Temperature: The reaction is highly exothermic (releases heat), so a lower temperature favours it. However, if it is too cold, the reaction becomes too slow. Therefore, a compromise temperature of 410°C to 450°C is maintained to get the maximum yield of sulphur trioxide.
2. Optimum Pressure: High pressure increases the production rate. But designing industrial, acid-resistant towers that can handle extreme pressure is difficult and expensive. Because of this, a practical pressure of 1 to 2 atmospheres (atm) is used.
3. Excess of Oxygen: Supplying an extra or excess amount of air/oxygen drives the chemical equilibrium forward, which directly boosts the production of sulphur trioxide (SO₃).
4. Choice of Catalyst: Vanadium pentoxide (V₂O₅) is used as the catalyst. Even though platinum is a better and more efficient catalyst, it is not preferred because it is highly expensive and easily stops working (gets poisoned) if arsenic oxide impurities are present.