Question

In conversion of $S{O}_2$ to $S{O}_3$, the required catalyst is:

• A. Fe
• B. Pt or V${}_2$O${}_5$
• C. Co
• D. Ni

Answer 1

Answer: (B)

Pt or V${}_2$O${}_5$

Sulphur trioxide is made by the contact process. Sulphur dioxide made by the burning of sulphur or iron pyrite is purified by electrostatic precipitation.

The purified sulphur dioxide is oxidised by oxygen at 400-600 degree celsius over a catalyst consisting of vanadium pentoxide with potassium oxide on a silica support. Platinum also works well but it is too expensive and poisoned by impurities.