Question

Which of the following metals is used as catalyst in manufacture of sulphuric acid by contact process?

• A. Iron
• B. Platinum
• C. Nickel
• D. Cobalt

Hint:

Logic Tip: In multiple-choice questions on classical industrial processes, if $V_2O_5$ is absent from the options, Platinum is the intended answer for the Contact Process.

Answer 1

The Correct Option is B

Concept:
The Contact Process is the current method of producing sulfuric acid in the high concentrations needed for industrial processes. The crucial step in this process is the oxidation of sulfur dioxide ($SO_2$) to sulfur trioxide ($SO_3$), which requires a catalyst to proceed at a commercially viable rate.
Step 1: Identify the key catalytic step in the Contact Process.
The reversible, exothermic reaction is: $$2SO_{2(g)} + O_{2(g)} \rightleftharpoons 2SO_{3(g)}$$
Step 2: Identify the catalysts historically and currently used.
Traditionally, platinised asbestos (finely divided Platinum metal on an asbestos support) was used as the catalyst for this reaction. It was highly effective but expensive and susceptible to poisoning by arsenic impurities. (Note: Modern industrial plants almost exclusively use Vanadium(V) oxide, $V_2O_5$, but among the given options, Platinum is the historically accurate metallic catalyst).
Step 3: Evaluate the options.

• Iron (Fe) is used as a catalyst in the Haber process (for ammonia).
• Nickel (Ni) is used as a catalyst in the hydrogenation of oils.
• Cobalt (Co) is not the standard catalyst here.
• Platinum (Pt) is the correct metal used for the Contact process.