SO$_2$ + O$_2$ → 2SO$_3$ In the reaction above, the most suitable catalyst is?

1. Analyze the question

The question asks for the most suitable catalyst used in the industrial production of sulfur(VI) oxide ($SO_3$) from sulfur(IV) oxide ($SO_2$) and oxygen ($O_2$). This specific reaction is a key stage in the Contact Process for the manufacture of sulfuric acid.

2. Explain the concept

In industrial chemistry, catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. They work by providing an alternative reaction pathway with a lower activation energy.

The reaction $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$ is a reversible, exothermic reaction. To maximize the yield of $SO_3$ efficiently, the Contact Process employs a specific transition metal oxide catalyst to speed up the conversion.

3. Show the solution

• The Reaction: This is the catalytic oxidation of sulfur(IV) oxide.
• The Catalyst: In the Contact Process, the mixture of $SO_2$ and $O_2$ is passed over a catalyst bed. Historically, platinum was used, but it is easily "poisoned" (rendered ineffective) by impurities like arsenic.
• Modern Standard: Today, Vanadium(V) oxide ($V_2O_5$) is the standard catalyst used because it is cheaper, more resistant to poisoning, and highly effective at the required operating temperatures (about 450°C).

Looking at the options provided:

• A, B, and C are metal oxides, but they are not the standard industrial catalysts for this specific reaction.
• D, Vanadium(V) oxide ($V_2O_5$), is the industry-standard catalyst for this reaction.

4. Identify the answer

The correct option is D.

5. Tip

When studying industrial processes for JAMB, always remember the "Catalyst-Process" pairs. For the Contact Process (Sulfuric Acid), remember V₂O₅. For the Haber Process (Ammonia), remember Finely divided Iron. These are classic JAMB favorites!