Industrial catalysis: in which of the following processes is sulfuric acid commonly used as the catalyst?

Introduction / Context:
Choosing the correct catalyst is central to refinery and petrochemical operations. Different reactions demand specific catalytic functions: acid catalysis, redox catalysis, or metal surface catalysis.

Given Data / Assumptions:

• Hydrogenation needs metal catalysts such as Ni, Pd, or Pt.
• Gas phase oxidation of SO2 to SO3 uses V2O5 based catalysts in the contact process.
• Alkylation is an acid catalyzed reaction.

Concept / Approach:
Refinery alkylation units produce high octane alkylate by reacting isobutane with olefins. This requires a strong acid catalyst; both sulfuric acid and hydrofluoric acid are industrial choices. Sulfuric acid provides a liquid acid medium to generate carbocations that drive the alkylation mechanism.

Step-by-Step Solution:
Identify process mechanisms: hydrogenation is metal surface driven, not acid.SO2 oxidation is a redox process, catalyzed by V2O5, not H2SO4.Alkylation relies on strong acids; sulfuric acid is standard in many units.

Verification / Alternative check:
Process design texts list H2SO4 alkylation units alongside HF units; catalyst circulation and spent acid regeneration practices are well documented in refining practice.

Why Other Options Are Wrong:
Hydrogenation does not use H2SO4; SO2 to SO3 uses V2O5; hence only alkylation matches sulfuric acid catalysis.

Common Pitfalls:
Confusing the presence of sulfuric acid in absorption or drying steps with its role as a true catalyst in a particular reaction system.

Final Answer:
Alkylation of hydrocarbons (e.g., isobutane with olefins)