Alkylation fundamentals What does refinery alkylation do, in terms of the reacting hydrocarbon families and the resulting product type?

Introduction / Context:
Alkylation is a cornerstone gasoline upgrading process in which light olefins from FCC/cokers react with isobutane to produce high-octane, low-vapour-pressure isoparaffins (alkylate). It complements polymerisation and reforming in shaping the gasoline pool.

Given Data / Assumptions:

• Feeds: light olefins (e.g., propene, butenes) and iso-paraffin (typically isobutane).
• Catalysts: strong acids (HF or H2SO4) in conventional units.
• Desired: high-octane iso-paraffinic product such as C7–C9 isoparaffins.

Concept / Approach:
Mechanistically, a carbocation formed from the olefin reacts with isobutane, leading to a branched isoparaffin product. This is distinct from polymerisation (olefin + olefin). The alkylate produced is prized for octane and clean burning.

Step-by-Step Solution:

Verification / Alternative check:
Refinery flow diagrams consistently show isobutane recycle and olefin feed to the alkylation reactor, confirming the correct chemistry.

Why Other Options Are Wrong:

• Olefins with each other: That is polymerisation.
• Iso-paraffin to olefin / olefin to normal paraffin: Not representative of alkylation's net transformation.

Common Pitfalls:
Assuming any octane-boosting process is alkylation; check the co-reactant (isobutane) to be sure.

Final Answer:
Causes olefins to combine with iso-paraffins to form higher iso-paraffins