Catalytic reforming chemistry: In standard petroleum reforming, which core transformation is emphasized for octane improvement?

Introduction / Context:
Catalytic reforming upgrades low-octane naphtha to high-octane reformate for gasoline blending and produces hydrogen for hydrotreating. Understanding the principal chemistry clarifies product quality shifts and hydrogen make.

Given Data / Assumptions:

• Feed: straight-run or hydrotreated naphtha (C6–C8 range typical).
• Objective: improve octane number substantially.
• Reactions occur over bifunctional catalysts (metal/acid sites).

Concept / Approach:
Key octane-boosting paths include dehydrogenation of naphthenes to aromatics and isomerization of paraffins. Among these, conversion of naphthenes to aromatics gives especially large octane gains and coproduces hydrogen.

Step-by-Step Solution:

Verification / Alternative check:
Typical reformer yields show increased aromatics (e.g., toluene, xylenes) and significant hydrogen production, confirming the transformation.

Why Other Options Are Wrong:

• Naphthenes → paraffins / olefins: Not the signature high-octane pathway.
• Olefins → paraffins: Hydrogenation may occur but does not define reforming’s octane improvement.

Common Pitfalls:
Confusing reforming with isomerization or cracking; reforming is not primarily a carbon number change process.

Final Answer:
Naphthenes into aromatics