Purpose of catalytic reforming: Which reaction best represents the principal desired transformation in catalytic reforming for octane improvement of naphtha?

Difficulty: Easy

Correct Answer: dehydrogenation of naphthenes

Explanation:


Introduction / Context:
Catalytic reforming is a key octane-boosting process that converts low-octane naphtha into high-octane reformate while generating hydrogen. The core chemistry targets molecular restructuring that elevates antiknock quality.


Given Data / Assumptions:

  • Pt-based bifunctional catalysts (metal + acid sites).
  • Feed rich in naphthenes and normal paraffins.
  • Objective: increase aromatics and isoparaffins content.


Concept / Approach:
The signature reaction is the dehydrogenation of naphthenes to aromatics (e.g., cyclohexane → benzene + H2). Aromatics and branched isoparaffins have higher octane numbers. Other listed reactions either consume hydrogen or decrease octane/liquid yield and are not the central reforming objective.


Step-by-Step Solution:

1) Identify high-octane structures: aromatics and branched paraffins.2) Map to reaction: naphthene dehydrogenation directly forms aromatics and liberates H2.3) Select the reaction that most directly embodies reforming’s purpose.


Verification / Alternative check:
Standard reforming schematics show naphthene → aromatic + hydrogen as a headline pathway, providing both octane uplift and valuable H2 for hydrotreating.


Why Other Options Are Wrong:

(b) Hydrogenation is opposite of the desired dehydrogenation/aromatization.(c) Hydrocracking is a different conversion process, not the reforming focus.(d) Saturation of olefins reduces octane and is not a reforming objective.(e) HDS is performed upstream in hydrotreaters; not the main reforming reaction.


Common Pitfalls:
Confusing catalytic reforming with hydrocracking or hydrotreating; each has distinct goals and chemistry.


Final Answer:
dehydrogenation of naphthenes

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