Catalytic reforming: evaluate the primary effect of increasing operating pressure in the reforming reactor, considering its influence on coke formation tendency, intrinsic reaction rates/selectivity, and the octane number of the produced gasoline (reformate).

Introduction / Context:
Catalytic reforming (platforming) converts low-octane naphtha into high-octane reformate by dehydrogenation of naphthenes to aromatics, isomerization, and limited hydrocracking. Operating variables include temperature, pressure, hydrogen partial pressure, and space velocity. This question asks what happens when reactor pressure is increased, and which of the listed statements correctly reflects industry practice and equilibrium principles.

Given Data / Assumptions:

• Feed: hydrotreated naphtha rich in paraffins/naphthenes.
• Key reactions: endothermic dehydrogenation to aromatics + H2; isomerization; mild hydrocracking.
• Variable of interest: higher total/partial pressure of hydrogen.

Concept / Approach:
Dehydrogenation and aromatization produce hydrogen; by Le Chatelier's principle, raising pressure and H2 partial pressure shifts equilibria against aromatic formation. As a result, octane number (primarily from aromatics) tends to decrease at higher pressure. Higher hydrogen partial pressure also suppresses coke formation on the catalyst surface, improving run length, not worsening coking. Apparent reaction rates for the desired endothermic dehydrogenations do not increase simply by raising pressure; severity is commonly achieved with higher temperature or lower pressure/space velocity.

Step-by-Step Solution:

Verification / Alternative check:
Operating strategies in reformers favor lower pressures (within metallurgy/decoking constraints) to maximize octane and hydrogen yield, accepting higher coking propensity controlled by good hydrotreating and regeneration cycles.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming that higher pressure always accelerates reactions or improves quality; for equilibrium-limited dehydrogenations, lower pressure is favorable to octane.

Final Answer:
None of these