Reforming feed selection: Which stream is most commonly used as the primary feedstock to a catalytic reforming unit to make high-octane reformate and hydrogen?
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AHeavy fuel oil
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BResiduum (vacuum residue)
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CStraight-run gasoline (naphtha)
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DCasing-head gasoline (natural gasoline)
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EKerosene
Answer
Correct Answer: Straight-run gasoline (naphtha)
Explanation
Introduction:Catalytic reforming increases octane by dehydrogenating naphthenes to aromatics and isomerising paraffins, while producing valuable hydrogen. The choice of feedstock is critical to yield and unit performance.
Given Data / Assumptions:
- Objective: produce high-octane reformate and hydrogen.
- Candidate feeds: naphtha-range vs much heavier/residual stocks.
Concept / Approach:Reforming targets naphtha boiling range hydrocarbons (roughly 70–180°C) rich in naphthenes/paraffins. Straight-run naphtha from crude distillation is therefore the standard feed. Heavier oils are unsuitable for reforming and are instead cracked or hydroprocessed.
Step-by-Step Solution:
Identify the process window: naphtha range feeds.Select the appropriate refinery stream: straight-run naphtha (often desulfurised first).Reject heavy/residual feeds that would coke and foul reforming catalysts.Verification / Alternative check:Typical refinery flow diagrams place hydrotreating before reforming, with straight-run naphtha as the routed feed.
Why Other Options Are Wrong:
- Heavy fuel oil / residuum: Too heavy; processed via cracking, visbreaking, or coking.
- Casing-head gasoline: Variable composition; not the standard reforming feed.
- Kerosene: Outside optimal reforming range; used for jet/kerosene pool or hydroprocessing.
Common Pitfalls:Confusing reforming (naphtha upgrading) with cracking (heavy oil conversion).
Final Answer:Straight-run gasoline (naphtha)