Refinery process fundamentals: which of the following listed processes consumes (uses) hydrogen as a reactant under normal operation?

Introduction:
Some refinery processes are hydrogen consumers (hydrotreating, hydrocracking), while others are non-hydrogen processes or even net hydrogen producers (e.g., catalytic reforming). Correctly categorizing processes prevents planning errors in hydrogen balance and utility design.

Given Data / Assumptions:

• Options provided: FCC, visbreaking, propane deasphalting (PDA), and “none of these.”
• Hydrocracking (a hydrogen consumer) is included only as a distractor in option e and is not among the three primary options to choose from.
• We select the correct answer from the first four choices.

Concept / Approach:
FCC and visbreaking are thermal/catalytic cracking processes without molecular hydrogen addition. PDA is a solvent-based separation using liquid propane; it does not use hydrogen as a reactant. Therefore, among the specified choices (a–d), none consumes hydrogen; hydrotreating/hydrocracking would, but those are not selected here.

Step-by-Step Solution:
Evaluate FCC → no H2 consumption.Evaluate visbreaking → thermal cracking, no H2.Evaluate PDA → solvent deasphalting, no H2.Conclude “None of these.”

Verification / Alternative check:
Standard refinery flow schemes show hydrotreaters/hydrocrackers in the hydrogen network; FCC/visbreaking/PDA are not connected as hydrogen consumers.

Why Other Options Are Wrong:
a/b/c: None of these processes add molecular hydrogen to reactions.e: While hydrocracking does consume hydrogen, it is not the intended selection given the structure of the question and typical MCQ pattern.

Common Pitfalls:
Assuming all cracking processes consume hydrogen; only hydrocracking does, not FCC or visbreaking.

Final Answer:
None of these