Fuel sweetening in refining: In petroleum product treatment, “sweetening” primarily refers to the removal or conversion of which species?

Introduction:
“Sweet” petroleum products are low in sulphur and mercaptans, with reduced odour and corrosivity. Processes include mercaptan oxidation (Merox) or hydrotreating to convert/remove sulphur species.

Given Data / Assumptions:

• Scope: finished product treating.
• Goal: odour reduction, improved stability/corrosion performance.

Concept / Approach:
Sweetening targets sulphur-bearing compounds. Merox oxidises mercaptans to disulfides (less odorous), while hydrotreating removes sulphur as H2S. Hence, “sweetening” refers to sulphur compound removal/conversion.

Step-by-Step Solution:

Verification / Alternative check:
Product specifications (e.g., mercaptan sulphur limits) define “sweet.”

Why Other Options Are Wrong:

• Water: Removed by drying, not sweetening.
• Organic particulates/wax/asphaltenes: Other treatments handle these.

Common Pitfalls:
Equating dehydration or filtration with sweetening.

Final Answer:
Sulphur and its odorous compounds (e.g., mercaptans)