What is the purpose of desulfurizing fuels?

• A. To remove sulfur compounds to lower sulfur dioxide emissions.
• B. To increase octane rating.
• C. To prevent formation of nitrogen oxides.
• D. To produce more sulfur dioxide.

Answer: (A)

Removing sulfur from fuels is done to cut sulfur dioxide emissions when the fuel is burned. Sulfur compounds in petrol and diesel react with oxygen during combustion to form sulfur dioxide, which contributes to acid rain and respiratory problems. By desulfurizing, refineries help fuels burn cleaner and meet environmental rules. A lot of refining uses hydrodesulfurization with hydrogen and a catalyst to remove sulfur compounds.

This isn’t about increasing octane rating, which is about preventing engine knocking, nor about preventing NOx formation, which depends on combustion conditions and exhaust controls rather than sulfur content. Producing more sulfur dioxide would be counterproductive and is not the aim.