Why are sulfur compounds undesirable in gasoline, diesel fuel, and refinery fuel gas?

Sulfur compounds are considered undesirable in petroleum products for several technical, environmental, and operational reasons:

• Engine and System Damage: In gasoline, sulfur compounds reduce the effectiveness of antiknock additives and interfere with the performance of exhaust-treatment systems. In diesel fuel, sulfur causes engine corrosion and can damage sensitive emission-control devices.12
• Environmental Impact: Sulfur compounds are significant air pollutants that contribute to the formation of acid rain. Consequently, many regions enforce strict regulations to limit sulfur levels in fuels to minimize noxious emissions.12
• Refinery Fuel Gas: Sulfur compounds, such as hydrogen sulfide, are often present in refinery process gases. These are typically desulfurized to prevent the release of harmful emissions when the gas is burned within the refinery’s own fuel system.1
• Odor: Beyond their technical drawbacks, sulfur compounds like mercaptans are known for their foul odor, making their removal necessary for consumer-facing products.1

Refineries typically use hydrotreating to remove these impurities, converting them into hydrogen sulfide, which can then be captured and processed.13