... to remove sulfur from fuels [ Return towards  Its applications  ]

Sulfur is naturally a part of the composition of fossil fuels. It is responsible for the rotten egg odor found near oil wells.

The combustion of fuels containing sulfur creates sulfur oxide: SO₂. This irritating gas causes serious respiratory problems, triggers asthma attacks and causes respiratory ailments especially in children. It also contributes to air pollution: the formation of smog above cities, acid rain, etc. Moreover, sulfur impedes the functioning of catalytic converters.

The process by which refiners remove sulfur from fuels is called desulfurization or sweetening. It uses hydrogen. Introduced at a high temperature (over 350°C) and high pressure (60 bars) during refining, hydrogen extracts the sulfur contained in the hydrocarbon molecules to form a new molecule: hydrogen sulfide (H₂S).

The hydrogen sulfide then reacts with oxygen to give sulfur, forming the yellow piles sometimes seen in refineries. The sulfur produced is used as a raw material in industry.