Which refinery process removes sulfur from petroleum products using hydrogen?

Hydrodesulfurization removes sulfur from petroleum products by reacting them with hydrogen.

In a hydrodesulfurization unit, a petroleum stream passes over a catalyst at elevated temperature and pressure in the presence of hydrogen. Sulfur compounds are converted mainly into hydrogen sulfide, which can then be processed into elemental sulfur in a sulfur-recovery unit.

The process is important because sulfur in fuels contributes to sulfur dioxide emissions and can poison catalysts in later refining and emissions-control systems. Regulations requiring cleaner gasoline, diesel, and jet fuel have driven extensive use of hydrodesulfurization.

Hydrodesulfurization is not the same as simple distillation. Distillation separates components by boiling range, while hydrodesulfurization changes the chemistry of sulfur-containing molecules. More severe forms can also remove nitrogen, metals, and other contaminants.