In petroleum refining, what process converts hydrogen sulfide into elemental sulfur?

In petroleum refining, the Claus process converts hydrogen sulfide into elemental sulfur.

Refineries and natural-gas processing plants remove hydrogen sulfide, a toxic and highly odorous compound, from sour gas and other hydrocarbon streams. The recovered gas is sent to a Claus unit, where part of the hydrogen sulfide is burned to form sulfur dioxide. The sulfur dioxide then reacts with the remaining hydrogen sulfide to produce sulfur and water.

Catalyst beds increase the conversion of sulfur compounds into recoverable elemental sulfur. The solid sulfur can be collected and sold for uses including fertilizer production and sulfuric-acid manufacture.

The process is named after German chemist Carl Friedrich Claus, who patented it in the 1880s. It is distinct from hydrotreating: hydrotreating removes sulfur from petroleum products, while the Claus process recovers sulfur from hydrogen sulfide-rich gas.