October 25, 2022
What Are COS and CS2?
Carbonyl Sulfide (COS) and Carbon Disulfide (CS2) are produced by side reactions in the Thermal Reactor of a Sulfur Recovery Unit. COS and CS2 exist in relatively low concentrations in the process gas but can have a significant impact on sulfur recovery efficiency since they do not take part in the Claus reaction.
However, most of the COS and CS2 created in the Thermal Reactor can be hydrolyzed to CO2 and H₂S in the first Claus bed with the proper catalyst, residence time, and a high outlet temperature. COS and CS2 will also be hydrolyzed in Tail Gas Units containing reducing catalysts.