Cold desulfur removal

Sulfur poisons most of the catalysts used in the reformer and the fuel cell very quickly and irreversibly. For continuous operation, all sulfur-containing components, such as hydrogen sulfide (H₂S), carbon monoxide (CO₃S), carbon disulfide (CS₂), mercaptans, and thiophenes, must be removed as completely as possible.

Natural gas typically has natural sulfur concentrations of less than 20 mg/m³. The sulfur content increases due to the odorants used for safety reasons, such as mercaptans or thiophenes, which have an intense, repulsive odor.

These natural and added sulfur components must be purified in a gas purification stage before the reformer and fuel cell catalysts to concentrations in the lower double-digit ppb range in order to avoid damage to the active centers through sulfide formation.