Poisoning of cobalt catalyst used for Fischer-Tropsch synthesis

Sulfur in the form of H₂S has been added at various concentration levels during cobalt Fischer-Tropsch synthesis. A steady-state FTS conversion was established prior to adding H₂S. At low levels (<500 ppb) H₂S addition does not cause a detectable decrease in activity during 5-10 days of exposure to H₂S. Above the threshold limit of about 500 ppb, the rate of decrease in CO conversion is linearly related to the H₂S concentration in the gas feed. At H₂S levels in the 500-1000 ppb range, it appears that the poisoning effect is reversible so that catalytic activity is recovered when the addition of H ₂S is terminated.