Abstract: The sulfurization and desulfurization of water gas shift catalyst CoMoK/Al₂O₃ have been investigated by TPS and TPDS techniques, using H₂S and CS₂ as sulfurizing agents. Only H₂S consumption and H₂O formation were found when the catalyst was sulfurized with H₂S/H₂. When CS₂/H₂ was used as sulfurizing agent,CO₂ was formed at first, then CH₄,H₂O and H₂S as shown by TPS curves. Carbon deposition on the catalyst during the sulfurization with CS₂/H₂ caused lowering of the catalytic activity, but the deposifed carbon could be reduced in the run of WGS reaction. The results of TPDS indicated that N₂ does not act in desulfurization and H₂ or CO also does not give an obvious effect on the desulfurization. However,H₂O shows a strong desulfurizing effect. Oxygen caused a permanent loss of the activity in some part of the catalyst. XPS results showed that Mo⁴⁺ has been changed to Mo⁵⁺ and Mo⁵⁺ in desulfurized catalyst,decreasing its activity.

Key words: CoMoK/Al₂O₃, water-gas, catalyst, sulfurization, desulfurization