Removal of COS in coke-oven gas by NiO/ZnO-Al₂O₃ adsorption

The NiO/ZnO-Al₂O₃ adsorbent was prepared by incipient method and characterized by XRD and mercury porosimeter. The performance of the adsorbent in the removal of COS from the simulated coke-oven gas was tested in a fixed-bed reactor. The results show that the appropriate reaction conditions are 350 ℃, 0.40 MPa and GHSV of 500~1 000 h^-1. The adsorbent could remove COS from 320~450 mg/m³ to 0.5 mg/m³ as well as olefins from 2.3%~4.5% to 0 without changing other component. The breadthrough sulfer capacity is 17.18%. The regeneration test shows that the crystal form, pore structure and sulfer capacity of the regenerated adsorbent have no significant change compared with the fresh adsorbent. A desulfurization mechanism is proposed as follows:first COS is absorbed on the reduced Ni atoms to form NiS via the breaking of the S-C bond, then NiS is transformed to H₂S in the presence of H₂, finally H₂S is captured by ZnO.