Resource Utilization of Spent Activated Coke as an Efficient Materialfor Simultaneous Removal of COS and H₂S

The desulfurization of blast furnace gas (BFG) ishighly desired by iron and steel enterprises to realize its resourceutilization with no environmental pollution. In this work, spentactivated coke (SAC) modified by NaOH was innovatively reusedas an efficient material for the removal of carbonyl sulfide (COS)and sulfuretted hydrogen (H2S) from BFG with admirablebreakthrough sulfur capacities of 126.58 and 141.62 mg/g,respectively, and 100% removal efficiency of both COS and H2Scould be reached with the total sulfur capacity of COS and H2Sashigh as 116.60 mg/g in the purification of the simulative BFG gas.The removal behaviors manifested that the removal processincluded catalytic hydrolysis of COS to H2S and subsequentoxidation of H2S to immobilize these sulfur species in the form ofS8. The multiple structural characterizations (X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transforminfrared (FTIR), X-ray photoelectron spectroscopy (XPS), H2-temperature-programmed reduction (TPR)) further revealed that thesurface carbonyl and pyridine/pyrrolic groups together with the loaded hydroxyl ion enhanced the COS hydrolysis and thesubsequent oxidation of H2S. The modified SAC possessed much richer pore structures and active groups than either fresh activatedcoke (FAC) or high specific surface area activated carbon (HAC). At the same time, a recycling scheme suitable for SAC afterremoving H2S and COS was proposed. The demonstrated excellent simultaneous removal capacity of COS and H2S over themodified SAC will provide a promising technical route for desulfurization of BFG with high efficiency and low cost.