Abstract: To tackle the challenges including difficult deep removal of multi-component sulfides (H₂S, COS and mercaptans), competitive adsorption interference of CO₂, and cumbersome traditional desulfurization processes in high-concentration CO₂ feed gas, a low-temperature multifunctional composite desulfurizer, 3%Fe₂O₃-1%CeO₂-5%K₂CO₃/activated carbon, was prepared via stepwise impregnation of Fe-Ce bimetallic active components and K₂CO₃ promoter onto a coal-based activated carbon support. Performance evaluation results reveal that the composite desulfurizer possesses strong resistance against competitive CO₂ adsorption. The optimal desulfurization temperature ranges from 50 to 100 °C,where efficient simultaneous removal of H₂S, COS and mercaptans can be achieved, with the removal efficiency of all three sulfur compounds exceeding 99.6%, and their mass concentrations in the effluent gas is below 0.02 mg/m³. The breakthrough sulfur capacity (mass fraction) for high-sulfur content CO₂ gas reaches over 25%, and the desulfurization products mainly consist of elemental sulfur and sulfuric acid. During the desulfurization reaction, continuous oxidative removal of H₂S shifts the COS hydrolysis equilibrium forward and improves COS removal efficiency, which eliminates the inhibitory effect of CO₂ on COS hydrolysis. Industrial application results for CO₂ gas desulfurization demonstrate that the composite desulfurizer can operate stably at ambient temperature, and the mass concentration of sulfur species in the reactor outletremains below 0.02 mg/m³. It is suitable for low-temperature fine desulfurization of industrial CO₂ gas, syngas and liquefied petroleum gas.

Key words: multifunctional desulfurizing agent, COS hydrolysis, H₂S oxidation, sulfur capacity, desulfurization accuracy