Adsorption and catalytic hydrolysis of carbonyl sulfur in gas of iron and steel industry

The composition of gas in the iron and steel industry is complex, and its main components are N2, CO2, CO, Cl2, etc., it also contains a large amount of carbonyl sulfur (COS). The traditional terminal treatment technology has high investment costs, and the reaction conditions of COS removal are difficult to control, resulting in low desulfurization efficiency and easy poisoning of catalysts, resulting in the concentration of sulfur-containing compounds emissions after the combustion of steel gas is difficult to meet the national ultra-low emission requirements. Recent research has shown that the other air pollutants (HCl, H2S) can also be removed through a synergistic effect in the treatment of sulfur-containing compounds before the utilization of steel gas. Therefore, the removing of COS from steel gas at the source is more promising. At present, the commonly used methods for removing COS include adsorption method and catalytic hydrolysis method. Adsorption method has the advantages of convenient use, economy and wide variety of adsorbents. However, the composition of steel gas is complex, and a large amount of impurity gases will compete with COS for adsorption, which affects the removal efficiency of COS. Catalytic hydrolysis is considered to be the most cost-effective method for removing COS due to its advantages of high catalytic efficiency, relatively low reaction temperature, fewer side reactions, and no hydrogen consumption, but has the inevitable problems of easily being poisoned and deactivation of catalyst. Given that the challenges in desulfurization of steel gas, there is an urgent need to develop a bifunctional catalyst with excellent adsorption performance, high activity and stability to remove COS from the source. In this paper, the two most commonly used COS removal technologies are summarized, and the commonly used adsorbents, the supports and active species of hydrolysis catalysts, and the influential features in deactivation of catalytic hydrolysis are analyzed in depth, and the reaction mechanisms of COS removal are introduced in detail. Finally, the advance in the research of COS adsorption and catalytic hydrolysis in recent years is summarized, which provides more scientific guidance for the centralized front desulfurization of steel gas.