Hydrolysis of Carbonyl Sulfide in Blast Furnace Gas Using Alkali Metal-Modified γ-Al2O3 Catalysts with High Sulfur Resistance

A carbonyl sulfide (COS) hydrolysis catalyst can play an efficient role in blast furnace gas (BFG), but the life of the catalyst is greatly shortened due to the presence of O2 and H2S in the atmosphere, so improving the sulfur resistance of the catalyst is the key to application. In this work, alkali metals Na and K modified γ-Al2O3 catalysts to improve COS hydrolysis efficiency and sulfur resistance by adding an alkaline center. Compared with γ-Al2O3 catalysts, the COS hydrolysis efficiency of the modified catalysts in the experiment was improved by 12% in the presence of H2S and O2. The main cause of catalyst sulfur poisoning is the presence of O2, which intensifies both the total amount of sulfur deposition and the proportion of sulfate. It is found that the NaOH/Al2O3 catalyst shows better sulfur resistance than the KOH/Al2O3 catalyst for two reasons: first, the support of Na can significantly improve the medium-strong alkaline site, which is the adsorption site of H2S. This is equivalent to increasing the "sulfur capacity" of H2S adsorption and reducing the impact of sulfur deposition on the main reaction. Second, the elemental sulfur is more easily produced on the NaOH/Al2O3 catalyst, but the sulfur is further oxidized to sulfate and sulfite on the KOH/Al2O3 catalyst. The molecular diameter of elemental sulfur is smaller than that of sulfate. Therefore, the NaOH/Al2O3 catalyst has better sulfur resistance.