Hydrolysis of Carbonyl Sulfide in Blast Furnace Gas Using Alkali Metal-Modified γ-Al 2 O 3 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 O 2 and H 2 S 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-Al 2 O 3 catalysts to improve COS hydrolysis efficiency and sulfur resistance by adding an alkaline center. Compared with γ-Al 2 O 3 catalysts, the COS hydrolysis efficiency of the modified catalysts in the experiment was improved by 12% in the presence of H 2 S and O 2 . The main cause of catalyst sulfur poisoning is the presence of O 2 , which intensifies both the total amount of sulfur deposition and the proportion of sulfate. It is found that the NaOH/Al 2 O 3 catalyst shows better sulfur resistance than the KOH/Al 2 O 3 catalyst for two reasons: first, the support of Na can significantly improve the medium-strong alkaline site, which is the adsorption site of H 2 S. This is equivalent to increasing the "sulfur capacity" of H 2 S adsorption and reducing the impact of sulfur deposition on the main reaction. Second, the elemental sulfur is more easily produced on the NaOH/Al 2 O 3 catalyst, but the sulfur is further oxidized to sulfate and sulfite on the KOH/Al 2 O 3 catalyst. The molecular diameter of elemental sulfur is smaller than that of sulfate. Therefore, the NaOH/Al 2 O 3 catalyst has better sulfur resistance.