Molecular insight into Al2O3 catalysts for blast furnace gas purification: K coordination and hierarchical pore enhanced COS hydrolysis

Blast furnace gas as a vital secondary energy in iron and steel industry, necessitates efficient removal of carbonyl sulfide (COS) to realize clean high-value utilization. However, conventional Al 2 O 3 catalysts suffer from low hydrolytic activity and poor sulfur resistance, limiting their industrial application. This work systematically elucidates the mechanisms of K coordination and hierarchical pore on COS hydrolysis. EXAFS and DFT reveal that appropriate K doping induces highly dispersed K species with four-coordinated K species featuring K-O-Al bonds, which increase the electron cloud density of O atom in surface hydroxyl groups (-OH) and significantly enhance the COS conversion by over 50%. For hierarchical pore catalysts, the introduction of expanding agent breaks the dense stacking of alumina particles, exposes more Al atoms and increases [AlO 6 ] coordination content, which synergistically enriches active -OH sites. More importantly, the interconnected hierarchical porous channels accelerate gaseous H 2 S desorption and effectively mitigate surface sulfur deposition, enabling the catalysts to maintain over 90% COS conversion for 8 h. This work provides atomic-level insights into K coordination and hierarchical pore, offering a rational strategy for designing high-efficiency and sulfur-resistant COS hydrolysis catalysts for blast furnace gas purification.