Alkali-induced metal-based coconut shell biochar for efficient catalytic removal of H2S at a medium-high temperature in blast furnace gas with significantly enhanced S selectivity

The low S selectivity of catalysts for H2S removal significantly hinders its application in blast furnace gas desulfurization. In this study, Cu-based coconut shell biochar was modified with different types and contents of alkali species. The results showed that the S selectivity close to 100% was prolonged from 0 to 750 min. At the same time, the sulfur capacity was increased from 242.1 mg/g (before the modification) to 373.4 mg/g by using K2CO3-induced Cu-based biochar at 120 degrees C. In CO, H2O, and O2 atmosphere, H2S was dissociated and oxidized to elemental S. Additionally, K2CO3 exhibited an elemental S anchoring effect, making the S more stable at medium-high temperatures and weakening the reactivity of S with CO and .O2-. Thus, less COS and SO2 were generated. Moreover, the basic sites enhanced by K2CO3 promoted the hydrolysis of COS to generate H2S, which entered the desulfurization cycle. K2CO3 also showed a synergistic effect with the active components, generating more .O2- to promote the oxygenation of H2S. The regeneration efficiency of the catalyst could be stabilized above 90%. These findings could provide guidance and reference for designing and applying desulfurization catalysts with high S selectivity and activity.