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 H 2 S 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 K 2 CO 3 -induced Cu-based biochar at 120 °C. In CO, H 2 O, and O 2 atmosphere, H 2 S was dissociated and oxidized to elemental S. Additionally, K 2 CO 3 exhibited an elemental S anchoring effect, making the S more stable at medium–high temperatures and weakening the reactivity of S with CO and ·O 2 – . Thus, less COS and SO 2 were generated. Moreover, the basic sites enhanced by K 2 CO 3 promoted the hydrolysis of COS to generate H 2 S, which entered the desulfurization cycle. K 2 CO 3 also showed a synergistic effect with the active components, generating more ·O 2 – to promote the oxygenation of H 2 S. 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.