Unveiling the effect of bidentate ligand enhanced sustainable arsenic removal from spent SCR denitration catalyst

Selective catalytic reduction (SCR) technology plays a vital role in promoting sustainable energy by reducing nitrogen oxide (NOₓ) emissions from coal-fired power plants. However, a persistent challenge lies in the accumulation of toxic arsenic (As) within catalysts, which gradually diminishes their effectiveness. To address this problem, we introduce a novel and environmentally friendly approach to remove arsenic from spent SCR denitration catalysts (V₂O₅-WO₃/TiO₂). The density functional theory (DFT) reveals that water is essential in this process, as it enhances the nucleophilicity of ethanolamine (Etae) in the hydrated alkaline deep eutectic solvents (HDESs) by facilitating the removal of amino hydrogen. This enhancement promotes stronger interactions between As species and hydroxyl groups, making the extraction more efficient. Notably, the HDES formulation containing 90 % water achieves an impressive As removal rate of 97.1 %, while maintaining the integrity of the TiO₂ structure. Etae functions as a bidentate ligand, coordinating with deactivated catalyst sites to form a stable five-membered ring complex. Following regeneration, the catalyst demonstrates excellent activity, reaching a nitrogen oxide conversion efficiency of 93.2 % at 300°C. This work underscores the significance of developing effective recycling strategies and contributes meaningfully to the progress of energy technologies.