Unveiling the journey of industrial selective catalytic reduction (SCR) catalysts: Understanding deactivation mechanisms and innovating regeneration techniques

The selective catalytic reduction (SCR) of nitrogen oxides (NO_x) using V₂O₅-WO₃/TiO₂ catalysts is critical for mitigating emissions from coal-fired power plants. However, catalyst deactivation by arsenic (As) and alkali metals in flue gas poses a major operational challenge. This study focuses on industrial SCR catalysts poisoned under real-world coal combustion conditions, specifically addressing deactivation mechanisms and regeneration strategies tailored to this high-arsenic, high-sulfur environment. Through multi-scale characterization (XPS, TGA, NH₃-TPD) and kinetic analyses, we demonstrate that arsenic (As₂O₃/As₂O₅) and sodium (Na) synergistically deactivate the catalyst by (i) blocking Brønsted acid sites, (ii) oxidizing V⁴⁺ to V⁵⁺ (reducing redox activity), and (iii) forming pore-clogging sulfates. To counteract this, we developed a novel two-step regeneration protocol combining ozone oxidation (0.5 wt% H₂SO₄, 120 min O₃ exposure) with ammonia alkaline washing (1.0 mol/L NH₄OH). Regenerated catalysts were prepared as industrial-scale honeycomb monoliths to emulate real-world operating conditions, achieving 97.31 % As removal and restoring 98.7 % NO_x conversion efficiency at 380 °C—performance comparable to fresh catalysts. Crucially, the regenerated catalyst exhibits sustained stability (>15 days, GB/T 31,587–2015 compliance) under simulated flue gas (500 ppm SO₂, 10 % H₂O), with a 30 % cost reduction versus fresh catalyst procurement. This work provides actionable insights for SCR catalyst regeneration in coal power systems, emphasizing the interplay between contaminant-specific chemistries (As vs. alkali metals) and process-driven reactivation strategies.