Investigating the Effects of K Species on V2O5-WO3/TiO2 Catalyst: A DFT-Supported Comparative Analysis of Poisoning Methods

Abstract

The deactivation of V₂O₅-WO₃/TiO₂ (V-W/TiO₂) catalysts in NH₃-selective catalytic reduction (SCR) due to potassium (K) species from coal-fired power plant emissions has garnered significant attention, though the underlying mechanisms remain unclear. This study explores these deactivation mechanisms by introducing K poisoning through incipient wetness impregnation (IWI) and solid-state diffusion methods. Comprehensive analyses, including characterization techniques and density functional theory (DFT) simulations, revealed that increased KCl loading and longer diffusion times of calcination significantly reduce the catalyst's denitration activity. The interaction of KCl with the V₂O₅ component leads to a reduction in surface acidity and promotes K₂O formation, which causes agglomeration on catalyst surface and reduces the surface area. Both methods of poisoning also diminish the redox properties of the catalyst due to an increased presence of low-valent vanadium (V⁴⁺, V³⁺) species. These results provide a detailed understanding of the deactivation process, offering a foundation for developing strategies to enhance the alkali metal poisoning resistance of commercial SCR catalysts.