Highly active and stable VO_x/TiO₂ nanosheets for low-temperature NH₃-SCR of NO: Structure-directing role of support

Low-temperature NH₃-SCR over conventional catalysts based on V₂O₅/TiO₂ is significantly limited by the narrow range of operating temperatures and poor activity at low temperatures. Herein, a novel catalyst consisting of defective TiO₂ nanosheets supported vanadia (V/TNS) is successfully developed for the low-temperature NH₃-SCR of NO. The V/TNS catalyst demonstrated excellent SCR performance, achieving over 95 % conversion with high N₂ selectivity (>90 %) over a wide temperature range of 140–380 °C. Importantly, V/TNS was highly resistant to H₂O and SO₂ poisoning during 30 h of continuous operation, maintaining an NO conversion efficiency that exceeded 92 % at 180 °C. In contrast, a high-surface-area anatase TiO₂ particle-supported catalyst (V/TiO₂(A)) suffered from catalytic deactivation. Detailed characterization revealed that the TNS support, with its abundant surface defects and high surface area, improved vanadia dispersion and facilitated the formation of surface V⁴⁺ species and oxygen vacancies. These factors synergistically enhanced the adsorption and activation of NH₃ and NO_x, boosting catalytic performance. Moreover, the presence of SO₂ had a notable inhibitory effect on the adsorption and activation of NH₃ and NO_x and their reactions on V/TiO₂(A), while these detrimental effects were considerably mitigated on V/TNS.