Hydrothermal Aging Treatment Activates V 2 O 5 /TiO 2 Catalysts for NO x Abatement.

Thermal stability is crucial for the practical application of deNO x catalysts. Vanadia-based catalysts are widely applied for the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). Generally, hydrothermal aging at high temperatures induces the deactivation of deNO x catalysts. However, in this work, a remarkable increase in low- and medium-temperature NH 3 -SCR activity was observed for a V 2 O 5 /TiO 2 catalyst after hydrothermal aging treatment, especially at 750 °C for 16 h. After the vanadia-based catalyst was hydrothermally treated at 750 °C, the specific surface area decreased and the surface VO x density and surface V ratio increased significantly. Therefore, the aged catalyst presented more abundant polymeric vanadyl species than the fresh one. Furthermore, the redox capability was improved markedly after hydrothermal treatment due to the strong interaction of vanadia and titania, contributing to the NH 3 -SCR reaction. 750 °C is the optimal temperature to activate the V 2 O 5 /TiO 2 catalyst, improving the SCR performance significantly. This study provides an in-depth understanding of vanadia-based catalysts for practical applications.