Hydrothermal Aging Treatment Activates V2O5/TiO2 Catalysts for NOx Abatement.

Thermal stability is crucial for the practical application of deNOx catalysts. Vanadia-based catalysts are widely applied for the selective catalytic reduction of NOx with NH3 (NH3-SCR). Generally, hydrothermal aging at high temperatures induces the deactivation of deNOx catalysts. However, in this work, a remarkable increase in low- and medium-temperature NH3-SCR activity was observed for a V2O5/TiO2 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 VOx 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 NH3-SCR reaction. 750 °C is the optimal temperature to activate the V2O5/TiO2 catalyst, improving the SCR performance significantly. This study provides an in-depth understanding of vanadia-based catalysts for practical applications.