Adsorption-Induced Active Vanadium Species Facilitate Excellent Performance in Low-Temperature Catalytic NOx Abatement.

Vanadia-based catalysts have been widely used for catalyzing various reactions, including their long-standing application in the deNOx process. It has been commonly considered that various vanadium species dispersed on supports with a large surface area act as the catalytically active sites. However, the role of crystalline V2O5 in selective catalytic reduction of NOx with NH3 (NH3-SCR) remains unclear. In this study, a catalyst with low vanadia loading was synthesized, in which crystalline V2O5 was deposited on a TiO2 support that had been pretreated at a high temperature. Surprisingly, the catalyst, which had a large amount of crystalline V2O5, showed excellent low-temperature NH3-SCR activity. For the first time, crystalline V2O5 on low-vanadium-loading catalysts was found to be transformed to polymeric vanadyl species by the adsorption of NH3. The generated active polymeric vanadyl species played a crucial role in NH3-SCR, leading to remarkably enhanced catalytic performance at low temperatures. This new finding provides a fundamental understanding of the metal oxide-catalyzed chemical reaction and has important implications for the development and commercial applications of NH3-SCR catalysts.