Unveiling the Reaction Mechanism of Selective Catalytic Reduction of NO with NH3 over Active Mn–W Dinuclear Sites

Abstract

Mn-based oxide catalysts have promising potential in the selective catalytic reduction of NO with NH₃ (NH₃-SCR) due to their excellent low-temperature activity. However, poor N₂ selectivity severely restricts their large-scale practical applications. In this study, we achieved an improvement in both activity and selectivity of Mn-based SCR catalysts by W modification and revealed the mechanism by which the formation of Mn–W dinuclear active sites enhances their performance. By combining experimental measurements and density functional theory (DFT) calculations, the improved NH₃-SCR performance of the MnW/TiO₂ catalyst was attributed to the significant redox role of W, resulting from the formation of strongly interacting Mn–W dinuclear sites. The entire NH₃-SCR reaction pathway over the Mn–W dinuclear site was elucidated at the atomic level, confirming that the W sites played a redox role in the reaction, specifically by directly participating in the oxidative activation of NH₃. This work elucidates the working principle of dinuclear active sites in the NH₃-SCR reaction and provides valuable insight for the development of future generation high-performance SCR catalysts.