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

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.