Unveiling the evolution of atomically dispersed Mn species supported on TiO2 for NO Selective Reduction Reaction with NH3

Observing catalysis behavior at atomic level for Mn sites can bring better understanding of its role towards NH3-SCR of NO. Herein, we prepared a series of highly dispersed MnOx/TiO2 via strong electrostatic adsorption with different loadings. Only very small concentration of Mn can achieve attractive NO conversion at elevated temperature. Notably, as Mn loading increased, NO conversion showed different behaviors, indicating Mn sites possibly exhibited different local environment. Based on our laboratory characterizations (XRD, HRTEM, HAADF-STM and Easy-XAFS), no nanoparticle was observed, however we cannot further confirm cluster or single atom which contributed to the performance. To resolve this puzzle, tracking molecularity and oxidation state of Mn at real time by operando XAS is the best option. We expect that this study will provide new insight towards relationship between structure and performance at atomic level for designing superior NH3-SCR catalysts.