Hexavalent Metal Cations Doped into Ceria Inducing the Formation of Binuclear Sites Ce<sup>3+</sup>–O–Ce<sup>3+</sup> to Boost the NH<sub>3</sub>-SCR Reaction
Shan Yang, Xiaoyue Zhu, Shurui Chen, Xuechen Zhu, Hao Liu, Jianjun Chen, Dezhan Chen, Chuanzhi Sun, Junhua Li
Abstract
The application of selective catalytic reduction with ammonia (NH 3 -SCR) technology urgently requires catalysts with good performance to control nitrogen oxide (NO x, x = 1, 2) emissions, and structural analysis of such catalysts is necessary and crucial to elucidate the performance of catalytically active sites. Thus, we prepared molybdenum (Mo)-doped CeO 2 catalysts to achieve a substantial leap in catalytic performance. The results revealed that the emergence of Ce 3+ –O–Ce 3+ structural units induced by Mo doping achieved the low-energy barrier activation of the NH 3 molecule, which transformed the dominant reaction mechanism in the catalytic reaction and thus led to a much better SCR performance. Furthermore, we designed tungsten (W)-doped CeO 2 catalysts with the same doping amount as Mo and found that the catalysts exhibited almost the same activity trend as the Mo-doped CeO 2 catalysts, which further confirmed the pivotal role of the Ce 3+ –O–Ce 3+ structural units. This study provides a basic theoretical foundation for the design of ceria-based SCR catalysts with efficient catalytic performance for NO x removal.