期刊
MOLECULAR CATALYSIS
卷 525, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.mcat.2022.112356
关键词
N2O; MnOx/TiO2; Mn/Ti ratio; NH3-SCR
资金
- National Natural Science Foundation of China [52170110]
- Key Project of Jiangsu Province Programs for Research and Development [BE2019115]
- Top-notch Academic Programs Project of Jiangsu Higher Education Institutions
This study investigates the formation of N2O during ammonia selective catalytic reduction (NH3-SCR) of NOx using MnOx-TiO2 catalyst. It is found that MnOx and TiO2 species serve as the main redox and acid sites, respectively. Increasing the Mn/Ti ratio expands the MnOx species layer on the TiO2 support, leading to an increase in redox sites but a decrease in surface acid sites, which contributes to the formation of N2O.
High N2O selectivity of MnOx-TiO2 catalyst hinders its development in ammonia selective catalytic reduction (NH3-SCR) of NOx. Herein, a series of MnOx-TiO2 catalyst with different Mn/Ti ratio were prepared by wet-impregnation method to study the N2O formation during ammonia selective catalytic reduction (NH3-SCR) of NOx from the perspective of catalyst. It is found that MnOx and TiO2 species are the mainly redox and acid sites for the NH3-SCR denitration reaction over MnOx-TiO2 catalyst, respectively. As the Mn/Ti ratio increases, MnOx species layer expanded on TiO2 support, leading to increase of redox sites but decrease of surface acid sites. These changes contribute to the occurrence of the no-selective oxidation of NH3 on MnOx species and the over-activation of NH3 at Mn-Ti interface, resulting in the formation of N2O via the route of 2NH(3) + 2O(2) -> N2O + 3H(2)O and 4NO + 4NH(3) + 3O(2) -> 4N(2)O + 6H(2)O, respectively. Through this work, it can be speculated that both improving MnOx dispersion and increasing surface acidity of catalyst are feasible strategy for suppressing the N2O formation on MnOx-TiO2.
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