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Comparative analysis of the dual origins of the N2O byproduct on MnOx, FeOx, and MnFeOx sphere catalysts for a low-temperature SCR of NO with NH3.
- Source :
- Journal of Materials Chemistry A; 10/28/2022, Vol. 10 Issue 40, p21474-21491, 18p
- Publication Year :
- 2022
-
Abstract
- Herein, the origin and evolution mechanism of N<subscript>2</subscript>O formation over the MnFeO<subscript>x</subscript> spherical catalyst were investigated in detail, accompanied by a comparison analysis of pristine MnO<subscript>x</subscript> and FeO<subscript>x</subscript> catalysts. The results showed that the MnFeO<subscript>x</subscript> catalyst possessed higher catalytic activity but poorer N<subscript>2</subscript> selectivity than the sole oxide catalysts, and the N<subscript>2</subscript>O concentration could even reach 300 ppm over 175 °C. Further activation tests under separate NH<subscript>3</subscript>/NO oxidation conditions revealed the N<subscript>2</subscript>O accumulation of the MnFeO<subscript>x</subscript> catalyst that was primarily derived from the NSCR pathway below 150 °C and then gradually turned to NH<subscript>3</subscript> over-oxidation with temperature. The coupling of Mn and Fe cations induced electron migration and released more Mn<superscript>4+</superscript> and Os, contributing to the upgraded redox capacity, which served as the inherent motivation of high activity but poor N<subscript>2</subscript> selectivity over the MnFeO<subscript>x</subscript> catalyst. For the NH<subscript>3</subscript> over-oxidation pathway, both gaseous O and catalyst oxygen acted as the oxidizers, and the double –NH<subscript>2</subscript>/NH species with the assistance of O was deemed as the restricted step for N<subscript>2</subscript>O generation. For the NSCR pathway, the byproduct N<subscript>2</subscript>O was generated through both E–R and L–H mechanisms, and the former contributed to more N<subscript>2</subscript>O. In addition, the kinetic analysis further verified the obtained conclusions. Finally, a possible mechanism model of N<subscript>2</subscript>O origins over the MnFeO<subscript>x</subscript> catalyst was proposed. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 20507488
- Volume :
- 10
- Issue :
- 40
- Database :
- Complementary Index
- Journal :
- Journal of Materials Chemistry A
- Publication Type :
- Academic Journal
- Accession number :
- 159741884
- Full Text :
- https://doi.org/10.1039/d2ta06199f