Study on the mechanism of K-poisoning in Mn/TiO<sub>2</sub> low temperature SCR catalysts

FANG Dingli; ZHANG Cheng; LI Junchen; TAN Peng; MA Lun; FANG Qingyan; CHEN Gang

doi:10.19906/j.cnki.JFCT.2023054

Volume 52 Issue 2

Feb. 2024

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Article Navigation > Journal of Fuel Chemistry and Technology > 2024 > 52(2): 195-205

FANG Dingli, ZHANG Cheng, LI Junchen, TAN Peng, MA Lun, FANG Qingyan, CHEN Gang. Study on the mechanism of K-poisoning in Mn/TiO2 low temperature SCR catalysts[J]. Journal of Fuel Chemistry and Technology, 2024, 52(2): 195-205. doi: 10.19906/j.cnki.JFCT.2023054

Citation:

FANG Dingli, ZHANG Cheng, LI Junchen, TAN Peng, MA Lun, FANG Qingyan, CHEN Gang. Study on the mechanism of K-poisoning in Mn/TiO₂ low temperature SCR catalysts[J]. Journal of Fuel Chemistry and Technology, 2024, 52(2): 195-205. doi: 10.19906/j.cnki.JFCT.2023054

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Study on the mechanism of K-poisoning in Mn/TiO₂ low temperature SCR catalysts

doi: 10.19906/j.cnki.JFCT.2023054

State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China

Funds: The project was supported by National Natural Science Foundation of China (52076090) and Natural Science Foundation of Hubei Province (2023AFA039) .

Received Date: 2023-06-01
Accepted Date: 2023-07-03
Rev Recd Date: 2023-07-03

Available Online: 2023-09-01

Publish Date: 2024-02-02

Abstract

Abstract

Mn/TiO₂ has good low temperature NH₃ selective catalytic reduction (SCR) activity for NO_x. The presence of alkali metals in the flue gas can physically and chemically poison the catalyst leading to toxic deactivation of the Mn/TiO₂ catalyst. This study investigated the mechanism of K-poisoning in Mn/TiO₂ low temperature SCR catalysts by preparing K-poisoning Mn/TiO₂ catalysts using exposed {101} surface TiO₂ as a carrier. It was found that the denitrification efficiency of the Mn/TiO₂ catalyst decreased with increasing K-poisoning concentration. Experimental characterisation and DFT calculations showed that the NH₃-SCR reaction on the surface of the fresh Mn/TiO₂ catalyst was controlled by both E-R and L-H mechanisms. K adsorption led to a reduction in the catalyst specific surface area, a decrease in the ratio of Mn⁴⁺ and chemisorbed oxygen on the catalyst surface and a decrease in the number of acidic sites on the surface, resulting in a decrease in denitrification activity; at the same time, K was more likely to adsorb near the Mn top site as well as the bridging O site, resulting in the activation of NO adsorption was severely curtailed and the adsorption of NH₃ was weakened, making the L-H mechanism blocked and the E-R mechanism the main control.
- low-temperature SCR,
- Mn/TiO₂,
- K-poisoning,
- catalyst

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References(35)

References

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