Lean NO<sub><i>x</i></sub> Capture and Reduction by NH<sub>3</sub> <i>via</i> NO<sup>+</sup> Intermediates over H-CHA at Room Temperature
書誌事項
- タイトル別名
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- Lean NOx Capture and Reduction by NH3 via NO+ Intermediates over H-CHA at Room Temperature
抄録
The oxidation of NO to NO2 and the subsequent reduction by NH3 via a NO+ intermediate over a proton-type chabazite zeolite (H-CHA) were investigated by the combination of in situ infrared (IR) spectroscopy and density functional theory (DFT) calculations. The in situ IR spectral results indicate that the NO' species formed under a flow of NO + O-2 at 27-250 degrees C are more stable at lower temperatures over both H-CHA and copper-cation-exchanged CHA zeolite (Cu-CHA). The Arrhenius plot (T = 27-120 degrees C) shows a negative apparent activation barrier energy (-11.5 kJ mol(-1)) for the formation of NO+ species under the NO + O(2 )flow over H-CHA. The time course of the IR spectra at 27 degrees C shows that NO is oxidized by O-2 to NO2 and then further converted via N2O4 to NO+ and NO3. The subsequent exposure to NH3 at 27 degrees C reduces the NO species to N-2. DFT calculations revealed that Bronsted acid sites in zeolite pores promote the dissociation of N2O4 intermediates into NO and NO3- species with a low activation barrier (15 kJ mol(-1)). Moreover, the computed activation barrier for the reduction of NO+ species by NH3 was considerably low (6 kJ mol(-1)). The experimental and theoretical results of this study demonstrate the high potential of Cu-free H-CHA zeolites for promoting lean NOx capture to form NO+ species and the subsequent reduction by NH3 at room temperature.
収録刊行物
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- Journal of physical chemistry c
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Journal of physical chemistry c 125 (3), 1913-1922, 2021-01-28
American Chemical Society
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詳細情報 詳細情報について
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- CRID
- 1050853987017587968
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- NII論文ID
- 120007187741
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- ISSN
- 19327455
- 19327447
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- HANDLE
- 2115/84014
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- 本文言語コード
- en
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- 資料種別
- journal article
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- データソース種別
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