<i>In Situ</i> Spectroscopic Studies on the Redox Cycle of NH<sub>3</sub>−SCR over Cu−CHA Zeolites
書誌事項
- タイトル別名
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- In Situ Spectroscopic Studies on the Redox Cycle of NH3−SCR over Cu−CHA Zeolites
抄録
The selective catalytic reduction of NO with ammonia (NH3-SCR) catalyzed by Cu-CHA zeolites is thoroughly investigated using in situ spectroscopic experiments combined with on-line mass spectroscopy (MS) under steady-state NH3-SCR conditions and transient conditions for Cu(II)/Cu(I) redox cycles. Quantitative analysis of the in situ XANES spectra of Cu-CHA under steady-state conditions of NH3-SCR show that NH3-coordinated Cu(II) species is the dominant Cu species at low temperatures (100-150 degrees C). At higher temperatures, Cu(II) species and [Cu(NH3)(2)](+) complex coexist, possibly because the rate of the Cu(II) -> Cu(I) reduction step is comparable to that of the Cu(I)-> Cu(II) oxidation step. In situ XANES, IR/MS, and UV-vis/MS experiments on the reduction half cycle demonstrate that the reduction of Cu(II) species occurs via the reaction of NH3-liganded Cu(II) with NO to yield N-2 and H2O. For the oxidation half cycle, in situ XANES experiments of Cu(I) oxidation in 10 % O-2 at 200 degrees C indicate that an increased density in CHA zeolite exhibits a higher oxidation rate. In situ UV-vis experiments of Cu(I) reoxidation using different mixtures of oxidant feed gas demonstrate the key role of O-2 in the oxidation cycle. It is suggested that the reoxidation of Cu(I) to Cu(II) species occurs with only O-2 as the oxidant, and a high Cu density in CHA zeolite promotes SCR activity by enhancing the oxidative activation of Cu(I) to Cu(II) during the catalytic cycle.
収録刊行物
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- ChemCatChem
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ChemCatChem 12 (11), 3050-3059, 2020-06-05
Wiley-Blackwell
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詳細情報 詳細情報について
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- CRID
- 1050569845445351040
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- NII論文ID
- 120007044524
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- ISSN
- 18673899
- 18673880
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- HANDLE
- 2115/81687
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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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