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In Situ Spectroscopic Studies on the Redox Cycle of NH3−SCR over Cu−CHA Zeolites

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Title: In Situ Spectroscopic Studies on the Redox Cycle of NH3−SCR over Cu−CHA Zeolites
Authors: Chong, Liu Browse this author
Hiroe, Kubota Browse this author
Takehiro, Amada Browse this author
Kon, Kenichi Browse this author
Toyao, Takashi Browse this author →KAKEN DB
Maeno, Zen Browse this author →KAKEN DB
Ueda, Kakuya Browse this author
Ohyama, Junya Browse this author
Satsuma, Atsushi Browse this author
Tanigawa, Takuya Browse this author
Tsunoji, Nao Browse this author
Sano, Tsuneji Browse this author
Shimizu, Ken-ichi Browse this author →KAKEN DB
Keywords: Selective catalytic reduction
Cu-CHA zeolite
In situ spectroscopy
Reaction mechanism
Issue Date: 5-Jun-2020
Publisher: Wiley-Blackwell
Journal Title: ChemCatChem
Volume: 12
Issue: 11
Start Page: 3050
End Page: 3059
Publisher DOI: 10.1002/cctc.202000024
Abstract: 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.
Rights: This is the peer reviewed version of the following article: C. Liu, H. Kubota, T. Amada, K. Kon, T. Toyao, Z. Maeno, K. Ueda, J. Ohyama, A. Satsuma, T. Tanigawa, N. Tsunoji, T. Sano, K.-i. Shimizu, ChemCatChem 2020 , 12 , 3050, which has been published in final form at . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Type: article (author version)
Appears in Collections:触媒科学研究所 (Institute for Catalysis) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 鳥屋尾 隆

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