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In Situ Spectroscopic Studies on the Redox Cycle of NH3−SCR over Cu−CHA Zeolites
| 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 | | XAFS | | 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 https://doi.org/10.1002/cctc.202000024 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/81687 |
| 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)
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Submitter: 鳥屋尾 隆
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