Cu- and Fe-speciation in a composite zeolite catalyst for selective catalytic reduction of NOx: insights from operando XAS
| Autor: | Marco Daturi, Valentin Valtchev, Houeida Issa Hamoud, Andrea Martini, Søren Birk Rasmussen, Carlo Lamberti, Kirill A. Lomachenko, Silvia Bordiga, I. A. Pankin, Philippe Bazin |
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| Přispěvatelé: | Dipartimento di Chimica [Torino], Università degli studi di Torino (UNITO), Laboratoire catalyse et spectrochimie (LCS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Université de Caen Normandie (UNICAEN), Normandie Université (NU) |
| Rok vydání: | 2021 |
| Předmět: |
X-ray absorption spectroscopy
Materials science Absorption spectroscopy Extended X-ray absorption fine structure 010405 organic chemistry Selective catalytic reduction [CHIM.CATA]Chemical Sciences/Catalysis 010402 general chemistry 01 natural sciences Catalysis XANES 0104 chemical sciences Chemical engineering Zeolite NOx |
| Zdroj: | Catalysis Science & Technology Catalysis Science & Technology, Royal Society of Chemistry, In press, ⟨10.1039/D0CY01654C⟩ |
| ISSN: | 2044-4761 2044-4753 |
| Popis: | Cu-SAPO-34 (Cu-CZC) and Fe-mordenite (Fe-MOR) and their mechanical mixture (50 : 50) have been exhaustively investigated by means of operando X-ray absorption spectroscopy under NH3-SCR conditions. Fe K-edge XANES and EXAFS analysis revealed similar Fe-speciation in both the pure Fe-MOR catalyst and the mechanical mixture after high-temperature pretreatment and under reaction conditions. In contrast, analysis of the Cu K-edge dataset unveiled different trends in temperature-driven Cu-speciation in the pure Cu-CZC and mechanical mixture under standard NH3-SCR conditions. This difference is more evident in a low-temperature range. The presence of the Fe-MOR component in the mixed catalyst can result in the increase of NH3 and NO concentration in the proximity of Cu-sites at a low temperature regime, which facilitates temperature-driven migration of NH3-solvated mobile di-amino complexes from Cu-CZC to the MOR framework. This decreases the density of mobile CuI complexes in the entire system and results in the higher reducibility of Cu in the mixed catalyst. The obtained results help in understanding the precise speciation of the active sites in such composite catalysts and thus provide future guidance on design of such systems. |
| Databáze: | OpenAIRE |
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