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Redox‐Driven Migration of Copper Ions in the Cu‐CHA Zeolite as Shown by the In Situ PXRD/XANES Technique
Author(s) -
Andersen Casper Welzel,
Borfecchia Elisa,
Bremholm Martin,
Jørgensen Mads Ry Vogel,
Vennestrøm Peter Nicolai Ravnborg,
Lamberti Carlo,
Lundegaard Lars Fahl,
Iversen Bo Brummerstedt
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201703808
Subject(s) - xanes , redox , catalysis , zeolite , copper , powder diffraction , oxidation state , chemistry , inorganic chemistry , ion , in situ , crystallography , spectroscopy , organic chemistry , physics , quantum mechanics
Using quasi‐simultaneous in situ PXRD and XANES, the direct correlation between the oxidation state of Cu ions in the commercially relevant deNO x NH 3 ‐SCR zeolite catalyst Cu‐CHA and the Cu ion migration in the zeolitic pores was revealed during catalytic activation experiments. A comparison with recent reports further reveals the high sensitivity of the redox‐active centers concerning heating rates, temperature, and gas environment during catalytic activation. Previously, Cu + was confirmed present only in the 6R. Results verify a novel 8R monovalent Cu site, an eventually large Cu + presence upon heating to high temperatures in oxidative conditions, and demonstrate the unique potential in combining in situ PXRD and XANES techniques, with which both oxidation state and structural location of the redox‐active centers in the zeolite framework could be tracked.

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