Redox and Kinetic Properties of Composition-Dependent Active Sites in Copper-Exchanged Chabazite for Direct Methane-to-Methanol Oxidation.

Autor: Brenig A; Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland.; Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232, Villigen, Switzerland., Fischer JWA; Institute for Molecular Physical Science, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland., Klose D; Institute for Molecular Physical Science, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland., Jeschke G; Institute for Molecular Physical Science, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland., van Bokhoven JA; Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland.; Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232, Villigen, Switzerland., Sushkevich VL; Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232, Villigen, Switzerland.
Jazyk: angličtina
Zdroj: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2024 Nov 04; Vol. 63 (45), pp. e202411662. Date of Electronic Publication: 2024 Sep 12.
DOI: 10.1002/anie.202411662
Abstrakt: The CH 4 oxidation performance of Cu-chabazite zeolites characterized by distinct Si/Al ratios and Cu loadings has been studied and the observed variations in reactivity have been correlated to the differences in the nature of the formed active centers. Plug flow reactor tests, in situ Fourier-transform infrared, and X-ray absorption spectroscopy demonstrate that a decrease in Cu loading shifts the reactivity/redox profile to higher temperatures and increases the CH 3 OH selectivity and Cu-efficiency. In situ electron paramagnetic resonance, Raman, ultraviolet-visible, Fourier-transform infrared, and photoluminescence spectroscopies reveal that this behavior is associated with the presence of monomeric Cu active sites, including bare Cu 2+ and [CuOH] + present at low Si/Al ratio and Cu loading. Formation of two distinct [Cu 2 (μ-O)] 2+ moieties at higher Si/Al ratio or Cu loading forces these trends into the opposite direction. Operando electron paramagnetic resonance and ultraviolet-visible spectroscopy show that the apparent activation energy of monomeric Cu active species decreases with increasing Si/Al ratio, whereas the one of dimeric centers is unaffected.
(© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)
Databáze: MEDLINE
Externí odkaz: