Journal article Open Access
Assessing the Influence of Zeolite Composition on Oxygen-Bridged Diamino Dicopper(II) Complexes in Cu-CHA DeNOx Catalysts by Machine Learning-Assisted X-ray Absorption Spectroscopy
Andrea Martini;
Chiara Negri;
Luca Bugarin;
Gabriele Deplano;
Reza K. Abasabadi;
Kirill A. Lomachenko;
Ton V. W. Janssens;
Silvia Bordiga;
Gloria Berlier;
Elisa Borfecchia
Cu-exchanged chabazite is the catalyst of choice for NOx abatement in diesel vehicles aftertreatment systems via ammonia-assisted selective catalytic reduction (NH3− SCR). Herein, we exploit in situ X-ray absorption spectroscopy powered by wavelet transform analysis and machine learning-assisted fitting to assess the impact of the zeolite composition on NH3-mobilized Cu-complexes formed during the reduction and oxidation half-cycles in NH3− SCR at 200 °C. Comparatively analyzing well-characterized Cu-CHA catalysts, we show that the Si/Al ratio of the zeolite host affects the structure of mobile dicopper(II) complexes formed during the oxidation of the [CuI (NH3)2] + complexes by O2. Al-rich zeolites promote a planar coordination motif with longer Cu−Cu interatomic distances, while at higher Si/Al values, a bent motif with shorter internuclear separations is also observed. This is paralleled by a more efficient oxidation at a given volumetric Cu density at lower Si/Al, beneficial for the NOx conversion under NH3−SCR conditions at 200 °C.
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- Publication date:
- July 27, 2022
- DOI:
-
- Keyword(s):
- Catalysts Extended X-ray absorption fine structure Oxidation Redox reactions Zeolites
- Published in:
- The Journal of Physical Chemistry Letters:.
- Grants:
-
European Commission:
- CHASS - Cu-CHA zeolite-based catalysts for the selective catalytic reduction of NOx in exhaust diesel gas: addressing the issue of Sulfur Stability (955839)
- Related identifiers:
- Supplementary material
- 10.5281/zenodo.7096004 (Dataset)
- Communities:
- License (for files):
- Creative Commons Attribution 4.0 International