Interpretation of H 2 -TPR from Cu-CHA Using First-Principles Calculations
In: Cu-CHA zeolite-based catalysts for the selective catalytic reduction of NOx in exhaust diesel gas: addressing the issue of Sulfur Stability (CHASS) Journal of Physical Chemistry C, Jg. 128 (2024), Heft 11, S. 4525-4534
Online
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Zugriff:
Temperature-programmed reduction and oxidation are used to obtain information on the presence and abundance of different species in complex catalytic materials. The interpretation of the temperature-programmed reaction profiles is, however, often challenging. One example is H2 temperature-programmed reduction (H2-TPR) of Cu-chabazite (Cu-CHA), which is a material used for ammonia assisted selective catalytic reduction of NOx (NH3-SCR). The TPR profiles of Cu-CHA consist generally of three main peaks. A peak at 220 °C is commonly assigned to ZCuOH, whereas peaks at 360 and 500 °C generally are assigned to Z2Cu, where Z represents an Al site. Here, we analyze H2-TPR over Cu-CHA by density functional theory calculations, microkinetic modeling, and TPR measurements of samples pretreated to have a dominant Cu species. We find that H2 can react with Cu ions in oxidation state +2, whereas adsorption on Cu ions in +1 is endothermic. Kinetic modeling of the TPR profiles suggests that the 220 °C peak can be assigned to Z2CuOCu and ZCuOH, whereas the peaks at higher temperatures can be assigned to paired Z2Cu and Z2CuHOOHCu species (360 °C) or paired Z2Cu and Z2CuOOCu (500 °C). The results are in good agreement with the experiments and facilitate the interpretation of future TPR experiments.
Titel: |
Interpretation of H 2 -TPR from Cu-CHA Using First-Principles Calculations
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Autor/in / Beteiligte Person: | Bjerregaard, Joachim ; Han, Joonsoo ; Creaser, Derek Claude ; Olsson, Louise ; Grönbeck, Henrik |
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Zeitschrift: | Cu-CHA zeolite-based catalysts for the selective catalytic reduction of NOx in exhaust diesel gas: addressing the issue of Sulfur Stability (CHASS) Journal of Physical Chemistry C, Jg. 128 (2024), Heft 11, S. 4525-4534 |
Veröffentlichung: | 2024 |
Medientyp: | unknown |
ISSN: | 1932-7447 (print) ; 1932-7455 (print) |
DOI: | 10.1021/acs.jpcc.3c07998 |
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