Volume 136, Issue 41 e202408328
Zuschrift

Quantitative Kinetic Insights from Operando-UV/Vis Spectroscopy: An Application to NH3−SCR of NOx on Cu-CHA Catalysts

Dr. Chiara Negri

Dr. Chiara Negri

Laboratory of Catalysis and Catalytic Processes, Dipartimento di Energia, Politecnico di Milano, Via La Masa 34, 20156 Milano, Italy

Contribution: Data curation (lead), Methodology (equal), Writing - original draft (lead)

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Dr. Nicola Usberti

Dr. Nicola Usberti

Laboratory of Catalysis and Catalytic Processes, Dipartimento di Energia, Politecnico di Milano, Via La Masa 34, 20156 Milano, Italy

Contribution: Data curation (equal), Formal analysis (equal), Validation (equal), Writing - original draft (equal)

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Gabriele Contaldo

Gabriele Contaldo

Laboratory of Catalysis and Catalytic Processes, Dipartimento di Energia, Politecnico di Milano, Via La Masa 34, 20156 Milano, Italy

Contribution: Conceptualization (supporting), Data curation (supporting), ​Investigation (supporting), Validation (supporting)

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Dr. Mauro Bracconi

Dr. Mauro Bracconi

Laboratory of Catalysis and Catalytic Processes, Dipartimento di Energia, Politecnico di Milano, Via La Masa 34, 20156 Milano, Italy

Contribution: Formal analysis (equal), Methodology (equal), Software (lead), Writing - review & editing (equal)

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Prof. Isabella Nova

Prof. Isabella Nova

Laboratory of Catalysis and Catalytic Processes, Dipartimento di Energia, Politecnico di Milano, Via La Masa 34, 20156 Milano, Italy

Contribution: Data curation (lead), ​Investigation (lead), Writing - review & editing (equal)

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Prof. Matteo Maestri

Corresponding Author

Prof. Matteo Maestri

Laboratory of Catalysis and Catalytic Processes, Dipartimento di Energia, Politecnico di Milano, Via La Masa 34, 20156 Milano, Italy

Contribution: Formal analysis (lead), Methodology (lead), Supervision (lead), Writing - review & editing (lead)

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Prof. Enrico Tronconi

Corresponding Author

Prof. Enrico Tronconi

Laboratory of Catalysis and Catalytic Processes, Dipartimento di Energia, Politecnico di Milano, Via La Masa 34, 20156 Milano, Italy

Contribution: Conceptualization (lead), Formal analysis (lead), ​Investigation (lead), Writing - review & editing (lead)

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First published: 03 June 2024

Abstract

We employ UV/Vis Diffuse Reflectance spectroscopy directly coupled with a packed bed flow reactor to extract quantitative kinetic information. We use as a show-case the CuII/CuI redox dynamics during the reduction half cycle of the NH3-Selective Catalytic Reduction (SCR) on Cu-CHA catalysts. Our measurements enable quantification of the fraction of oxidized Cu, reconstructed by Multivariate Curve Resolution (MCR) together with monitoring of the gas-phase evolution during the reaction. These data both on the dynamics of the gas-phase and of the active site oxidation state have been used to assess the reduction half cycle rate equation and estimate the rate constant. Our results in terms of reaction orders and kinetic constant are in line with previous findings in the literature. Overall, our results demonstrate that the combined analysis of the UV spectra and of the gas-phase dynamics provides converging and unparalleled kinetic insight: this approach effectively resolves ambiguities concerning RHC kinetics and mechanism. More in general, this work provides evidence that operando spectroscopy can be used to extract quantitative kinetic information on catalytic cycles.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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