Infrared spectroscopy is typically not used to establish the oxidation state of metal-based catalysts. In this work, we show that the baseline of spectra collected in diffuse reflectance mode of a series of Pd/Al2O3 samples of increasing Pd content varies significantly and reversibly under alternate pulses of CO or H2 and O2. Moreover, these baseline changes are proportional to the Pd content in Pd/Al2O3 samples exhibiting comparable Pd particle size. Similar measurements by X-ray absorption spectroscopy on a different 2 wt.% Pd/Al2O3 confirm that the baseline changes reflect the reversible reduction-oxidation of Pd. Hence, we demonstrate that changes in oxidation state of metal-based catalysts can be determined using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and that this behavior is part of the spectral changes that are returned by experiments under operando conditions.

Changes of pd oxidation state in pd/al2o3 catalysts using modulated excitation drifts / G.L. Chiarello, Y. Lu, M. Agote-Aran, R. Pellegrini, D. Ferri. - In: CATALYSTS. - ISSN 2073-4344. - 11:1(2021 Jan), pp. 116.1-116.13. [10.3390/catal11010116]

Changes of pd oxidation state in pd/al2o3 catalysts using modulated excitation drifts

G.L. Chiarello
Primo
Investigation
;
2021

Abstract

Infrared spectroscopy is typically not used to establish the oxidation state of metal-based catalysts. In this work, we show that the baseline of spectra collected in diffuse reflectance mode of a series of Pd/Al2O3 samples of increasing Pd content varies significantly and reversibly under alternate pulses of CO or H2 and O2. Moreover, these baseline changes are proportional to the Pd content in Pd/Al2O3 samples exhibiting comparable Pd particle size. Similar measurements by X-ray absorption spectroscopy on a different 2 wt.% Pd/Al2O3 confirm that the baseline changes reflect the reversible reduction-oxidation of Pd. Hence, we demonstrate that changes in oxidation state of metal-based catalysts can be determined using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and that this behavior is part of the spectral changes that are returned by experiments under operando conditions.
Baseline; DRIFTS; Modulated excitation; Oxidation state; Palladium; Phase sensitive detection; QuickEXAFS
Settore CHIM/02 - Chimica Fisica
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/825294
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