In a number of hydrogenation reactions, palladium nanoparticles may undergo a transition to the hydride or the carbide phase, which affects the catalytic properties. In the current work, we determine the structural evolution of an industrial Pd/C catalyst in the presence of hydrogen and acetylene by means of in situ X-ray absorption spectroscopy and X-ray powder diffraction. We observe reversible hydride phase formation and irreversible formation of the carbide phase. The near-edge structure of the absorption spectra (XANES) plays the key role in distinguishing between hydride and carbide phases. We show that the presence of hydrogen and carbon atoms have a direct effect on the near-edge region which is reproduced by theoretical simulations performed in the Monte-Carlo approach.

In situ formation of hydrides and carbides in palladium catalyst: When XANES is better than EXAFS and XRD

LAZZARINI, ANDREA;LOMACHENKO, KIRILL;GROPPO, Elena Clara;PELLEGRINI, RICCARDO;PIOVANO, ANDREA;LAMBERTI, Carlo
2017-01-01

Abstract

In a number of hydrogenation reactions, palladium nanoparticles may undergo a transition to the hydride or the carbide phase, which affects the catalytic properties. In the current work, we determine the structural evolution of an industrial Pd/C catalyst in the presence of hydrogen and acetylene by means of in situ X-ray absorption spectroscopy and X-ray powder diffraction. We observe reversible hydride phase formation and irreversible formation of the carbide phase. The near-edge structure of the absorption spectra (XANES) plays the key role in distinguishing between hydride and carbide phases. We show that the presence of hydrogen and carbon atoms have a direct effect on the near-edge region which is reproduced by theoretical simulations performed in the Monte-Carlo approach.
2017
283
119
126
http://www.sciencedirect.com/science/journal/09205861
http://www.sciencedirect.com/science/article/pii/S0920586116302255
EXAFS; Monte Carlo simulations; Palladium carbide; Palladium hydride; XANES simulations; XRPD; Catalysis; Chemistry (all)
Bugaev, Aram L.; Guda, Alexander A.; Lazzarini, Andrea; Lomachenko, Kirill A.; Groppo, Elena; Pellegrini, Riccardo; Piovano, Andrea; Emerich, Hermann; Soldatov, Alexander V.; Bugaev, Lusegen A.; Dmitriev, Vladimir P.; van Bokhoven, Jeroen A.; Lamberti, Carlo
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1633120
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