Title

Evolution Of The Structure And Chemical State Of Pd Nanoparticles During The In Situ Catalytic Reduction Of No With H2

Abstract

An in-depth understanding of the fundamental structure of catalysts during operation is indispensable for tailoring future efficient and selective catalysts. We report the evolution of the structure and oxidation state of ZrO2-supported Pd nanocatalysts (∼5 nm) during the in situ reduction of NO with H2 using X-ray absorption fine-structure spectroscopy and X-ray photoelectron spectroscopy. Prior to the onset of the reaction (≤120 °C), a NO-induced redispersion of our initial metallic Pd nanoparticles over the ZrO2 support was observed, and Pd δ+ species were detected. This process parallels the high production of N2O observed at the onset of the reaction (>120 °C), while at higher temperatures (≥150 °C) the selectivity shifts mainly toward N2 (∼80%). Concomitant with the onset of N 2 production, the Pd atoms aggregate again into large (6.5 nm) metallic Pd nanoparticles, which were found to constitute the active phase for the H2-reduction of NO. Throughout the entire reaction cycle, the formation and stabilization of PdOx was not detected. Our results highlight the importance of in situ reactivity studies to unravel the microscopic processes governing catalytic reactivity. © 2011 American Chemical Society.

Publication Date

8-31-2011

Publication Title

Journal of the American Chemical Society

Volume

133

Issue

34

Number of Pages

13455-13464

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/ja203709t

Socpus ID

80052080886 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/80052080886

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