Unveiling the Ir single atoms as selective active species for the partial hydrogenation of butadiene by operando XAS.
Nanoscale
; 14(20): 7641-7649, 2022 May 26.
Article
em En
| MEDLINE
| ID: mdl-35548860
ABSTRACT
Single-atom catalysts represent an intense topic of research due to their interesting catalytic properties for a wide range of reactions. Clarifying the nature of the active sites of single-atom catalysts under realistic working conditions is of paramount importance for the design of performant materials. We have prepared an Ir single-atom catalyst supported on a nitrogen-rich carbon substrate that has proven to exhibit substantial activity toward the hydrogenation of butadiene with nearly 100% selectivity to butenes even at full conversion. We evidence here, by quantitative operando X-ray absorption spectroscopy, that the initial Ir single atoms are coordinated with four light atoms i.e., Ir-X4 (X = C/N/O) with an oxidation state of +3.2. During pre-treatment under hydrogen flow at 250 °C, the Ir atom loses one neighbour (possibly oxygen) and partially reduces to an oxidation state of around +2.0. We clearly demonstrate that Ir-X3 (X = C/N/O) is an active species with very good stability under reactive conditions. Moreover, Ir single atoms remain isolated under a reducing atmosphere at a temperature as high as 400 °C.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Nanoscale
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
França