Deciphering the Nature of Ru Sites in Reductively Exsolved Oxides with Electronic and Geometric Metal–Support Interactions
Научная публикация
| Общее |
Язык:
Английский,
Жанр:
Статья (Full article),
Статус опубликования:
Опубликована,
Оригинальность:
Оригинальная
|
| Журнал |
The Journal of Physical Chemistry C
ISSN: 1932-7447
, E-ISSN: 1932-7455
|
| Вых. Данные |
Год: 2020,
Том: 124,
Номер: 46,
Страницы: 25299-25307
Страниц
: 9
DOI:
10.1021/acs.jpcc.0c07203
|
| Авторы |
Naeem Muhammad A.
1
,
Burueva Dudari B.
2,3
,
Abdala Paula M.
1
,
Bushkov Nikolai S.
1
,
Stoian Dragos
4
,
Bukhtiyarov Andrey V.
5
,
Prosvirin Igor P.
3,5
,
Bukhtiyarov Valerii I.
5
,
Kovtunov Kirill V.
2,3
,
Koptyug Igor V.
2,3
,
Fedorov Alexey
1
,
Müller Christoph R.
1
|
| Организации |
| 1 |
Department of Mechanical and Process Engineering, ETH Zürich, CH 8092 Zürich, Switzerland
|
| 2 |
International Tomography Center, SB RAS, 630090 Novosibirsk, Russia
|
| 3 |
Novosibirsk State University, 630090 Novosibirsk, Russia
|
| 4 |
The Swiss−Norwegian Beamlines (SNBL) at ESRF, Grenoble 38043, France
|
| 5 |
Boreskov Institute of Catalysis, SB RAS, 630090 Novosibirsk, Russia
|
|
Информация о финансировании (7)
|
1
|
Федеральное агентство научных организаций России
|
0333-2016-0002 (АААА-А16-116121510087-5)
|
|
2
|
Российский фонд фундаментальных исследований
|
19-43-540004 (АААА-А19-119090590009-9)
|
|
3
|
Российский фонд фундаментальных исследований
|
19-29-10003 (АААА-А19-119100890052-8)
|
|
4
|
Российский научный фонд
|
19-13-00172
|
|
5
|
Swiss National Science Foundation
|
4879135 (R’Equip)
|
|
6
|
Fondation Claude et Giuliana
|
|
|
7
|
Swiss National Science Foundation
|
200020_156015
|
The reductive exsolution of metallic Ru from fluorite-type solid solutions Ln2Ru0.2Ce1.8O7 (Ln = Sm, Nd, La) leads to materials with metal–support interactions that influence the electronic state and the catalytic activity of Ru. In situ X-ray absorption spectroscopy at the Ru K-edge identified that with increasing temperature, the exsolution of Ru from Sm2Ru0.2Ce1.8O7 in a H2 atmosphere proceeds via an intermediate Ruδ+ state, that is, Ru4+→Ruδ+→Ru0. X-ray photoelectron spectroscopy (XPS) established that, in parallel (H2 atmosphere at ca. 500 °C), also Ce4+ ions reduce to Ce3+, which is accompanied by an electron transfer from the reduced host oxide to the exsolved Ru0 clusters, creating Ruδ− states. Low-temperature diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) using CO as a probe molecule reveals a red shift of the CO adsorption bands by ca. 18 cm–1 when increasing the temperature during the H2 treatment from 300 to 500 °C, consistent with an increased π-backdonation from more electron-rich Ru species to CO. However, at a lower reduction temperature of ca. 100 °C, a blue-shifted CO band is observed that is explained by a Lewis-acidic Ruδ+–CO adduct. Nuclear magnetic resonance (NMR) signal enhancement in parahydrogen-induced polarization experiments was used as a structure-sensitive probe and revealed a decreasing propene hydrogenation rate with increasing exsolution temperature, accompanied by a notable enhancement of propane hyperpolarization (ca. 3-fold higher at 500 °C than at 300 °C). These data suggest that the exsolved, subnanometer-sized Ru species are more active in propene hydrogenation but less selective for the pairwise addition of p-H2 to propene than Ruδ− sites engaged in a strong metal–support interaction.