Highly Active Ceria-Supported Ru Catalyst for the
Dry Reforming of Methane: In Situ Identification of Ru<sup>δ+</sup>–Ce<sup>3+</sup> Interactions for Enhanced Conversion
Zongyuan Liu
Feng Zhang
Ning Rui
Xing Li
Lili Lin
Luis E. Betancourt
Dong Su
Wenqian Xu
Jiajie Cen
Klaus Attenkofer
Hicham Idriss
José A. Rodriguez
Sanjaya D. Senanayake
10.1021/acscatal.8b05162.s001
https://acs.figshare.com/articles/journal_contribution/Highly_Active_Ceria-Supported_Ru_Catalyst_for_the_Dry_Reforming_of_Methane_In_Situ_Identification_of_Ru_sup_sup_Ce_sup_3_sup_Interactions_for_Enhanced_Conversion/7849640
The
metal–oxide interaction changes the surface electronic
states of catalysts deployed for chemical conversion, yet details
of its influence on the catalytic performance under reaction conditions
remain obscure. In this work, we report the high activity/stability
of a ceria-supported Ru–nanocluster (<1 nm) catalyst during
the dry reforming of methane. To elucidate the structure–reactivity
relationship underlying the remarkable catalytic performance, the
active structure and chemical speciation of the catalyst was characterized
using in situ X-ray diffraction (XRD) and X-ray absorption fine structure
(XAFS), while the surface chemistry and active intermediates were
monitored by in situ ambient-pressure X-ray photoelectron spectroscopy
(AP-XPS) and diffuse reflectance infrared Fourier transform spectroscopy
(DRIFTS). Methane activates on the catalyst surface at temperatures
as low as 150 °C. Under reaction conditions, the existence of
metal–support interactions tunes the electronic properties
of the Ru nanoclusters, giving rise to a partially oxidized state
of ruthenium stabilized by reduced ceria (Ru<sup>δ+</sup>–CeO<sub>2–<i>x</i></sub>) to sustain active chemistry, which
is found to be very different from that of large Ru nanoparticles
supported on ceria. The oxidation of surface carbon is also a crucial
step for the completion of the catalytic cycle, and this is strongly
correlated with the oxygen transfer governed by the Ru<sup>δ+</sup>–CeO<sub>2–<i>x</i></sub> interactions at
higher temperatures (>300 °C). The possible reaction pathways
and stable surface intermediates were identified using DRIFTS including
ruthenium carbonyls, carboxylate species, and surface −OH groups,
while polydentate carbonates may be plain spectators at the measured
reaction conditions.
2019-03-04 00:00:00
XAFS
ambient-pressure X-ray photoelectron spectroscopy
OH
XRD
interaction
AP-XPS
catalyst
DRIFTS
Active Ceria-Supported Ru Catalyst
reaction conditions
surface