Thermally Stable and Regenerable Platinum–Tin Clusters for Propane Dehydrogenation Prepared by Atom Trapping on Ceria

Article abstract of DOI:10.1002/anie.201701115

Ceria (CeO₂) supports are unique in their ability to trap ionic platinum (Pt), providing exceptional stability for isolated single atoms of Pt. The reactivity and stability of single-atom Pt species was explored for the industrially important light alkane dehydrogenation reaction. The single-atom Pt/CeO₂ catalysts are stable during propane dehydrogenation, but are not selective for propylene. DFT calculations show strong adsorption of the olefin produced, leading to further unwanted reactions. In contrast, when tin (Sn) is added to CeO₂, the single-atom Pt catalyst undergoes an activation phase where it transforms into Pt–Sn clusters under reaction conditions. Formation of small Pt–Sn clusters allows the catalyst to achieve high selectivity towards propylene because of facile desorption of the product. The CeO₂-supported Pt–Sn clusters are very stable, even during extended reaction at 680 °C. Coke formation is almost completely suppressed by adding water vapor to the feed. Furthermore, upon oxidation the Pt–Sn clusters readily revert to the atomically dispersed species on CeO₂, making Pt–Sn/CeO₂ a fully regenerable catalyst.

Full text of DOI:10.1002/anie.201701115

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Accepted Article
Title: Thermally Stable and Regenerable Pt-Sn Clusters for Propane
Dehydrogenation Prepared via Atom Trapping on Ceria
Authors: Haifeng Xiong, Sen Lin, Joris Goetze, Paul D Pletcher, Libor
Kovarik, Kateryna Artyushkova, Hua Guo, Bert Weckhuysen,
and Abhaya Datye
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201701115
Angew. Chem. 10.1002/ange.201701115
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10.1002/anie.201701115
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Thermally Stable and Regenerable Pt-Sn Clusters for Propane
Dehydrogenation Prepared via Atom Trapping on Ceria
Haifeng Xiong, Sen Lin *, Joris Goetze, Paul Pletcher, Hua Guo, Libor Kovarik, Kateryna Artyushkova,
Bert M. Weckhuysen *, and Abhaya K. Datye *
oxidizing conditions leads to sintering of Pt, forming large Pt
particles.[8] To achieve redispersion of Pt, it is necessary to add
halogens (e.g., Cl2, HCl, CCl4 or fluorine) so that the small particle
size of Pt in the initial catalyst can be restored.[9] In the present
work we explore an alternative support, ceria, that is unique in its
ability to trap Pt atoms in ionic form.[10] The ceria support also
allows facile redispersion, restoring the atomic dispersion of Pt
without the need for corrosive halogens. Furthermore, the redox
properties of ceria allow the use of water vapor to almost
completely eliminate the deposition of coke traditionally seen
during propane conversion at these high reaction temperatures.
The catalyst synthesis takes advantage of the ability of ceria to
Abstract: CeO2 supports are unique in their ability to trap ionic Pt,
providing exceptional stability for isolated single atoms of Pt. Here,
we explore the reactivity and stability of single atom Pt species for the
industrially important reaction of light alkane dehydrogenation. The
single atom Pt/CeO2 catalysts are stable during propane
dehydrogenation, but we observe no selectivity towards propene. DFT
calculations show strong adsorption of the olefin produced, leading to
further unwanted reactions. In contrast, when Sn is added to ceria,
the single atom Pt catalyst undergoes an activation phase where it
transforms into Pt-Sn clusters under reaction conditions. Formation of
small Pt-Sn clusters allows the catalyst to achieve high selectivity
towards propene, due to facile desorption of the product. The CeO2-
supported Pt-Sn clusters are very stable, even during extended
reaction at 680 °C. By adding water vapor to the feed, coke formation
can almost completely be suppressed. Furthermore, the Pt-Sn
clusters can be readily transformed back to the atomically dispersed
species on ceria via oxidation, making Pt-Sn/CeO2 a fully regenerable
catalyst.
trap Pt atoms, as explained in our previous work.[11] This requires
o
heating Pt/ceria to 800 C for 10 h in flowing air. The Scanning
Transmission Electron Microscope (STEM) image of the Pt/CeO2
(1 wt.%Pt) shows that the Pt species are atomically dispersed (Fig.
1b). XPS spectra of the Pt 4f region for the fresh and spent
Pt/CeO2 are shown in Fig. 1a. The only Pt species in the as-
prepared Pt/CeO2 catalyst are Pt2+ and Pt4+, consistent with the
STEM image (as confirmed previously via FTIR and XRD[11]).
After 3 cycles of propane dehydrogenation at an elevated reaction
temperature of 680 oC, the XPS spectrum shows that a portion of
the ionic Pt has transformed into metallic Pt. STEM images of the
sample after reaction show that atomically dispersed Pt co-exists
with Pt nanoclusters and the nanoclusters have an average size
of ca. 1.2 nm (Fig. 1c and Figure S1). The Pt/CeO2 catalyst is very
reactive for propane conversion at 680 oC, showing 100%
propane conversion (Table 1). However, the products are CH4
and CO2, and no propylene was detected, indicating that the
isolated Pt single atoms are highly efficient catalysts but they only
lead to C-C bond cleavage of the hydrocarbons with no observed
selectivity towards dehydrogenation. Pure ceria and Sn/CeO2 (3
wt.%Sn) were also tested for propane dehydrogenation under the
same conditions (680 oC). No dehydrogenation and
decomposition reactivity was found on the pure ceria and
Sn/CeO2. This observation is consistent with an earlier report that
low loaded (1000 ppm) Pt catalysts showed low activity for
propane dehydrogenation.[12]
Light olefins are important building blocks in the chemical
industry. Their growing demand has led to an increased interest
in the dehydrogenation of light alkanes[1], such as ethane and
propane[2], which are now much more abundant due to the vast
amounts of shale gas deposits.[3] The production of light olefins
via alkane dehydrogenation is practiced commercially, but
because of its endothermicity, it requires high reaction
temperatures to achieve economically attractive yields.[4] The high
reaction temperatures cause catalyst deactivation due to
sintering[5], and coke formation[6]. While carbon deposits can be
effectively oxidized during regeneration in air, it is more difficult to
achieve redispersion of the Pt.[7] In fact, heating Pt/Al2O3 under
[*]
Dr. H. Xiong, Dr. K. Artyushkova, Prof. Dr. A.K. Datye
Department of Chemical & Biological Engineering and Center for
Microengineered Materials, University of New Mexico
Albuquerque, New Mexico 87131, USA
E-mail: datye@unm.edu
Dr. S. Lin
Research Institute of Photocatalysis, State Key Laboratory of
Photocatalysis on Energy and Environment, Fuzhou University,
Fuzhou 350002, China
Table 1. Propane dehydrogenation performance of the supported Pt and Pt-Sn
catalysts under investigation.
Email: slin@fzu.edu.cn
J. Goetze, Dr. P. Pletcher, Prof. Dr. B.M. Weckhuysen
Inorganic Chemistry and Catalysis, Debye Institute for
Nanomaterials Science, Utrecht University, Universiteitsweg 99,
3584 CG Utrecht, The Netherlands
Email: B.M.Weckhuysen@uu.nl
Prof. Dr. H. Guo
Department of Chemistry and Chemical Biology, University of New
Mexico, Albuquerque, New Mexico 87131, USA
Dr. L. Kovarik
Catalyst[a]
Conversion of
propane (%)
Propylene
Carbon content at end of
6h run at 680 oC (wt.%)[c]
selectivity[b]
Pt/CeO2
100
0
0.9 (3.4)
0.5 (2.8)
0.3 (3.0)
Pt-Sn/CeO2
Pt-Sn/Al2O3
39.5
32.6
84.5
71.4
Environmental Molecular Sciences Laboratory, Pacific Northwest
National Laboratory, Richland, WA 99352, USA
[a] 0.1 g catalyst; 0.005 mL/min water; ambient pressure; reaction temperature:
T=680 oC. [b] The calculation is based on the hydrocarbons as detected by FID
and the formula is shown in the SI. [c] The weight loss of the spent catalyst was
Supporting information for this article is given via a link at the end of
the document.
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obtained from TGA carried out from 25 to 800 oC in the flowing air, the data for
reactions without water vapor are shown in parenthesis.
an atomic ratio ~ Pt:Sn = 1:5 (as confirmed by both EDS and
EPMA). Co-impregnation and sequential impregnation yield
similar results. The catalysts undergo calcination in flowing air at
800 °C to disperse the Pt and Sn. In the as-prepared Pt-Sn/CeO2
catalyst (Fig. 2b), we see atomically dispersed species as well as
sub-nanometer clusters with an average diameter of 0.6 nm (Fig.
2b and Figure S6). Because the Sn has similar atomic mass as
Ce, HAADF (high-angle annular dark field) STEM images cannot
provide enough contrast to image atomically dispersed Sn on the
CeO2 support, but the high atomic number of Pt makes it easy to
detect by HAADF STEM. We have used STEM-EDS mapping to
determine the distribution of Pt and Sn on this Pt-Sn/CeO2 sample.
The sub-nm clusters in the as-prepared (calcined at 800 oC in air)
catalyst show Pt:Sn ~1:1 to 5:1 as determined by EDS analysis
(Figure S7). The average composition of these sub-nm clusters is
Pt:Sn ~3:1. Since the ceria can trap single atoms, we also
analyzed regions of the support that do not contain any sub-nm
clusters. Here we found excess Sn (Sn:Pt ratio from 100:0 to
2.5:1, Figures S7-S8). We infer that the Pt-Sn/CeO2 catalyst as-
prepared contains both Sn and Pt in atomically dispersed form,
with more Sn than Pt, while the sub-nm clusters contain more Pt
than Sn, consistent with the overall composition of the catalyst.
To investigate the causes for the observed lack of selectivity of
the single atom Pt/CeO2 material towards propylene, we
performed density functional theory (DFT) calculations for the
single atom Pt supported on CeO2 (see details in Supporting
Information (SI)). The Pt adsorbs strongly at a surface Ce4+
vacancy; the adsorption structures of pertinent species are
displayed in Figures S2-S4 and the corresponding adsorption
energies are listed in Table S1. On single atom Pt supported by
CeO2, the product of the dehydrogenation (propylene) adsorbs
strongly at the atomic Pt sites via di- bonds with Pt. The
configurations for the initial states, transition states and final
states along the reaction path are shown in Figure S5 and the
barriers and reaction energies are listed in Table S2. Both
dehydrogenation steps at the single Pt atoms for Pt/CeO2 catalyst
are facile with relatively low activation energies. The strongly
adsorbed propylene is expected to undergo further reactions,
leading eventually to C-C bond cleavage. Hence, despite facile
dehydrogenation, the observed propylene selectivity is low.
Figure 1. Pt is atomically dispersed on CeO2 in the as-prepared catalyst,
undergoes some reduction to form sub-nm Pt particles after reaction. Circles
point to isolated single atoms of Pt. Despite its high activity (100% conversion
at 680 °C), the monometallic catalyst does not show any selectivity to propylene.
(a) XPS spectra of the fresh and spent Pt/CeO2 catalyst after propane
dehydrogenation at 680 oC for 6 h. (b) STEM image of the as-prepared Pt/CeO2
catalyst (calcined 800 oC in air). (c) STEM image of the spent Pt/CeO2 catalyst
after three cycles of propane dehydrogenation at 680 oC for 6h each, with an
intermediate oxidation at 580 oC for 2 h after each cycle.
Figure 2. Pt-Sn/CeO2 catalyst evolves during reaction to convert the atomically
dispersed Pt species into Pt-Sn clusters that are selective for propane
dehydrogenation. (a) XPS spectra of the fresh and spent Pt-Sn/CeO2 catalyst
after propane dehydrogenation at 680 oC. (b) STEM image of the as-prepared
Pt-Sn/CeO2 catalyst. (c) STEM image of the Pt-Sn/CeO2 catalyst after 3 cycles
of propane dehydrogenation at 680 oC with intermediate oxidative treatment at
It is known that Pt-Sn alloys (i.e., nanoparticles) are highly
selective for the dehydrogenation of light alkanes.[13] Therefore, to
modify the selectivity, we added Sn to the Pt single atom catalyst.
The Pt-Sn/CeO2 catalyst contains 1wt.% Pt and 3wt.% Sn, with
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580 oC for 2h. (d) the propane dehydrogenation reactivity of Pt-Sn/CeO2
showing 3 cycles of a 6 h run, followed by oxidative treatment in flowing air at
580 °C. The catalyst goes through an activation phase (self-assembly) where
selectivity (based on hydrocarbons) improves and activity drops, but achieves
stable performance after this initial phase.
catalysts show very low coke content of  1 wt.% after a 6 h run
at 680 oC. This is due to the co-feeding of water vapor to the
catalyst.[14] If no water vapor was fed to the Pt-Sn/CeO2 catalyst,
the coke content increased from 0.5 to 2.8 wt.% and the
conversion dropped. The results confirm that the addition of water
vapor can suppress the formation of coke during propane
dehydrogenation at high temperature.[15] The coke formed under
the high temperature conditions was investigated by electron
microscopy and Raman spectroscopy. As shown in Figure S13,
coke layers were found to cover only the support surface for the
spent Pt-Sn/CeO2 catalyst. Raman spectra of the spent Pt-
Sn/CeO2 and Pt-Sn/Al2O3 catalysts showed the presence of both
D and G bands (Figure S14), indicating that the coke layers are
composed of graphitic carbon.[16] The existence of graphitic
carbon on the spent Pt-Sn/CeO2 catalyst was also confirmed by
the wide-area Raman spectroscopy scan, labelled in yellow in
Figure S14.
It is commonly accepted that carbon deposits can lead to
lowered reactivity during dehydrogenation.[17] These catalysts,
after the initial activation phase during the first 2 h of reaction, did
not show any deactivation during the 6 h run. However, we
performed an oxidative treatment to contrast the regenerability of
the Pt and Sn species on the ceria and alumina supports. On the
Al2O3 support, the reactivity of Pt-Sn decreased during reaction
and the oxidative treatment was not able to restore the reactivity
(Figure S12). This suggests that the deactivation of the alumina-
supported catalyst was caused by sintering of this catalyst which
is not reversed during the oxidative treatment, rather than the
small amount of coke, which is readily removed during oxidation
at 580 oC.[5b] In contrast, we found that the reactivity pattern of the
Pt-Sn/CeO2 catalyst was similar after each oxidative regeneration.
The initial activity, after regeneration is high. Over time, the
reactivity drops and the selectivity improves and during this period
a phenomenon we termed ‘self-assembly‘ takes place. This
reactivity pattern was reproducible over the three cycles as
shown in Fig. 2d. The STEM images of the regenerated Pt-
Sn/CeO2 catalyst, after ‘self-assembly‘ (i.e., after 2 h run), and at
the end of the 6 h run are shown in Figure S10. These results
show that the Pt-Sn clusters have formed during self-assembly
and remain stable thereafter.
The propane dehydrogenation reactivity of the Pt-Sn/CeO2
catalyst as a function of time on stream at 680 oC is shown in Fig.
2d and the results are summarized in Table 1. The as-prepared
Pt-Sn/CeO2 catalyst starts with a relatively high initial reactivity
(~45% conversion) but a low selectivity to propylene (~78%).
During the first 2 h, the activity drops (to 40%) and the selectivity
towards propylene improves (to 85%). The selectivity is based on
the effluent composition of hydrocarbons detected via a flame
ionization detector (FID). After this initial catalyst activation phase,
the catalyst is remarkably stable during the 6 h run (Fig. 2d) with
~39.5% propane conversion and ~84% propylene selectivity at
the end of the 6h run (Table 1). The catalyst was subjected to an
oxidative regeneration step after 6 h on stream, since similar
treatments are used in industrial practice. This involved treating
the sample in flowing air at 580 oC for 2 h. The pattern of reactivity
seen in the first cycle is reproduced in the second and third cycles.
The Pt-Sn/CeO2 catalyst was also tested in a second reactor
setup for propane dehydrogenation at reaction temperatures of
550 and 680 oC to verify the stability and carbon balance, and the
results show that in addition to the hydrocarbons, we also detect
CO and CO2. These data confirm that the initial catalyst has low
selectivity for propylene, which improves over the first 2 h and the
catalyst is stable over the remainder of the run (Figure S9 and
Table S3).
STEM images of the Pt-Sn/CeO2 catalyst after propane
o
dehydrogenation at 680 C are shown in Fig. 2 and Figures S10
and S11. We now observe well-defined nanoclusters with an
average diameter of 1.1 nm. The particle size distribution is shown
in Figure S11d and EDS analysis shows a Pt:Sn ratio of ca. 1:3
on the small particles (Figure S11). These results show that the
Pt-Sn/CeO2 catalyst is very stable, once the initial activation
phase is complete. To understand this initial activation of the
catalyst, we can compare the as-prepared catalyst (after 800 oC
calcination, Fig, 2b and Figure S7) with the catalyst after 2 h on
stream (Figure S10) and the end of run catalyst (Fig. 2c and
Figure S1c and S1d). The major difference is the presence of
atomically dispersed Pt in the as-prepared catalyst, which is
missing in the end of run catalyst. As already discussed in the
context of the monometallic catalyst, the single Pt atoms are very
active but only lead to C-C bond cleavage. Another significant
change during reaction is the formation of Pt-Sn clusters having
diameter ~1.1 nm and a Pt:Sn atomic ratio of 1:3. As a
comparison, on an alumina supported catalyst subjected to the
same reaction conditions, the Pt-Sn particles are much larger
(~8nm) (Figure S12). We also studied the Pt and Sn species on
the Pt-Sn/CeO2 catalyst via XPS (Fig. 2a). The initial catalyst
contains only ionic Pt, similar to the fresh Pt/CeO2. After
dehydrogenation, the Pt 4f XPS spectra of spent Pt-Sn/CeO2
catalyst show the formation of metallic Pt as well as the existence
of Pt2+. This is consistent with the STEM result that nanoclusters
(i.e. metallic Pt) are formed on the spent catalyst after
dehydrogenation (Fig. 2c and Figure S11). The Sn 3d spectra are
broad and correspond to oxidized Sn species in the as-prepared
catalyst, while after reaction the Sn 3d peak shifts to lower binding
energy, which is consistent with the transformation of a portion of
the oxidized Sn into metallic Pt-Sn nanoparticles.
To gain insight into this “self-assembly“ process, we have
examined carefully the Pt-Sn/CeO2 after oxidative regeneration,
the state of the catalyst where the reactivity is high, but the
selectivity is poor (Fig. 2d). The STEM images and STEM-EDS
maps are shown in Fig. 3 and Figure S15. The high magnification
STEM image in Fig. 3a shows that the Pt is present as atomically
dispersed, isolated species, similar to the as-prepared catalyst.
The STEM EDS maps confirm that Pt is well dispersed, but Sn is
present in the form of particles which are devoid of Pt (Fig. 3f and
Figure S15). One such particle is seen in the inset of Fig. 3a and
indicated with an arrow. The lattice images index to SnO2 (inset
of Fig. 3a and Figure S16). Other evidence of crystalline SnO2 on
the ceria is via Moiré fringes, which result from the interference
between the two crystalline phases present on top of each other.
The EDS map in Fig. 3f clearly shows high concentrations of Sn
correponding to the particles seen on the support.
The coke content on the spent Pt-Sn catalysts was
investigated at the end of the first cycle by performing both TGA
in flowing air and elemental analysis using a CHN analyzer (Table
S4). Both techniques gave similar carbon contents. The coke
deposited on the sample is reported in Table 1. All of these
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since it is able to trap the Pt atoms. In a recent study, Moliner et
al.[20] showed that zeolite cages could trap Pt atoms during
oxidative regeneration. However, during reduction, they observed
the formation of large metallic Pt particles. The ceria support is
unique because trapping sites allow the size of the Pt-Sn clusters
to remain small even when used at such high temperatures. We
also investigated the CO DRIFTS of the Pt/CeO2 and Pt-Sn/CeO2
catalysts (Figure S18). The initial catalyst shows linearly
adsorbed CO at a frequency that is consistent with the isolated
single atoms seen in Figs. 1b and Fig. 2b. In the reduced catalyst,
we see both linearly and bridge-bonded CO on both catalysts.
The TPD of the the two catalysts are consistent with previous
literature [21]. However, no significant changes on the FTIR
spectra between the two catalysts were observed suggesting that
this technique may not be able to distinguish between these two
catalysts [22]
.
To further test the stability of the Pt-Sn/CeO2 catalyst we
treated it in CH4 at 800 C. This caused a growth in particle size
and a drop in activity, but the sizes of these particles are still
smaller than those on the alumina support after reaction at 680
C (Table S5 and Figure S19).
Figure 3. Pt-Sn/CeO2 catalyst after regeneration. (a) High magnification STEM
image of spent Pt-Sn/CeO2 after treatment at 580 oC for 2 h in air showing the
Pt species re-dispersed on the support (circles showing the Pt species) and the
existence of SnO2 particles (arrow in insert). (b) Low magnification STEM image
of spent Pt-Sn/CeO2 after regeneration in air. (c)-(f), STEM-EDS maps showing
the locations of cerium (Ce, yellow), oxygen (O, green), platinum (Pt, yellow)
and tin (Sn, green).
Figure 4a presents a schematic diagram showing how the Pt-
Sn/CeO2 catalyst changes from the initial state after regeneration
to its final steady-state morphology. The regenerated catalyst
contains Pt single atoms dispersed on the ceria (Fig. 4b) and
SnO2 particles. After reaction we do not see any atomically
dispersed Pt. Instead, we see Pt-Sn clusters (Fig. 4c). The
composition of these clusters was analyzed via EDS and found to
be Pt:Sn = 1:3.
As explained in the discussion of DFT results in SI, single
atoms of Pt on ceria are not selective for propane
dehydrogenation because the strongly adsorbed propylene is
amenable to further reactions. When Sn is added, DFT
calculations suggest that it can bind strongly to ceria. The Pt
atoms can bind strongly with Sn embedded in ceria. Our DFT
results also indicate that the Pt-Sn/CeO2 catalyst has a much
lower adsorption energy for propylene product than that on the
single atom Pt/CeO2 catalyst. As a result, once formed, propylene
desorbes easily, which prevents its further reaction. This unique
property is similar to bulk Pt-Sn alloy surfaces, which have been
discussed extensively in the literature.[6b, 13c, 18] Adding Sn to Pt in
the atomically dispersed catalyst improves the selectivity, but it
lowers the rate of propane dehydrogenation due to a higher
activation barrier (Table S2 and Figure S17). Adding a second Pt
atom to Sn causes it to bind strongly suggesting that Sn helps to
serve as a nucleation site for forming Pt-Sn clusters. These DFT
results help explain the evolution of the catalyst during reaction,
where H2 is generated which causes the ionic Pt to transform into
metallic Pt. The single atoms of Pt are mobile and interact with
the Sn to form bimetallic Pt-Sn clusters, which grow to a size of
~1.1 nm. The ability of of mobile Pt to reduce the dispersed Sn
species is similar to that seen previous where Pt was found to
reduce PdO to form bimetallic Pt-Pd particles.[19]
Figure 4. (a) Schematic illustration showing the self-assembly and regeneration
processes of Pt-Sn nanocluster in propane dehydrogenation at 680 oC; (b)
STEM image of regenerated Pt-Sn/CeO2 catalyst (air, 580 oC); (c) STEM image
of spent Pt-Sn/CeO2 catalyst after propane dehydrogenation at 680 oC.
To summarize, Pt-Sn/CeO2 is a thermally stable, active and
regenerable catalyst for light alkane dehydrogenation. The atom
trapping sites on ceria help achieve complete redispersion of Pt
atoms under mild oxidative regeneration conditions, without the
need for chlorine containing molecules, providing a regenerable,
thermally stable catalyst for light alkane activation. The redox
properties of ceria allow water vapor to be used as the oxidant,
suppressing coke formation during the dehydrogenation.
What is unique about the ceria support is that these Pt-Sn
clusters do not grow in size during reaction at steady state (Fig.
2d). In contrast, the Pt-Sn/Al2O3 catalyst shows particle sizes ~ 8
nm in diameter (Figure S12). The primary mechanism for sintering
of the Pt-Sn catalyst is Ostwald ripening at these high
temperatures. The ceria support slows the process of ripening
Acknowledgements
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Financial support from US Department of Energy (DE-FG02-
05ER15712), Center for Biorenewable Chemicals (CBiRC)
supported by NSF under grant EEC-0813570, National Natural
Science Foundation of China (21673040), Natural Science
Foundation of Fujian Province (2016J01052), National Science
Foundation (CHE-1462019) and European Research Council
(ERC Advanced Grant no. 321140). We thank A. Nicholls at the
University of Illinois at Chicago for recording some of the AC-
STEM images. Part of the research was conducted at the
Environmental Molecular Sciences Laboratory located at Pacific
Northwest National Laboratory (PNNL), supported by the DOE's
Office of Biological and Environmental Research. B.M.W.
acknowledges the NWO Gravitation program, Netherlands Center
for Multiscale Catalytic Energy Conversion (MCEC), and a
European Research Council (ERC) Advanced Grant (no. 321140).
We thank Fouad Soulimani (Utrecht University) for assistance
with the FTIR measurements.
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.
Keywords: Light alkane dehydrogenation • Catalyst
regeneration • Subnanometer Pt-Sn catalysis • Single atoms •
Ceria
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This article is protected by copyright. All rights reserved.

10.1002/anie.201701115
Angewandte Chemie International Edition
COMMUNICATION
Table of Content
COMMUNICATION
Haifeng Xiong, Sen Lin, Joris Goetze,
Paul Pletcher, Hua Guo, Libor Kovarik,
Kateryna Artyushkova, Bert M.
Weckhuysen, and Abhaya K. Datye *
Page No. – Page No.
Title
Isolated Pt single atoms are active but not selective for alkane dehydrogenation. Pt
single atoms self-assemble into sub-nanometer Pt-Sn clusters during reaction. The
spent Pt-Sn catalyst can be readily transformed back to the atomically dispersed
state after an oxidation treatment, without the need for added chlorine.
This article is protected by copyright. All rights reserved.