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We report a series of Pd K-edge and Pt L3-edge X-ray absorption spectra (XAS) collected in situ during thermal treatment of functionalized UiO-67-Pd and UiO-67-Pt metal-organic frameworks in inert and reducing atmospheres. We present raw synchrotron data from three subsequent experiments at different beamlines, normalized XAS spectra and k2-weighted oscillatory χ(k) functions extracted from one of the datasets. Pd K-edge spectra were collected for the samples in 5% H2/He, 3% H2/He and pure He in the temperature range from room temperature (RT) to 450 °C. Pt L3-edge were collected for the samples in 3% H2/He, 10% H2/He and pure He in the temperature range from RT to 300 °C. All spectra are reported together with the used atmosphere and temperature. For the analysis of all reported datasets, please see "Evolution of Pt and Pd species in functionalized UiO-67 metal-organic frameworks". Fourier-analysis of Pd K-edge is reported in "Formation and growth of Pd nanoparticles in UiO-67 MOF by in situ EXAFS".
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Data Article
In situ X-ray absorption spectroscopy data during
formation of active Pt- and Pd-sites in
functionalized UiO-67 metal-organic
frameworks
Aram L. Bugaev
a
,
*
, Alina A. Skorynina
a
,
Elizaveta G. Kamyshova
a
, Kirill A. Lomachenko
b
,
Alexander A. Guda
a
, Alexander V. Soldatov
a
,
Carlo Lamberti
a
,
c
a
The Smart Materials Research Institute, Southern Federal University, Sladkova 178/24, 344090, Rostov-on-
Don, Russia
b
European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS 40220, 38043 Grenoble Cedex 9,
France
c
Department of Physics and CrisDi Interdepartmental Centre, University of Turin, Via P. Giuria 1, 10125
Turin, Italy
article info
Article history:
Received 26 March 2019
Received in revised form 9 July 2019
Accepted 10 July 2019
Available online 17 July 2019
Keywords:
EXAFS
XANES
MOFs
Nanoparticles
abstract
We report a series of Pd K-edge and Pt L
3
-edge X-ray absorption
spectra (XAS) collected in situ during thermal treatment of func-
tionalized UiO-67-Pd and UiO-67-Pt metal-organic frameworks in
inert and reducing atmospheres. We present raw synchrotron data
from three subsequent experiments at different beamlines,
normalized XAS spectra and k
2
-weighted oscillatory
c
(k) functions
extracted from one of the datasets. Pd K-edge spectra were
collected for the samples in 5% H
2
/He, 3% H
2
/He and pure He in the
temperature range from room temperature (RT) to 450
C. Pt L
3
-
edge were collected for the samples in 3% H
2
/He, 10% H
2
/He and
pure He in the temperature range from RT to 300
C. All spectra are
reported together with the used atmosphere and temperature. For
the analysis of all reported datasets, please see Evolution of Pt and
Pd species in functionalized UiO-67 metal-organic frameworks.
DOI of original article: https://doi.org/10.1016/j.cattod.2019.03.054.
*Corresponding author.
E-mail address: abugaev@sfedu.ru (A.L. Bugaev).
Contents lists available at ScienceDirect
Data in brief
journal homepage: www.elsevier.com/locate/dib
https://doi.org/10.1016/j.dib.2019.104280
2352-3409/©2019 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://
creativecommons.org/licenses/by/4.0/).
Data in brief 25 (2019) 104280
Fourier-analysis of Pd K-edgeis reported in Formation and growth
of Pd nanoparticles in UiO-67 MOF by in situ EXAFS.
©2019 The Authors. Published by Elsevier Inc. This is an open
access article under the CC BY license (http://creativecommons.
org/licenses/by/4.0/).
1. Data
The dataset contains 77 Pt L
3
-edge XAS spectra and 72 Pd K-edge XAS spectra collected during
thermal treatment of UiO-67 samples functionalized by Pt [1] and Pd [1,2], respectively, in inert (He)
and reducing (H
2
/He) atmospheres with different H
2
/He content. The raw data is presented in the form
of unnormalized X-ray absorption coefcient
m
(E) (see les with extension *.mu in the Supporting
materials) together with the normalized ones (see Figs. 1e6and les with extension *.norm in the
Supporting materials). For 10 extended X-ray absorption ne structure (EXAFS) spectra collected at Pd
K-edge, extracted k
2
-weighted oscillatory
c
(k) functions are also reported in Fig. 6b and le
11_Pd_5H2_ramp.chik2of the Supporting materials. The experimental conditions under which the
spectra were collected are reported in Tables 1 and 2 for Pt L
3
-edge and, respectively, Pd K-edge data.
2. Experimental design, materials, and methods
Samples. The sample are metal-organic frameworks of UiO-67 type. by palladium and platinum was
achieved via substitution of 10% standard bpdc linkers by MCl
2
bpydc (M ¼Pd, Pt) ones using the pre-
made linker synthesis (PMLS) approach [3]. The synthesis procedure have been described in more
detail in our previous works for both Pd [4] and Pt [5,6].
Specications table
Subject area Physics, chemistry
More specic subject area In situ spectroscopy of functionalized metal-organic frameworks
Type of data Table, text le, gure
How data was acquired X-ray absorption spectra were collected in transmission mode at BM01B, BM31 and BM23
beamlines of ESRF synchrotron.
Data format Raw
Experimental factors X-ray absorption spectra in transmission mode
Experimental features UiO-67 metal organic frameworks functionalized by Pt and Pd activated in inert and
reducing atmospheres
Data source location Grenoble, France (45.209749, 5.688410)
Data accessibility Data is provided with this article
Related research article A. L. Bugaev, A. A. Skorynina, L. Braglia, K. A. Lomachenko, A. A. Guda, A. Lazzarini, S. Bordiga,
U. Olsbye, K. P. Lillerud, A. V. Soldatov, C. Lamberti. Evolution of Pt and Pd species in
functionalized UiO-67 metal-organic frameworks.
Catalysis Today
https://doi.org/10.1016/j.cattod.2019.03.054
Value of the data
Extensive datasets of X-ray absorption spectra collected at Pd K- and Pt L
3
-edges under various external conditions for
functionalized UiO-67 metal-organic frameworks.
EXAFS data can be used for single- and multiple-shell Fourier analysis.
XANES data can be used to characterize the local atomic and electronic state of Pd and Pt atoms in the as synthesized
functionalized UiO-67 and during treatment in inert and reducing atmospheres.
XANES spectra of the initial structures and intermediates can be utilized for databases, e.g. for implementation of machine
learning approaches.
A.L. Bugaev et al. / Data in brief 25 (2019) 1042802
Pt L
3
-edge XAS spectra for UiO-67-Pt samples (Figs. 1e3) were collected at BM01B beamline [7]
(now moved to BM31 port) of ESRF. The sample powder was loaded inside a 1.5 mm capillary and
xed by the quartz wool from both sizes. The mass of the samples was varied from 2.4 to 2.8 mg in the
three subsequent experiments with different treatment procedures. The capillary was glued inside a
metal holder, which was then connected to a remotely controlled gas line, equipped with Bronkhorst
mass ow controllers. Below the sample, there was a gas blower mounted, calibrated using a ther-
mocouple. The sample was heated from room temperature (RT) to 300
C with the ramp of 5
C/min.
The total ux of the gas through the capillary was adjusted to 1.4 mL/min, which was checked by the
mass ow meter. Three different gas mixtures were sent: pure He (Figs. 1), 3% H
2
/He (Figs. 2), and 10%
H
2
/He (Fig. 3). XAS spectra were collected continuously during the ramp and after reaching 300
C. The
photon energy was scanned from 11.35 to 12.42 keV by Si(111) double crystal monochromator operated
in continuous scanning mode. In such mode, one full spectrum was collected in 4 minutes. The
Fig. 1. Normalized Pt L
3
-edge X-ray absorption near-edge structure (XANES) spectra collected for UiO-67 functionalized by Pt during
activation in He (part a) from RT (black) to 300 C (red), and subsequently collected (4 minutes per spectrum) at 300 C (part b, from
bottom to top).
Fig. 2. Normalized Pt L
3
-edge XANES spectra collected for UiO-67 functionalized by Pt during activation in 3% H
2
/He (part a) from RT
(black) to 300 C (red), and subsequently collected (4 minutes per spectrum) at 30 0 C (part b, from bottom to top).
A.L. Bugaev et al. / Data in brief 25 (2019) 104280 3
rejection of higher harmonics was achieved by detuning of the second crystal until 60% of the maximal
intensity (when both crystals are perfectly tuned) was observed.
Pd K-edge XAS spectra for UiO-67-Pd samples (Figs. 4e5) were collected at BM31 beamline [7]
ESRF, using a similar setup as described above for Pt L
3
-edge. The mass of the sample inside the
capillaries was around 5 mg. The samples were sieved before loading into the capillaries and the
fraction below 100
m
m was removed. The total ux of 50 mL/min was applied. Two different gas
mixtures were sent: pure He (Figs. 4), 3% H
2
/He (Fig. 5). The samples were rst heated stepwise until no
spectral changes were observed and were then kept at 300 and 215
C in inert and reducing ux,
respectively, and the spectra were measured continuously. The photon energy was scanned from 24.0
to 25.4 keV using Si(111) double crystal monochromator operated in continuous scanning mode. In
such mode, one full spectrum was collected in 11 minutes. The rejection of higher harmonics was
achieved by detuning of the second crystal until 80% of the maximal intensity (when both crystals are
perfectly tuned) was observed.
Fig. 3. Normalized Pt L
3
-edge XANES spectra collected for UiO-67 functionalized by Pt during activation in 10% H
2
/He (part a) from
RT (black) to 300 C (red), and subsequently collected (4 minutes per spectrum) at 300 C (part b, from bottom to top).
Fig. 4. Normalized Pd K-edge XANES spectra collected for UiO-67 functionalized by Pd during activation in He (part a) from RT
(black) to 300 C (red), and subsequently collected (11 minutes per spectrum) at 300 C (part b, from bottom to top).
A.L. Bugaev et al. / Data in brief 25 (2019) 1042804
Additional measurements were performed at BM23 beamline of ESRF using the sample in a
pelletized form to optimize the absorption step and collect also high-quality EXAFS data (Fig. 6). A
pelletized sample was held in a microtomo cell [8] and was activated in a ow of 5% H
2
/He (50 mL/min).
A double-crystal xed-exit Si(111) monochromator was employed. Harmonic rejection was done by
two at Pt-coated mirrors positioned at 2 mrad angle. The spectra were collected in the energy range
from 24.1 to25.1 eV, which correspond to k
max
of about 14 Å
1
. The energy step in the pre-edge region
was set to 5 eV with acquisition time of 1 s per point. In XANES region, 1 eV step was used with 1 s/
point. In the EXAFS region, the step of 0.04 Å
1
in the k-space was used, with the time per point
increasing linearly from 1 to 4 s.
All spectra were collected in transmission mode, and Pt and Pd foils weremeasured simultaneously
with third ionization chamber for energy calibration. Demeter software [9] was used to normalize the
data and to obtain oscillatory
c
(k) functions reported in Fig. 6a. The capillary setups used at BM01B and
BM31 also allowed quasi-simultaneous collection of X-ray diffraction as described elsewhere [10e13].
Fig. 5. Normalized Pd K-edge XANES spectra collected for UiO-67 functionalized by Pd during activation in 3% H
2
/He (part a) from RT
(black) to 215 C (red), and subsequently collected (11 minutes per spectrum) at 215 C (part b, from bottom to top).
Fig. 6. Normalized Pd K-edge XANES spectra (part a) and corresponding k
2
-weighted oscillatory
c
(k) functions (part a) collected for
UiO-67 functionalized by Pd in the pelletized form during activation in 5% H
2
/He from RT (black) to 450 C (red).
A.L. Bugaev et al. / Data in brief 25 (2019) 104280 5
Table 1
Experimental conditions applied during Pt L
3
-edge spectra collection and their correspondence with the column in *.mu and
*.norm les. Tis the temperature in
C registered in the beginning of each spectrum acquired during the ramp. tis the time in
minutes, the sample had spent at 300
C before the beginning of the corresponding spectrum. The rst and second columns in
each le correspond to energy in eV and absorption spectrum of the reference Pt foil, respectively.
Conditions Column He 3% H
2
/He 10% H
2
/He
T,
Ct, min T,
Ct,min T,
Ct, min
3 200 220 220
4 224 404 404
5 408 588 588
6 5812 77 7712
7 7716 95 9516
8 95 20 113 113 20
9 113 24 131 131 37
10 131 28 149 149 41
11 149 32 167 167 45
12 167 36 185 185 49
13 185 40 203 203 53
14 203 44 221 221
15 221 48 239 239
16 239 52 257 257
17 257 274 274
18 274 293 293
19 293
Table 2
Experimental conditions applied during Pd K-edge spectra collection and their correspondence with the column in *.mu and
*.norm les. Tis the temperature at which the spectra were
C registered. tis the time in minutes, the sample had spent at 300
and 215
C in He and 3% H
2
/He, respectively, before the beginning of the corresponding spectrum. The rst and second columns
in each le correspond to energy in eV and absorption spectrum of the reference Pd foil, respectively.
Conditions column He 3% H
2
/He
T,
Ct, min T,
Ct, min
3 46 0 46 0
4 8911 8911
5 131 22 131 22
6 174 33 174 33
7 217 44 44
8 260 55 55
96669
10 77 80
11 88 91
12 99 102
13 110 133
14 121 144
15 132 155
16 143 166
17 154 177
18 165 188
19 176 199
20 187 210
21 198 221
22 209 232
23 220 250
24 231 261
25 272
26 283
27 294
28 305
29 316
30 327
31 338
32 349
A.L. Bugaev et al. / Data in brief 25 (2019) 1042806
Acknowledgments
Authors acknowledge Russian Science Foundation project No. 18-73-00189 for funding this
research.
Conict of interest
The authors declare that they have no known competing nancial interests or personal relation-
ships that could have appeared to inuence the work reported in this paper.
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://doi.org/10.1016/j.dib.2019.104280.
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Functionalization of metal-organic frameworks with metal nanoparticles (NPs) is a promising way for producing advanced materials for catalytic applications. We present synthesis and in situ characterization of palladium NPs encapsulated inside functionalized UiO-67 metal-organic framework. The initial structure was synthesized with 10% of PdCl2bpydc moieties with grafted Pd ions replacing standard 4,4'-biphenyldicarboxylate linkers. This material exhibits the same high crystallinity and thermal stability of standard UiO-67. Formation of palladium NPs was initiated by sample activation in hydrogen and monitored by in situ X-ray powder diffraction and X-ray absorption spectroscopy (XAS). The reduction of PdII ions to Pd⁰ occurs above 200 °C in 6% H2/He flow. The formed palladium NPs have the average size of 2.1 nm as limited by the cavities of UiO-67 structure. The resulting material showed high activity towards ethylene hydrogenation. In reaction conditions, palladium was found to form carbide structure indicated by operando XAS, while formation of ethane was monitored by mass spectroscopy and infra-red spectroscopy.
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Formation of palladium hydride and carbide phases in palladium-based catalysts is a critical process which changes the catalytic performance and selectivity of the catalysts in important industrial reactions, such as selective hydrogenation of alkynes or alkadienes. We present a comprehensive study of a 5 wt.% carbon supported Pd nanoparticles (NPs) catalyst under various environments by in situ and operando X-ray absorption spectroscopy and diffraction, to determine structure and evolution of palladium hydride and carbide phases, and their distribution over the volume of the NPs. We demonstrate how the simultaneous analysis of extended X-ray absorption fine structure (EXAFS) spectra and X-ray powder diffraction (XRPD) patterns allows discriminating between the inner “core” and outer “shell” regions of the nanoparticle during hydride phase formation at different temperatures and under different hydrogen pressures, indicating that the amount of hydrogen in the shell region of the nanoparticle is lower than that in the core. For palladium carbide, advanced analysis of X-ray absorption near-edge structure (XANES) spectra allows detecting Pd-C bonds with carbon-containing molecules adsorbed at the surface of the nanoparticles. In addition, H/Pd and C/Pd stoichiometries of PdHx and PdCy phases were obtained by theoretical modelling and fitting of XANES spectra. Finally, the collection of operando time-resolved XRPD patterns (with a time resolution of 5 s) allowed highlighting, during ethylene hydrogenation reaction, periodic oscillations in the NPs core lattice parameter, which are in phase with the MS signal of the ethane (product) and in antiphase with the MS signal of the H2, highlighting an interesting direct structural-reactivity relationship. The presented studies show how a careful combination of X-ray absorption and diffraction can highlight the structure of core, shell and surface of the palladium nanoparticles and prove their relevant roles in catalysis.
Article
We report an in situ, temperature and H2 pressure-dependent, characterization of (2.6  0.4) nm palladium nanoparticles supported on active carbon during the process of hydride phase formation. For the first time the core-shell structure is highlighted in the single-component particles on the basis of a different atomic structure and electronic configurations in the inner “core” and surface “shell” regions. The atomic structure of these particles is examined by combined X-ray powder diffraction (XRPD), which is sensitive to the crystalline core region of the nanoparticles, and by first shell analysis of extended X-ray absorption fine structure (EXAFS) spectra, which reflects the averaged structure of both the core and the more disordered shell. In whole temperature range (085 °C), XRPD the analysis confirms the existence of two well-separated α- and β- hydride phases with the characteristic flat plateau in the phase transition region of the pressure-lattice parameter isotherms. In contrast, first shell interatomic distances obtained from EXAFS exhibit a smoother behavior in the phase transition region, typical for nanostructured palladium. Such difference is explained by distinct properties of bulk “core” which has crystalline structure and sharp phase transition, and surface “shell” which is amorphous and absorbs hydrogen gradually without forming distinguishable α- and β- phases. Combining EXAFS and XRPD we extract, for the first time, the Pd-Pd first-shell distance in the amorphous shell of the nanoparticle, that is significantly shorter than in the bulk core and relevant in catalysis. The core/shell model is supported by the EXAFS analysis of the higher shells, in the frame of the multiple scattering theory, showing that the evolution of the third shell distance (ΔR3/R3) is comparable to the evolution of (Δa/a) obtained from XRPD since amorphous PdHx shell gives a negligible contribution in this range of distances This operando structural information is relevant for the understanding of structure-sensitive reactions. Additionally, we demonstrate the differences in the evolution of the thermal parameters obtained from EXAFS and XRPD along the hydride phase formation.
Article
The exceptional thermal and chemical stability of the UiO-66, -67 and -68 classes of isostructural MOFs [J. Am. Chem. Soc., 2008, 130, 13850] makes them ideal materials for functionalization purposes aimed at introducing active centres for potential application in heterogeneous catalysis. We previously demonstrated that a small fraction (up to 10%) of the linkers in the UiO-67 MOF can be replaced by bipyridine-dicarboxylate (bpydc) moieties exhibiting metal-chelating ability and enabling the grafting of Pt(ii) and Pt(iv) ions in the MOF framework [Chem. Mater., 2015, 27, 1042] upon interaction with PtCl2 or PtCl4 precursors. Herein we extend this functionalization approach in two directions. First, we show that by controlling the activation of the UiO-67-Pt we can move from a material hosting isolated Pt(ii) sites anchored to the MOF framework with Pt(ii) exhibiting two coordination vacancies (potentially interesting for C-H bond activation) to the formation of very small Pt nanoparticles hosted inside the MOF cavities (potentially interesting for hydrogenation reactions). The second direction consists of the extension of the approach to the insertion of Cu(ii), obtained via interaction with CuCl2, and exhibiting interesting redox properties. All materials have been characterized by in situ X-ray absorption spectroscopy at the Pt L3- and Cu K-edges.
Article
In the current work we present a detailed analysis of the hydride phase formation in industrial Pd/C nanocatalysts by means of combined in situ X-ray absorption spectroscopy (EXAFS), X-ray diffraction (XRD) and volumetric measurements for the temperatures from - 10 to 50 °C in the hydrogen pressure range from 0 to 1000 mbar. α- and β- hydride phases are clearly distinguished in XRD. For the first time, H/Pd atomic ratio were obtained by theoretical fitting of the near-edge region of the absorption spectra (XANES) and compared with volumetric measurements.
Article
We present three equivalent methods of the synthesis of zirconium metal-organic framework UiO-67 functionalized with platinum bipyridine coordination complexes (bpydcPtIICl2 and bpydcPtIVCl4) acting as linkers in the MOF framework. These Pt complexes can be reduced to bpydcPt0 under flow of H2 gas in the 600-700 K range, as probed by a sophisticated parametric refinement of in situ EXAFS data. IR spectroscopy testifies the high coordinative unsaturation of the reduced centers, able to form bpydcPt0(CO)2 di-carbonyl complexes upon CO adsorption. The large pore size of UiO-67 allows for Cl to S ligand exchange reactions with bulky ligands such as toluene-3,4-dithiol. Framework bpydcPtIICl2 complexes can also be oxidized at room temperature to bpydcPtIVBr4 with strong oxidation agents such as Br2 from the liquid phase. XANES spectroscopy was used to monitor the changes in the Pt oxidation state along the observed reactions. Platinum bipyridine-functionalized UiO-67-Pt displays the same exceptional stabili