Bimetallic Au-Pd alloy nanoparticles supported on MIL-101(Cr) as highly efficient catalysts for selective hydrogenation of 1,3-butadiene

Article abstract of DOI:10.1039/d0ra06432g

Gold-palladium (Au-Pd) bimetallic nanoparticle (NP) catalysts supported on MIL-101(Cr) with Au : Pd mole ratios ranging from 1 : 3 to 3 : 1 were prepared through coimpregnation and H₂reduction. Au-Pd NPs were homogeneously distributed on the MIL-101(Cr) with mean particle sizes of 5.6 nm. EDS and XPS analyses showed that bimetallic Au-Pd alloys were formed in the Au(2)Pd(1)/MIL-101(Cr). The catalytic performance of the catalysts was explored in the selective 1,3-butadiene hydrogenation at 30-80 °C on a continuous fixed bed flow quartz reactor. The bimetallic Au-Pd alloy particles stabilized by MIL-101(Cr) presented improved catalytic performance. The as-synthesized bimetallic Au(2)Pd(1)/MIL-101(Cr) with 2 : 1 Au : Pd mole ratio showed the best balance between the activity and butene selectivity in the selective 1,3-butadiene hydrogenation. The Au-Pd bimetallic-supported catalysts can be reused in at least three runs. The work affords a reference on the utilization of a MOF and alloy nanoparticles to develop high-efficiency catalysts.

Full text of DOI:10.1039/d0ra06432g

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PAPER
Bimetallic Au–Pd alloy nanoparticles supported on
MIL-101(Cr) as highly efficient catalysts for
selective hydrogenation of 1,3-butadiene†
Cite this: RSC Adv., 2020, 10, 33417
*
*
Xiaojing Zhou, Luxia Guo, Shijuan Yan, Yingjie Li, Shuai Jiang and Xishi Tai
Lili Liu,
Gold–palladium (Au–Pd) bimetallic nanoparticle (NP) catalysts supported on MIL-101(Cr) with Au : Pd mole
ratios ranging from 1 : 3 to 3 : 1 were prepared through coimpregnation and H2 reduction. Au–Pd NPs were
homogeneously distributed on the MIL-101(Cr) with mean particle sizes of 5.6 nm. EDS and XPS analyses
showed that bimetallic Au–Pd alloys were formed in the Au(2)Pd(1)/MIL-101(Cr). The catalytic
performance of the catalysts was explored in the selective 1,3-butadiene hydrogenation at 30–80 ꢀC on
a continuous fixed bed flow quartz reactor. The bimetallic Au–Pd alloy particles stabilized by MIL-101(Cr)
presented improved catalytic performance. The as-synthesized bimetallic Au(2)Pd(1)/MIL-101(Cr) with
2 : 1 Au : Pd mole ratio showed the best balance between the activity and butene selectivity in the
selective 1,3-butadiene hydrogenation. The Au–Pd bimetallic-supported catalysts can be reused in at
least three runs. The work affords a reference on the utilization of a MOF and alloy nanoparticles to
develop high-efficiency catalysts.
Received 24th July 2020
Accepted 2nd September 2020
DOI: 10.1039/d0ra06432g
rsc.li/rsc-advances
Al2O3 catalyst shows higher BD hydrogenation activity and 1-
butene selectivity than Pd/g-Al2O3 and Ni/g-Al2O3 catalysts.24
1. Introduction
Aguilar-Tapia et al. found that the Au–Ni bimetallic nano-
particle catalyst supported on TiO2 with Au : Ni mole ratio of
1 : 0.08 displays an excellent balance between the activity and
butene selectivity for the selective hydrogenation of BD.25 Pd–
Cu0.06/Mn2O3-SI shows a good balance between butene selec-
tivity (92%) and BD conversion (99.1%) at 20 ꢀC.13 Pattama-
komsan et al. prepared Pd–Sn/MA and Pd/MA (MA ¼ mixed
phase alumina) catalysts through impregnation.26 For the
bimetallic Pd–Sn/MA catalyst, the butene selectivity reached to
100% at 80% BD conversion, and butane formation was sup-
pressed.26 By contrast, the butene selectivity was 94% even at
about 70% BD conversion with the monometallic Pd catalysts.26
Ag–Pd alloy nanoparticles supported on g-Al2O3 exhibit supe-
rior catalytic performance and high stability for the selective
hydrogenation of BD.26 The conversion of BD and selectivity of
butenes were 98.2% and 88.1% with the AgPd/g-Al2O3 catalyst,
which is remarkably enhanced compared with corresponding
Ag/Pd monometallic catalysts.27 Therefore, the addition of
amount of second metal to the Au/Pd-supported catalysts could
enhance catalytic activity and butene selectivity. Bimetallic
catalysts are suitable to lower the catalyst cost and maximize the
efficiency of Au/Pd.
Selective 1,3-butadiene (BD) hydrogenation is an important
reaction in petroleum rening and in heterogeneous catalysis
studies.1,2 In recent years, various catalysts, such as nano-
particle supported catalysts and single site catalysts, have been
designed and used in diverse chemical reactions.3–15 Palladium
and gold supported nanoparticle catalysts have been intensively
investigated and extensively used in the selective BD hydroge-
nation because of their superior catalytic activity and selec-
tivity.14–17 Previous studies on supported Pd-based nanoparticle
catalysts have revealed that they have superior catalytic activity
in the selective BD hydrogenation reaction.13–15 However, the
supported Pd-based catalysts showed a strong affinity to the
byproduct butane due to double bond and geometric isomeri-
zation, thereby lowering the purity of butenes.13–15 In particular,
supported Au-based catalysts were highly selective for BD
hydrogenation without overhydrogenation to butane.16,17
Recently, bimetallic nanoparticle catalysts have attracted much
attention in heterogeneous catalysis.13,18–22 Bimetallic catalysts
generally show better catalytic performance than the corre-
sponding monometallic catalysts because catalytic activity
could be enhanced by synergistic effects between different
components.23 Hou et al. reported that the bimetallic PdNi/g-
Metal–organic frameworks (MOFs) are compounds built
from metal ions or metal clusters with organic ligands and have
been attracted a great deal of attention from scientists and
engineers.28–44 In recent years, MOFs have been increasingly
used as supports for heterogeneous catalyst due to their large
surface areas, innite synthetic and structural tunability, and
School of Chemistry & Chemical Engineering and Environmental Engineering, Weifang
University, Weifang 261061, P. R. China. E-mail: liulili122@wfu.edu.cn; taixs@wfu.
edu.cn
† Electronic supplementary information (ESI) available. See DOI:
10.1039/d0ra06432g
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well-dened open cavities.45–51 Among various MOF-types, MIL- atomic emission spectroscopy (ICP-AES), and the Au : Pd mole
101(Cr) has been shown to possess extremely large windows and ratio was 2 : 1 (Au(2)Pd(1)/MIL-101) (Table S1,† entry 2). Au(3)
surface areas (SLangmuir ¼ 5900 m2 gꢁ1), remarkable thermal Pd(1)/MIL-101(Cr), Au(1)Pd(2)/MIL-101(Cr), and Au(1)Pd(3)/
ꢀ
stability (up to 300 C), and excellent chemical stability toward MIL-101(Cr) were synthesized by the same method to deter-
many solvents.52–54 These properties have enabled MIL-101(Cr) mine the Au : Pd mole ratio with the best catalytic perfor-
to be successfully applied in various elds, including its mance. Monometallic Au/MIL-101(Cr) and Pd/MIL-101(Cr)
particularly attractive use as a supports for heterogeneous catalysts were also received using the similar method as above,
catalyst.55–64 Recently, various metal nanoparticle (NP) catalysts except using the corresponding pure Au3+ and Pd2+ salts. The
supported on MIL-101(Cr) (NPs/MIL-101(Cr)), such as Au/MIL- actual Au and Pd loadings on the MIL-101(Cr) were tested by
101(Cr),59 Pd/MIL-101(Cr),65 Ru/MIL-101(Cr),66 and Pt/MIL- ICP-AES (Table S1†).
101(Cr),67,68 have been tested for the hydrogenation catalytic
reaction. These researches have exhibited promising results in
the hydrogenation of 4-nitrophenol,59 2-butyne-1,4-diol,65 levu-
2.3 Catalyst characterization
linic acid,66 cinnamaldehyde,67 benzaldehydes,68 and nitroben-
The structures of samples were determined by X-ray powder
zenes68 with superior catalytic activity, selectivity, and stability.
¨
diffractometer (XRD, Bruker D8, Germany) using Cu Ka radi-
Few studies have been published on the application of catalysts
supported on MIL-101(Cr) for the BD hydrogenation reaction.
Herein, bimetallic Au–Pd nanoparticles were successfully
immobilized on the MOF MIL-101(Cr) using the precursors of
HAuCl4$4H2O and Pd(CH3COO)2 through coimpregnation and
H2 reduction method. For comparison, monometallic Au/MIL-
101(Cr) and Pd/MIL-101(Cr) catalysts were prepared using the
similar approach, except using the corresponding pure Au3+ and
Pd2+ salts. The catalytic performance of these catalysts was
examined through the BD selective hydrogenation reaction
under excess hydrogen. The bimetallic AuPd/MIL-101(Cr) pre-
sented improved catalytic performance in the BD hydrogena-
tion reaction compared with the monometallic catalysts. The
effect of reaction temperature, particle size, and Au : Pd mole
ratio on catalytic activity and selectivity for the BD hydrogena-
tion were investigated.
ation (l ¼ 0.15406 nm). The samples were measured in the
angle range (2q) of 1ꢀ–10ꢀ. Transmission electron microscopy
(TEM) was performed on a JEOL-2100F microscope (Tokyo,
Japan) at 200 kV. Energy dispersive X-ray spectroscopy (EDS)
was carried out utilizing the Oxford X-MaxN 80T IE250
instrument (UK). The valence states of Au and Pd were deter-
mined through X-ray photoelectron spectroscopy (XPS, AXIS
ULTRADLD, Shimadzu, Japan). The each XPS spectrum
binding energy was calibrated by the carbon element C 1s peak
with carbon binding energy 284.8 eV. MIL-101(Cr) and Au(2)
Pd(1)/MIL-101(Cr) were characterized through nitrogen sorp-
tion measurements at 77 K on an automatic physical adsorp-
tion instrument (Quantachrome, Boynton Beach, Florida,
USA). MIL-101(Cr) and Au(2)Pd(1)/MIL-101(Cr) were outgassed
ꢀ
at 150 C for 24 h before analysis. The surface areas of MIL-
101(Cr) and Au(2)Pd(1)/MIL-101(Cr) were obtained by Bru-
nauer–Emmett–Teller (BET) method at the relative pressure (P/
P0) range of 0.01–0.3. The pore volume and average pore size
were obtained by using the Barrett–Joyner–Halenda equation
based on the adsorption branch of the isotherm. ICP-AES was
performed on an Optima 5300DV instrument (Perkin-Elmer,
USA) to test the Au and Pd loadings of the as-synthesized
bimetallic and monometallic catalysts.
2. Experimental section
2.1 Materials
Cr(NO3)3$9H2O, HAuCl4$4H2O, Pd(CH3COO)2, and terephthalic
acid (H2BDC) were bought from Macklin (China) and used as
received. 1,3-Butadiene (1.0 vol% in N2), H2 (99.999%) and N2
(99.999%) were purchased from Anqiu Hengan Gas Manufac-
ture Factory (Weifang, China).
2.4 Activity test
2.2 Preparation of the catalysts
Selective hydrogenation of BD catalyzed by monometallic and
Chromium(III) terephthalate MOF (MIL-101(Cr)) was prepared bimetallic catalysts was carried out in a homemade continuoꢀus
and puried according to the procedures in the literature.69 ow xed bed quartz micro-reactor (i.d. ¼ 6 mm) at 30–80 C
The MIL-101(Cr)-supported catalysts were synthesized under atmospheric pressure. Typically, 2 mg of catalyst and
through coimpregnation followed by H2 reduction.52,70 First, 500 mg quartz sand (inert diluents, 40–80 mesh) were mixed
24.0 mg of HAuCl4$4H2O and 7.0 mg of Pd(CH3COO)2 were and placed in tubular furnace, and the mixture was further
melted in 1 mL of ethanol. Subsequently, the mixture solution pretreated in a ow of 8.0 mL minꢁ1 N2 or H2 at 50–100 C for
ꢀ
of HAuCl4$4H2O and Pd(CH3COO)2 was added slowly dropwise 1 h. The reactant of 1.0 vol% BD in N2 (20.0 mL minꢁ1) was
into MIL-101(Cr) (0.5 g). Aer sonicating for 1 h, the suspen- premixed with H2 (6.5 mL minꢁ1) and was owed through the
sion liquid was sustained at 4 ꢀC in darkness for 24 h. The nal catalyst with space velocities of 795 000 mL (h gcat ꢁ1. The
)
homogenous mixture was further dried in vacuum oven (0.1 effluent from the reactor was collected and analyzed using an
ꢀ
Mpa) for 18 h at 40 C. The catalyst was then heat-treated at online gas chromatography (GC-6890, Purkinje General Instru-
50 ꢀC for 2 h in H2 ow (8.0 mL minꢁ1). The Au and Pd weight ment Co., Ltd., China) equipped with a 30 m ꢂ 0.53 mm ꢂ 10
percents in AuPd/MIL-101(Cr) were 2.03 and 0.58 wt%, mm Al2O3 capillary column and a hydrogen ame ionization
respectively, as identied through inductively coupled plasma- detector.
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3. Results and discussion
3.1 Synthesis strategy
Scheme 1 illustrates the synthetic strategy to synthesize the
bimetallic AuPd/MIL-101(Cr) catalyst. First, MIL-101(Cr) was
hydrothermally prepared using Cr(NO3)3$9H2O, H2BDC, and
water at 218 ꢀC for 18 h.69 The as-prepared MIL-101(Cr) was
washed with hot ethanol at 80 ꢀC in order to eliminate the
unreacted H2BDC trapped in the pores of MIL-101(Cr).71 The
particles of MIL-101(Cr) were vacuum-dried and activated at
150 ꢀC overnight.69,71 Second, the solution of HAuCl4$4H2O and
Pd(CH3COO)2 was added slowly dropwise into MIL-101(Cr).
Aer sonicating for 1 h, the suspension was stored for 24 h
ꢀ
and dried in vacuum oven at 40 C for 18 h. Finally, the solid
ꢀ
was reduced at 50 C for 2 h under H2 ow at the rate of 8.0
mL minꢁ1. The AuPd/MIL-101(Cr) catalysts with Au : Pd mole
ratio ranging from 1 : 3 to 3 : 1 were prepared to determine the
Au : Pd mole ratio with the best catalytic activity and selectivity.
Monometallic Au/Pd supported catalysts were also synthesized
using the similar method, except using the corresponding pure
Au3+ and Pd2+ salts.
Fig. 1 XRD patterns of MIL-101(Cr) (a), Au(2)Pd(1)/MIL-101(Cr) (b), Au/
MIL-101(Cr) (c), and Pd/MIL-101(Cr) (d).
the dispersion and size of the nanoparticles loaded on MIL-
101(Cr). The TEM micrograph and nanoparticle-size distribu-
tion histogram of Au(2)Pd(1)/MIL-101(Cr) were presented in
Fig. 2a and b. The STEM-HAADF image and EDS mapping of
elements are presented in Fig. 2c–f. The TEM micrograph
revealed that Au–Pd nanoparticles were uniformly distributed
on the MIL-101(Cr). The diameter of Au–Pd nanoparticles
immobilized by MIL-101(Cr) spanning from 3 nm to 11 nm, and
the mean particle size of Au–Pd nanoparticles in Au(2)Pd(1)/
MIL-101(Cr) was 5.6 nm. The HAADF-STEM and EDS analyses
of randomly chosen Au–Pd nanoparticles revealed that bime-
tallic Au–Pd alloys were formed. The TEM micrographs for Au/
MIL-101(Cr) and Pd/MIL-101(Cr) catalysts were given in
Fig. S1.† Au and Pd nanoparticles were uniformly immobilized
on the MIL-101(Cr). The Au and Pd nanoparticle sizes for
monometallic Au/MIL-101(Cr) and Pd/MIL-101(Cr) catalysts
ranged from 3 nm to 15 nm and 2 nm to 14 nm, respectively.
The mean diameters of Au and Pd nanoparticles were 6.6 nm
and 4.6 nm for Au/MIL-101(Cr) and Pd/MIL-101(Cr), respec-
tively. Obviously, the mean particle size of the Au(2)Pd(1)/MIL-
101(Cr) catalyst was between that of Au/MIL-101(Cr) and Pd/
MIL-101(Cr) catalysts. The bimetallic Au(2)Pd(1)/MIL-101(Cr)
catalyst had a narrower particle size distributions compared
with monometallic catalysts Au/MIL-101(Cr) and Pd/MIL-
101(Cr).
3.2 XRD study
Fig. 1 shows the XRD patterns of MIL-101(Cr), Au(2)Pd(1)/MIL-
101(Cr), Au/MIL-101(Cr), and Pd/MIL-101(Cr). The XRD
diffraction peaks observed at 2q of 1.82ꢀ, 2.89ꢀ, 3.37ꢀ, 3.52ꢀ,
4.05ꢀ, 4.41ꢀ, 4.95ꢀ, 5.27ꢀ, 5.72ꢀ, 5.99ꢀ, 8.55ꢀ, 8.73ꢀ, and 9.18ꢀ,
which were similar to the reported data for MIL-101(Cr) in other
studies, thereby indicating that pure MIL-101(Cr) crystals were
successfully prepared.52,72 The X-ray diffraction relative inten-
sities and the peak positions of Au(2)Pd(1)/MIL-101(Cr), Au/
MIL-101(Cr), and Pd/MIL-101(Cr) were consistent with MIL-
101(Cr).73 The results exhibited that the MIL-101(Cr) structure
was kept well aer loading of Au–Pd alloy, Au, and Pd
nanoparticles.45
3.3 Microscopic study
TEM analysis was performed on the Au(2)Pd(1)/MIL-101(Cr),
Au/MIL-101(Cr), and Pd/MIL-101(Cr) catalysts to investigate
3.4 XPS study
The valence states of Au and Pd in the Au(2)Pd(1)/MIL-101(Cr),
Au/MIL-101(Cr), and Pd/MIL-101(Cr) catalysts were received
through XPS measurements. The Au 4f and Pd 3d XPS spectras
were presented in Fig. 3. In recently published papers, the
binding energy of Au0 4f5/2 and Au0 4f7/2 were 87.3 eV–87.8 eV
and 83.6 eV–84.5 eV.74,75 Binding energy peaks of Pd 3d5/2 and
3d3/2 at 335.6 eV and 340.4 eV were assigned to metallic
Scheme 1 The synthetic strategy for the AuPd/MIL-101(Cr) catalyst by
coimpregnation and the H2 reduction method.
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Fig. 2 (a) TEM micrograph and (b) the Au–Pd nanoparticle size
distribution histogram of Au(2)Pd(1)/MIL-101(Cr); (c) HAADF-STEM
image and (d–f) EDS elemental mapping images.
palladium (Pd0).76,77 For the bimetallic Au(2)Pd(1)/MIL-101(Cr)
catalyst, two obvious peaks were obtained in the Au 4f spectra
at the binding energy of 83.8 eV and 87.7 eV, respectively
(Fig. 3a). These binding energy values were the characteristic
peaks of metallic Au0 4f7/2 and Au0 4f5/2, respectively.74,75 The
XPS spectrum of Pd 3d for Au(2)Pd(1)/MIL-101(Cr) catalyst
exhibited two intense binding energy peaks at 341.2 eV and
335.9 eV, corresponding to the metallic palladium 3d3/2 and 3d5/
2, respectively (Fig. 3b).76,77 As shown in the Au 4f spectra of Au/
MIL-101(Cr) in Fig. 3c, two obvious binding energy peaks
centered at 84.2 eV and 87.9 eV corresponded to metallic gold
74,75
4f7/2 and 4f5/2
.
For the Pd/MIL-101(Cr) catalyst, the binding
energy peaks at 341.1 eV and 335.6 eV were attributed to Pd 3d3/2
and Pd 3d5/2, respectively, which is consistent with Pd0
(Fig. 3d).76,77 There was a negative shi (0.4 eV) of the Au0 4f7/2
binding energy centered at 83.8 eV for bimetallic catalyst Au(2)
Pd(1)/MIL-101(Cr) compared with the monometallic catalyst Au/
MIL-101(Cr) (84.2 eV). And there was a positive shi (0.3 eV) of
the Pd0 3d5/2 binding energy of the Au(2)Pd(1)/MIL-101(Cr)
catalyst centered at 335.9 eV compared with the Pd/MIL-
101(Cr) catalyst (335.6 eV). The obvious binding energy shis
of Pd0 3d5/2 and Au0 4f7/2 between bimetallic and monometallic
catalysts suggest the existence of charge transfer between Au
Fig. 3 Au 4f and Pd 3d XPS of the catalysts (a and b) Au(2)Pd(1)/MIL-
101(Cr); (c) Au/MIL-101(Cr); (d) Pd/MIL-101(Cr).
and Pd, thereby conrming the formation of Au–Pd alloy.75,76
Cai et al. found that the Au 4f peaks of TiO2–Pd–Au shi toward
higher binding energy and Pd 3d peaks toward lower binding
energy compared to TiO2–Au and TiO2–Pd.75 Chen et al. re-
ported that the apparent binding energy shis of Au 4f7/2 and Pd
3d5/2 for PdAu/Fe3O4, Au/Fe3O4 and Pd/Fe3O4 catalysts.76
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3.5 Nitrogen physisorption study
Fig. 4 presents the nitrogen physisorption isotherms of MIL-
101(Cr) and Au(2)Pd(1)/MIL-101(Cr). The nitrogen phys-
isorption isotherms of MIL-101(Cr) show typical type IV curves,
with a rapid nitrogen adsorbed and a slight hysteresis loop in
a P/P0 range of 0.9–1.0, thereby suggesting its mesoporous
structure.78,79 Aer depositing the Au–Pd nanoparticles on the
MIL-101(Cr), the bimetallic Au(2)Pd(1)/MIL-101(Cr) catalysts
show a largely decreased in adsorption of nitrogen, but the type
of nitrogen physisorption isotherms stays the same with mes-
oporous features. The BET specic surface areas calculated
from isotherms are 1186.0 m2 gꢁ1 and 991.9 m2 gꢁ1 for MIL-
101(Cr) and Au(2)Pd(1)/MIL-101(Cr), respectively. The pore
volume and mean pore diameter of MIL-101(Cr) are 0.49 m3 gꢁ1
and 2.8 nm, respectively, whereas Au(2)Pd(1)/MIL-101(Cr)
possesses a pore volume of 0.40 m3 gꢁ1 and a mean pore
diameter of 2.7 nm. The BET surface area of bimetallic Au(2)
Pd(1)/MIL-101(Cr) catalysts reduces compared with that of
MIL-101(Cr), because of the immobilization of Au–Pd alloy
nanoparticles inside the pores of MIL-101(Cr).45,52
Fig. 5 (a) The BD conversion on Au(2)Pd(1)/MIL-101(Cr) (-), Pd/MIL-
101(Cr) (,), Au/MIL-101(Cr) (:), and MIL-101(Cr) (B) at different
reaction temperature; (b) product selectivity on the Au(1)Pd(2)/MIL-
101(Cr) and Pd/MIL-101(Cr) catalysts at different reaction temperature
(the catalysts were pretreated in flowing N2 at 50 ꢀC for 1 h before
reaction).
3.6 Catalytic performance
The as-synthesized catalysts were tested in the selective BD
hydrogenation at 30–80 ꢀC in a homemade continuous-ow
xed-bed quartz micro-reactor. Fig. 5a displays the BD conver-
sions for Au(2)Pd(1)/MIL-101(Cr), Pd/MIL-101(Cr), Au/MIL-
101(Cr), and MIL-101(Cr). The pure MIL-101(Cr) has very low
catalytic activity with BD conversion less than 1% toward the
selective BD hydrogenation because of lack of active sites. For
the Au(2)Pd(1)/MIL-101(Cr) and Pd/MIL-101(Cr) catalysts, the
BD conversion continuously increased with the enhancement of
reaction temperature from 30 ꢀC to 60 ꢀC (Fig. 5a). The BD
conversion was 10.8% at 30 ꢀC and reached 98.8% at 60 ꢀC over
the Au(2)Pd(1)/MIL-101(Cr) catalyst. The BD conversions were
11.5%, 30.7%, and 99.9% on the Pd/MIL-101(Cr) catalyst at
conversion of ca. 1.4% was found on the Au/MIL-101(Cr) catalyst
at 30–70 ꢀC. The BD hydrogenation could produces 1-butene
and cis/trans-2-butenes by 1,2-hydrogenation and 1,4-hydroge-
nation, and butane could further obtain by the hydrogenation
of butenes.14,80,81 The selectivities for BD hydrogenation for
Au(2)Pd(1)/MIL-101(Cr) and Pd/MIL-101(Cr) catalysts are dis-
played in Fig. 5b. For the bimetallic Au(2)Pd(1)/MIL-101(Cr)
catalysts, the main product detected was butenes (containing
1-butene and cis/trans-2-butenes), with a small amount of
butane produced. At reaction temperatures from 30 ꢀC to 60 ꢀC,
the percentages of different products were shown below: trans-
2-butene (46–58%) > 1-butene (35–41%) > cis-2-butene (5–9%) >
butane (0–5%). The high selectivities of butenes for Au(2)Pd(1)/
MIL-101(Cr) at all reaction temperatures suggested that the
hydrogenation of butenes to butane was prevented even at low
BD concentrations.82–84 Highly preferential adsorption to BD
was observed compare with other butenes on Au(2)Pd(1)/MIL-
101(Cr) under catalytic reaction conditions.82–84 The results
showed that the selectivities to 1-butene and cis/trans-2-butene
slightly changed with the increase in BD conversion. The
selectivities of 1-butene, trans-2-butene, and cis-2-butene for
Au(2)Pd(1)/MIL-101(Cr) were 35.6%, 57.7%, and 5.9% at 31.1%
BD conversion. The selectivities for 1-butene, trans-2-butene,
and cis-2-butene were 40.4%, 47.7%, and 10.7%, respectively,
when the conversions increased from 31.1% to 75.2%. The
change in selectivities to different butenes indicated that some
isomerizations occurred in the processing of BD hydrogena-
tion.80 When the BD conversions lower than 30.7%, Pd/MIL-
ꢀ
ꢀ
30 C, 40 ꢀC, and 50 C, respectively. At low temperature range
(30–40 ꢀC), no difference was observed between the activities of
Pd/MIL-101(Cr) and Au(2)Pd(1)/MIL-101(Cr). The BD conversion
on the Pd/MIL-101(Cr) catalyst increased faster than that on the
bimetallic Au(2)Pd(1)/MIL-101(Cr) catalyst at high temperature
(>40 ꢀC). The Au/MIL-101(Cr) catalyst had poor catalytic activity
for the selective BD hydrogenation. The maximum BD
Fig. 4 Nitrogen physisorption isotherms of MIL-101(Cr) and Au(2)
Pd(1)/MIL-101(Cr).
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101(Cr) displayed the best butene selectivity of 99.7%. However, Au(2)Pd(1)/MIL-101(Cr) (95–100%) showed excellent butene
the selectivity of butenes quickly reduced at high conversion of selectivity than PdAu–ZnO-n (23%) and PdAu–ZnO-t (32%)
99.9%. The selectivity for trans-2-butene rapidly dropped with catalysts. These results indicate that MIL-101(Cr) supported Au–
a quick increase in butane when the conversion was 99.9%. Pd bimetallic catalyst is an excellent catalyst for selective BD
Secondary hydrogenation of trans-2-butene to butane occurred hydrogenation reaction.
rst with the increase in BD conversion.85 These results clearly
The particle size effect is the primary factor to enhance the
showed that Au(2)Pd(1)/MIL-101(Cr) exhibited much better catalytic activity of supported nanocatalysts.14,80,89 The bime-
activity for the BD selective hydrogenation reaction than Au/ tallic Au(2)Pd(1)/MIL-101(Cr) catalysts were pretreated at
MIL-101(Cr) but its activity was still lesser than Pd/MIL- different temperature (50 ꢀC, 80 ꢀC, and 100 ꢀC) and atmo-
101(Cr). The selectivity of butenes for bimetallic Au(2)Pd(1)/ spheres (N2 and H2) to determine the inuences of pretreat-
MIL-101(Cr) catalyst was higher than Pd/MIL-101(Cr) at near ment temperatures and atmospheres on the Au–Pd
complete 1,3-butadiene conversion. By contrast to the Au/MIL- nanoparticle size. Fig. S2† displays the TEM micrographs and
101(Cr) and Pd/MIL-101(Cr), the catalyst containing the Au–Pd nanoparticle size distribution of Au(2)Pd(1)/MIL-101(Cr) cata-
alloy nanoparticles showed excellent balance between the lyst pretreated at different temperatures and atmospheres. The
activity (BD conversion) and selectivity to butenes for the BD Au–Pd alloy nanoparticles were close to spherical with mean
selective hydrogenation. Table 1 displays the BD conversion and diameter of 5.6 nm for the as-synthesized Au(2)Pd(ꢀ1)/MIL-
ꢀ
butene selectivity on different Au–Pd bimetallic catalysts in the 101(Cr) (Fig. 2a and b). Aer pretreatment at 50 C, 80 C, and
selective BD hydrogenation reaction. Bachiller-Baeza et al. 100 ꢀC in owing N2, the Au–Pd alloy nanoparticles were close to
prepared bimetallic PdAu–ZnO-n and PdAu–ZnO-t catalysts spherical and their mean diameters were 6.2 nm, 8.2 nm, and
with 0.3–0.4 Au : Pd mole ratio using two differently shaped 9.4 nm, respectively, which are larger than Au–Pd alloy nano-
ZnO supports (needles ZnO-n and tetrapods ZnO-t) by wet particles (5.6 nm) in the as-synthesized Au(2)Pd(1)/MIL-101(Cr)
impregnation method.86 They found that both bimetallic PdAu– (Fig. S2a–f†). The Au–Pd alloy nanoparticles appeared to
ZnO-n and PdAu–ZnO-t catalysts displayed the similar BD agglomerate aer pretreatment at 50–100 ꢀC in owing N2. Aer
conversion and selectivity in the selective BD hydrogenation pretreating the Au(2)Pd(1)/MIL-101(Cr) catalyst at 50 ꢀC in
reaction.86 The BD conversions and butene selectivities over owing H2, the Au–Pd alloy nanoparticles also appeared to
PdAu–ZnO-n and PdAu–ZnO-t were 92% and 23%, and 99% and agglomerate, and the mean diameters of Au–Pd alloy nano-
32%, respectively, at 40 ꢀC.86 Hugon et al. compared the catalytic particles increased from 5.6 nm to 8.5 nm (Fig. S2g and h†).
properties of Al2O3 supported bimetallic DP-Au/Pd(90) and Fig. S3 and S4† present the XRD patterns and Au 4f and Pd 3d
monometallic DP-Au catalysts for the selective BD hydrogena- XPS spectras of Au(2)Pd(1)/MIL-101(Cr) with different Au–Pd
tion reaction.87 The results showed that bimetallic DP-Au/Pd(90) nanoparticle sizes. The XRD results exhibited that the structure
catalyst presented better catalytic active than the monometallic of Au(2)Pd(1)/MIL-101(Cr) with different Au–Pd nanoparticle
ꢀ
DP-Au catalyst: BD conversion is reached 100% at 120 C and sizes was similar to those of the MIL-101(Cr), thereby indicating
170 ꢀC, respectively.87 The production of butane increases more that the integrity of Au(2)Pd(1)/MIL-101(Cr) with different Au–
noticeably when 100% BD conversion was reached.87 The BD Pd nanoparticle sizes was maintained (Fig. S3†). The Au 4f and
conversion (45–54%) of bimetallic Pd–Au/SiO2 microfabricated Pd 3d XPS spectras indicated that Au and Pd on Au(2)Pd(1)/MIL-
catalyst was lower than the Pd/SiO2 catalyst (60%) at 220 ꢀC for 101(Cr) with different Au–Pd nanoparticle sizes are in a zero
the selective hydrogenation of BD.88 The bimetallic Pd–Au/SiO2 valence state (Fig. S4†).74–77 The catalytic activity and selectivity
catalyst was more selective towards butenes (90–100%) than Pd/ of the bimetallic Au(2)Pd(1)/MIL-101(Cr) with Au–Pd nano-
SiO2 (66%) at BD conversion of 55%.88 Thus, our Au(2)Pd(1)/ particle sizes ranged from 6.2 nm to 9.4 nm were investigated in
ꢀ
MIL-101(Cr) catalyst (98.8% at 60 C) displays higher catalytic the BD selective hydrogenation (Fig. 6). The catalytic activity of
activity (BD conversion) than Al2O3 supported bimetallic DP-Au/ BD hydrogenation was closely related to the Au–Pd nanoparticle
Pd(90) (100% at 120 ꢀC) and Pd–Au/SiO2(45–54% at 220 ꢀC). size of the Au(2)Pd(1)/MIL-101(Cr) catalyst. The bimetallic Au(2)
Although the catalytic activity (BD conversion) of Au(2)Pd(1)/ Pd(1)/MIL-101(Cr) catalyst with the smallest Au–Pd particle size
MIL-101(Cr) is lower than those of PdAu–ZnO-n (92% at 40 showed higher catalytic activity (BD conversion). In particular,
ꢀC) and PdAu–ZnO-t catalysts (99% at 40 ꢀC), the bimetallic the BD conversions were 75.22%, 37.47%, 34.92%, and 27.55%
at 50 ꢀC on Au(2)Pd(1)/MIL-101(Cr) with Au–Pd nanoparticle
size of 6.2 nm, 8.2 nm, 8.5 nm, and 9.4 nm, respectively. The
bimetallic Au(2)Pd(1)/MIL-101(Cr) catalyst with an Au–Pd
nanoparticle size of 6.2 nm presented the highest BD conver-
sion of 98.75% at 60 ꢀC. The catalytic results of Au(2)Pd(1)/MIL-
Table 1 The BD conversion and butene selectivity on different Au–Pd
bimetallic catalysts in the selective BD hydrogenation reaction
101(Cr) on the hydrogenation of BD were consistent with those
Catalyst
T (ꢀC)
Conv. (%)
Sel.(%)
Ref.
published in previous studies.14,80,89 Lozano-Martın et al.
´
Au(2)Pd(1)/MIL-101(Cr)
PdAu–ZnO-n
PdAu–ZnO-t
DP-Au/Pd(90)
Pd–Au/SiO2
60
40
40
120
220
98.8
92
99
100
45–54
95.7
23
32
This work
showed that the catalyst with the smallest particle size (AuFGO)
exhibits high catalytic activity at high temperatures on the BD
hydrogenation reaction.80 Liu et al. stated that the catalytic
activity was dependent on the Au nanoparticle size of the Au NP-
coated SiO2–N catalyst.89 They found that the catalyst with
86
86
87
88
0
90–100
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Fig. 6 The BD conversions on the Au(2)Pd(1)/MIL-101(Cr) catalyst with
different Au–Pd particle size (-) 6.2 nm; (,) 8.2 nm; (C) 8.5 nm; and
(B) 9.4 nm.
smaller nanoparticle size exhibits higher BD conversion.89
Decarolis et al. found that the particle size of Pd-supported
catalyst affects the catalytic activity in BD hydrogenation reac-
tion.14 Fig. 7 presents the product selectivities on Au(2)Pd(1)/
MIL-101(Cr) with different Au–Pd particle sizes at reaction
temperatures of 30–70 ꢀC. Au(2)Pd(1)/MIL-101(Cr) with different
particle sizes exhibited similar butane and butene selectivity. At
low reaction temperatures, butane selectivity was close to 0%.
Butane selectivity slightly increased with the increase in reac-
tion temperature, but never exceeded 5%. The Au(2)Pd(1)/MIL-
101(Cr) with different nanoparticle sizes of Au–Pd maintained
the high selectivity of butenes (95–100%) at investigated
temperature range (30–70 ꢀC). The percentages of various
butenes were varied as follows: trans-2-butene (46–60%) > 1-
butene (34–41%) > cis-2-butene (5–12%). The butene selectiv-
ities did not apparently variation on Au(2)Pd(1)/MIL-101(Cr)
with different Au–Pd particle sizes, thereby indicating the lack
of isomerization.80
The catalytic activity of Au–Pd-supported catalysts relied on
the mole ratio of Au : Pd for the BD hydrogenation reaction.
Au(3)Pd(1)/MIL-101(Cr), Au(2)Pd(1)/MIL-101(Cr), Au(1)Pd(2)/
MIL-101(Cr), and Au(1)Pd(3)/MIL-101(Cr) catalysts with
Au : Pd mole ratios varying from 3 : 1 to 1 : 3 for the BD
hydrogenation were investigated with space velocities of
795 000 mL (h gcat.)
ꢁ1 under atmosphere pressure to determine
the Au : Pd mole ratio with the best catalytic activity. Fig. 8 and
S5† present the inuence of Au : Pd mole ratio on BD conver-
sions and product selectivities on Au–Pd-supported catalysts.
The results showed that the BD conversion and product selec-
tivity strongly depended on the mole ratio of Au : Pd for the BD
hydrogenation reaction. The BD conversion increased with the
decrease in Au : Pd mole ratio under identical reaction condi-
tions. In particular, the BD conversion amounted to 10.71%,
31.06%, 65.21%, and 99.95% on Au(3)Pd(1)/MIL-101(Cr), Au(2)
Pd(1)/MIL-101(Cr), Au(1)Pd(2)/MIL-101(Cr), and Au(1)Pd(3)/
MIL-101(Cr), respectively, at 40 ꢀC (Fig. 8). The BD conver-
sions of 98.75% and 100% were obtained on Au(2)Pd(1)/MIL-
101(Cr) and Au(3)Pd(1)/MIL-101(Cr) when the reaction temper-
atures were 60 ꢀC and 80 ꢀC, respectively. However, the BD
conversion suddenly increased on Au(1)Pd(3)/MIL-101(Cr) and
Au(1)Pd(2)/MIL-101(Cr) catalysts, and approximately 100%
conversion was reached when the reaction temperature was
Fig. 7 The product selectivities on the Au(2)Pd(1)/MIL-101(Cr) catalyst
with different Au–Pd particle size: (a) 6.2 nm; (b) 8.2 nm; (c) 8.5 nm; (d)
9.4 nm.
ꢀ
ꢀ
40 C and 45 C. The selectivity of butenes increased, whereas
butane decreased with the enhancement of the Au : Pd mole
ratio of Au–Pd-supported catalysts when the BD conversion was
close to 100% (Fig. S5†). At conversions more than 99%, the
selectivities to butane, 1-butene, trans-2-butene, and cis-2-
butene were 2.54%, 38.78%, 51.98%, and 6.7% for Au(3)Pd(1)/
MIL-101(Cr) catalysts, respectively (Fig. S5a†). The selectivity
of butane, 1-butene, trans-2-butene, and cis-2-butene were
4.32%, 39.7%, 46.96%, and 9.01% on Au(2)Pd(1)/MIL-101(Cr),
respectively, when the mole ratio of Au : Pd decreased from
3 : 1 to 2 : 1 (Fig. S5b†). For Au(1)Pd(2)/MIL-101(Cr), butene
selectivity rapidly decreased (the 1-butene, trans-2-butene, and
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Fig.
8 The BD conversion over Au–Pd bimetallic catalysts with
different Au : Pd mole ratio (,) Au(3)Pd(1)/MIL-101(Cr); (-) Au(2)
Pd(1)/MIL-101(Cr); (B) Au(1)Pd(2)/MIL-101(Cr); (C) Au(1)Pd(3)/MIL-
101(Cr) (the catalysts were pretreated in flowing N2 at 50 ꢀC for 1 h
before reaction).
cis-2-butene selectivities were 48.45%, 4.54%, 19.99%), whereas
the butane selectivity rapidly increased (27.03%) at conversion
more than 99% (Fig. S5c†). The selectivities of butane, 1-butene,
trans-2-butene, and cis-2-butene were 23.04%, 50.11%, 5.71%,
and 21.15%, respectively, when the Au : Pd mole ratio decreased
to 1 : 3 (Fig. S5d†). The bimetallic Au(2)Pd(1)/MIL-101 catalysts
with an Au : Pd mole ratio of 2 : 1 showed the best balance
between the activity and butene selectivity in the BD selective
hydrogenation.
3.7 Reusability of catalysts
Reusability studies of Au(2)Pd(1)/MIL-101(Cr) and Pd/MIL-
101(Cr) were conducted on the BD selective hydrogenation
reaction. The Au(2)Pd(1)/MIL-101(Cr) and Pd/MIL-101(Cr) were
repeatedly used without any treatment (Fig. 9 and S6). The BD
conversion of Au(2)Pd(1)/MIL-101(Cr) catalyst decreased slightly
in the rst run compared with the fresh catalysts (Fig. 9a).
However, the BD conversion was greatly reduced in the second
and third runs for the Au(2)Pd(1)/MIL-101(Cr) catalyst (Fig. 9a).
Some differences were observed with the catalyst of Pd/MIL-
101(Cr). The BD conversion in the rst run of Pd/MIL-101(Cr)
was almost the same as that of fresh catalyst (Fig. S6a†). No
drop in conversion of BD was found on Pd/MIL-101(Cr) in the
second run at low reaction temperatures (30 ꢀC and 40 ꢀC). Pd/
MIL-101(Cr) featured a remarkable deactivation mode at high
temperature (50 ꢀC). The third run of Pd/MIL-101(Cr) displayed
a rapid decrease in BD conversion. The product selectivities of
recycled Au(2)Pd(1)/MIL-101(Cr) and Pd/MIL-101(Cr) catalysts Fig. 9 The reusability of Au(2)Pd(1)/MIL-101(Cr): (a) BD conversion;
(b–d) Product selectivity.
were the same as that of as-synthesized catalysts at the similar
1,3-butadiene conversion (Fig. 9b–d and S6b–d†).
The stability of bimetallic Au(2)Pd(1)/MIL-101(Cr) catalysts
was 8.9 nm. The mean particle diameter of reused Au(2)Pd(1)/
MIL-101(Cr) (8.9 nm) was larger than that of the as-
synthesized catalyst (5.6 nm) (Fig. 2b and S8b†). The particle
size of Au(2)Pd(1)/MIL-101(Cr) takes a crucial role in the deter-
mination of catalytic activity. Considering that the Au–Pd
nanoparticle sizes of reused Au(2)Pd(1)/MIL-101(Cr) catalyst
were aggregated from 5.6 nm to 8.9 nm, the decrease in catalytic
activity in the rst, second, and third runs for the BD
was studied by XRD and TEM. The XRD spectra of Au(2)Pd(1)/
MIL-101(Cr) aer three runs was similar to those of the as-
synthesized catalyst, thereby indicating that the integrity of
Au(2)Pd(1)/MIL-101(Cr) was maintained aer three runs under
the present reaction condition (Fig. S7†).70 The TEM micrograph
and Au–Pd size distribution for the reused Au(2)Pd(1)/MIL-
101(Cr) catalyst were presented in Fig. S8.† The mean size of
Au–Pd particles for the reused Au(2)Pd(1)/MIL-101(Cr) catalyst
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hydrogenation was because of the conglomeration of Au–Pd
nanoparticles.
7 L. M. Yang and E. Ganz, Phys. Chem. Chem. Phys., 2016, 18,
17586–17591.
8 J. Liu, L. M. Yang and E. Ganz, ACS Sustainable Chem. Eng.,
2018, 6, 15494–15502.
9 J. H. Liu, L. M. Yang and E. Ganz, J. Mater. Chem. A, 2019, 7,
3805–3814.
4. Conclusions
Bimetallic Au–Pd alloy nanoparticles on MIL-101(Cr) were
successfully synthesized through coimpregnation and the H2 10 J. H. Liu, L. M. Yang and E. Ganz, J. Mater. Chem. A, 2019, 7,
reduction. Au–Pd alloy particles were homogeneously distrib- 11944–11952.
uted on the MIL-101(Cr) with mean particle size of 5.6 nm. The 11 J. H. Liu, L. M. Yang and E. Ganz, RSC Adv., 2019, 9, 27710–
catalytic activity and selectivity of the as-synthesized AuPd/MIL-
27719.
101(Cr) were evaluated on the BD hydrogenation reaction. 12 J. H. Liu, L. M. Yang and E. Ganz, Energy Environ. Mater.,
Compared with monometallic catalysts, the AuPd/MIL-101(Cr) 2019, 2, 193–200.
catalyst displayed improved catalytic properties for the BD 13 T. Odoom-Wubah, Q. Li, M. Chen, H. Fang, B. B. A. Bediako,
selective hydrogenation. The bimetallic Au(2)Pd(1)/MIL-101(Cr) I. Adilov, J. Huang and Q. Li, ACS Omega, 2019, 4, 1300–1310.
catalysts with mole ratio of Au : Pd of 2 : 1 showed the best 14 D. Decarolis, I. Lezcano-Gonzalez, D. Gianolio and
balance between the activity and butene selectivity for the BD A. M. Beale, Top. Catal., 2018, 61, 162–174.
hydrogenation reaction. The catalytic activity of the BD hydro- 15 Y. Xu, D. Ma, J. Yu, X. Jiang, J. Huang and D. Sun, Ind. Eng.
genation reaction was signicantly affected by the Au–Pd
Chem. Res., 2017, 56, 10623–10630.
particle size. The bimetallic Au(2)Pd(1)/MIL-101(Cr) catalyst 16 E. Castillejos, B. Bachiller-Baeza, E. Asedegbega-Nieto,
´
which possesses the smallest Au–Pd particle size, exhibited high
A. Guerrero-Ruiz and I. Rodrıguez-Ramos, RSC Adv., 2015,
BD conversion. The bimetallic Au(2)Pd(1)/MIL-101(Cr) catalysts
5, 81583–81598.
can be reused repetitively at least three runs, and the selectivity 17 N. Masoud, L. Delannoy, H. Schaink, A. V. D. Eerden,
to butenes remains basically unchanged. This work affords
a reference of the utilization of MOF and alloy nanoparticles to
develop high-efficiency catalysts.
J. W. D. Rijk, T. A. G. Silva, D. Banerjee, J. D. Meeldijk,
K. P. D. Jong, C. Louis and P. E. D. Jongh, ACS Catal.,
2017, 7, 5594–5603.
˚
˚
18 S. Kumar, D. Waller, H. Fjellvag and A. O. Sjastad, J. Alloys
Compd., 2019, 786, 1021–1029.
19 L. Guo, J. Mao, S. Guo, Q. Zhang, S. Cai and W. He, Nano Res.,
2019, 12, 1659–1662.
Conflicts of interest
There are no conicts to declare.
20 F. Lu, D. Sun and X. Jiang, New J. Chem., 2019, 43, 13891–
13898.
21 M. Duan, L. Jiang, G. Zeng, D. Wang, W. Tang, J. Liang,
H. Wang, D. He, Z. Liu and L. Tang, Appl. Mater. Toda,
2020, 19, 100564–100582.
Acknowledgements
The authors gratefully acknowledge the nancial support of the
National Natural Science Foundation of China (No. 21802104),
the Natural Science Foundation of Shandong Province (No. 22 P. Qu, S. Wang, W. Hu, Y. Wu, J. Chen, G. Zhang, P. Shen,
ZR2017MB056), and High-tech Industrial Development Zone
Science and Technology Huimin Plan of Weifang (No.
2019KJHM18).
Y. Chen and L. Zhong, Catal. Commun., 2020, 135, 105900–
105904.
23 L. Zhang, Z. Xie and J. Gong, Chem. Soc. Rev., 2016, 45, 3916–
3934.
24 R. Hou, W. Yu, M. D. Porosoff, J. G. Chen and T. Wang, J.
Catal., 2014, 316, 1–10.
Notes and references
1 R. Hou, M. D. Porosoff, J. G. Chen and T. Wang, Appl. Catal., 25 A. Aguilar-Tapia, L. Delannoy, C. Louis, C. W. Han,
A, 2015, 490, 17–23.
V. Ortalan and R. Zanella, J. Catal., 2016, 344, 515–523.
2 L. Lozano, J. L. Brito, C. Olivera, J. Guerra and S. Curbelo, 26 K. Pattamakomsan, E. Ehret, F. Morn, P. Gelin, Y. Jugnet,
´
Fuel, 2013, 110, 76–82.
S. Prakash, J. C. Bertolini, J. Panpranot and F. J. C. S. Aires,
3 B. Song, Y. Zhou, H. M. Yang, J. H. Liao, L. M. Yang,
Catal. Today, 2011, 164, 28–33.
X. B. Yang and E. Ganz, J. Am. Chem. Soc., 2019, 141, 3630– 27 F. Lu, D. Sun, J. Huang, M. Du, F. Yang, H. Chen, Y. Hong
3640. and Q. Li, ACS Sustainable Chem. Eng., 2014, 2, 1212–1218.
4 L. M. Yang, V. Bacic, I. A. Popov, A. I. Boldyrev, T. Heine, 28 L. M. Yang, V. Ponniah, R. Ponniah, H. Fjellvag and
ˇ ´
T. Frauenheim and E. Ganz, J. Am. Chem. Soc., 2015, 137,
2757–2762.
5 L. M. Yang, I. A. Popov, A. I. Boldyrev, T. Heine,
M. Tilset, Inorg. Chem., 2010, 49, 10283–10290.
29 L. M. Yang, G. Y. Fang, J. Ma, E. Ganz and S. S. Han, Cryst.
Growth Des., 2014, 14, 2532–2541.
T. Frauenheim and E. Ganz, Phys. Chem. Chem. Phys., 2015, 30 L. M. Yang, P. Ravindran, P. Vajeeston and M. Tilset, RSC
17, 17545–17551. Adv., 2012, 2, 1618–1631.
6 L. M. Yang, I. A. Popov, T. Frauenheim, A. I. Boldyrev, 31 L. M. Yang, E. Ganz, S. Svelle and M. Tilset, J. Mater. Chem. C,
ˇ ´
T. Heine, V. Bacic and E. Ganz, Phys. Chem. Chem. Phys.,
2014, 2, 7111–7125.
2015, 17, 26043–26048.
This journal is © The Royal Society of Chemistry 2020
RSC Adv., 2020, 10, 33417–33427 | 33425

View Article Online
RSC Advances
Paper
32 L. M. Yang, P. Ravindran, P. Vajeeston and M. Tilset, Phys. 58 D. Gao, Y. Zhang and L. Zhou, Appl. Surf. Sci., 2018, 427, 114–
Chem. Chem. Phys., 2012, 14, 4713–4723. 122.
33 L. M. Yang, P. Ravindran, P. Vajeeston and M. Tilset, J. 59 K. Wang, L. Xu, H. Z. Chen, H. Y. Qiao, C. Chen and
Mater. Chem., 2012, 22, 16324–16335. N. Zhang, Chem. Res. Chin. Univ., 2016, 37, 723–727.
34 W. R. Lee, H. Jo, L. M. Yang, H. Lee, D. W. Ryu, K. S. Lim, 60 P. Zhao, N. Cao, W. Luo and G. Cheng, J. Mater. Chem. A,
J. H. Song, D. Y. Min, S. S. Han, J. G. Seo, Y. K. Park,
D. Moone and C. S. Hong, Chem. Sci., 2015, 6, 3697–3705.
35 K. Wang, L. M. Yang, X. Wang, L. Guo, G. Cheng, C. Zhang,
S. Jin, B. Tan and A. Cooper, Angew. Chem., Int. Ed., 2017, 56,
14149–14153.
2015, 3, 12468–12475.
61 Z. J. Liang, X. Z. Xiao, X. Y. Yu, X. Huang, Y. Q. Jiang,
X. L. Fan and L. X. Chen, J. Alloys Compd., 2018, 741, 501–
508.
62 S. P. Jian and Y. W. Li, Chin. J. Catal., 2016, 37, 91–97.
36 L. M. Yang, P. Ravindran and M. Tilset, Inorg. Chem., 2013, 63 K. Z. Yang, L. Q. Zhou, X. Xiong, M. L. Ye, L. Li and Q. H. Xia,
52, 4217–4228. Microporous Mesoporous Mater., 2016, 225, 1–8.
37 L. M. Yang, P. Vajeeston, P. Ravindran, H. Fjellvg and 64 L. Zhang, L. Q. Zhou, K. Z. Yang, D. D. Gao, C. Huang,
M. Tilset, Phys. Chem. Chem. Phys., 2011, 13, 10191–10203.
38 L. M. Yang, P. Ravindran, P. Vajeeston, S. Svelle and
Y. F. Chen, F. Zhang, X. Xiong, L. Li and Q. H. Xia, J. Alloys
Compd., 2016, 677, 87–95.
M. Tilset, Microporous Mesoporous Mater., 2013, 175, 50–58. 65 D. D. Yin, C. Li, H. X. Ren, O. Shekhah, J. X. Liu and
39 L. M. Yang and R. Pushpa, J. Mater. Chem. C, 2014, 2, 2404–
2416.
40 L. M. Yang, Microporous Mesoporous Mater., 2014, 183, 218–
233.
41 L. M. Yang, M. Dornfeld, P. M. Hui, T. Frauenheim and
E. Ganz, J. Chem. Phys., 2015, 142, 244706–244717.
42 L. M. Yang, E. Ganz, S. Wang, X. J. Li and T. Frauenheim, J.
Mater. Chem. C, 2015, 3, 2244–2254.
C. H. Liang, RSC Adv., 2017, 7, 1626–1633.
66 Y. Guo, Y. Li, J. Chen and L. Chen, Catal. Lett., 2016, 146,
2041–2052.
67 N. Y. Lu, F. Zhou, B. B. Fan and R. F. Li, Chin. J. Inorg. Chem.,
2015, 31, 2324–2330.
68 H. Pan, X. Li, Y. Yu, J. Li, J. Hu, Y. Guan and P. Wu, J. Mol.
Catal. A: Chem., 2015, 399, 1–9.
69 L. L. Liu, X. S. Tai and X. J. Zhou, Materials, 2017, 10, 99–111.
43 L. M. Yang, G. Y. Fang, J. Ma, R. Pushpa and E. Ganz, Phys. 70 L. L. Liu, X. J. Zhou, L. Liu, S. Jiang, Y. J. Li, L. X. Guo,
Chem. Chem. Phys., 2016, 18, 32319–32330. S. J. Yan and X. S. Tai, Catalysts, 2019, 9, 538–555.
44 H. Zhang, L. M. Yang and E. Ganz, ACS Appl. Mater. 71 J. W. Chen, X. L. Chen, Z. G. Zhang, Z. B. Bao, H. B. Xing,
Interfaces, 2020, 12, 18533–18540. Q. W. Yang and Q. L. Ren, Mol. Catal., 2018, 445, 163–169.
45 L. L. Liu, X. J. Zhou, Y. M. Yan, J. Zhou, W. P. Zhang and 72 H. Rajati, A. H. Navarchian and S. Tangestaninejad, Chem.
X. S. Tai, Polymers, 2018, 10, 1089–1104. Eng. Sci., 2018, 185, 92–104.
46 J. Tang, M. Cai, G. Xie, S. Bao, S. Ding, X. Wang, J. Tao and 73 S. J. Zhao, J. Mei, H. M. Xu, W. Liu, Z. Qu, Y. Cui and
G. Li, Chem.–Eur. J., 2020, 26, 4333–4340. N. Q. Yan, J. Hazard. Mater., 2018, 351, 301–307.
47 X. Fan, R. Vakili, E. K. Gibson, S. Chansai, S. Xu, P. Wells, 74 L. L. Liu, X. S. Tai, N. N. Zhang, Q. G. Meng and C. L. Xin,
C. Hardacre, A. Walton and N. Al-Janabi, ChemCatChem,
2018, 10, 4238–4242.
48 X. Li, Q. Deng, L. Zhang, J. Wang, R. Wang, Z. Zeng and
S. Deng, Appl. Catal., A, 2019, 575, 152–158.
React. Kinet., Mech. Catal., 2016, 119, 335–348.
75 X. T. Cai, J. W. Wang, R. X. Wang, A. Wang, S. X. Zhong,
J. R. Chen and S. Bai, J. Mater. Chem. A, 2019, 7, 5266–5276.
76 X. Chen, D. J. Qian, G. D. Xu, H. Xu, J. T. Dai and Y. K. Du,
Colloids Surf., A, 2019, 573, 67–72.
49 W. W. Jin, J. Z. Zou, S. Z. Zeng, S. Inguva, G. Z. Xu, X. H. Li,
M. Peng and X. R. Zeng, Appl. Surf. Sci., 2019, 469, 404–413. 77 A. V. Bukhtiyarov, D. B. Burueva, I. P. Prosvirin,
50 Z. Jin, Z. Wang, H. Yuan and F. Han, Int. J. Hydrogen Energy,
2019, 44, 19640–19649.
51 H. Alamgholiloo, S. Zhang, A. Ahadi, S. Rostamnia,
A. Y. Klyushin, M. A. Panadin, K. V. Kovtunov,
V. I. Bukhtiyarov and I. V. Koptyug, J. Phys. Chem. C, 2018,
122, 18588–18595.
R. Banaei, Z. Li, X. Liu and M. Shokouhimehr, Mol. Catal., 78 Y. Q. Li, Q. Gao, L. J. Zhang, Y. S. Zhou, Y. X. Zhong, Y. Ying,
2019, 467, 30–37.
52 L. L. Liu, X. S. Tai, X. J. Zhou, J. X. Hou and Z. H. Zhang, J.
Alloys Compd., 2019, 790, 326–336.
53 D. Ding, Z. Jiang, Q. Ouyang, L. J. Wang, Y. X. Zhang and
L. Zan, J. Taiwan Inst. Chem. Eng., 2018, 82, 226–232.
M. C. Zhang, C. Q. Huan and Y. A. Wang, Dalton Trans., 2018,
47, 6394–6403.
79 C. Sarkar, P. Koley, I. Shown, J. Lee, Y. F. Liao, K. An,
J. Tardio, L. Nakka, K. H. Chen and J. Mondal, ACS
Sustainable Chem. Eng., 2019, 7, 10349–10362.
´
54 Q. L. Zhu, J. Li and Q. Xu, J. Am. Chem. Soc., 2013, 135, 80 M. C. Lozano-Martın, E. Castillejos, B. Bachiller-Baeza,
´
10210–10213.
I. Rodrıguez-Ramos and A. Guerrero-Ruiz, Catal. Today,
55 Z. Lin, M. Luo, Y. Zhang, X. Wu, Y. Fu, F. Zhang and W. Zhu,
Appl. Catal., A, 2018, 563, 54–63.
56 G. Li, X. He, F. Yin, B. Chen and H. Yin, Int. J. Hydrogen
Energy, 2019, 44, 11754–11764.
57 N. Kamyar, Y. Khani, M. Amini, F. Bahadoran and N. Safari,
ChemistrySelect, 2019, 4, 6113–6122.
2015, 249, 117–126.
81 X. Zhang, Y. C. Guo, Z. C. Zhang, J. S. Gao and C. M. Xu, J.
Catal., 2012, 292, 213–226.
82 D. Yardimci, P. Serna and B. C. Gates, ChemCatChem, 2012,
4, 1547–1550.
83 A. Corma, P. Serna, P. Concepcion and J. J. Calvino, J. Am.
Chem. Soc., 2008, 130, 8748–8753.
33426 | RSC Adv., 2020, 10, 33417–33427
This journal is © The Royal Society of Chemistry 2020

View Article Online
Paper
RSC Advances
84 P. Serna, M. Boronat and A. Corma, Top. Catal., 2011, 54, 87 A. Hugon, L. Delannoy, J. M. Kra and C. Louis, J. Phys.
439–446. Chem. C, 2010, 114, 10823–10835.
85 H. Yi, Y. Xia, H. Yan and J. Lu, Chin. J. Catal., 2017, 38, 1581– 88 A. C. Krauth, G. H. Bernstein and E. E. Wolf, Catal. Lett.,
1587. 1997, 45, 177–186.
86 B. Bachiller-Baeza, A. Iglesias-Juez, G. Agostini and 89 C. Liu, K. Yang, J. Zhao, Y. Pan and D. Liu, Catal. Commun.,
´
E. Castillejos-Lopez, Catal. Sci. Technol., 2020, 10, 2503–
2015, 67, 72–77.
2512.
This journal is © The Royal Society of Chemistry 2020
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