Catalytic properties of palygorskite supported Ru and Pd for efficient oxidation of alcohols

Article abstract of DOI:10.1016/j.catcom.2015.02.021

Natural palygorskite (PG) was employed to prepare cost-effective, reusable supported catalyst of Pd/PG and Ru/PG through wet impregnation method. The catalysts were characterized through AFM, ICP-AES, XPS, XRD, BET, TEM and FTIR. The catalytic properties of the synthesized catalysts were assessed and optimized through oxidation of alcohols with PhIO as oxidant. It showed that the existence of Ru and Pd in the catalysts dramatically enhanced the catalytic activity with a prominent selectivity of far more than 99% compared with the palygorskite.

Full text of DOI:10.1016/j.catcom.2015.02.021

Catalytic properties of palygorskite supported Ru and Pd for efficient oxida-
tion of alcohols
Zhi-Wang Yang, Xia Zhao, Tian-Jing Li, Wen-Long Chen, Qiao-Xiang
Kang, Xue-Qing Xu, Xi-Xi Liang, Ying Feng, Huan-Huan Duan, Zi-qiang Lei
PII:
DOI:
Reference:
S1566-7367(15)00080-1
doi: 10.1016/j.catcom.2015.02.021
CATCOM 4238
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
13 December 2014
12 February 2015
13 February 2015
Please cite this article as: Zhi-Wang Yang, Xia Zhao, Tian-Jing Li, Wen-Long Chen,
Qiao-Xiang Kang, Xue-Qing Xu, Xi-Xi Liang, Ying Feng, Huan-Huan Duan, Zi-qiang
Lei, Catalytic properties of palygorskite supported Ru and Pd for efficient oxidation of
alcohols, Catalysis Communications (2015), doi: 10.1016/j.catcom.2015.02.021
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ACCEPTED MANUSCRIPT
Catalytic properties of palygorskite supported Ru and Pd
for efficient oxidation of alcohols
Zhi-Wang Yang, Xia Zhao, Tian-Jing Li, Wen-Long Chen, Qiao-Xiang Kang,
Xue-Qing Xu, Xi-Xi Liang, Ying Feng, Huan-Huan Duan, Zi-qiang Lei
Key Laboratory of Polymer Materials of Gansu Province
Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education
College of Chemistry and Chemical Engineering, Northwest Normal University
Lanzhou 730070, China
Abstract
Natural palygorskite (PG) was employed to prepare cost-effective, reusable
supported catalyst of Pd/PG and Ru/PG through wet impregnation method. The
catalysts were characterized through AFM, ICP-AES, XPS, XRD, BET, TEM and
FTIR. The catalytic properties of the synthesized catalysts were assessed and
optimized through oxidation of alcohols with PhIO as oxidant. It showed that the
existence of Ru and Pd in the catalysts dramatically enhanced the catalytic activity
with a prominent selectivity of far more than 99% compared with the palygorskite.
Keywords: palygorskite; support; ruthenium; palladium; catalytic oxidation; alcohol.
 Corresponding author. Tel: +86 931 7971261.
E-mail address: leizq@nwnu.edu.cn (Z. Lei).
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1 Introduction
The oxidation of alcohols to carbonyl compounds is an important task in fine
chemical industry. Traditional methods for the oxidation of alcohols are based on the
use of stoichiometric amounts of either inorganic or organic oxidants [1, 2]. These
methods are easy to cause environmental and economical problems due to disposal of
large amounts of byproducts [3]. An alternative more environmentally friendly method
is to use molecular oxygen or hydrogen peroxide in the presence of a catalyst, the
main byproduct being water [4]. Previously, some base metal systems catalysts were
[6, 7]
used in oxidation of alcohols such as Co [5], Cu
and Fe [8, 9]. However, most of
these existing methods suffer at least from one of the disadvantages such as, pollution,
high cost, harsh reaction conditions, need of dehydrating agents, tedious work-up
procedures, stoichiometric amount of catalyst and low yields. In this field of research,
the sol-immobilization of stabilized noble metal nanoparticles (including Pd [10], Au
[12, 13]
[11], Ru
and Ag [14], or combinations thereof [15]) from a solution onto a support
surface is a well-established preparation route to obtain active catalysts. Yet, due to
the high costs of the noble metal, it is necessary to extend and enhance their catalytic
performance by depositing them homogenously on the support in order to optimize
the active surface [16, 17]. For this purpose, there was an urgent need to develop a new
support.
Recently, mineral clays have attracted great interest in the area of heterogeneous
catalysis due to their reduced costs and easier availability [18]. As one of typical
mineral clay, palygorskite (PG), a hydrated magnesium aluminum silicate present in
nature owning 1-D fibrous morphology with a diameter in the nanometers and a
length from several hundreds of nanometers to a few micrometers, has further be
considered [19]. It also has large surface area and ion-exchanging ability exhibiting
excellent activity and chemical adsorption property, making it a very promising
candidate as support substrate [20]. The applications of palygorskite as support of
catalysts have been reported. For example, the catalyst, Ce1-xMnxO2 oxides supported
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[21]
on palygorskite, exhibited a higher activity in degradation of methyl orange
,
probably due to the fact that impregnation ensures better dispersion of Ce1-xMnxO2 in
palygorskite. The performance of Fe3Ni8/PG showed comparable selectivity of
catalytic decomposition of benzene [22]. In addition, compared with other supports,
palygorskite is much cheaper due to its accessibility and abundance. Palygorskite is
also chemical inert and environmentally friendly. These properties make it a potential
candidate as a promising support for supporter-based noble metal nanoparticles
catalyst.
Herein, supported ruthenium (Ru/PG) and palladium (Pd/PG) catalysts were
prepared with palygorskite as support. The supported samples were successfully used
as the catalysts for the oxidation of alcohols with PhIO as oxidant. The oxidation
conditions were optimized and the recyclability of the catalysts was also well
investigated. As we expected, the palygorskite supported ruthenium (Ru/PG) and
palladium (Pd/PG) catalysts performed a promising catalytic activity as well as high
stability.
2 Experimental
2.1 Pretreatment of palygorskite
Palygorskite was pretreatment with dilute HCl not only to remove impurity of
the natural mineral but also to activate the surface hydroxyl groups for the supporting
of the metal particles. As conventional programs, 1 g of natural palygorskite mineral
was dissolved into 20 mL of 1M HCl solution. The mixture was stirred for 24 h at 80
oC and then filtered, washed and dried.
2.2 Preparation of Ru/PG and Pd/PG [23, 24]
RuCl3·xH2O (0.33 g) was dissolved in distilled water (20 mL), and then added
the solution to purified palygorskite (0.3 g), the above suspension was vigorous stirred
at room temperature for 24 h. The precipitate was filtered, washed with deionized
water until the filtrate was colorless and dried in vacuum at room temperature for 24 h,
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the final brown-powdered was denoted as Ru/PG.
Pd/PG was prepared through the same procedures as that of Ru/PG using
Pd(OAc)2 (0.3 g) as precursor. The brown-powdered Pd/PG was also obtained.
2.3 Instruments
The catalysts were characterized by Fourier transform-infrared spectroscopy
(FTIR) on a Nicolet NEXUS 670 spectrometer using KBr disks in the scanning range
of 4000-400 cm-1. The morphologies of palygorskite and the prepared Ru/PG and
Pd/PG were characterized by atomic force microscope (AFM) on a Nanoscopy III-A
instrument using tapping mode. Transmission electron microscope (TEM)
measurements were made by a JEOL 2010 microscope. The metal content of Ru/PG
and Pd/PG were obtained through inductively coupled plasma-atomic emission
spectrometry (ICP-AES) on an ARL-3520 spectrograph. The BET-nitrogen isotherms
were used to quantify changes in the specific surface area using an ASAP 2020
specific surface area and pore size analyser. The X-ray diffractometer (XRD,
D/max-2400) was used for identifying palladium and ruthenium oxides as well as
their oxidation states on the surface of the palygorskite. An XPS (Thermo VG
Scientific Sigma Probe) using an Al K radiation was used to study the surface
compositions of the catalysts. The product of the oxidation was recorded through gas
chromatograph (GC) analyses on a Shimadzu GC-2010 equipped with a
25m×0.25mm SE-54 column and a FID detector.
2.4 Catalytic performance test [25]
Oxidation of alcohols was typically carried out as follows: a suspension with 5
mg of the synthesized catalyst in acetonitrile (2 mL) was magnetically stirred, and the
substrate namely alcohols (0.1 mmol) and PhIO (2.5 equiv.) was then added. The
o
resulting mixture was kept at 60 C with magnetically stirred for a set time. The
selectivity and conversion were determined by GC analysis.
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3 Results and discussions
3.1 Properties of the catalysts
3.1.1 TEM
Fig. 1 TEM photographs of the Ru/PG (a) and Pd/PG (b).
Fig. 1 shows the TEM images of Ru/PG and Pd/PG catalysts. The rodlike shape
of palygorskite (diameter between 20 and 80 nm) can be seen clearly in the images. In
addition, the small Ru particles (<3 nm) and Pd particles (<5 nm) can be also
observed on the photos. It is indicated that metals was loaded on palygorskite
successfully. The rodlike morphologies of palygorskite in TEM images were good
agreement with the corresponding AFM images.
3.1.2 FTIR
Farther more, the active groups exist on the surface of palygorskite were
confirmed by FTIR. The characteristic bands of 3616, 3550 and 3423 cm-1 were
assigned to the hydroxyl group in the PG crystal, whereas the broad band nearby at
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1651 cm-1 was attributed to the adsorbed water. The band at 1449 cm-1 and 1026 cm-1
was attributed to Mg-O and Si-O [18, 26]. The bending vibration of the hydroxyl water
was shown at 470 cm-1. There was no difference between the FTIR spectrum of PG
and PG loaded metal catalysts except for the Ru-O and Pd-O absorption at 1547 and
1495 cm-1 [27, 28], respectively. It is also indicated that the metal was loaded on
palygorskite successfully.
3.1.3 XRD
Fig. 2 XRD patterns of the Ru/PG and Pd/PG.
The XRD patterns of Ru/PG and Pd/PG catalysts are presented in Fig. 2. These
peaks at 2θ= 8.3o, 13.7o, 19.7o, 24o, 35.1o and 20.8o, 26.5o are observed and attributed
to palygorskite and quartz, respectively [29-31]. No characteristic angles for Ru were
observed for Ru/PG catalysts [32]. It may be due to a low loading or denote a high
metal dispersion in the obtained catalyst. Four characteristic peaks of Pd (II) at 2θ =
39.74o, 45.67o, 67.16o, corresponding to the (0 0 1), (1 0 0), (1 0 -1), (1 0 1) lattice
planes, are observed. All the diffraction peaks can be well-indexed to Pd (II)
according to the JCPDS card No. 54-0217, indicating that the as-prepared Pd (II)
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pompons have a high purity and high crystallinity.
3.1.4 ICP
The contents of Ru and Pd in the prepared catalysts were determined by ICP
method. The ICP data of Ru/PG and Pd/PG indicate that the catalyst contained 0.5%
Ru and 0.2% Pd (quality ratio), respectively.
3.1.5 XPS
The Si, Al, Mg, O, C and Pd elements were found in the XPS analysis of the
Pd/PG catalyst (Fig.3 a). The Si, Al, Mg, and O derived from the surface of the
palygorskite, and the Pd elements came from the Pd(OAc)2. Fig. 3 b shows the XPS
spectra of Ru/PG. Besides the standard peak of Si, Al, Mg, and O of palygorskite, the
XPS spectra of Ru/PG showed the peak of Ru elements, which was came from the
RuCl3·xH2O.
Fig. 3 XPS spectras of the Pd/PG (a) and Ru/PG (b).
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Fig. 4 shows the XPS spectra of Pd3d for Pd/PG catalyst. For Pd/PG catalyst,
three peaks could be observed due to the Pd3d5/2 and Pd 3d3/2. Generally speaking, the
peaks at 337.3 eV are assigned to Pd2+ [29]. Obviously, the Pd were mainly +2 valence
state, The XPS data were consistent with the XRD data, which indicated that the
palladium appeared in the Pd/PG catalyst as active species.
Fig. 4 XPS spectra of the Pd3d for Pd/PG catalyst.
Ru 3p3/2 region was chosen for the XPS analysis. The spectra from as-prepared
catalysts can be deconvoluted into three peaks of different intensities located around
461, 462.6 and 463.6 eV, as shown in Fig. 5. The lower binding energies (BE) at 461
and 462.6 eV were assigned to Ru0 and Ru3+ species, respectively, whereas the
component with BE 463.6 eV matched the character of Ru4+ [33]. It was found that
most of the Ru was in the Ru4+ and Ru3+ state, and very small amounts of metallic
state were detectable from the spectrum of Ru/PG catalyst. These results indicate the
oxidization activity of the Ru/PG catalyst was due to the surface high valence Ru
species.
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Fig. 5 XPS spectra of the Ru3p for Pd/PG catalyst.
3.1.6 BET
Fig. 6 N2 adsorption-desorption isotherms of Pd/PG (a) and Ru/PG (b).
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Table 1 Structural characteristics of Pd/PG and Ru/PG catalysts.
Catalyst Surface area (m2/g) Pore volume (cm3/g) Average pore diameter (nm)
Pd/PG
Ru/PG
139.04
263.88
0.43
0.83
12.44
12.62
The nitrogen adsorption-desorption isotherms of Pd/PG and Ru/PG catalysts are
shown in Fig. 6, and the structural characteristics are listed in Table 1. Fig. 6 shows
the nitrogen adsorption-desorption isotherms of samples, which can be classified as
type III hysteresis loop according to IUPAC classification [21]. These two catalysts
have almost the same average pore diameter, however, the surface area and pore
volume of Pd/PG is almost half of the surface area and pore volume of Ru/PG,
respectively. It may be due to some pores of carrier was blocked after coating Pd
metal-salt [24]. The BET specific surface area of Ru/PG was higher than that of Pd/PG,
which may indicate the catalyst activity of Ru/PG was higher than that of Pd/PG at
latter oxidation reaction.
3.2 Catalytic properties of the samples
3.2.1 Contrast experiments
In an effort to compare the potential abilities of these palygorskite supported
metal catalysts with those of the related metal-salt catalysts and that of the pure
palygorskite, oxidations of benzyl alcohol were carried out at presence of PhIO as an
oxidant or none with all kinds of other catalysts. The results are summarized in Table
2.
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Table 2 The contrast experiments of catalytic oxidation of benzalcohol under same conditions.
Entry Cat./amount
Oxidant/Dosage (mg) Conv. (%) Sele. (%)
1
2
3
4
5
6
7
8
Palygorskite/10mg
None
0
0
0
Palygorskite/10mg
RuCl3/1mg
PhIO/55mg
None
0
0
0
RuCl3/1mg
PhIO/55mg
None
15
5
>99
>99
>99
>99
>99
Pd(OAc)2/1mg
Pd(OAc)2/1mg
Ru/PG/5mg
PhIO/55mg
PhIO/55mg
PhIO/55mg
8
100
100
Pd/PG/5mg
Reaction conditions: benzalcohol 0.1 mmol, CH3CN 2 mL, 25 oC, 6 h.
According to these data, only palygorskite supported metal with PhIO as oxidant
system showed high activation for the oxidation of benzyl alcohol. It can be also
observed that the conversion more than the selectivity is the improved catalytic
propriety by the catalytic system after the using of palygorskite as support for the
catalysts. All of the results confirmed the high catalytic activity of Ru/PG and Pd/PG
in the objective reactions. The catalytic activity of prepared catalysts was also
compared with some other reports related to supported metal catalysts. It was found
that the prepared Ru/PG and Pd/PG catalysts showed higher selectivity compared
with the same metal with different carrier [12, 15, 34]
.
3.2.2 Optimizing of the conditions for the catalytic oxidation of benzalcohol
The influence of the temperature, the reaction time, the dosage of the catalyst, as
well as the solvent on catalytic activity were investigated in the liquid phase oxidation
of benzyl alcohol to benzaldehyde with Pd/PG as catalyst at the presence of PhIO.
The results were concluded in Tables 3-6.
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Table 3 The catalytic oxidation of benzalcohol by Pd/PG under different temperatures.
Entry
Temperature (oC)
Conv. (%)
Sele. (%)
>99
1
2
3
25
40
60
42
50
>99
100
>99
Reaction conditions: benzalcohol 0.1 mmol, PhIO 2.5 equiv., Pd/PG 5 mg, CH3CN 2 mL, 4 h.
Table 4 The catalytic oxidation of benzalcohol by Pd/PG in different reaction times.
Entry
Time (h)
Conv. (%)
Sele. (%)
>99
1
2
3
4
1
2
3
4
76
88
>99
96
>99
100
>99
Reaction conditions: benzalcohol 0.1 mmol, PhIO 2.5 equiv., cat. 5 mg, CH3CN 2 mL, 60 oC.
Table 5 The catalytic oxidation of benzalcohol with different amounts of Pd/PG.
Entry Cat. (mg) Conv. (%) Sele. (%) Time required for the conv. (h) TOF(h-1)
1
2
3
4
2
3
4
5
50
83
>99
>99
>99
>99
10
10
8
133
147
166
213
100
100
4
Reaction conditions: benzalcohol 0.1 mmol, PhIO 2.5 equiv., CH3CN 2 mL, 60 oC.
Table 6 The catalytic oxidation of benzalcohol by Pd/PG in different solvents
Entry
Solvent
Toluene
Conv. (%)
Sele. (%)
>99
1
2
3
4
85
73
Dichloroethane
Fluorobenzene
Acetonitrile
>99
70
>99
100
>99
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Reaction conditions: benzalcohol 0.1 mmol, PhIO 2.5 equiv., Pd/PG 5 mg, solvent 2 mL, 60 oC, 4 h.
It was seen from the tables (Tables 3-6) that all of the listed factors showed
important influence on the oxidation. As for the influence of solvent, when the
oxidation of benzalcohol was examined in the presence of different solvents, such as
C6H5F, CH2ClCH2Cl, CH3CN and PhMe, significant variation of the oxidation results
obtained. The oxidation of benzalcohol was positively related to polarity solvents. The
decrease order of dielectric constants of the selected four solvents is: PhMe
(2.38)<C6H5F(5.42)<CH2ClCH2Cl(10.4)<CH3CN(37.5). Obviously, the benzaldehyde
selectivity was highly in aprotic solvents. Perhaps the reaction in the presence of
acetonitrile can increase the capability of dehydrogenation of alcohols in this system.
Hence the CH3CN is found to be an optimal solvent.
Based on all of the investigated factors of the optimum reaction conditions for
the catalytic oxidation of benzalcohol with the catalysis of Pd/PG in the presences of
PhIO can be concluded. That is, with 5 mg of Pd/PG as the catalyst, the oxidation can
o
be completely carried out during 4 hours in CH3CN solution at 60 C. The above
conditions were also employed to the catalytic oxidation of other alcohols with the
catalysts of Pd/PG and Ru/PG.
The hydrogen peroxide and oxygen as oxidant for the oxidation of benzalcohol
were also investigated. These two catalysts didn’t show any catalytic activity. The
activity of PhIO in this system may be due to the nucleophilicity of I(III) in PhIO. At
the presence of Lewis acid such as BF3, Et2O, Et3O, BF4 and non-redox metal salts,
the PhIO reaction activity could be greatly improved. It is general considered that this
activation is due to formed an irresolvable and electrophilic complex. Some metal
salts and transition metal complexes can also play the same role such as Ru (Ⅲ) [35]
.
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3.2.3 Oxidation of alcohols with the catalysis of Pd/PG
The scope of the Pd/PG catalyst for a wide variety of alcohols was examined.
The present catalyst system showed excellent oxidation and selectivity for all of
alcohols, as can be seen from Table 7.
Table 7 Catalytic oxidation of alcohols by Pd/PG with PhIO as oxidant.
Entry
1
Substrate
Product
Conv. (%) Sele. (%) Time (h)TOF (h-1)
CH2OH
CHO
100
>99
5
213
CH3O
NO2
CH2OH
CH3O
NO2
CHO
2
3
100
100
>99
>99
2
2
532
532
CH2OH
CHO
CH3
CH2OH
CH3
4
5
100
100
>99
>99
6
4
177
266
CHO
CH3
CH3
CH2OH
CHO
CH3O
CH3O
CH3O
CH3O
6
100
>99
3
355
CHO
CH2OH
PhO
PhO
7
8
100
100
44
>99
>99
>99
>99
3
7
8
8
355
152
59
CH2OH
CHO
Cl
CH2OH
Cl
CHO
OH
O
9
OH
O
10
56
75
Cl
Cl
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OH
O
11
54
>99
8
72
CH3
CH3
OH
O
12
13
14
62
>99
>99
>99
8
3
5
83
100
100
355
213
OH
O
O
OH
CH2CH2OH
CH2CHO
15
5
91
8
7
Reaction conditions: alcohol 0.1 mmol, PhIO 2.5 equiv., Pd/PG 5 mg, CH3CN 2 mL, 60 oC.
It can be seen from the Table 7 that various benzylic and aliphatic alcohols were
selectively converted into the corresponding carbonyl compounds under mild reaction
conditions. As for the benzylic alcohols, benzalcohol and its derivatives always
showed higher oxidation activity than that of the benzohydrol derivatives under the
same condition, which can be attributed to the steric hindrance of the latter. We can
also find that Pd/PG showed excellent catalytic property for the oxidation of aliphatic
alcohols, which always think to be “inert” under a common oxidative condition
(entries 12-15). The two selected long-chained alcohols, e.g. hexanol and dodecanol
(entries 12, 13), showed even higher oxidation activities than that of some benzylic
alcohols (entries 1-3, 7). As a cyclic secondary alcohol, cyclohexanol can obtain 62%
conversion of cyclohexanone in this catalytic system. Unfortunately, the catalyst
hardly showed catalytic activity for the oxidation of β-phenylethanol in its oxidation
(entry 15).
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3.2.4 Oxidation of alcohols with the catalysis of Ru/PG
Catalytic property of Ru/PG for the oxidation of alcohols was also studied, the
results were summarized in Table 8.
Table 8 Catalytic oxidation of alcohols by Ru/PG with PhIO as oxidant.
Entry
1
Substrate
Product
Conv. (%) Sele. (%) Time (h)TOF (h-1)
CH2OH
CHO
100
>99
5
213
CH3O
NO2
CH2OH
CH3O
NO2
CHO
2
3
100
100
>99
>99
1
1
1065
1065
CH2OH
CHO
CH3
CH2OH
CH3
4
5
100
100
>99
>99
2
2
532
532
CHO
CH3
CH3
CH2OH
CHO
CH3O
CH3O
CH3O
CH3O
6
100
>99
4
266
CHO
CH2OH
PhO
PhO
7
8
100
100
92
>99
>99
>99
>99
>99
2
8
8
8
8
532
133
122
130
129
CH2OH
CHO
Cl
CH2OH
Cl
CHO
OH
O
9
OH
O
10
11
98
Cl
Cl
OH
O
97
CH3
CH3
OH
O
12
13
94
>99
>99
8
4
125
266
OH
100
O
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O
OH
14
15
100
36
>99
96
6
8
178
48
CH2CH2OH
CH2CHO
Reaction conditions: alcohol 0.1 mmol, PhIO 2.5 equiv., Ru/PG 5 mg, CH3CN 2 mL, 60 oC.
The results demonstrated that the prepared Ru/PG showed somewhat higher
catalytic activity than that of Pd/PG under same conditions. For the oxidation of
p-methoxyl benzalcohol and p-methoxyl benzalcohol, 100% conversions were
achieved within 1 hour (entries 4, 6). All of the selected benzohydrol derivates can
also be transformed to the corresponding ketones in 8 hours (entries 9-11). Superior to
that of Pd/PG, 36% conversion of β-phenylethanol was obtained with the catalysis of
Ru/PG catalyst.
Fig. 7 Conversion/selectivity for the recycling of Pd/PG (a) and Ru/PG (b).
The reusability of Pd/PG and Ru/PG for the oxidation of benzalcohol were also
investigated. The recovered catalyst was reused after being separately washed with
ethanol and deionized water several times and dried in vacuum at room temperature.
Under the same conditions, the conversion of benzalcohol could be kept 88% and
92% after the fifth recycling experiment for Pd/PG and Ru/PG, respectively. All the
selectivity of benzaldehyde was kept over 99% in every recycling, as shown in Fig. 7.
Therefore, for this substrate, the Pd/PG and Ru/PG catalysts can be easily reused at
least five times with high catalytic activity and selectivity.
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4 Conclusions
Two palygorskite supported ruthenium and palladium catalysts (Ru/PG and
Pd/PG) were prepared through an easy impregnation method. The prepared catalysts
were highly active in the oxidation of various alcohols under mild conditions. At a
uniform condition, Ru/PG catalyst is always more active than Pd/PG catalyst for the
oxidation of alcohols. The results argued that palygorskite can be used as excellent
support for the preparation of heterogeneous metal-containing catalysts.
Acknowledgements
The research was financial supported by NSFC (21163016, 21174114), Gansu
provincial Natural Science Foundation of China (1208RJZA287), the Program for
Changjiang Scholars and Innovative Research Team in University (IRT1177). We also
thank Key Laboratory of Eco-Environment-Related Polymer Materials (Northwest
Normal University), Ministry of Education, for financial support.
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Graphical abstract
Catalytic properties of palygorskite supported Ru and Pd for
efficient oxidation of alcohols
Zhi-Wang Yang, Xia Zhao, Tian-Jing Li, Wen-Long Chen, Qiao-Xiang Kang,
Xue-Qing Xu, Xi-Xi Liang, Ying Feng, Huan-Huan Duan, Zi-qiang Lei
Key Laboratory of Polymer Materials of Gansu Province
Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of
Education
College of Chemistry and Chemical Engineering, Northwest Normal University
Lanzhou, 730070 China
Palygorskite (PG) Supported Ru (Ru/PG) and Pd (Pd/PG) catalysts were prepared. Excellent
catalytic performance achieved in the oxidation of alcohols with PhIO as oxidant.
 Corresponding author. Tel: +86 931 7971261.
E-mail address: leizq@nwnu.edu.cn (Z. Lei).
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Highlights
 Natural abundant palygorskite as support;
 Excellent catalytic activity for oxidation of alcohols;
 Wide application scopes of alcohols;
 Promising recyclability.
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