Supported Palladium Oxide Nanoparticles in SBA-15 as a Heterogeneous Catalyst for the Aerobic Oxidation of Alcohols

Article abstract of DOI:10.1002/jccs.201300609

Palladium nanoparticles were first synthesized through the thermal decomposition method and subsequently immobilized on ordered mesoporous silica material, SBA-15, to afford PdO/SBA-15 catalyst. The synthesized catalyst was characterized by X-ray diffraction, nitrogen adsorption-desorption measurement, transmission electron microscopy, and inductively coupled plasma atomic emission spectrometry. The catalytic activity was tested for the aerobic oxidation of alcohols. Easy recovery, high yeilds and relatively short reaction times were observed for the mentioned catalyst.

Full text of DOI:10.1002/jccs.201300609

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Article
Supported Palladium Oxide Nanoparticles in SBA-15 as a Heterogeneous Catalyst for
the Aerobic Oxidation of Alcohols
Hassan Atashin and Reihaneh Malakooti*
Nanochemistry Research Laboratory, Department of Chemistry, University of Birjand, P. O. Box: 97175-615, Birjand,
Iran
(Received: Nov. 20, 2013; Accepted: Mar. 5, 2014; Published Online: May 26, 2014; DOI: 10.1002/jccs.201300609)
Palladium nanoparticles were first synthesized through the thermal decomposition method and subse-
quently immobilized on ordered mesoporous silica material, SBA-15, to afford PdO/SBA-15 catalyst. The
synthesized catalyst was characterized by X-ray diffraction, nitrogen adsorption–desorption measure-
ment, transmission electron microscopy, and inductively coupled plasma atomic emission spectrometry.
The catalytic activity was tested for the aerobic oxidation of alcohols. Easy recovery, high yeilds and rela-
tively short reaction times were observed for the mentioned catalyst.
Keywords: SBA-15; Heterogeneous catalyst; Palladium oxide nanoparticles; Aerobic oxidation of
alcohols.
INTRODUCTION
The selective oxidation of alcohols to form carbonyl
on SBA-15 by the use of bipyridyl ligands.7 Although, they
observed short reaction time only for the activated sub-
strate, formation of palladium black aggregation and re-
duction of reusability because of leaching of organic ligand
make this catalytic system less practical. Despite various
systems contain heterogeneous catalyst for oxidation of al-
cohols, there are still major challenges such as high catalyst
loading, homogeneous behavior of palladium, potentially
susceptible to degradation under oxidation conditions, cat-
alyzed only active substrate without sterically demanding
substituent and instability of support which can restrict cat-
alyst applications.8-16
A new way was developed by Somorjai group17,18 in
order to prepare supported catalyst containing metal nano-
particles. In this technique, first the metal nanoparticles are
synthesized with capping agents in the solution and then
are guided into the pores of SBA-15 which showed superi-
ority over other methods such as ion exchange,19 chemical
vapor deposition20 and impregnation21 in control of the par-
ticle size, shape and formation of metal nanoparticles both
inside and outside of the pores.17,18 In addition the porous
SBA-15 can inhibit further particles growth, agglomera-
tion in catalyst preparation and especially in subsequent
catalytic reactions.22
compounds is one of the most important processes in or-
ganic synthesis, because the corresponding carbonyl com-
pounds, as intermediates, could be used for producing im-
portant compounds in the pharmaceutical, agricultural and
chemical industries. From the economical and more envi-
ronmentally friendly aspect, much attention of research
was directed to the development of new protocols for oxi-
dation of alcohols using transition-metal catalysts with
mild oxidants such as dioxygen (O2) or air.1-5
Although, many homogeneous catalysts of palladium
have been reported,1-3 they suffer drawbacks such as diffi-
culty in separation of catalyst from reaction mixture, reus-
ing of expensive noble metal and purification of products.
In comparison, palladium heterogeneous catalysts possess
the advantages of easier catalyst recycling and product pu-
rification and have received much attention for the oxida-
tion of alcohols in recent years.4,5
Mesoporous silica materials, with pore diameters
ranging from 2-50 nanometers, particularly SBA-15, have
been shown to be one of the most appropriate supports for
heterogenization of catalysts because of high surface area,
regular channels, suitable pores diameters and thermal sta-
bility.6
Herein, we investigate the synthesis and characteriza-
tion of SBA-15 supported palladium oxide nanoparticles,
PdO/SBA-15 catalyst, and its applications for oxidation of
As a quite efficient heterogeneous catalyst, Karimi
and co-worker reported palladium nanoparticles supported
* Corresponding author. Tel: +989151604376; Fax: +985614437502;
Email: rmalakooti@birjand.ac.ir, reihaneh.malakooti@gmail.com
Supporting information for this article is available on the www under http://dx.doi.org/10.1002/jccs.201300609
J. Chin. Chem. Soc. 2014, 61, 1039-1044
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Atashin and Malakooti
alcohols in two different conditions which develops a more
active and recyclable heterogeneous catalyst.
phous silica wall of SBA-15.29
Fig. 3 shows the TEM image of unsupported Palla-
dium nanoparticles with average diameter of about 5 nm
even by considering of TOP molecules length (1 nm)30
which are still smaller than pore diameters of SBA-15.
The morphology of PdO/SBA-15 nanocatalyst and
the distribution of the PdO nanoparticles in the SBA-15
were also studied by Transmission electron microscopy.
The image (Fig. 4) clearly revealed retaining of mesochan-
nels after immobilization and high dispersion of the nano-
particles in the material.
RESULTS AND DISCUSSION
The small angle diffraction patterns of the SBA-15
and PdO/SBA-15 samples after calcinations were shown in
Fig. 1. SBA-15 XRD pattern (Fig. 1a) showed three peaks
at 0.8, 1.36 and 1.4 degrees assigned to 100, 110 and 200
reflections respectively, indicate ordered hexagonal unit
cell of mesoporous materials. Also, Fig. 1b illustrated the
XRD pattern of mesostructured silica after impregnation
with colloidal Pd nanoparticles. The similarity in peak in-
tensities and relative positions indicate retaining the mor-
phology and structure of the catalyst during the activation
process and the binding of the PdO nanoparticles. The dif-
fraction exhibited a slightly shift to the higher angles
(lower d-values) conveying a change in the distance be-
tween the pores. This may be due to the shrinking of the lat-
tice as a result of condensation after palladium incorpora-
tion and calcination.25,26 The reduction in the XRD intensi-
ties could originate from low scattering contrast between
pores and walls, from a loss of regularity in the material,
and/or from inhomogeneous condensation levels in the
silica framework.26
N2 adsorption-desorption measurements of the PdO/
SBA-15 and SBA-15 silica are shown in Fig. 5. Both ex-
The high angle X-ray diffraction pattern of PdO/SBA-
15 was shown in Fig. 2. The characteristic peak of palla-
dium oxide is observed at 2q = 33.7 (JCPDS Data no
43-1024 for tetragonal PdO).27 Other expected peaks of
PdO nanoparticles were not observed probably due to the
highly dispersed PdO in the support28 or the low signal-
to-noise ratio resulting in unsuccessful determination of
the particle size based on the XRD pattern. In addition a
very broad peak at 2q = 22.75 is attributed to the amor-
Fig. 2. High angle XRD pattern of PdO/SBA-15.
Fig. 3. TEM image of Pd nanoparticles.
Fig. 1. XRD patterns of: SBA-15 (a) and PdO/SBA-15
(b).
Fig. 4. TEM image of the PdO/SBA-15 catalyst.
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PdO/SBA-15 Catalyst for Alcohols Oxidation
Table 1. Characteristics of support and catalyst
b
c
d
e
f
Materials
C(M)a
SBET
VBJH
DBJH
Ao
D100
Wg
SBA-15
-
-
650
630
548
0.97
0.95
0.91
8.68
8.41
6.96
12.72
12.72
12.14
11
11
10.5
4.04
4.31
5.18
SBA-15h
PdO /SBA-15
0.066
a Initial concentration of palladium species (mmol g- 1), b specific surface area (m2g- 1),
c pore volume (cm3g- 1), d pore diameter (calculated from the adsorption branch) (nm),
e cell parameter (nm), f interplanar spacing (nm), g wall thickness (Ao – DBJH), (Ao =
2D100
/
), h SBA-15 was further calcined under heat treatment conditions of the
3
catalyst (at 350 °C for 3 hours).
hibited the type IV isotherms with H1 hysteresis loop at
high relative pressure, characteristic of materials with cy-
lindrical mesopores as per the IUPAC classification.31 The
observed sharpness of adsorption branches in the relative
pressure of 0.6–0.8, indicate a uniform mesopore size dis-
tribution. This result can also be evidenced from corre-
sponding size distribution curves (inset in Fig. 5).
15 is optimal for these reactions.
The acceptable activity was observed at 70 °C, and it
was selected as suitable temperature for the reaction.
Higher temperatures were avoided due to giving rise to
acid formation. To find the best solvent, the reaction was
studied in different solvents such as n-hexane, DMF, CHCl3
and Toluene at 70 °C (Table S3 and S4, supporting infor-
mation). The best yield was obtained in toluene. It may be
due to the fact that residual of TOP ligands on the surface of
PdO molecules creates an organic environment surround-
ing them in the pores of SBA-15 which result in good ac-
cessibility for substrate during oxidation process in organic
solvent such as toluene. Also it was found that without sol-
vent no product was observed even after prolong of heating
(entry 7).
However, a decrease in the surface area, pore volume
and pore size was observed after modification (Table 1).
These results reveal that the palladium oxide nanoparticles
had been dispersed inside the pores and have the most con-
tribution for observed reductions, although about 3% of de-
cline was originated from the heat treatment of SBA-15.
Aerobic oxidation of alcohols
To optimize the reaction conditions, the oxidation re-
action of benzyl alcohol was used as a model reaction, so
the reaction between benzyl alcohol with different amounts
of PdO/SBA-15 catalyst in the presence of potassium car-
bonate (Table S1, supporting information) and hydrogen
peroxide (Table S2, supporting information) were carried
out. As it is shown in Table S1 and S2, 0.1 g of PdO/SBA-
Subsequently, with optimal conditions in hand, to ex-
tend the scope of protocol, a wide range of substituted pri-
mary and secondary alcohols were allowed to undergo se-
lective oxidation reaction under air atmosphere in the pres-
ence of PdO/SBA-15 (Table 2).
As shown in Table 2, primary and secondary ben-
zylic, and the heterocyclic alcohols were oxidized to the
corresponding carbonyl compounds in good to excellent
isolated yields with very short times. In addition, oxidation
of primary benzylic alcohols to carboxylic acids was not
observed. In the other hand, sterically hindered ortho-sub-
stituted aromatic benzylic alcohols (Table 2, entry3) un-
dergo oxidation reaction without any difficulty.
One of the interesting properties of this catalyst was
its ability to convert hydrobenzoin to benzoin contrasting
to the results obtained by many other catalysts, which
cleave the carbon-carbon bond to give the corresponding
aldehyde or acid. Cinnamyl alcohol as a a,b-unsaturated
alcohol was easily converted to 4-cinnemaldehyde in 100%
yield (entry 4) showing that carbon-carbon double bonds
are not prone to cleavage using this method and no iso-
Fig. 5. Nitrogen adsorption/desorption isotherms in-
corporated with pore size distributions at inset
of: SBA-15 (a) and PdO /SBA-15(b).
J. Chin. Chem. Soc. 2014, 61, 1039-1044
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Atashin and Malakooti
Table 2. Aerobic oxidation of alcohols using PdO/SBA-15
catalyst in toluene in the presence of K2CO3 a and
hydrogen peroxideb
Table 3. Reusability of PdO/SBA-15 catalyst on the synthesis of
benzyl alcohola
Run
1
3
2
3
4
5
6
7
Entry
Substrate
Benzyl alchol
1-Phenylethanol
Furfuryl alcohol
Cinnamyl alcohol
3-Butyn-2-ol
Time (h)
yield (%)
Time (h)
3
3
3
3
3
3
1
2
3
4
3 (8) [c]
3 (8.5)
2.5 (3)
9 (6)
95 (70) [d]
95 (40)
100 (100)
70 (95)
95 (100)
95 (85)
Yeild (%) 95
95
95
95
95
95
95
[a] Reaction conditions: benzyl alcohol (1 mmol), PdO/SBA-15
catalyst (0.1 g, 0.66 mol% Pd), and K2CO3 (1 mmol) in 3 mL
toluene at 70 °C.
5
3 (8.5)
2 (6.5)
2 (6.5)
7.5 (4)
7.5 (2)
3.5 (2)
5.5 (2)
2.5 (3)
2.5 (2)
2.5 (5)
2.5 (4)
2 (2)
6
7
8
9
10
11
12
13
14
15
16
2-Hydroxybenzyl alcohol
4-Methoxybenzyl alcohol
4-Nitrobenzyl alcohol
4-Chlorobenzyl alcohol
2-Chlorobenzyl alcohol
2,4-Dichlorobenzyl alcohol
1-Phenyl-1-propanol
Diphenylmethanol
Benzoin
85 (90)
70 (80)
95 (95)
90 (80)
95 (90)
90 (95)
95 (90)
studied by reusability of the catalyst. After each run, the
catalyst was separated by easy filtration, washed with abso-
lute ethanol and drying. As shown in Table 3, the catalyst
was reused 7 times without significant decrease in yield
which reveals that the catalyst is stable in the reaction con-
ditions and palladium oxide nanoparticles have fair inter-
action with the support.
100 (90)
100 (100)
100 (100)
4-chlorostyrene
Styrene
Based on our results and reported mechanism in the
literature,32,33 the plausible mechanism for oxidation of al-
cohols may be through the firstly attachment of alcohol to
palladium species by an oxidative addition of an O-H bond
from alcohol to the Pd species (Scheme 3). Hydride elimi-
nation from alcohol and its transformation to the Pd species
in the presence of base, gives the carbonyl product and Pd-
hydride species. Finally, reaction of the hydride species
with air happens to produce water and continue catalytic
cycles.
[a] Reaction conditions: Alcohol (1 mmol), PdO/SBA-15 (0.1 g,
0.66 mol% Pd), K2CO3 (1 mmol), Toluene (3 mL) at 70 °C.
[b] Reaction conditions: Alcohol (1 mmol), PdO/SBA-15 (0.1 g,
0.66 mol% Pd), H2O2 (1 mmol), Toluene (3 mL) at 70 °C. [c] and
[d] the data in the parenthesis corresponding to hydrogen perox-
ide test.
merization of double bonds is observed. It is worth men-
tioning that aromatic olefins such as styrene can be oxi-
dized to the corresponding aldehydes with high rates in the
presence of PdO/SBA-15 and no polymerization reaction
was observed.
To indicate the high activity of PdO/SBA-15 as a cat-
alyst in oxidation reaction, we compared our finding with
some previously reported results for the oxidation of ben-
zyl alcohols in Table 4. Relatively higher activity was ob-
served in comparison with other results.
To determine whether the PdO catalyst is really oper-
ating in a heterogeneous manner or whether in the solution
phase by leached Pd species, a hot filtration test was per-
formed.7 To do that, the synthesis of benzaldehyde from the
oxidation of benzyl alcohol in the presence of K2CO3 in to-
luene at 70 °C under atmosphere with PdO/SBA-15 cata-
lyst was carried out. After 30 min (20% yield), the reaction
mixture was filtered off in the reaction temperature to avoid
redeposition of solubilized palladium oxide nanoparticles.
The filtrate was then transferred to another tube containing
1 mmol K2CO3 in toluene at 70 °C under air atmosphere
and stirred. It was found that no further reaction progress
occurred even after 4 hours. In addition, after analysis of
the filtrate solution by atomic adsorption spectrophotome-
ter, no palladium was detected in the solution. Based on
these results, the heterogeneous behavior of catalytic system
was confirmed.
EXPERIMENTAL
Materials and Characterizations: A poly (ethylene ox-
ide)-block-poly (propylene oxide)-block-poly (ethylene oxide)
triblock copolymer (P123) was purchased from Aldrich. Tri-n-
octylphosphine (TOP, tech 90%), Octadecene (ODE), Palladium
Table 4. Comparison of catalytic activities in the oxidation of
benzyl alcohol using heterogeneous catalysts
Catalyst
Time (h) mol %Pd Tem (°C) yield (%)
Pd/SBA-16
10
6.6
6
4
8
1
0.5
0.5
0.25
0.35
0.66
50
100
100
110
95
96.5[9]
94[12]
79[13]
68[14]
99[15]
95
Pd@SBA-15
Pd/MCM-41
Pd/Porous-SiO2
Pd@PMO-IL
This work
3
80
The stability of the catalyst, PdO/SBA-15, was also
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PdO/SBA-15 Catalyst for Alcohols Oxidation
(II) acetate (99%), Tetraethyl orthosilicate (TEOS), Toluene, Hy-
drochloric acid (HCl), Potassium carbonate (K2CO3), Hydrogen
peroxide (H2O2 30%) and other materials were purchased from
Merck. All materials were used without further purification.
X-ray diffraction patterns (XRD) were conducted using
Bruker D8Advance model with Ni-filtered Cu Ka radiation
(1.5406 Å). Data was recorded with a speed of 2º min-1 and a step
of 0.05º. TEM images were performed on a Philips CM10 elec-
tron microscope at 100 kV. N2 adsorption/desorption isotherms
were acquired at 77.35 K utilization Quantachrome Nova 2200,
Version 7.11 Analyzer. Before measurements, the samples were
out-gassed at 120 °C for overnight. The specific surface area and
the pores size distributions were obtained from the desorption
branch of the isotherms using the Brunauer–Emmett–Teller (BET)
method and Barrett–Joyner–Halenda (BJH) analysis. Amount of
palladium in catalyst was determined by 7300DV inductively
coupled Optical Emission Spectrometry (ICP-OES). A Shimadzu
AA-6300 flame atomic absorption spectrometer was utilized to
determine the amount of palladium oxide leached from PdO/
SBA-15 catalyst.
toluene and stirred vigorously. Then 1.5 g of SBA-15, dried in a
vacuum oven at 120 °C overnight, was added to the solution and
stirred for 24 h at room temperature accompanied with sonication
for 1 h. The Pd-TOP/SBA-15 was separated from the solution by
centrifugation, dried at 60 °C in oven. Finally for the removal of
TOP surfactants surrounding the Pd nanoparticles; the Pd-TOP/
SBA-15 was calcined to give PdO/SBA-15 catalyst as the temper-
ature was increased to 150 °C at a rate of 1 °C/min, kept for 2 h,
then heated to 350 °C at 5 °C/min and allowed to keep for more 3
h (Scheme 1).
Schematic synthesis of Pd nanoparticles and
PdO/SBA-15 catalyst
Scheme 1
Synthesis of colloidal Pd nanoparticles: Palladium nano-
particles were synthesized according to the reported procedure by
literature.23 In a typical synthesis, ODE (5 mL), TOP(0.5 mL) and
palladium(II) acetate (0.0225 g, 0.10 mmol) were mixed in a 50
mL three-necked round-bottomed flask equipped with magnetic
stirrer, reflux condenser and thermometer. The solution was de-
gassed by N2 at room temperature for 40 min under vigorous stir-
ring. The solution turned orange. Then temperature was raised up
to 260 °C during 10 min and the color changed to black. The reac-
tion was allowed to proceed for 20 min. Then the mantel was re-
moved, and the resulting mixture was allowed to cool down to
room temperature followed by addition of 5 mL toluene to the
flask. The Pd nanoparticles were collected by the addition of etha-
nol, then centrifuged and washed with toluene.
General procedure for the oxidation of alcohols: A mix-
ture of K2CO3 (0.138 g, 1.0 mmol) and PdO/SBA-15 catalyst (0.1
g, 0.66 mol% Pd) in 3 mL of toluene was placed into a glass tube
equipped with a magnetic stirrer. Next the alcohol (1 mmol) was
added into the solution. The resulting mixture was stirred at 70 °C
under O2 atmosphere. In another condition instead of K2CO3, hy-
drogen peroxide (0.2 mL, 2 mmol) was used. The progress of all
of the reactions was monitored by Gas Chromatography (Scheme
2).
Synthesis of SBA-15: SBA-15 was prepared according to
the procedure reported by Zhao group.6 2.0 g of pluronic P123
was first dissolved in a mixture of (15 g) H2O plus 2 M HCl (60 g),
and then 4.25 g of TEOS (tetraethyl orthosilicate) was added with
vigorous stirring at 40 °C. After that, the mixture was stirred at 40
°C for 24 h and then heated at 100 °C for another 24 h under static
conditions. Finally the sample was filtered off, washed with dis-
tilled water, air-dried at room temperature, and then calcined at
600 °C in air for 6 h (heating ramp of 2 °C min-1) to remove the
template.
Reaction scheme for the oxidation of alco-
hols over PdO/SBA-15 catalyst
Scheme 2
CONCLUSIONS
The preparation and characterization of a palladium
Preparation of mesoporous silica supported PdO nano-
particles: To immobilize palladium nanoparticles on mesoporous
silica support, First Pd nanoparticles was dispersed in 200 mL of
oxide catalyst based on ordered mesoporous silica, SBA-
15, were described. The catalyst was active for the oxida-
J. Chin. Chem. Soc. 2014, 61, 1039-1044
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Atashin and Malakooti
M. J. Mol. Catal. A: Chem. 2013, 372, 167.
Schematic of proposed mechanism for the
oxidation of alcohols
Scheme 3
12. Zhang, G.; Wang, Y.; Wen, X.; Ding, C.; Li, Y. Chem.
Commun. 2012, 48, 2979.
13. Wang, H.; Wang, J. G.; Shen, Z. R.; Liu, Y. P.; Ding, D. T.;
Chen, T. H. J. Catal. 2010, 275, 140.
14. Yang, H.; Chong, Y.; Li, X.; Ge, H.; Fan, W.; Wang, J. J. Ma-
ter. Chem. 2012, 22, 9069.
15. Karimi, B.; Elhamifar, D.; Clark, J. H.; Hunt, A. J. Org.
Biomol. Chem. 2011, 9, 7420.
16. Yang, H.; Han, X.; Ma, Z.; Wang, R.; Liu, J.; Jia, X. Green
Chem. 2010, 12, 441.
17. Witham, C. A.; Huang, W.; Tsung, C. K.; Kuhn, J. N.;
Somorjai, G. A.; Toste, F. D. Nat. Chem. 2010, 2, 36.
18. Konya, Z.; Molnar, E.; Tasi, G.; Niesz, K.; Somorjai, G. A.;
Kiricsi, I. Catal. Lett. 2007, 113, 19.
19. Yang, C. M.; Sheu, H. S.; Chao, K. J. Adv. Funct. Mater.
2002, 12, 143.
tion of a variety of alcohols in two different conditions.
High conversion, relatively short reaction times and good
reusability are advantages of our work.
20. Raja, R.; Sankar, G.; Hermann, S.; Shephard, D. S.; Bromley,
S.; Thomas, J. M.; Johnson, B. F. G. Chem. Commun. 1999,
16, 1571.
21. Han, Y. J.; Kim, J. M.; Stucky, G. D. Chem. Mater. 2000, 12,
2068.
ACKNOWLEDGEMENTS
22. White, R. J.; Luque, R.; Budarin, V. L.; Clark, J. H.;
Macquarrie, D. J. Chem. Soc. Rev. 2009, 38, 481.
23. Liu, Q.; Bauer, J. C.; Schaak, R. E.; Lunsford, J. H. Angew.
Chem. Int. Ed. 2008, 47, 6221.
Authors are thankful to University of Birjand Re-
search Council for the funding of this study. We also grate-
fully acknowledge Dr. R. Hosseinabadi and Dr. E. Ghiamati
(University of Birjand) for their useful consults
24. Jana, S.; Dutta, B.; Bera, R.; Koner, S. Inorg. Chem. 2008,
47, 5512.
REFERENCES
25. Wang, X.; Wu, G.; Wei, W.; Sun, Y. Catal. Lett. 2010, 36, 96.
26. Lim, M. H.; Stein, A. Chem. Mater. 1999, 11, 3285.
27. Hernandez-Pineda, J.; Del-Rio, J. M.; Carreto, E.; Terres, E.;
Montoya, J. A.; Zuniga-Gonzaleza, M. D. J.; Morgado, J. J.
Alloys Compd. 2009, 481, 526.
1. Stahl, S. S. Angew. Chem. Int. Ed. 2004, 43, 3400.
2. Brink, G. J.; Arends, I. W. C. E.; Sheldon, R. A. Science
2000, 287, 1636.
3. Shi, Z.; Zhang, C.; Tang, C.; Jiao, N. Chem. Soc. Rev. 2012,
41, 3381.
28. Feng, Y.; Li, L.; Li, Y.; Zhao, W.; Gu, J.; Shi, J. J. Mol. Catal.
A: Chem. 2010, 322, 50.
4. Mallat, T.; Baiker, A. Chem. Rev. 2004, 104, 3037.
5. Parmeggiani, C.; Cardona, F. Green Chem. 2012, 14, 14547.
6. Zhao, D.; Feng, J.; Huo, Q.; Melosh, N.; Fredrickson, G. H.;
Chmelka, B. F.; Stucky, G. D. Science 1998, 279, 548.
7. Karimi, B.; Abedi, S.; Clark, J. H.; Budarin, V. Angew.
Chem. Int. Ed. 2006, 45, 4776.
29. Zhao, X. G.; Shi, J. L.; Hu, B.; Zhang, L. X.; Hua, Z. L. Ma-
ter. Lett. 2004, 58, 2152.
30. Chen, X.; Hirtz, M.; Rogach, A. L.; Talapin, D. V.; Fuchs,
H.; Chi, L. Nano. Lett. 2007, 11, 3483.
31. Zhao, D.; Sun, J.; Li, Q.; Stucky, G. D. Chem. Mater. 2000,
12, 275.
8. Chen, J.; Zhang, Q.; Wang, Y.; Wan, H. Adv. Synth. Catal.
2008, 350, 453.
32. Layek, K.; Maheswaran, H.; Arundhathi, R.; Lakshmi-
Kantam, M.; Bhargavab, S. K. Adv. Synth. Catal. 2011, 353,
606.
9. Ma, Z.; Yang, H.; Qin, Y.; Hao, Y.; Li, G. J. Mol. Catal. A:
Chem. 2010, 331, 78.
10. Hou, Y.; Ji, X.; Liu, G.; Tang, J.; Zheng, J.; Liu,Y.; Zhang,
W.; Jia, M. Catal. Commun. 2009, 10, 1459.
11. Alizadeh, A.; Khodaei, M. M.; Kordestania, D.; Beygzadeh,
33. Mori, K.; Hara, T.; Mizugaki, Tomoo.; Ebitani, K.; Kaneda,
K. J. Am.Chem. Soc. 2004, 126, 10657.
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© 2014 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim J. Chin. Chem. Soc. 2014, 61, 1039-1044