The oxidation of benzothiophene using the Keggin-type lacunary polytungstophosphate as catalysts in emulsion

Article abstract of DOI:10.1016/j.molcata.2010.08.021

A series of emulsion catalysts were successfully synthesized with quarternary ammonium cations and heteropolyanions, and they were characterized by TG/DTA, FTIR, ³¹P MAS NMR and EPR. The emulsion catalyst with intact Keggin-structure, [C₁₈H₃₇N(CH₃) ₃]H₂[PW₁₂O₄₀] (PW₁₂), is inactive for benzothiophene (BT) oxidation with H₂O₂ as oxidant under atmospheric pressure at 30 °C. Moreover, the metal-substituted catalysts PW₁₁M (M = Ti, Mn, Fe, Co, Ni and Cu) show rather low activity with the conversion less than 15% for BT oxidation. Whereas, the catalyst with mono-lacunary Keggin-structures, [C₁₈H ₃₇N(CH₃)₃]₅Na₂[PW ₁₁O₃₉] (PW₁₁), could completely catalytic oxidize BT into the corresponding sulfone under the same conditions. After careful characterizations of the catalysts, it is found that only PW ₁₁ catalyst could effectively transform into the active polyperoxometalates species in the presence of hydrogen peroxide in non-polar solvent.

Full text of DOI:10.1016/j.molcata.2010.08.021

Journal of Molecular Catalysis A: Chemical 332 (2010) 59–64
Contents lists available at ScienceDirect
Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
The oxidation of benzothiophene using the Keggin-type lacunary
polytungstophosphate as catalysts in emulsion
a
b
a
a
a
a
Yongna Zhang , Hongying Lü , Lu Wang , Yuliang Zhang , Peng Liu , Hongxian Han ,
a,∗,1
a,∗,1
Zongxuan Jiang
, Can Li
a
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
Science and Engineering College of Chemistry and Biology, Yantai University, Yantai 264005, China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 15 July 2010
Received in revised form 26 August 2010
Accepted 26 August 2010
Available online 12 October 2010
A series of emulsion catalysts were successfully synthesized with quarternary ammonium cations and
heteropolyanions, and they were characterized by TG/DTA, FTIR, P MAS NMR and EPR. The emulsion
31
catalyst with intact Keggin-structure, [C18H37N(CH3)3]H2[PW12O40] (PW12), is inactive for benzoth-
◦
iophene (BT) oxidation with H2O2 as oxidant under atmospheric pressure at 30 C. Moreover, the
metal-substituted catalysts PW11M (M = Ti, Mn, Fe, Co, Ni and Cu) show rather low activity with the
conversion less than 15% for BT oxidation. Whereas, the catalyst with mono-lacunary Keggin-structures,
Keywords:
Lacunary
Polyoxotungstates
Benzothiophene oxidation
Transition metal
[C18H37N(CH3)3]5Na2[PW11O39] (PW11), could completely catalytic oxidize BT into the corresponding
sulfone under the same conditions. After careful characterizations of the catalysts, it is found that only
PW11 catalyst could effectively transform into the active polyperoxometalates species in the presence of
hydrogen peroxide in non-polar solvent.
©
2010 Elsevier B.V. All rights reserved.
1
. Introduction
Polyoxometalates (POMs) have been attracting much attention
in the fields of acid and oxidation catalysis, because the acidic
and redox properties of POMs can be designed and tuned at the
molecular or atomic level [18–26]. POMs can be used as effec-
tive catalysts for benign oxidations of hydrocarbons with oxidants
SOx produced from the burning of organic sulfur-containing
compounds present in fuel oils not only can cause acid rain, air
pollution, and harmfulness to human health, but also can poi-
son irreversibly the three-way catalysts in the tail gas cleanup
systems of engines. Therefore, ultra-deep desulfurization of fuel
oils has been attracting researchers’ attention and becomes one
of the most challenging subjects for petroleum refining indus-
try. Conventional hydrodesulfurization (HDS) is highly efficient in
removing thiols, sulfides, and disulfides [1,2]. However, the cap-
ital investment and operating costs of HDS are both rather high
due to more severe operating conditions to achieve the ultra-deep
desulfurization [3–6]. As an alternative to the other desulfuriza-
tion processes, oxidative desulfurization (ODS) [7–10] has stolen
the limelight owing to its advantages like mild reaction conditions,
being considered one of the most promising ultra-deep desulfur-
ization processes. In this process, sulfur-containing compounds in
such as H O2 or even O2 [19–24]. For example, tungsten-based
2
POMs have been demonstrated to be effective for the oxidation
of olefins, alcohols, glycols, and phenols using H O2 as oxidants
2
[27–36].
In recent years, POMs, such as a quaternary ammonium poly-
tungstophosphate catalyst assembled at the interface of the emul-
sion droplets, have been used for the oxidation of sulfur-containing
compounds presented in fuel oils [37–40]. In our previous work
[41,42], we reported two catalysts, [(C18H37) N(CH ) ] [PW12O40
]
2
3 2 3
and [C18H37N(CH ) ] [H NaPW10O36], assembled in an emulsion
3
3
4
2
system. The former catalyst could selectively catalyze oxidation
reaction of dibenzothiophene (DBT) and its derivatives into their
corresponding sulfones under mild conditions with H O2 as oxi-
2
fuels are oxidized with H O2 using zeolitic titanosilicates [11–14],
dant. The latter catalyst could catalytically oxidize benzothiophene
(BT), which has much lower reactivity than DBT, to the correspond-
ing sulfone. This work developed another quarternary ammonium
polytungstophosphate [C18H37N(CH ) ]5Na [PW11O39] with lacu-
2
ionic liquids [15], or metal oxide catalysts [16,17]. Developing ultra-
deep desulfurization catalysts with high activity has been one of the
most challenging and important subjects.
3
3
2
nary Keggin-structures, which could be used for oxidative
desulfurization in emulsion system. It was found that the cata-
lyst exhibit high catalytic activity toward the oxidation of BT under
mild conditions; however, the catalytic activity decreased consid-
erably when its lacunary sites were coordinated with the transition
∗ Corresponding authors. Tel.: +86 411 84379070; fax: +86 411 84694447.
E-mail addresses: zxjiang@dicp.ac.cn (Z. Jiang), canli@dicp.ac.cn (C. Li).
1
URL: http://www.canli.dicp.ac.cn.
1
381-1169/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.molcata.2010.08.021

6
0
Y. Zhang et al. / Journal of Molecular Catalysis A: Chemical 332 (2010) 59–64
metal cations. It is implied that the mono-lacunary POMs could be
propitious to the oxidation of BT.
2.3. Catalytic activity test
A typical procedure of the catalytic activity test is as follows:
certain amount of BT was dissolved in a solution of decalin (25 mL)
at 30 C to quantify the sulfur content to be 1000 ppm. The catalysts
2
2
2
. Experimental
◦
(PW11 or metal-coordinated PW11M) (0.015 mmol) and oxidant
.1. Preparation of catalysts
H O (0.27 mL, 30 wt%) were added to the above BT solution
2
2
simultaneously with a magnetic stirring at a speed of 1000 rpm.
Immediate formation of turbid W/O emulsion was observed. To
follow the reaction, the emulsion was sampled at a time interval
of 1 h and stored in an icebox in order to quench the reaction. The
catalyst in the sampled emulsion was separated from the emulsion
phase by centrifugation. The content of BT in oil was determined
by gas chromatography coupled with flame photometric detec-
tor (GC-FPD, Agilent 6890N equipped with a capillary column
.1.1. [C18H37N(CH ) ]5Na [PW11O39] (abbreviated as: PW11
)
3
3
2
This compound was prepared consulting the synthesis of
TBA] H [PW11O39] in the literature [43–45]. It is a direct synthesis
[
4
3
process, which is starting from an aqueous solution of the required
anion, to which was added a solution of octadecyltrimethylammo-
nium chloride instead of TBA bromide. And the simple process is
as following: sodium tungstate dehydrate (3.3 g), and disodium
hydrogen phosphate (0.33 g) were dissolved in distilled water
[
PONA, 50 m × 0.2 mm i.d. × 0.5 ␮m]; FPD: Agilent H9261) under
(
80 mL), followed by adjusting pH to 4.8 with 1 M HNO3 solution.
◦
the following analytical conditions: injection port temperature,
2
The reaction mixture was then warmed up to 80 C and a solution of
octadecyltrimethylammonium chloride (1.6 g) dissolved in alcohol
◦ ◦ ◦
80 C; detector temperature, 250 C; oven temperature, 280 C;
split ratio, 1/100; carrier gas, ultra-purity nitrogen with column
flow of 0.8 mL/min; reagent gases, air and hydrogen with air flow of
100 mL/min and hydrogen flow of 85 mL/min; the injection volume
of sample was 1 ␮L.
(
20 mL) was added dropwise. A white precipitate was immediately
formed. After continuous stirring for several minutes, the resulting
mixture was filtered and dried at 60 C in vacuum for 12 h to obtain
PW11
◦
.
The synthesis procedure of PW11M (M = Ti, Mn, Fe, Co, Ni and
Cu) are quite similar as in the literature [43]. And here is the typical
process: sodium tungstate dehydrate (3.3 g), disodium hydrogen
phosphate (0.33 g) and cupric nitrate (0.22 g) were dissolved in dis-
tilled water (80 mL), followed by adjusting pH to 4.8 with 1 M HNO3
3. Results and discussion
3.1. Characterization of catalysts
◦
solution. The reaction mixture was then warmed up to 80 C and
In the curves of TG–DTA (Fig. 1), a distinct two-step weight loss
process was observed for PW11, with an inflexion at 443 C. The
◦
a solution of octadecyltrimethylammonium chloride (1.6 g) dis-
solved in alcohol (20 mL) was added dropwise. A kind of white
precipitate was immediately formed. After continuous stirring for
first weight loss of 34.9% observed in the temperature range from
◦
161 to 443 C, was due to the decomposition of the alkyl chains
several minutes, the resulting mixture was filtered and dried at
of quaternary ammonium cations. The molar ratio of quaternary
ammonium cations to heteropolyanions is 4.6:1. And the molar
ratio of Na/P is determined to be 1.8:1.1 by XRF. According to the
results of elemental analysis, the amount of C, H, and N are found
to be 30.94%, 5.95%, and 1.52%, respectively. These results indicate
that the molecular formula of the catalyst is mainly composed of
◦
6
0 C in vacuum for 24 h to obtain PW11Cu. Accordingly, PW11
M
(
M = Ti, Mn, Fe, Co and Ni) samples were also synthesized following
the above procedures by using the proper content of the corre-
sponding nitrate or sulfate salts.
[
C18H37N(CH ) ]5Na [PW11O39], for which the amount of C, H, and
2
.1.2. [C18H37N(CH ) ]H [PW12O40] (abbreviated as: PW12
A solution of octadecyltrimethylammonium chloride (0.35 g) in
0 mL of alcohol was added dropwise into 80 mL aqueous solution
)
3 3 2
3
3
2
N are calculated to be 29.41%, 5.37%, and 1.63%, respectively.
Fig. 2 shows the FTIR spectra of PW12, PW11, and PW11M (M = Ti,
Mn, Fe, Co, Ni and Cu). The IR bands in the range of 700–1100 cm
2
−
1
of H PW12O40 (2.9 g) under stirring at room temperature. A white
3
are due to the contributions from the vibrations of P–O in the
central PO4 unit, W O, and W–O–W [46–48]. The detailed vibra-
tions assignments of PW12, PW11, and PW11Cu are summarized
in Table 1. The spectra of PW exhibit the characteristic bands
precipitate was immediately formed. After continuously stirring
for several minutes, the resulting mixture was filtered and dried at
◦
6
0 C in vacuum for 24 h to obtain PW12
.
12
3−
−1
of [PW12O40
]
anion, and the distinct band at ca. 1080 cm due
2.2. Characterization of catalysts
X-ray fluorescence (XRF) was performed with a Panalytical
Magix spectrometer to determine the Na/P molar ratio. Elemental
analysis was performed on a PE2400 CHN elemental analyzer. Ther-
mogravimetric and differential thermal analyses (TG–DTA) were
performed using a Pyris Diamond TG/DTA thermal analyzer under
a flowing air atmosphere. Transmission IR spectra were recorded
−1
from 32 scans with a resolution of 4 cm using a KBr method by
a Nicolet 470 Fourier transform infrared (FTIR) spectrometer. The
high-power proton decoupling 31P MAS NMR spectra were per-
formed on a Bruker DRX 400 spectrometer operating at 161.8 MHz
with a BBO MAS probe-head using 4-mm ZrO2 rotors spun at
1
2
0 kHz. The recording parameters were set to be 2.0 ␮s pulse,
s repetition time, and 2048 scans. The 31P chemical shift was
normalized with 85% H PO4 aqueous solution. X-band Electron
3
Paramagnetic Resonance (EPR) spectra were recorded on a Bruker
A-2000 X-band EPR spectrometer at 293 K. A microwave frequency
of 9.40 GHz and a power of 20 mW were used. The spectra were
calibrated with diphenylpicrylhydrazyl (DPPH: g = 2.0036).
Fig. 1. TG–DTA curves of PW11.

Y. Zhang et al. / Journal of Molecular Catalysis A: Chemical 332 (2010) 59–64
61
Table 1
IR bands assignments of POM and Cu coordinated POM catalysts.
Wavenumbers (cm 1
−
)
Catalysts
ꢀ
as(P–O)
ꢀas(W Ot)
ꢀas(W–Oc–W)
ꢀas(W–Oe–W)
ꢀas(W–O–[Cu])
PW11
PW11Cu
PW12
1078, 1045, 1035
1101, 1061
1080
945
953
978
891, 854
881
897
800
816, 797
808
762, 727
748, 696
–
ꢀ
as: asymmetric stretching vibration; Ot: terminal oxygen; Oc: oxygen atoms connecting the corner-sharing WO6 octahedra; Oe: oxygen atoms connecting the edge-sharing
WO6 octahedra.
to the vibration of the central PO4 tetrahedron. As the symmetry
decrease of the PO tetrahedron in the structure of PW11, this band
4
is blue shifted and split into mainly two components, one with a
−1
peak maximum at 1078 cm and the other with a double band
−1
at 1045 and 1035 cm , respectively. These FTIR observations are
consistent with the reports in the literature [46–48], indicating that
the structures of the primary heteropoly tungstophosphate anions
remain intact after assembling with the quaternary ammonium
cations (see Scheme 1). The IR spectra of PW11Cu (Fig. 2) display
−1
one absorption band at 881 cm , which belong to the vibration of
W–Oc–W. This implies that the filling of the vacant in the octahedral
lacunae by Cu cations restores the symmetry of the central tetra-
hedron to some extent owing to the interaction between Cu2+ and
the available oxygen anions of the central PO4 group. At the same
time, all of the copper-coordinated catalysts and the lacunary cat-
−
1
alyst PW11 show that the band around about 800 cm is split into
one broad band and two weak bands, which is an indication that the
symmetry of the octahedron of WO is distorted. Except a little blue
6
1
−
shift in the range of 700–1000 cm , the FTIR spectra of PW11Cu are
in well agreement with that of H PW12O40, which has a complete
3
Keggin-structure. Similar phenomenon was also observed for the
PW11M sample treated by various other transition metals (M = Ti,
Mn, Fe, Co, Ni, or Cu) (Fig. 2). Therefore, the FTIR spectroscopic study
strongly implies that the metal ions should be coordinated with the
lacunae of the Keggin-type structured samples.
The X-band EPR spectra (293 K) of PW11 and PW11Cu are shown
in Fig. 3. The calculated g values are gꢀ = 2.408 and g⊥ = 2.096 for
PW Cu, respectively, which are in well agreement with the reports
11
in the literature [49]. The special four weak hyperfine line splittings
Scheme 1. The amphiphilic catalyst PW11 assembled at the interface of the emul-
sion droplet (O atom at the vertex of octahedron, W atom in the center of octahedron
and P atom in the center of tetrahedron).
Fig. 2. FTIR spectra of PW12, PW11, and PW11M (M = Ti, Mn, Fe, Co, Ni and Cu) for
comparison.

6
2
Y. Zhang et al. / Journal of Molecular Catalysis A: Chemical 332 (2010) 59–64
Fig. 3. X-band EPR spectra (293 K) of the catalysts: PW11Cu and PW11.
Fig. 5. 31P MAS NMR spectra of the catalyst PW11Cu–EDTA.
with splitting constant of ca. 90 G in the EPR spectra of PW11Cu
Fig. 3) reveal that copper cations are located in a tetragonally
(
distorted octahedral crystal field and surrounded by less than six
ligands (gꢀ =/ g⊥) [50]. And the coordination form of copper is pos-
sibly a square-pyramidal belonging to five-coordinate copper(II)
complexes (gꢀ > g⊥) [51].
quency as compared with that of PW11 (ı = −10.2 ppm), and near
to that of the intact Keggin-type PW12, which is much more sta-
ble than the lacunary Keggin-type PW11. It is indicated that the
incorporation of Cu possibly make the structure of PW11 to be
more stable and rigid [53], which is even in agreement with the
result of the IR blue shift. What is more, P MAS NMR study also
demonstrates that the structure of the PW11 cluster tend to be satu-
rated after being coordinated by Cu cations, probably by the strong
The catalyst PW is also characterized by 31P MAS NMR (Fig. 4)
1
1
to confirm the structure. The peak at −10.2 ppm in Fig. 4 (in the
31
middle) is due to the resonance of the central PO4 unit of PW
11
cluster, which is quite different from the chemical shift of PW12
at −15.1 ppm. As shown in Fig. 4 (at the bottom), it is interesting
chemical interactions between copper and PW11
.2. Catalytic reactions
The reaction activity data (Table 2) indicate the catalyst PW12
.
that no P species signal was found in the 31P MAS NMR spectra of
PW11Cu, which may be resulted from the interaction of free copper
3
31
cations to magnetic field. The further evidence is the P MAS NMR
spectrum of PW11Cu–EDTA. After treatment by EDTA, two new sig-
3
1
nals appear in the P MAS NMR spectrum of PW11Cu–EDTA. As
is inactive for the BT oxidation under the mild reaction con-
ditions. The metal-substituted Keggin-type emulsion catalysts,
PW11M (M = Ti, Mn, Fe, Co, Ni and Cu), behave very much
poor activity. However, under the same experimental conditions,
the oxidation conversion of BT catalyzed by PW11 is 98%. The
amphiphilic catalyst PW11 shows remarkably high activity toward
BT oxidation in the emulsion catalytic systems. Peroxo-POMs
have been proved to be the active intermediates in many reac-
shown in Fig. 5, the peaks at −12.8 ppm and −15.6 ppm are origi-
nated from the central PO unit of PW Cu cluster and byproduct
4
11
3−
fragment of [PW12O40
]
[44,52], respectively. It should be also
noted that the resonance of PW11Cu is shifted toward low fre-
3
−
tions. The {PO [WO(O ) ] } , one of the most active POMs for
4
2 2 4
H O -based oxidations, is the real active species in the Keggin-
2
2
type H PW12O40/H O system [30,31]. It was established that
3
2
2
3−
3−
and [PW11O39] , which can rapidly convert into
[
PW12O40
]
3−
polyperoxometalate {PO [WO(O ) ] } , are the effective species
4
2 2 4
Table 2
Conversions of BT oxidation on the various polyoxotungstate catalysts.
Catalyst
Conversion (%)
PW11
PW12
98
0
PW11Ti
PW11Mn
PW11Fe
PW11Co
PW11Ni
PW11Cu
14
1
13
3
1
3
Fig. 4. 31P MAS NMR spectra of the catalysts: PW12, PW11, and PW11Cu.
Reaction conditions: T = 30 C, BT (S: 1000 ppm) in decalin, H2O2/BT = 3, 1 h.
◦

Y. Zhang et al. / Journal of Molecular Catalysis A: Chemical 332 (2010) 59–64
63
Fig. 6. Conversion of BT catalyzed by PW11 + Cu (Cu/P = 0, 0.1, 0.3, 0.6, 1), PW11Cu
and PW11Cu–EDTA, respectively. Reaction conditions: T = 30 C, BT (S: 1000 ppm) in
Fig. 7. FTIR spectra of PW11Cu–EDTA.
◦
decalin, H2O2/BT = 3.
rate was quite high, it became quite slow after 2 h. The concen-
tration of hydrogen peroxide solution is determined by cerous
for the epoxidation of the terminal alkenes [31]. In addition, a
peroxotungstate complex has been shown to be the active oxidiz-
ing species. Rui Zhang’s group [54] has reported that a tungsten
peroxo complex rather than a high valent transition–metal oxo
species operates as the key intermediate in the sandwich-type
POM-catalyzed epoxidations of chiral allylic alcohols. The similar
phenomenon may be in the present reaction system with PW11
as catalyst (see more evidences and results in the correspond-
ing Supplementary material). The amphiphilic catalysts PW12 and
PW11 are assembled at the interface of the emulsion droplets (as
shown in Scheme 1). Furthermore, decalin is non-polar solvent,
of which the character is quite different from polar solvent used
in the reported oxidation system [31], and the amphiphilic cata-
lyst PW11 could much more rapidly form polyperoxometalate than
that PW12 do in the H O -based oxidation system. On the other
sulfate titration method, and the results are listed in Table 3. The
◦
decomposition conversion of H O2 at 30 C in 1 h is only 8.1% in
2
the presence of PW11, but is 50.0% and 60.7% in the presence of
PW11Cu and PW11 + Cu, respectively. Treatment of PW11Cu with
EDTA can significantly inhibit the decomposition conversion of
H O , as evidenced by the only 1.5% H O decomposition in 1 h
2
2
2
2
in the presence of PW11Cu–EDTA. In the meantime, the conver-
sion of BT in 1 h is 15.1% by PW11Cu–EDTA, which is much higher
than 0.7% by PW11Cu. These results indicate that a proportion of
copper cations weakly interacts with the catalysts and can be eas-
ily removed from the PW11 catalyst by the treatment with EDTA.
Moreover, these copper cations could accelerate the decomposition
of hydrogen peroxide, leading to the insufficient oxidant for BT oxi-
dation to proceed. However, the catalytic activity of PW11Cu–EDTA
was still much lower than that of PW11 under the same experi-
mental conditions, indicating that treatment with EDTA can only
remove copper cations weakly bounded with PW11, but those cop-
per cations, which have strong interactions with PW11, remain
therein. Therefore, the low catalytic activity is due to not only the
2
2
hand, it is observed that the catalytic activity of PW11 can be largely
blocked by the coordination of transition metals (Ti, Mn, Fe, Co,
Ni and Cu) (see the results in Table 2). The reason is that PW11
M = Ti, Mn, Fe, Co, Ni and Cu) with the intact Keggin-structure could
M
(
not effectively transform into the active polyperoxometalate in the
presence of hydrogen peroxide. Furthermore, the reduction of the
catalytic activity may be related with the coordination capability
of the transition metals. Among these transition metals, coordina-
tion of manganese or nickel results in the lowest catalytic activity
due to the stronger interactions between the metals (manganese
side reaction of H O2 decomposition but also the transformation
2
of the intact Keggin-structure catalysts into active polyperoxomet-
alate being blocked by the metal cations (M = Ti, Mn, Fe, Co, Ni
and Cu) in the presence of hydrogen peroxide. This made us draw
a conclusion that the metals coordinating with the lacunary het-
eropolyanions lead the catalyst lose activity for the oxidation of
sulfur-containing compounds, such as BT.
or nickel) and the lacunae of PW11
.
In order to investigate the effect of the free copper cation on the
catalytic activity of PW11 for BT oxidation, a certain amount of cop-
per salt was added into the reaction mixture. A visible decrease of
BT conversion is observed even if the Cu/P molar ratio was only 0.1,
as shown in Fig. 6. The conversion of BT was about 60% in 2 h when
Cu/P molar ratio was 1. However, the conversion of BT catalyzed
by PW11Cu was close to zero under the same reaction conditions.
In order to investigate the interaction between copper and het-
eropolyanions, PW11Cu was treated with 20-fold stoichiometry of
ethylene diamine tetraacetic acid (EDTA) as coordination reagent,
and the obtained sample is described as PW11Cu–EDTA. The IR
spectra of the structure of PW11Cu were nearly remained after
being treated by EDTA (Fig. 7). However, the catalytic activity of
PW11Cu–EDTA was significantly improved compared with that of
PW11Cu (Fig. 6). Conversion of BT catalyzed by PW11Cu–EDTA could
reach up to 94% in 9 h. When the catalyst PW11 was mixed with cop-
per nitrate (abbreviated as: PW11 + Cu), though the initial reaction
Table 3
H2O2 decomposition on PW11 catalysts in the presence of Cu cation.
Catalyst
Final
concentration
of H2O2 (wt%)
H2O2
decomposition
a
conversionb (%)
PW11
24.8
10.6
13.5
26.6
8.1
60.7
50.0
1.5
PW11 + Cuc
PW11Cu
d
PW11Cu–EDTA
◦
Reaction conditions: T = 30 C, decalin (25 mL), the initial concentration of H2O2
(
0.306 mL) is 27 wt%.
a
The concentration of H2O2 after 1 h.
H2O2 decomposition conversion after 1 h.
Cu/P (mol/mol) = 1.
b
c
d
PW11Cu after treating with EDTA.

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Y. Zhang et al. / Journal of Molecular Catalysis A: Chemical 332 (2010) 59–64
4
. Conclusion
[19] Y. Zhang, D.L. Li, Y. Chen, X.H. Wang, S.T. Wang, Appl. Catal. B: Environ. 86
2009) 182–189.
20] N. Mizuno, M. Misono, Chem. Rev. 98 (1998) 199–218.
21] O.A. Kholdeeva, G.M. Maksimov, R.I. Maksimovskaya, L.A. Kovaleva, M.A. Fedo-
tov, V.A. Grigoriev, C.L. Hill, Inorg. Chem. 39 (2000) 3828–3837.
(
[
[
Under mild conditions, mono-lacunary polyoxotungstates cat-
alyst PW11 shows high catalytic activity on the oxidation of BT in
emulsion. Once the lacunae are coordinated by the transition metal
cations, the catalysts will lose the catalytic activity. It is proved that
the well performance of these catalysts could be due to the mono-
lacunary Keggin-structures of the tungstophosphoric compounds,
which could rapidly transform into the active polyperoxometa-
late in the presence of hydrogen peroxide. And it is important
for ultra-deep desulfurization of fuel oil to further investigate
the reaction mechanism between lacunary polyoxotungstates and
sulfur-containing compounds.
[
[
22] I.V. Kozhevnikov, Chem. Rev. 98 (1998) 171–198.
23] X. Zhang, Q. Chen, D.C. Duncan, C.F. Campana, C.L. Hill, Inorg. Chem. 36 (1997)
4208–4215.
[24] J. Server-Carrió, J. Bas-Serra, M.E. González-Nú n˜ ez, A. García-Gastaldi, G.B.
Jameson, L.C.W. Baker, R. Acerete, J. Am. Chem. Soc. 121 (1999) 977–984.
[
[
25] N. Mizuno, T. Watanabe, M. Misono, J. Phys. Chem. 89 (1985) 80–85.
26] S. Yoshida, H. Niiyama, E. Echigoya, J. Phys. Chem. 86 (1982) 3150–3154.
[27] Y. Ishii, K. Yamawaki, T. Ura, H. Yamada, T. Yoshida, M. Ogawa, J. Org. Chem. 53
(1988) 3587–3593.
[28] C. Venturello, E. Alneri, M. Ricci, J. Org. Chem. 48 (1983) 3831–3833.
[29] C. Venturello, R. D’Aloisio, J.C.J. Bart, M. Ricci, J. Mol. Catal. 32 (1985) 107–110.
[30] C. Aubry, G. Chottard, N. Platzer, J.-M. Brégeault, R. Thouvenot, F. Chauveau, C.
Huet, H. Ledon, Inorg. Chem. 30 (1991) 4409–4415.
[
[
31] D.C. Duncan, R.C. Chambers, E. Hecht, C.L. Hill, J. Am. Chem. Soc. 117 (1995)
Acknowledgements
681–691.
32] K. Kamata, K. Yonehara, Y. Sumida, K. Yamaguchi, S. Hikichi, N. Mizuno, Science
300 (2003) 964–966.
33] K. Kamata, Y. Nakagawa, K. Yamaguchi, N. Mizuno, J. Catal. 224 (2004) 224–228.
34] K. Kamata, K. Yamaguchi, S. Hikichi, N. Mizuno, Adv. Synth. Catal. 345 (2003)
This work was supported by the National Natural Science Foun-
dation of China (NSFC Grant No. 20673114), and the State Key
Project of China (No. 2006CB202506).
[
[
1193–1196.
[
[
[
35] K. Kamata, K. Yamaguchi, N. Mizuno, Chem. Eur. J. 10 (2004) 4728–4734.
36] C. Venturello, M. Gambaro, J. Org. Chem. 56 (1991) 5924–5931.
37] C. Li, J.B. Gao, Z.X. Jiang, S.G. Wang, H.Y. Lü, Y.X. Yang, F. Jing, Topics Catal. 35
Appendix A. Supplementary data
(
2005) 169–175.
[38] D. Huang, Y.C. Lu, Y.J. Wang, G.S. Luo, Ind. Eng. Chem. Res. 46 (2007) 6221–6227.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.molcata.2010.08.021.
[
[
[
[
[
39] D. Huang, Z. Zhai, Y.C. Lu, L.M. Yang, G.S. Luo, Ind. Eng. Chem. Res. 46 (2007)
1447–1451.
40] D. Huang, Y.J. Wang, L.M. Yang, G.S. Luo, Ind. Eng. Chem. Res. 45 (2006)
1880–1885.
41] C. Li, Z.X. Jiang, J.B. Gao, Y.X. Yang, S.J. Wang, F.P. Tian, F.X. Sun, X.P. Sun, P.L.
Ying, C.R. Han, Chem. Eur. J. 10 (2004) 2277–2280.
References
[
[
[
[
[
1] C.S. Song, Catal. Today 86 (2003) 211–263.
42] H.Y. Lü, J.B. Gao, Z.X. Jiang, F. Jing, Y.X. Yang, G. Wang, C. Li, J. Catal. 239 (2006)
2] C.S. Song, X.L. Ma, Appl. Catal. B: Environ. 41 (2003) 207–238.
3] X.L. Ma, K.Y. Sakanishi, I. Mochida, Ind. Eng. Chem. Res. 33 (1994) 218–222.
4] U.T. Turaga, C.S. Song, Catal. Today 86 (2003) 129–140.
369–375.
43] M.M.Q. Simões, C.M.M. Concei c¸ ão, J.A.F. Gamelas, P.M.D.N. Domingues, A.M.V.
Cavaleiro, J.A.S. Cavaleiro, A.J.V. Ferrer-Correia, R.A.W. Johnstone, J. Mol. Catal.
A: Chem. 144 (1999) 461–468.
5] J.M. Manoli, P.D. Costa, M. Brun, M. Vrinat, F. Mauge, C. Potvin, J. Catal. 221
(
2004) 365–377.
[
[
[
[
44] I.V. Kozhevnikov, Catalysts for Fine Chemical Synthesis, V. 2: Catalysis by Poly-
oxometalates, John Wiley & Sons, Ltd., Chichester, England, 2002.
45] C.M. Tourni, G.F. Tourni, S.A. Malik, T.J.R. Weakley, J. Inorg. Nucl. Chem. 32
[
[
[
[
6] A. Niquille-Rothlisberger, R. Prins, Catal. Today 123 (2007) 198–207.
7] X.L. Ma, A.N. Zhou, C.S. Song, Catal. Today 123 (2007) 276–284.
8] P.S. Tam, J.R. Kittrell, J.W. Eldridge, Ind. Eng. Chem. Res. 29 (1990) 321–324.
9] F.M. Collins, A.R. Lucy, C. Sharp, J. Mol. Catal. A: Chem. 117 (1997) 397–403.
(
1970) 3875–3890.
46] L.G. Detttshe, M.A. Fedotav, L.I. Kuznetsova, A.A. Vlasov, V.A. Likhoiobov, Russ.
Chem. Bull. 46 (1997) 874–880.
47] N.I. Kuznetsova, L.G. Detusheva, L.I. Kuznetsova, M.A. Fedotov, V.A. Likholobov,
J. Mol. Catal. A: Chem. 114 (1996) 131–139.
[
[
10] F. Al-Shahrani, T.C. Xiao, S.A. Llewellyn, S. Barri, Z. Jiang, H.H. Shi, G. Martinie,
M.L.H. Green, Appl. Catal. B: Environ. 73 (2007) 311–316.
11] Ch.Z. Jin, G. Li, X.S. Wang, Y. Wang, L.X. Zhao, D.W. Sun, Micropor. Mesopor.
Mater. 111 (2008) 236–242.
[
[
48] R. Neumann, M. Dahan, Polyhedron 17 (1998) 3557–3564.
49] Y. Kim, H. Kim, J. Lee, K. Sim, Y. Han, H. Paik, Appl. Catal. A: Gen. 155 (1997)
[
[
[
12] L.Y. Kong, G. Li, X.S. Wang, Catal. Lett. 92 (2004) 163–167.
13] V. Hulea, F. Fajula, J. Bousquet, J. Catal. 198 (2001) 179–186.
14] S.F. Cheng, Y.M. Liu, J.B. Gao, L.L. Wang, X.L. Liu, G.H. Gao, P. Wu, M.Y. He, Chin.
J. Catal. 27 (2006) 547–549.
1
5–26.
50] R. Cousin, S. Capelle, E. Abi-Aad, D. Courcot, A. Aboukaïs, Chem. Mater. 13 (2001)
862–3870.
51] A. Bencini, I. Bertini, D. Gatteschi, A. Scozzafava, Inorg. Chem. 17 (1978)
194–3197.
[
[
3
[
[
[
[
15] L. Lu, S.F. Cheng, J.B. Gao, G.H. Gao, M.Y. He, Energy Fuels 21 (2007) 383–
3
84.
16] L. Cede n˜ o Caero, F. Jorge, A. Navarro, A. Gutiérrez-Alejandre, Catal. Today 116
2006) 562–568.
3
[
[
[
52] P.J. Domaille, G. Watunya, Inorg. Chem. 25 (1986) 1239–1242.
53] A. Mazeaud, Y. Dromzee, R. Thouvenot, Inorg. Chem. 39 (2000) 4735–4740.
54] W. Adam, P.L. Alsters, R. Neumann, C.R. Saha-Möller, D. Sloboda-Rozner, R.
Zhang, J. Org. Chem. 68 (2003) 1721–1728.
(
17] L. Cede n˜ o-Caero, H. Gomez-Bernal, A. Fraustro-Cuevas, H.D. Guerra-Gomez, R.
Cuevas-Garcia, Catal. Today 133 (2008) 244–254.
18] N. Mizuno, K. Yamaguchi, K. Kamata, Coord. Chem. Rev. 249 (2005) 1944–1956.