Liquid phase oxidation of diphenylmethane to benzophenone with molecular oxygen over nano-sized Co-Mn catalyst supported on calcined Cow bone

Article abstract of DOI:10.1016/j.molcata.2013.11.019

A well-dispersed Co-Mn catalyst immobilized on calcined Cow bone was synthesized and used, for the first time for the selective synthesis of benzophenone by liquid phase oxidation of diphenylmethane under various reaction conditions. The catalyst was characterized using techniques such as UV-vis, SEM, TEM and BET. The catalyst has shown an excellent activity (87%), selectivity to diphenyl ketone (90%) and stability under solvent free conditions. To investigate the leaching of the metals from the support, results of the original and reusable catalyst was correlated and compared, and the catalytic activity of washed catalyst was also demonstrated. Based on the all catalytic results for this reaction, the new catalyst was found to be a highly active and environmentally friendly solid catalyst and has superior catalytic activity.

Full text of DOI:10.1016/j.molcata.2013.11.019

Journal of Molecular Catalysis A: Chemical 383–384 (2014) 58–63
Contents lists available at ScienceDirect
Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
Liquid phase oxidation of diphenylmethane to benzophenone with
molecular oxygen over nano-sized Co–Mn catalyst supported on
calcined Cow bone
B.H. Monjezi, M.E. Yazdani, M. Mokfi, M. Ghiaci∗
Department of Chemistry, Isfahan University of Technology, 8415683111 Isfahan, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
A well-dispersed Co–Mn catalyst immobilized on calcined Cow bone was synthesized and used, for the
first time for the selective synthesis of benzophenone by liquid phase oxidation of diphenylmethane
under various reaction conditions. The catalyst was characterized using techniques such as UV–vis, SEM,
TEM and BET. The catalyst has shown an excellent activity (87%), selectivity to diphenyl ketone (90%) and
stability under solvent free conditions. To investigate the leaching of the metals from the support, results
of the original and reusable catalyst was correlated and compared, and the catalytic activity of washed
catalyst was also demonstrated. Based on the all catalytic results for this reaction, the new catalyst was
found to be a highly active and environmentally friendly solid catalyst and has superior catalytic activity.
Received 17 September 2013
Received in revised form
11 November 2013
Accepted 14 November 2013
Available online 26 November 2013
Keywords:
Cobalt
Manganese
Cow bone
© 2013 Elsevier B.V. All rights reserved.
Benzophenone
Diphenylmethane
1. Introduction
by the reaction of benzene with carbon tetrachloride followed by
hydrolysis of the resulting diphenyldichloromethane and the oxi-
Oxidation is one of the most fundamental transformations in
organic chemistry and selective oxidation of diphenylmethane
(DPM) to benzophenone is an industrially important synthetic
process. Benzylic oxidation is the foundation of many current
important industrial and fine-chemical processes, as the prod-
uct benzophenone is known as a component of many consumer
products. Benzophenone is primarily used as a photo initiator and
fragrance enhancer. It is also used as an ultraviolet curing agent in
sunglasses and ultraviolet curable ink. It is also used as an ultra-
violet absorber, to block UV-B, UV-A and UV-C radiation, perfume
fixative in soaps, flavor ingredient, and polymerization inhibitor for
styrene, additive for plastics, coatings and adhesive formulations, in
the manufacture of insecticides, agricultural chemicals, hypnotics,
antihistamines, and other pharmaceuticals.
It is usually synthesized by the Friedel–Crafts acylation of ben-
zene with benzoyl chloride in the presence of AlCl3. Other processes
for the production of benzophenone contain atmospheric oxidation
of diphenymethane and decarboxylation of o-benzoylbenzoic acid
over copper catalysts [1], and oxidation of diphenylmethane using
stoichiometric quantities of oxidizing agents like KMnO4 [2], SeO2
[3] or CrO3–SiO2 [4]. Alternatively, benzophenone is also produced
dation of DPM in the presence of chromic acid and nitric acid [5].
In the above processes, a large amount of waste produced and
the usage of stoichiometric amount of catalyst makes the process
unacceptable. Also difficult operational problems such as corrosion,
the usage of large amounts of catalyst, separation and recovery,
deactivation via the aggregation of metal nanoparticles formed
in situ during the reaction, disposal of used catalyst, high toxicity,
and catalyst removal from the product are other drawbacks.
Homogeneous catalysts are most active catalysts, with many
attractive properties such as high chemo- and regioselectivity and
high activities. In order to overcome the difficulties of a homoge-
neous system, the development and utilization of a solid catalyst is
important. Recently there has been increased interest in the devel-
opment of processes mediated by heterogeneous catalysts [6–8]
that is one of the best options to overcome these drawbacks. They
have excellent stability, are easily accessible, and most importantly,
they can be easily separable from the reaction mixture. However,
they do have some drawbacks, first, inferior catalytic performance
relative to their homogeneous counterparts, because of reduced
contacts between catalyst and substrates and second drawback is
the use of filtration to isolate the catalyst from reaction mixture,
which reduces the efficiency of the system at each cycle. Clark
et al. [9] reported the first heterogeneous oxidation of diphenyl-
methane to benzophenone over alumina supported chromium and
manganese.
∗
Corresponding author. Tel.: +98 3113913254; fax: +98 3113912350.
E-mail addresses: mghiaci@cc.iut.ac.ir, mehranghiaci@gmail.com (M. Ghiaci).
1381-1169/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molcata.2013.11.019

B.H. Monjezi et al. / Journal of Molecular Catalysis A: Chemical 383–384 (2014) 58–63
59
Nanoparticles show very interesting and useful properties in
comparison with bulk materials and they have more application
and efficiency than micro-scale materials. Nano-catalysis can be
considered as a bridge between homogeneous and heterogeneous
catalysis. Because of nano-size, i.e., high surface area, the contact
between reactants and catalyst increases dramatically and they can
operate in the same manner as homogeneous catalysts, at the same
time, due to their insolubility in the reaction media, they can be
separated out easily from the reaction mixture.
In the last two decades, for selective oxidation of diphenyl-
methane different research groups have used heterogeneous
catalysts such as KMnO4 impregnated on alumina [10], KMnO4
supported on montmorillonite K10 [11], cobalt substituted silicate
xerogel and N-hydroxyphthalimide-acridine yellow-Br2 system
[12,13], manganese(III) Schiff base complex [14], metal incorpo-
rated molecular sieves (M-MCM-41 where M is Ti, V, Cr) [15], cobalt
doped mesoporous TiO2 (Co/MTiO2) [16,17], Mn–Mg–Al [18],
Ru–Co–Al [19], and more recently cobalt porphyrin on CeO2@SiO2
[20], CrSBA-15 [21]. Probably to prepare most of the reported cat-
alysts, one should spend a lot of time and efforts, and even uses
expensive raw materials. More importantly, for selective oxidation
of diphenylmethane, most of these catalysts are not environmental
friendly catalysts.
Particle size and morphology were evaluated from the transmis-
sion electron microscopy (TEM) images obtained in a JEM 2100F
microscope operated with an accelerating voltage of 200 kV. The
standard procedure involved dispersing 4 mg of the sample in
ethanol in an ultrasonic bath for 15 min. The sample was then
placed on a Cu carbon grid where the liquid phase was evaporated.
BET surface area and pore size distribution were measured on a
Micromeritics Digisorb 2600 system at −196 ◦C using N2 as adsor-
bate. Before measurements, the samples were degassed at 450 ◦C
for 3 h under vacuum (0.1333 Pa).
2.1. Preparation of the bone supported catalyst by osmosis
method
In the first step, 450 mL aqueous solution of Co(NO3)2·6H2O
(0.01 M) was added to 50 mL of an aqueous solution of
Mn(NO3)2·6H2O (0.01 M). Co/Mn molar ratio was 10:1 in the resul-
tant solution. Pieces of Cow bone were cleaned, piecemealed and
were put into the resultant solution for a period of one week. After
one week, the pieces of the bone were extracted from the solution.
We expected that cobalt and manganese were loaded on the sup-
port. Attained sample was dried at 100 ◦C, and finally calcined at
700 ◦C for 24 h (Co/Mn-BSO0.01).
Bone inorganic composition is formed from carbonated
hydroxyapatite. Hydroxyapatite (HAP) is a phosphate mineral that
having stability, and because of its high adsorption capacity has
intrigued much attention as support for transition metal catalysts
in various reactions. Structure of pure hydroxyapatite is very simi-
lar to hydroxyapatite of bone but there are tiny differences between
those due to presence of other ions such as iron in structure of bone
hydroxyapatite. In continuation of our research in the field of mod-
ifying solid supports and exploring new supports [22], in this work
we have synthesized a heterogeneous hybrid Co/Mn nano catalyst
on a cheap support, i.e., calcined bone and used it for preparation of
benzophenone by liquid-phase oxidation of diphenylmethane with
oxygen as the greenest oxidant. The oxidation of diphenylmethane
has been carried out in different conditions by monitoring param-
eters such as time, temperature, amount of catalyst, pressure of
oxygen gas, and reusability.
2.2. Catalytic experiments
According to the optimized reaction conditions, the appropri-
ate amount of diphenylmethane, and solid catalyst were added to
a titanium batch reactor. The correct pressure was provided with
oxygen (99.98%) and the desired temperature selected. After the
reaction, the reactor was cooled to room temperature and the mass
balances were calculated from the weights of the reaction mixture
before and after the reaction. In the next step, the solid precipitate
which mainly consists of catalyst was separated by centrifugation.
After addition of n-decane as internal standard to the organic phase,
the reaction mixture was analyzed by GC and the products were
identified by GC–MS.
3. Results and discussion
3.1. Characterization of the catalyst
2. Experimental
3.1.1. The Co/Mn immobilized on the Cow bone
The reactor and procedures have been previously described [23].
The source of chemicals is Merck chemical company. The cobalt and
manganese salts were the (+II) nitrate hexahydrates.
A BEIFEN 3420 gas chromatograph equipped with a FID detec-
tor was used to identify the reaction products. The column was a
30 m HP-FFAP with 0.32 mm i.d. and 0.5 ␮m film thickness. The ini-
tial temperature was 170 ◦C for 5 min. The GC was then ramped at
10 ◦C/min to 280 ◦C, and hold for 1 min at that temperature. The
products of the oxidation of diphenylmethane were identified by
GC/MS (Fisons Instruments 8060, USA).
In our previous work [22], we have characterized this catalyst
which has been prepared by immobilizing cobalt and manganese
over calcined bone by osmosis method, and used for oxidation of
2,6-diisopropylnaphthalene.
Nitrogen adsorption–desorption isotherm of the Co/Mn-BSO0.01
catalyst is demonstrated in Fig. 1. According to IUPAC catego-
rization [24,25], the Co/Mn-BSO0.01 catalyst presented a typical
Type IIb nitrogen isotherm with H3 hysteresis loop. The observed
hysteresis loop between adsorption and desorption isotherms is
associated with differences in the rates of capillary condensation
and evaporation. Generally, Type IIb isotherms are obtained with
aggregates of plate-like particles, which therefore possess non-
rigid slit-shaped pores. Because of delayed capillary condensation,
multilayer adsorption is able to proceed on the particle surface until
a high p/po is reached. Once the condensation has occurred, the
state of the adsorbate is changed and desorption curve therefore
follows a different path until the condensate becomes unstable
at a critical p/po. The sharpness of the isotherm and the pres-
ence of hysteresis loop at P/P0 > 0.7 illustrates that the catalyst is
mostly mesoporous. At low relative pressure, nitrogen adsorption
and interaction between nitrogen and partition pores of the cata-
lyst were low. Adsorption of N2 increases sharply under the high
relative pressure because of the capillary condensation within the
Scanning electron micrographs were obtained using
a
Cambridge Oxford 7060 Scanning Electron Microscope (SEM)
connected to a four-quadrant back scattered electron detector
with resolution of 1.38 eV. The samples were dusted on a double
sided carbon tape placed on a metal stub and coated with a layer
of gold to minimize charging effects.
A high-resolution Hitachi S4160 field emission scanning elec-
tron microscope equipped with an EDX system was utilized in the
scanning electron microscopy (SEM/EDS) measurements. The sup-
ported catalyst sample was conserved under nitrogen atmosphere.
The microstructure and surface morphology of the supported cat-
alysts were characterized by scanning electron microscopy (SEM)
method.

60
B.H. Monjezi et al. / Journal of Molecular Catalysis A: Chemical 383–384 (2014) 58–63
Fig. 2. XRD pattern of (a) calcined bone hydroxyapatite and (b) Co/Mn-BSO0.01
nanocatalyst.
3.1.2. XRD data
Fig. 1. Adsorption/desorption isotherm of the Co/Mn-BSO0.01 nanocatalyst.
Fig. 2 shows the powder X-ray diffraction patterns of calcined
bone (hydroxyapatite), and Co/Mn-BSO0.01 catalyst. Both pow-
der XRD patterns were very similar. Identification of the phases
was realized by comparing the experimental XRD pattern to stan-
dards compiled by the International Centre for Diffraction Data
(ICDD). Sharp peak intensity and well resolved peaks in XRD pat-
terns of the powders at high calcinations temperature proves
complete crystallization of the powder. It is clear that the main
phase of Co/Mn-BSO0.01 nano-catalyst is hydroxyapatite because
the amount of nano-catalyst is very low.
Table 1
Textural properties of the Co/Mn-BSO0.01 catalyst.
b
d
Sample
Co/Mna
10/1
SBET (m2 g−1
)
dBJH (nm)c
Vtot (cm3 g−1
)
Co/Mn-BSO0.01
2.8
3.3
0.63
a
Molar ratio of metal ions deduced from ICP-AES results.
Brunauer–Emmet–Teller (BET) surface area.
Pore diameter calculated by the Barrett–Joyner–Halenda (BJH) method utilizing
b
c
the adsorption branches.
d
Total pore volume calculated as the amount of nitrogen adsorbed at a relative
3.1.3. SEM and TEM images
pressure of 0.99.
The SEM micrographs of calcined bone powder (Fig. 3) were soft
agglomerated fine HAP particles. The image shows that the sample
is consisted of particles with diameter of 100–500 nm. SEM/EDX
mapping indicated a content of nano-particles throughout the cata-
lyst pores that these were related to Co and Mn. Representative TEM
images of the Co/MN-BSO0.01 catalyst are demonstrated in Fig. 4.
Formation of the Co and Mn nano-particles over bone support was
confirmed by TEM images. The average size of the nano-particles
was estimated to be 2–5 nm for the Co/Mn-BSO0.01 catalyst. The
cobalt and manganese contents of the bone and the supported cat-
alyst sample were determined by ICP-AES. The molar ratio of the
mesopores of the catalyst. In Table 1, the specific surface area (SBET),
total pore volume, and Barrett–Joyner–Halenda (BJH) desorption
average pore diameter of the catalyst are reported. BET measure-
ments revealed a low surface area (2.8 m2 g−1). Even by having a
low surface area, oxidation activity of this catalyst was very well.
So the active surface sites, related to BET surface area, were signif-
icant for the adsorption of diphenylmethane and desorption of the
benzophenone molecules.
Fig. 3. SEM images of the Co/Mn-BSO0.01 nanocatalyst.

B.H. Monjezi et al. / Journal of Molecular Catalysis A: Chemical 383–384 (2014) 58–63
61
Table 2
Analytical data of the catalyst and support.
Catalyst (1 g)
Analysis (mmol)
Ca
Na
Mg
Li
K
Sr
Fe
Se
B
Co
Mn
BSOa
Co/Mn-BSO0.01
7.77
0.26
0.24
0.068
0.021
0.015
0.013
0.010
0.007
0.000
0.169
0.000
0.017
a
Calcined Cow bone.
could be interpreted as being an evidence of the presence of tetra-
hedrally coordinated Mn2+ in the framework.
3.2. Catalytic performance
The performance of the Co/Mn-BSO0.01 catalyst was tested in
diphenylmethane oxidation without the need of any solvent and
reducing reagent at 353 K. Oxygen was used as the best oxidant.
The results of the % selectivity to benzophenone and % conversion
of diphenylmethane are presented in Table 3. The conversion and
selectivity were monitored by GC analysis. Products were identified
by considering their GC–MS and by comparison with the GC of the
authentic samples. The oxidation takes place on the alpha-carbon
of the alkylbenzene. Formation of the products benzophenone, 1,
and benzoic acid, 2 are illustrated in Scheme 1. It is remarkable to
mention that no oxidation was observed in the aromatic ring of
the diphenylmethane. The catalyst activity of the solid catalyst was
higher in solvent free condition than in the presence of solvent such
as CH3CN.
Fig. 4. TEM image of the Co/Mn-BSO0.01 nanocatalyst.
3.2.1. Effect of temperature
The catalytic activity of Co/Mn-BSO0.01 catalyst was investigated
as a function of temperature. Table 3 shows the results of the oxi-
dation at 100, 150, 180, and 200 ◦C. The reaction temperature has
a great influence on the progress of the reaction. By increasing the
temperature to 200 ◦C, the conversion increased remarkably. The
reaction temperature also affected the distribution of the products
and selectivity. By performing the reaction at higher temperature,
the selectivity for benzophenone decreases. Therefore, the opti-
mum temperature for the oxidation was chosen at 200 ◦C.
measured Co and Mn contents in the supported catalyst sample was
10:1. The ions contents of the initial bone and the Co/Mn-BSO0.01
catalyst are reported in Table 2.
3.1.4. DR UV–vis spectroscopy
UV–vis spectra were recorded with aim to reveal changes in
the chemical structure of the hydroxyapatite upon immobiliza-
tion of nano-particles, and also to provide further evidence on
the morphology of metal ions. UV–vis spectra of the support and
the catalyst are shown in Fig. 5. There should be bands in the
region between 300 and 400 nm, which is typical of Co3+ octahe-
dral species, as well as a few absorption bands around 543, 580,
and 630 nm, which is typical of Co2+ ions in tetrahedral coordina-
tion. Also bands with similar positions (350–460 nm) have been
expected for manganese in the calcined bone environment, which
3.2.2. Effect of pressure of oxygen
Table 3 summarizes the effect of different pressures of oxygen
on the oxidation of diphenylmethane over Co/Mn-BSO0.01 catalyst
at 200 ◦C. These results showed that the higher conversion was
achieved with 17 bars pressure of oxygen as oxidant. In this condi-
tion the selectivity of the benzophenone increased to 87% and the
conversion increased to 90%. Therefore, the optimum pressure of
oxygen for oxidation was chosen 17 bars.
Fig. 5. UV–vis spectra of (a) bone, (b) bone containing Mn, (c) bone containing Co,
Fig. 6. Reusability of the catalyst at optimum conditions: temperature, 200 ◦C; pres-
and (d) bone containing Co and Mn.
sure of oxygen, 17 bars; amount of catalyst, 100 mg; and time of reaction, 3 h.

62
B.H. Monjezi et al. / Journal of Molecular Catalysis A: Chemical 383–384 (2014) 58–63
Table 3
Effect of the reaction parameters.
Entry
Temperature (◦C)
Pressure (bar)
Time (h)
Catalyst (mg)
Conversion %
Selectivity %
Benzoic acid
Benzophenone
Others
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
100
150
180
200
200
200
200
200
200
200
200
200
200
200
200
17
17
17
17
10
12
15
17
17
17
17
17
17
17
17
3
3
3
3
3
3
3
3
1
3
6
12
3
3
100
100
100
100
100
100
100
100
100
100
100
100
50
21
51
79
87
78
81
79
87
21
87
89
90
81.5
87
85.5
3.5
6
9.5
7
14
15.5
16
7
12
7
5
3
13.5
7
10
95
93
88
90
80
80.5
81
90
86
90
93
90
83.5
90
87
1.5
1
2.5
3
6
4
3
3
2
3
3
7
3
3
100
150
3
3
Scheme 1.
Table 4
Catalytic activities of Co/Mn-BSO0.01 and some previously reported catalysts in the diphenylmethane oxidation.
Entry
Catalyst
Conversion %
Selectivity %
Oxidant
Reference
1
2
3
4
5
6
7
8
9
Co/Mn-SBO
MnMCM-41
MnMCM-48
CrMCM-41
Ni–Al–hydrotalcite
Mn–MgAlhydrotalcite
NHPI–acridine yellow–Br2
MnO4−1 exchanged MgAlhydrotalcite
CuMgAl-13
87
14
15
51
62
70
65
27
95
75
61
90
100
100
98
97
95
O2
O2
O2
O2
O2
O2
O2
O2
This work
[26]
[26]
[27]
[28]
[18]
[13]
[29]
[30]
99
100
100
95
TBHP
t-BuOOH
TBHP
10
11
RuCl2(PPh3)3
CrSBA-15
[31]
[20]
95
3.2.3. Effect of time
drying at 100 ◦C the catalyst was used for a new run at the opti-
mum conditions. The activity of the catalyst after at least five runs
was approximately steady. We have reported in our previous work
[23], that this catalyst did lose its activity after the first run. But it
should be mentioned that the medium of that oxidation reaction
was acetic acid, and deactivation of the catalyst was attributed to
leaching of the catalyst from the support. However, in the oxida-
tion of diphenylmethane which has been conducted in a solvent
free conditions, and on the basis of ICP measurements the leaching
was not the case.
Table 3 shows the effect of time on the diphenylmethane oxi-
dation with Co/Mn-BSO0.01 catalyst. The results show that by
increasing the reaction time, the diphenylmethane conversion was
increased. By increasing the time of the reaction from 1 h to 3 h, the
conversion increased from 21% to 90%, and from 3 h to 12 h almost
kept unchanged. Then the optimum time for oxidation was selected
3 h.
3.2.4. Effect of amount of catalyst
To study the effect of amount of catalyst, oxidation was carried
out at 200 ◦C, 17 bars, and 3 h. The results are summarized in Table 3.
As seen, 100 mg of the catalyst was enough to increase appreciably
conversion of the reaction (87%) and selectivity to benzophenone
(89%). However, by further increasing of amount of the catalyst, a
slight decrease in the conversion was observed. It should be men-
tioned that in the absence of the catalyst, the oxidation reaction
was very poor.
4. Conclusion
In this investigation, the preparation and characterization of a
new heterogeneous nano-catalyst with excellent properties have
been described. The synthesized nano-catalyst was characterized
by XRD, UV–vis, BET, TEM, and SEM techniques. In summary, the
new catalyst could catalyze the oxidation of diphenylmethane to
benzophenone. A higher yield of benzophenone was obtained by
optimizing of temperature, time, and the amount of nano-catalyst
and pressure of oxygen. Under the optimized conditions, a maxi-
mum of 87% diphenylmethane with 90% selectivity was achieved.
3.2.5. Reusability of the catalyst
The catalytic stability of the catalyst in the oxidation of diphenyl-
methane is shown in Fig. 6. By just separating the catalyst from the
reaction mixture by centrifugation, washing it with chloroform and

B.H. Monjezi et al. / Journal of Molecular Catalysis A: Chemical 383–384 (2014) 58–63
63
The data in Table 4 compares the results obtained over Co/Mn-
BSO0.01 catalyst and other catalysts used for this reaction. As shown
in Table 4, the catalyst used in the present study might be one of
the best catalysts in respect of oxidation of diphenylmethane to
benzophenone. The extension of application of this nano-catalyst
to different oxidation reactions is currently under investigation in
our laboratory.
[9] J.H. Clark, A.P. Kybett, P. London, D.J. Macquarrie, K. Martin, J. Chem. Soc. Chem.
Commun. (18) (1989) 1355–1356.
[10] A. Oussaid, A. Loupy, J. Chem. Res. (S) (9) (1997) 342–343.
[11] A. Shaabani, A. Bazgir, F. Teimouri, D.G. Lee, Tetrahedron Lett. 43 (2002)
5165–5167.
[12] M. Rogovin, R. Neumann, J. Mol. Catal. A: Chem. 138 (1999) 315–318.
[13] X. Tong, J. Xu, H. Miao, J. Gao, Tetrahedron Lett. 47 (2006) 1763–1766.
[14] H.R. Mardani, H. Golchoubian, J. Mol. Catal. A: Chem. 259 (2006) 197–200.
[15] R.K. Jha, S. Shylesh, S.S. Bhoware, A.P. Singh, Micropor. Mesopor. Mater. 95
(2006) 154–163.
[16] F. Chang, W. Li, F. Xia, Z. Yan, J. Xiong, J. Wang, Chem. Lett. 34 (2005) 1540–1541.
[17] L. Tang, B. Li, Z. Zhai, J. Li, E. Ou, J. Wang, Catal. Lett. 121 (2008) 63–69.
[18] S.K. Jana, Y. Kubota, T. Tatsumi, J. Catal. 247 (2007) 214–222.
[19] T. Matsushita, K. Ebitani, K. Kaneda, Chem. Commun. (3) (1999) 265–266.
[20] M. Selvaraj, D.W. Park, S. Kawi, I. Kim, Appl. Catal. A: Gen. 415 (2012) 17–21.
[21] X. Guo, Y. Li, D. HuaShen, Y. Song, X. Wang, Z. Liu, J. Mol. Catal. A: Chem. 367
(2013) 7–11.
[22] A.M. Ghahfarrokhi, P. Moshiri, M. Ghiaci, Appl. Catal. A: Gen. 456 (2013) 51–58.
[23] M. Ghiaci, M. Mostajeran, A. Gil, Ind. Eng. Chem. Res. 51 (2012) 15821–15831.
[24] S. Brunauer, P.H. Emmett, E. Teller, J. Am. Chem. Soc. 60 (1938) 309–319.
[25] E.P. Barrett, L.G. Joyner, P.P. Halenda, J. Am. Chem. Soc. 73 (1951) 373–380.
[26] N.N. Tusar, S.C. Laha, S. Cecowski, I. Arcon, V. Kaucic, R. Glaser, Micropor. Meso-
por. Mater. 146 (2011) 166–171.
Acknowledgments
Thanks are due to the Iranian Nanotechnology Initiative and the
Research Council of Isfahan University of Technology and Centre
of Excellence in the Chemistry Department of Isfahan University of
Technology for supporting this work.
References
[1] S. Kuhn, Nippon Shokukai Kagaku, Jap. Patent No. 59,219,248 (1983).
[2] R. Gopalan, R.W. Sugumar, Ind. J. Chem. 16A (1978) 198–201.
[3] N.D. Valechha, A. Pradhan, J. Ind. Chem. Soc. 61 (1984) 909–911.
[4] S.D. Borkar, B.M. Khadilkar, Synth. Commun. 29 (1999) 4295–4298.
[5] Y. Ogata, H. Tezuka, T. Kamei, J. Org. Chem. 34 (1969) 845–847.
[6] Y. Ono, J. Catal. 216 (2003) 406–415.
[27] S.E. Dapurkar, H. Kawanami, T. Yokoyama, Y. Ikushima, Catal. Commun. 10
(2009) 1025–1028.
[28] S.K. Jana, P. Wu, T. Tatsumi, J. Catal. 240 (2006) 268–274.
[29] V.R. Choudhary, J.R. Indurkar, V.S. Narkhede, R. Jha, J. Catal. 277 (2004) 257–261.
[30] D. Kishore, A.E. Rodrigues, Catal. Commun. 10 (2009) 1212–1215.
[31] S.I. Murahashi, N. Komiya, Y. Oda, T. Kuwabara, T. Naota, J. Org. Chem. 65 (2000)
9186–9193.
[7] H. Hattori, Appl. Catal. A: Gen. 222 (2001) 247–259.
[8] D. Kishore, S. Kannan, Green Chem. 4 (2002) 607–610.