Epoxidation of alkenes using inorganic polymer of silica zirconia molybdate as catalyst

Article abstract of DOI:10.1016/j.molcata.2013.11.008

Silica zirconia sulfate was prepared by sol-gel copolymerization of the sulfated zirconium octanoxide and tetraethylorthosilicate (TEOS). Active polymer oxidation catalysts were obtained by introducing sodium molybdate into the polymer by a ligand exchange reaction. The prepared inorganic polymer designated as SZ-Mo was characterized by FT-IR, SEM, XRD, N₂ sorption isotherms, and ICP techniques. It was found that SZ-Mo successfully catalyzes the epoxidation of cyclooctene, cyclohexene, trans-stilbene, and norbornene with 22-95% conversion and 60-100% selectivity. The dependence of the SZ-Mo catalytic activity to the amount of adsorbed Mo within the polymer as well as the study of catalyst stability during the course of reactions will be described in this presentation.

Full text of DOI:10.1016/j.molcata.2013.11.008

Journal of Molecular Catalysis A: Chemical 382 (2014) 79–85
Contents lists available at ScienceDirect
Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
Epoxidation of alkenes using inorganic polymer of silica zirconia
molybdate as catalyst
M. Sharbatdarana,b, F. Farzaneha,∗, M.M. Larijanib
a Department of Chemistry, Alzahra University, Vanak, Tehran, Iran
b Agricultural, Medical and Industrial Research School, NSTRI, Karaj, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Silica zirconia sulfate was prepared by sol–gel copolymerization of the sulfated zirconium octanoxide and
tetraethylorthosilicate (TEOS). Active polymer oxidation catalysts were obtained by introducing sodium
molybdate into the polymer by a ligand exchange reaction. The prepared inorganic polymer designated as
SZ-Mo was characterized by FT-IR, SEM, XRD, N2 sorption isotherms, and ICP techniques. It was found that
SZ-Mo successfully catalyzes the epoxidation of cyclooctene, cyclohexene, trans-stilbene, and norbornene
with 22–95% conversion and 60–100% selectivity. The dependence of the SZ-Mo catalytic activity to the
amount of adsorbed Mo within the polymer as well as the study of catalyst stability during the course of
reactions will be described in this presentation.
Received 7 March 2013
Received in revised form
29 September 2013
Accepted 10 November 2013
Available online 20 November 2013
Keywords:
Inorganic polymer
Silica zirconia molybdate
Alkenes
© 2013 Elsevier B.V. All rights reserved.
Peroxides
Sol–gel synthesis
1. Introduction
mesoporous have been used for immobilization, encapsulation, or
incorporation of Mo compounds [14–18].
Epoxidation of alkenes catalyzed by metal complexes is one of
the important oxidation reactions in industrial chemistry. Epoxides
are important synthetic intermediates for the synthesis of oxygen
containing natural or synthetic compounds [1,2]. Many transition
metal complexes such as Co, Ti, Mn, V, and Mo have been used
as catalyst for epoxidation of cyclic olefins with high selectivity
[2]. Molybdenum complexes as the efficient oxyfunctionalization
catalysts of alkenes have been the subject of intense research
over the last three decades. Different types of molybdenum com-
plexes such as Mo carbonyl derivatives [3,4], molybdenum (VI)
aminopyridinium [5], Mo2O6 (4,4ꢀ-ditertbutyl 2,2ꢀ-bipyridine)2 [6],
and dioxomolybdenum (VI) complexes of Schiff-bases derivatives
[7–10] have been used as catalyst in epoxidation type reactions.
Liquid phase epoxidation is usually performed either in homo-
geneous or in heterogeneous systems. Due to easier recovery
and recycling of the reaction catalysts, many research and devel-
opments have been directed on the heterogeneous processes.
Different solid supports such as polymers [11,12], silica and sil-
icate layers [13], microporous, mesoporous, and functionalized
Recent utilization of inorganic polymer supports such as sul-
fated silica zirconia materials has attracted much attention in the
last years due to their high acidity induced by silica sulfation. These
materials are known with the extensive catalytic activities in pro-
cesses such as isomerization [19], alkylation [20], esterification
[21], and those involving oxygenation of hydrocarbons [22].
In this work, inorganic polymer of silica zirconia molybdate was
prepared using tetraethylorthosilicate, sulfated zirconia octanox-
ide, and sodium molybdate. Exploration of factors such as SO42−/Zr
or Si/Zr and catalytic epoxidation behavior of SZ-Mo with TBHP and
H2O2 will be discussed.
2. Experimental
2.1. Preparation of the catalysts
2.1.1. Preparation of sulfated silica–zirconia inorganic polymer
The preparation method of silica–zirconia sulphate is almost
similar to that of our previously reported for the synthesis of
Si–Zr–Mo nanocomposite [23] with minor modification. In a typi-
cal procedure,zirconium octanoxide was prepared from zirconium
tetra-n-butoxide and 1-octanol by alcohol interchange method.
Zr(Oct)2 SO4 was then prepared by addition of sulfuric acid to dif-
ferent amounts of Zr(Oct)4 solution in order to adjust the SO42−/Zr
∗
Corresponding author. Tel.: +98 21 88258977; fax: +98 21 88041344.
E-mail addresses: faezeh farzaneh@yahoo.com, Farzaneh@alzahra.ac.ir
(F. Farzaneh).
1381-1169/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molcata.2013.11.008

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M. Sharbatdaran et al. / Journal of Molecular Catalysis A: Chemical 382 (2014) 79–85
H2SO4
Na2MoO4
TEOS
SZ1-Mo , SZ2-Mo
Zr(Oct)4
SZ1, SZ2
Zr(Oct)2SO4
Scheme 1. Preparation of SZ1-Mo and SZ2-Mo.
ration as 0.6/1 or 1:1. Zr–Si inorganic polymer designated as SZ1
and SZ2 were prepared with two different molar ratios as follows:
For SZ1: Zr(Oct)2SO4 (4 mmol, 1.80 g), TEOS(40 mmol, 8.87 ml),
EtOH (308 mmol, 17.96 ml), H2O (440 mmol, 7.92 ml), and AcOH
(88 mmol, 5.03 ml) and for SZ2: Zr(Oct)2SO4 (4 mmol, 1.80 g),
TEOS (4 mmol, 0.89 ml), EtOH (56 mmol, 3.27 ml), H2O (80 mmol,
1.44 ml), and AcOH (16 mmol, 0.92 ml). Therefore, in a typical pro-
cedure, TEOS, ethanol, H2O, and AcOH were mixed by stirring and
Zr(Oct)2SO4 (0.1 M in 1-octanol) was then added under vigorous
stirring. The resulting sol was stirred for 3 h. The produced gel was
decanted by centrifugation using 3900 r/min for 15 min and then
dried at 180 ◦C for several hours.
Zr–Si inorganic polymer SZ1 and SZ2. Upon addition of Na2MoO4,
SZ1-Mo, and SZ2-Mo were generated presumably via reaction
between Zr–SO4 and MoO42−. The weight percentages of Zr, Si, S,
and Mo in SZ1, SZ2, SZ1-Mo, and SZ2-Mo were measured using
ICP-OES technique in order to calculate the molar ratios of Zr/Si
and S/Zr (Tables 1 and 2). The mole ratios of Zr/Si and S/Zr were
found to be 0.06 and 1.16 in SZ1 (Table 2) and 0.30 and 1.78 in SZ2
(Table 2), respectively. ICP-OES analysis also showed that weight
percents of Mo in SZ1-Mo and SZ2-Mo are 45.42 and 31.31, respec-
tively (Tables 1 and 2). After Mo adsorption, no significant amount
of sulfur was detected using ICP-OES technique (Tables 1 and 2).
2−
As seen in Table 1, the sulfur moles of SO4
anions in SZ-1 and
SZ-2 are 0.035 and 0.160, respectively. Moreover, the moles of Mo
as MoO42− are 0.473 and 0.326, respectively. Based on the results
2.1.2. Immobilization of Mo on the surface of sulfated
silica–zirconia inorganic polymer
2−
obtained from ICP, EDX, and FT-IR, the MoO4 not only have been
2−
exchanged with SO4 in both SZ-1 and SZ-2, but also some were
MoO3 (1.5 g, 7.7 mmol) dissolved in NaOH (10 ml, 5 M) was ini-
tially titrated with HCl (0.5 M) until pH was adjusted on 7. Sulfated
silica–zirconia inorganic polymer (0.5 g) was then added and the
mixture heated at reflux for 3 h. Subsequently, the solid product
(SZ1-Mo or SZ2-Mo) was decanted by centrifugation, washed with
deionized water, and dried at 100 ◦C.
partly adsorbed on the sample surfaces. Since the surface area of
SZ-1 and SZ-2 are 141 and 83 m2/g respectively, some MoO42− may
have been exchanged with other anionic species accordingly.
The FT-IR spectrum of Zr(Oct)2SO4 (Fig. 1a) shows vibra-
tions at 500, 610, and 725 cm−1, corresponding to Zr O bending
and stretching vibrations. The bands appearing at 1000–1300,
1300–1400, and 2800–2900 cm−1 are attributed to the C O, CH3
or CH2, and C H stretching of alkoxy groups, respectively. A broad
band displaying at 3400 cm−1 is due to the OH stretching associated
with alcohol residue present in zirconium alkoxide. Furthermore,
2.2. Characterization
All chemicals were purchased from Merck chemical company
and used without further purification. Infrared spectra were per-
formed (KBr pellets) on a Bruker Tensor 27FT-IR spectrometer.
X-ray diffraction (XRD) patterns were recorded on a Philips PW-
1800 diffractometer with Cu K␣ radiation. Chemical analysis of
samples was carried out with Varian 150AX inductively cou-
pled plasma optical emission spectrometer (ICP-OES). Electron
microscopy was performed on a Vega Tescan, scanning electron
microscope (SEM). Surface areas, pore volume, and pore size distri-
butions were obtained from the N2 isotherms which determined
at 77 K using Quantachrome Nova 2200, Version 7.11 Analyzer.
The products were analyzed by GC and GC–MS using Agilent 6890
Series, with FID detector, HP-5, 5% phenylmethylsiloxane capillary
and Agilent 5973 Network, mass selective detector, HP-5 MS 6989
Network GC system, respectively.
2−
the band due to SO4 stretching vibrations observed in the range
of 900–1200 cm−1 is attributed to the symmetric and asymmetric
stretching vibrations of S O bonds present in inorganic chelating
bidentate sulfate [20]. The FT-IR spectrum of SZ1 in Fig. 1b displays
the bands at 800, 1070, and 1225 cm−1 due to the stretching vibra-
tions of Si O and a band appearing at 520 cm−1 belongs to the Si
O
bending vibration. The broad bond appearing at 1000–1500 cm−1 is
probably due to the vibrations of Zr Si group present between
O
ZrO2 and SiO2 fragments [21]. As seen in Fig. 1c, the bands display-
ing at 907 and 960 cm−1 corresponding to Mo O vibration are due
to the immobilized Mo on SZ1 polymer [17,24]. Comparison of the
FT-IR spectra presented Fig. 1a, b with that shown in Fig. 1c reveals
2−
2−
that the MoO4 has been exchanged with SO4 anions because
no vibration due to this group is detected.
2.3. Catalytic epoxidation
The catalytic reactions were carried out in a round-button
flask equipped with a magnetic stirrer and condenser. In a typical
procedure, the alkene (20 mmol, trans-stilbene, 1 mmol), catalyst
(50 mg), and CH3CN (5 ml) were added into the flask. The reaction
was started by adding H2O2 (20 mmol, 2.04 ml, 30% in H2O) or TBHP
(20 mmol, 2.74 ml, 70% in H2O). The mixture was heated at reflux
for 8 h. The catalyst was filtered and the filtrate was subjected to
GC and GC–MS analyses. The Mo, Si, and Zr contents of the recycled
catalyst were measured using ICP-OES techniques.
3. Results and discussion
3.1. Characterization of the catalysts
SZ1-Mo and SZ2-Mo were prepared according to the procedure
presented in Scheme 1.
The sulfated zirconia was prepared using the reaction between
sulfuric acid and Zr(Oct)4. Subsequent treatment with a mixture of
TEOS, EtOH, AcOH, and distilled H2O afforded the corresponding
Fig. 1. FT-IR spectra of (a) Zr(Oct)2SO4, (b) SZ1, (c) SZ1-Mo, and (d) SZ1-Mo after
used as catalyst.

M. Sharbatdaran et al. / Journal of Molecular Catalysis A: Chemical 382 (2014) 79–85
81
Table 1
Chemical composition of the prepared materials.
Entry
Sample
Si % (mole)
Zr % (mole)
S % (mole)
Mo % (mol)
1
2
3
4
SZ1
SZ2
SZ1-Mo
SZ2-Mo
13.77 (0.490)
8.50 (0.300)
5.69 (0.203)
6.89 (0.250)
2.83 (0.031)
8.08 (0.089)
1.17 (0.013)
7.01 (0.077)
1.13 (0.035)
5.05 (0.160)
0.000
–
–
45.42 (0.473)
31.31 (0.326)
0.000
Table 2
Physical properties of the prepared materials.
Entry
Sample
(Zr/Si)th
(Zr/Si)e
(S/Zr)th
(S/Zr)e
Mo (wt.%)
SBET (m2/g)
Pore volume (cc/g)
Pore diameter (nm)
1
2
3
4
SZ1
SZ2
SZ1-Mo
SZ2-Mo
0.10
1.00
0.10
1.00
0.06
0.30
0.06
0.31
0.60
1.00
–
1.16
1.78
0.00
0.00
–
–
141
83
37
0.08
0.13
0.04
0.09
1.19
1.17
2.44
1.93
45.42
31.31
–
79
th: theoretical.
e: experimental.
The nitrogen adsorption/desorption isotherms and pore size dis-
tribution of SZ1, SZ2, SZ1-Mo, and SZ2-Mo are shown in Fig. 2a–c.
Nitrogen adsorption/desorption analyses were performed in order
to investigate the textural properties of the resulted compounds.
Based on the pore distribution, it is assumed that the isotherm plot
is close to type IV and the pores are close to meso species on the
basis of IUPAC definition. The calculation of surface area and pore
size distribution was obtained based on the BET and BJH meth-
ods [25]. The surface area, pore volume, and pore diameter were
determined as 141 m2/g, 0.08 cc/g, and 1.19 nm for SZ1 and 83, 0.13,
are presented in Fig. 3a–d. The EDX analyses confirm the presence
of Si, Zr, and S in the SZ1 and SZ2 and Mo in the SZ1-Mo and SZ2-
Mo. The higher Mo content of SZ1-Mo than SZ2-Mo, resulted by
comparison of Fig. 3b with d, is also approved by ICP-OES results.
The micrographs of SEM reveal that whereas the particle size and
morphology of SZ1 and SZ1-Mo differ to some extent, SZ2 and SZ2-
Mo have same morphology. Based on the SEM images, SZ1, SZ2,
and SZ2-Mo exhibit particles of 20 nm with nearly spherical shape
but SZ1-Mo is formed from nanoribbon with preferential growth
(Fig. 2b). From the SEM images, one can conclude that polymer with
higher amount of Mo may significantly accelerate the formation of
crystalline structure together with a better control of the inorganic
polymer morphology. The urchin-like-shaped crystals synthesized
by microwave heating with Zr and nanorod-shape crystal obtained
by the external heating have been already reported [27,28].
2−
and 1.17 for SZ2, respectively (Table 1). After interchange of SO4
2−
with MoO4
in SZ1, SZ2 and formation of SZ1-Mo, and SZ2-Mo
the surface areas were found to decrease from 141 to 37 and 83
to 79, respectively with concomitant increasing pore volumes and
diameters [25,26].
The scanning electron microscopy (SEM) and energy-dispersive
X-ray spectroscopy (EDX) results of SZ1, SZ1-Mo, SZ2, and SZ2-Mo
Whereas SZ1, SZ2, and SZ2-Mo show no crystalline phase on the
basis of the XRD patterns (Fig. 4a–c), the formation of SZ1-Mo in
Fig. 2. N2 adsorption-desorption isotherms and pore size distribution of (a and b) SZ1 and SZ2 and (c and d) SZ1-Mo and SZ2-Mo, respectively.

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M. Sharbatdaran et al. / Journal of Molecular Catalysis A: Chemical 382 (2014) 79–85
Fig. 3. SEM micrographs and EDX analysis of (a) SZ1, (b) SZ1-Mo, (c) SZ2, and (d) SZ2-Mo.
crystalline phase is evident (Fig. 4d). The crystallinity of SZ1-Mo
remains even after using as catalyst is of particular significance.
3.2. Catalytic tests
The SZ1-Mo and SZ2-Mo were used as catalyst for epoxidation
of alkenes such as norbornene, trans-stilbene, cyclohexene, and
cyclooctene. Norbornene was used as the representative substrate
for the early exploration of oxidation reactions. In order to study
the effect of time on product distribution, reaction times of 0.5, 1,
2, 3, 4, 6, 8, 12, and 24 h were examined in the presence of 50 mg
of SZ1-Mo as catalyst and TBHP as oxidant (Fig. 5). Based on the
obtained results, the catalytic activity of the prepared catalyst is
strongly influenced by the reaction time. As seen, norbornene is oxi-
dized to the corresponding epoxides with 65% conversion and 100%
selectivity. Although the conversion increased to 85% by increas-
ing reaction time to 12 h, decrease in selectivity from 100% to 95%
with concomitant formation of some norbornyl-t-butyl ether was
observed.
The effects of the amount of SZ1-Mo shown in Fig. 6 reveal
that whereas increasing the amount of catalyst from 20 to 100 mg
enhances the conversion from 44 to 81%, decreases in the selec-
tivity occur from 100% to 95%. Based on the optimized conversion
and selectivity obtained using 50 mg of catalyst, all the epoxidation
reactions were carried out using this amount.
Effect of SZ1-Mo and SZ2-Mo as catalysts on the epoxidation
reactions with TBHP is presented in Table 2. Under the same reac-
tion conditions, SZ1-Mo was found to be more reactive in alkene
epoxidation in comparison to that of SZ2-Mo. The lower reactiv-
ity of SZ2-Mo seems to arise from the lower loading of active
Fig. 4. XRD patterns of (a) SZ2, (b) SZ1, (c) SZ1-Mo and (d) SZ1-Mo after used as
catalyst.

M. Sharbatdaran et al. / Journal of Molecular Catalysis A: Chemical 382 (2014) 79–85
83
Table 3
Oxidation results of alkenes with TBHP in the presence of SZ1-Mo and SZ2-Mo catalysts.
Entry
Alkene
Conversion (%) SZ1-Mo (SZ2-Mo)
Product distribution (%)
TONa
1
85
(66)
94
(92)
6
(8)
–
–
71
(81)
2
80
61
26
13
67
(38)
(26)
(53)
(21)
(47)
3
38
(11)
64
(73)
36
(27)
–
–
32
(14)
4
95
(54)
100
(100)
–
–
–
–
3
(3)
a
The mmol of product to mmol of catalyst, solvent: CH3CN, alkene (20 mmol), trans-stilbene (1 mmol), TBHP (20 mmol), catalyst (0.05 g), time 8 h.
Fig. 6. The effects of catalyst amount on the oxidation of norbornene. Reaction con-
ditions: solvent; CH3CN, norbornene (20 mmol), TBHP (20 mmol), reaction time:
8 h.
Fig. 5. Kinetic oxidation profiles of norbornene with TBHP over SZ1-Mo catalyst.
Reaction conditions: solvent: CH3CN, norbornene (20 mmol), catalyst (0.05 g), TBHP
(20 mmol).
catalytic species under oxidation conditions. The stability of the
SZ1-Mo as catalyst was also studied by recycling the recovered cat-
alyst and redetermined the Mo content using ICP techniques. The
Mo content of fresh and used catalysts was determined as 45.42 and
45.36%, respectively. ICP determination showed that, no significant
amount of Mo content in the filtrate solution. We also found that
the catalyst can be recovered and reused at least three times with
no significant loss of its catalytic activity. The same determination
has been made for SZ2-Mo; the Mo content for fresh and used one
was 31.33 and 31.23.
The FT-IR and XRD of SZ1-Mo before and after oxidation reac-
tions were the same (Fig. 1d and Fig. 4d). These results indicate that
the SZ1-Mo has survived after using the catalyst in the epoxidation
reactions.
The epoxidation results of mentioned olefins with H2O2 in ace-
tonitrile catalyzed by SZ1-Mo are given in Table 4. The obtained
results indicate that even though the epoxidation selectivity for
molybdenum sites, perhaps due to the lower BET surface area of
the SZ2 precursor.
Quantitative epoxidation of trans-stilbene either with SZ1-Mo
or with SZ2-Mo is notable (entry 4, Table 3). On the other hand,
cyclohexene or cyclooctene undergoes oxidation on both dou-
ble bond and allylic site, affording epoxide and alcohol or ketone
(entries 2 and 3, Table 3). The increase in the ring size of a cyclic
olefin decreases the epoxidation rate as reflected in Table 3. The
lower activity of cyclooctene may be attributed to the decrease in
the ability of cyclooctene for complexation with the catalyst due to
the larger steric hindrance [29].
The formation of both double bond and allylic site indicates the
involvement of a concerted as well as stepwise oxygen transfer
processes from TBHP to the alkene (Scheme 2) [30,31].
The observation of no significant desorption of active catalytic
species in the experimental reactions reveals the stability of the

84
M. Sharbatdaran et al. / Journal of Molecular Catalysis A: Chemical 382 (2014) 79–85
O
ROOH
(a)
O
O
O
O
OH
O
O
O
O
O
O
Si
Zr
Mo
Si
Zr
Mo
Si
OOR
I
II
O
(b)
C6H12
O
O
O
O
O
O
H
O
- ROH
II
Zr
Mo
O
- I
R
-ROH
OOR
(c)
(d)
C6H12
- I , - H2O
II
RO
ROO
+
ROOH
(e)
2 C6H12
-2 ROH
2 ROOH
+
2
-2 ROH
OH
O
Scheme 2. Proposed mechanism for the epoxidation of cyclohexene with SZ1-Mo.
cyclohexene and cyclooctene with H2O2 is higher than TBHP, the
conversion is lower. The epoxidation of NBD, cyclooctene, and
trans-stilbene with 100% selectivity is considerable.
Since hydrogenation energies of norbornene, cyclohexene, and
cyclooctene are −33.80, −28.60, and −22.98 kcal/mole, respec-
tively, 2-norbornyl-tert-butyl ether (entry 1, Table 3) may
have been generated from addition of tert-butanol due to
the rather more activity of its double bond [32]. Recall that
tert-butanol is produced via decomposition of tetr-butyl hydroper-
oxide.
A possible mechanism for the inorganic polymer catalyzed oxi-
dation of cyclohexene with H2O2 or TBHP is suggested in Scheme 2.
Whereas the species responsible for the allylic site oxidation in
cyclohexene seems to arise from cleavage of the O O bond (routes
a, c, and e Scheme 2), the epoxidation reaction may have been
proceeded either mainly by a concerted reaction of olefin with
coordinated ROO radical II (routes a and b, Scheme 2) or partially
through a stepwise process (routes a, c, and d Scheme 2). Due to the
more efficient epoxidation results indicated in Table 4, implication
of H2O2 in a concerted reaction with more efficiency seems likely.
Table 4
Oxidation results of alkenes with H2O2 in the presence of SZ1-Mo catalyst.
Entry
Alkene
Conversion (%)
Product distribution %)
TONa
1
51
100
–
43
2
3
94
86
14
78
73
22
100
100
–
–
61
1
4
a
The mmol of product to mmol of catalyst, solvent: CH3CN, alkene (20 mmol), trans-stilbene (1 mmol), H2O2 (20 mmol, 2.04 ml, 30% in H2O), catalyst (0.05 g), time 8 h.

M. Sharbatdaran et al. / Journal of Molecular Catalysis A: Chemical 382 (2014) 79–85
85
On the other hand, the preferential participation of TBHP in a step-
wise process is anticipated. Such proposal is convincing since the
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Based on the results obtained in this work, it was found that
the ratio of Zr/Si and S/Zr plays a crucial role on the particle size,
morphology, and surface area of the prepared materials. The novel
molybdenum polymers described in this paper exhibit high activ-
ity and selectivity in the catalytic epoxidation of olefins. Overall
four alkenes were investigated for oxidation either with TBHP
or with H2O2. The formation of the desired epoxides in higher
yields using H2O2 was attributed to the stronger peroxide bond
of this oxidant. Moreover, the key role of the amount of Mo in cat-
alytic activity was documented by obtaining better results using
SZ1-Mo.
Acknowledgement
The authors would appreciate the Alzahra University and
Agricultural, Medical and Industrial Research School (AMIRS) for
financial support.
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