Liquid phase catalytic oxidation of benzyl alcohol to benzaldehyde over vanadium phosphate catalyst

Article abstract of DOI:10.1016/j.apcata.2011.11.016

Vanadium phosphate (VPO) is well known as a heterogeneous catalyst in gas phase oxidation reactions. Till date, this material has not drawn much attention for its application in liquid phase reactions. This paper briefly highlights our recent research on vanadyl metaphosphate concerning its fabrication, characterization and application towards liquid phase oxidation of benzyl alcohol to benzaldehyde using tert-butyl hydroperoxide (TBHP) as the oxidant. In our preliminary catalytic studies, we find that the VO(PO₃) ₂ exhibits extraordinarily high activity and selectivity in oxidation of benzyl alcohol under mild conditions. The benzyl alcohol conversion is largely increased but the selectivity for benzaldehyde is slightly decreased with the increase in reaction period or temperature. The present catalyst VO(PO₃)₂ showed remarkable catalytic activity with respect to other catalytic system; conversion and selectivity with respect to aldehyde is 97 and 99%, respectively.

Full text of DOI:10.1016/j.apcata.2011.11.016

Applied Catalysis A: General 413–414 (2012) 245–253
Contents lists available at SciVerse ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Liquid phase catalytic oxidation of benzyl alcohol to benzaldehyde over
vanadium phosphate catalyst
∗
Gobinda Chandra Behera, K.M. Parida
Colloids and Materials Chemistry Department, Institute of Minerals and Materials Technology (CSIR), Bhubaneswar 751013, Orissa, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 24 August 2011
Received in revised form 4 November 2011
Accepted 13 November 2011
Available online 22 November 2011
Vanadium phosphate (VPO) is well known as a heterogeneous catalyst in gas phase oxidation reactions.
Till date, this material has not drawn much attention for its application in liquid phase reactions. This
paper briefly highlights our recent research on vanadyl metaphosphate concerning its fabrication, char-
acterization and application towards liquid phase oxidation of benzyl alcohol to benzaldehyde using
tert-butyl hydroperoxide (TBHP) as the oxidant. In our preliminary catalytic studies, we find that the
VO(PO3)2 exhibits extraordinarily high activity and selectivity in oxidation of benzyl alcohol under mild
conditions. The benzyl alcohol conversion is largely increased but the selectivity for benzaldehyde is
slightly decreased with the increase in reaction period or temperature. The present catalyst VO(PO3)2
showed remarkable catalytic activity with respect to other catalytic system; conversion and selectivity
with respect to aldehyde is 97 and 99%, respectively.
Keywords:
Vanadium phosphate
Benzyl alcohol
Benzaldehyde
tert-Butyl hydroperoxide
Vandyl metaphosphate
© 2011 Elsevier B.V. All rights reserved.
1
. Introduction
Vanadium phosphate materials continue to attract attention of
reactions such as oxidations, oxidative dehydrogenations and
ammoxidations [12–19]. However, VO(PO3)2 catalyst has shown
poor catalytic performance in gas phase oxidation of n-butane to
maleic anhydride when compared to high catalytic performance
of (VO) P O7 catalyst. The poor catalytic performance of VO(PO )
researchers as a well studied heterogeneous catalyst. Recent inter-
est in VPO solid materials stems from their structural diversity and
potential application in catalysis and material science. An astonish-
ing variety of novel phases of this material arises due to versatility
of vanadium in terms of its variable oxidation states (III, IV, V)
and co-ordination geometry (tetrahedral, square pyramidal and
octahedral). There are many well characterized, crystalline VPO
phases were identified whose structure and catalytic properties
have been well documented. Some of the most widely studied are
2
2
3 2
catalyst in n-butane oxidation has made to test its application in
other reactions.
Liquid phase oxidation of benzyl alcohol is a hot topic in modern
organic synthesis. The design and development of a catalyst with
high conversion and selectivity for partial oxidation must also be
carried out with regard to the preservation of oil related resources.
For selective oxidation reactions, there is tremendous challenge
to prevent over oxidation of the products, which are often more
sensitive to be oxidized than the reactants. The direct oxidation
of benzyl alcohol to benzaldehyde is such type of reaction. Ben-
zaldehyde is a chief raw material in the synthesis of other organic
compounds, ranging from pharmaceuticals to plastic additives. It is
also an important intermediate for the processing of perfume and
flavoring compounds and in the preparation of certain aniline dyes.
Several methods are available for alcohol oxidations using
metal salts in the form of homogeneous catalysis [20–26] or sup-
ported metal ions as heterogeneous catalysts [27–31]. However the
common methods of alcohol oxidation may use toxic, corrosive,
expensive oxidants such as chromium (VI), and setting up a severe
condition, like high pressure or temperature, using strong mineral
acids.
the V5+ vanadyl ortho phosphate (␣-, ␤-, ␥-, ␦-, ␧- and ␻-VOPO )
4
4+
and VOPO ·2H O), and the V
vanadyl hydrogen phosphates
4
2
(
VOHPO ·4H O, VOHPO ·0.5H O, VO(H PO ) ), vanadyl pyrophos-
4
2
4
2
2
4 2
phate ((VO) P O7) and vanadyl metaphosphate (VO(PO ) ).
2
2
3 2
The (VO) P O7 catalyst and its precursor VOHPO ·0.5H O phase
2
2
4
2
have been extensively studied, including preparation procedures,
activation conditions, crystal structures, activity and catalytic
kinetics [1–9]. On the other hand, the crystalline VO(PO3)2 cata-
lyst is mostly a combination of amorphous VO(PO ) , monoclinic
3
2
␣
-VO(PO3)2 [10] and tetragonal ␤-VO(PO3)2 phases [11]. The crys-
talline VO(PO3)2 was obtained from calcination of VO(H PO )
phase under air flow conditions. The catalytic performance of
both VO(PO3)2 and (VO) P O7 have been evaluated in gas phase
2
4 2
2
2
Structural stability, heterogeneity, deactivation rates and recy-
clability of the solid acid catalysts are still critical impending to
the liquid phase reaction’s impact on solid catalyst [32]. Although
∗ Corresponding author. Tel.: +91 674 2581636 425; fax: +91 674 2581637.
E-mail address: paridakulamani@yahoo.com (K.M. Parida).
0
926-860X/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.apcata.2011.11.016

2
46
G.C. Behera, K.M. Parida / Applied Catalysis A: General 413–414 (2012) 245–253
2.2. Catalytic tests
In a typical reaction procedure, a mixture of 0.05 g catalyst,
acetonitrile (15 ml, S.d. fine, 99.0%) and benzyl alcohol (30 mmol,
S.d. fine, 99.5%) was stirred in a three-necked glass batch reac-
tor equipped with a double walled air condenser and magnetic
stirrer. The reaction was carried out under atmospheric N2 at
◦
5
0 C for 30 min. Then the oxidant tert-butyl hydroperoxide (TBHP)
(
30 mmol, Merck, 70%) was added and the mixture was refluxed
◦
at 80 C for 6 h. The reaction mixture was altered and the prod-
ucts were isolated by column chromatography and then analyzed
by offline GC (Shimadzu, GC-17A) equipped with capillary column
(ZB-1, 30 m length, 0.5 nm ID and 3.0 ␮m film thickness) using
flame ionization detector (FID). The main products were then quan-
tified by HPLC (equipped with a C18 column) with UV–vis detector.
The conversion, selectivity and yield were calculated by using Eqs.
(1)–(3).
moles of benzyl alcohol reacted
total moles of benzyl alcohol
Conversation (%) =
×100 (1)
× 100 (2)
× 100 (3)
Fig. 1. XRD patterns of the (a) VO(H2PO4)2 and (b) VO(PO3)2.
moles of product formed
Selectivity (%) = moles
of benzyl alcohol reacted
mole amount of product
mole amount of benzyl alcohol
Yield (%) = initial
VPO catalyst system has been studied extensively in gas phase
oxidations, including the catalyst structure stability, morphol-
ogy, crystalline structure, surface composition after hundreds
hours of testing, these type of studies are very limited in liquid
phase reactions. It is well known that VPO catalysts are struc-
tural sensitive to its catalytic activation and reaction conditions
3
. Results and discussion
3.1. X-ray diffraction
[
33–35].
Herein, we investigated the impact of benzyl alcohol oxidation
reaction on VO(PO ) catalysts structures, micro structural proper-
Fig. 1 shows the XRD patterns of VPO materials. For the precur-
3
2
sor, all major diffraction peaks can be attributed to VO(H PO ) .
2
4 2
ties and their recyclability performance. The main purpose of our
investigation is to prove the catalytic activity of VO(PO3)2 in liquid
phase reaction. The catalysts were characterized by powder XRD,
XPS, SEM, FTIR and BET surface area techniques.
◦
The highly intense (0 0 1) peak at 2ꢀ = 13.9 corresponds to the
reflectance patterns of VO(PO ) . Besides this, additional peaks are
present with most intense line at d = 2.94 A˚ . The most intense peak
3
2
◦
at 2ꢀ = 15.5 corresponds to the reflectance patterns of VO(H PO )
2
4
2
with d value = 3.11 A˚ . The XRD patterns reveal that the (0 0 1) peak
for VO(H PO ) is shifted to lower end after activation i.e. in the
2
4 2
2
2
2
. Experimental
VO(PO3)2 phase. This is in accordance with JCPDS file 4-880. After
◦
activation, the intensity of the peak at 2ꢀ = 13.9 increases while the
.1. Materials and methods
◦
◦
◦
peak at 2ꢀ = 15.5 gets decreased. The peaks at 2ꢀ = 11.09 and 12.3
can be attributed to the presence of V5+ species (␦-VOPO ), which
4
.1.1. Preparation of catalyst
The vanadyl hydrogen phosphate precursor was prepared
suggest the well crystallinity of the material. The crystallite size (D)
of VPO catalyst was determined from (0 0 1) plane of VO(PO3)2 by
employing Scherer’s formula:
according to the procedure as follows: V O5 (5.0 g, Strem, 99%) and
o-H PO (30 ml, 85% Aldrich) was refluxed with isobutanol for 24 h.
2
3
4
The solid was recovered by vacuum filtration, washed with cold
water (100 ml) and acetone (100 ml) and dried in air (110 C, 24 h).
kꢁ
D =
◦
ˇ cos ꢀ
The VO(H PO ) precursors thus obtained was calcined in air at
2
4 2
◦
00 C for 5 h.
5
For which ꢁ is the wave length of the X-ray (Mo K␣), ˇ is the full
width at half maximum of the diffraction peak, k is a shape factor
(
0.94) and ꢀ is the angle of diffraction. The intensity of the XRD
2
.1.2. Characterization of catalyst
Phase analysis of the material was performed by X-ray diffrac-
peaks, as well as the sharpness indicates high crystallinity and also
large crystallite size. The crystallite size of the catalyst was found
to be 24.3 nm.
tion (XRD, P ANAlytical) using Mo K␣ radiation of 0.7093 A˚ .
The FE-SEM was performed with a ZEISS 55 microscope. Mag-
nification in the range 15.83–44.90 K has been used to get a better
micrograph.
3.2. Scanning electron microscope studies
The X-ray photoelectron spectroscopy (XPS) measurements
were performed on a VG Microtech Multilab ESCA 3000 spectrome-
ter with a non-monochromatized with Mg K␣ X-ray source. Energy
resolution of the spectrometer was set at 0.8 eV with Mg K␣ radi-
ation at pass energy of 50 eV. The binding energy correction was
performed using the C 1s peak of carbon at 284.9 eV as a reference.
Fig. 2 shows the FE-SEM micrograph of VO(PO ) . The SEM
3
2
picture of the material revealed that the samples possess slate
like morphology. Further, aggregates without regular shapes are
observed in VO(PO ) . This is the reason for the low surface area of
3
2
the VO(PO3)2 catalyst.

G.C. Behera, K.M. Parida / Applied Catalysis A: General 413–414 (2012) 245–253
247
Fig. 2. Scanning electron micrograph of VPO.
3.3. X-ray photoelectron spectroscopy (XPS) studies
The XPS-investigations reported herein were aimed towards the
determination of the vanadium oxidation state present in the cat-
alyst sample. The representative photoelectron peaks of O 1s, V
2
p3/2, P 2p are depicted in Fig. 3(a), (b) and (c) respectively. Since
controversial interpretations of the right broad V 2p3/2 photoelec-
tron peak as well as somewhat contradictory values for the binding
n+
energies for the V contributions is found in the literature, VOPO4
with phase structure found by UV–vis spectra was used to calibrate
5+
the binding energy of the reference V 2p3/2 (V ) peak. The mea-
sured value of 517.3 eV and the independently obtained value of
4
+
5
16 eV for V state [36] are in a good agreement with the liter-
ature [37–39], and were used for the V 2p3/2 peak deconvolution
for VO(PO ) catalyst studied herein. The high resolution P 2p with
3
2
binding energy 134 eV corresponding to a formal effective oxida-
tion state of +5 was depicted in Fig. 3(c). Binding energy value
5
O
31.8 eV of the O 1s peak indicated that the oxygen species was
2
−
in oxides, and therefore the increase of O/V ratio supports the
4+
fact that a measurable fraction of V at the equilibrated surface is
oxidized to V
5
+
.
The calcined VPO catalysts showed vanadyl metaphosphate
VO(PO3)2 as the predominant phase present in addition to some
VOPO4 phase. P/V ratios in the precursor higher than stoichiomet-
ric stabilize the VO(PO3)2 phase from re-oxidation in the reactant
atmosphere as well as during calcination in air at high temperatures
Fig. 3. XPS spectra of (a) O 1s, (b) V 2p and (c) P 2p.
[
40]. It has been suggested that VPO catalysts may be terminated by
a distorted vanadyl pyrophosphate structure [41], which may result
in the generation of more Lewis (V4 and Bronsted (P–OH) acid
sites on the catalyst surface. It is also reported that maximum cat-
alytic performance requires a certain degree of disorder in the VPO
lattice [42,43]. XPS studies have shown that catalysts calcined at
+)
incorporated latter. Hence the presence of couple V4+/V5+ on the
surface of our material facilitates the reaction. This is in good
agreement with the literature [45]. Experimental results on pure
vanadium phosphate phases and active catalysts suggest that the
◦
5+
lower temperatures (<750 C) contain superficial V species [44].
From the above physical properties it has been found that the
5+
active catalyst is vanadyl metaphosphate with domains of V
on the (1 0 0) face. Thus V4+/V couple is the active site, which
is present on the surface of a range of vanadyl meta-phosphate
phases.
5+
material contains V4+ phase along with a little V phase. We have
5+
4
+
studied from the literature that the oxygen associated with V
activates the substrate while the oxygen associated with V5+ is

2
48
G.C. Behera, K.M. Parida / Applied Catalysis A: General 413–414 (2012) 245–253
Table 1
a
Benzyl alcohol conversion using various heterogeneous catalysts .
Catalyst
Oxidant
Time (h)
Benzyl alcohol
conversion (%)
Aldehyde
selectivity (%)
Yield (%)
Reference
Without catalyst
VO(PO3)2
VO(PO3)2
TBHP
TBHP
–
O2
TBHP
O2
TBHP
O2
O2
TBHP
TBHP
O2
TBHP
TBHP
TBHP
6
6
6
6
1
6
5
1.5
10
97
53
66
30
8
50
16
1
60
20
45
53
100
63
30
99
48
78
82
3
96
25
51
24
8
42
15
0.5
42
–
–
Our catalyst
Our catalyst
Our catalyst
[54]
[47]
[49]
[48]
[46]
[53]
[51]
VO(PO3)2
Ru 1.9/TiO2
H5PV2Mo10O40
Mn-Cr-LDH
RuO2
CuCl
Co-Cr-LDH
CuCl2
100
84
99
50
70
–
98
100
85
79
48
5
17
1
8
2
PdO·CuO·3H2O
44
53
85
50
[50]
[55]
[56]
[57]
[Co(bpy)2]/bentonite
Au/U3O8
Au/TiO2
2
a
◦
Conditions: catalyst: 0.05 g, temp.: 80 C, molar ratio: (1:1) (substrate:oxidant).
Table 2
Conversion of TBHP with and without benzyl alcohol.
constant. But the yield for benzaldehyde was increased up to 6 h
and then slightly decreased. The decrease in benzaldehyde yield
was due to the increase in benzyl benzoate formation. With the
progress of the reaction time benzaldehyde gets oxidized to benzoic
acid. From Fig. 4, it was concluded that 6 h was the optimum reac-
tion period to achieve high degree of benzaldehyde product. It is
interesting to note that benzyl benzoate was the only other product
formed apart from benzaldehyde and the formation of benzoic acid
was not at all detected in GC analysis. This is expected because of the
fact that the benzoic acid formed in the oxidation reaction instantly
react with the benzyl alcohol, thereby increasing the benzyl alcohol
conversion, forming benzyl benzoate (Scheme 1).
Entry
Substrate
Oxidant
Benzyl alcohol
conversion (%)
TBHP
conversion (%)
1
2
3
Benzyl alcohol
–
Benzyl alcohol
TBHP
TBHP
–
97
–
53
99
96
–
◦
Conditions: catalyst: 0.05 g, substrate:oxidant molar ratio(1:1), temp.: 80 C, time:
6
h.
3.4. Catalytic reaction
The oxidation of benzyl alcohol over VO(PO3)2 using TBHP was
carried out and the result was illustrated in Table 1 along with the
various catalytic systems. The present catalyst VO(PO3)2 showed
remarkable catalytic activity with respect to other catalytic system
3
.4.2. Effect of reaction temperature
Oxidation of benzyl alcohol was carried out at 40, 60, 80 and
◦
1
00 C in the same reaction conditions. The results were illustrated
[
46–57]. For our catalytic system, the conversion and selectivity
in Fig. 5. Although VPO material uses its lattice oxygen at higher
temperature in gas phase oxidation, the use of oxidant in liquid
phase made it easy to carry out the reaction at lower temperature.
As expected the influence of reaction temperature on benzyl alco-
hol conversion is very strong. However the yield for benzaldehyde
is influenced appreciably only when the temperature is increased
from 80 to 100 C. The catalyst showed promising results at 80 C
that means 80 C is the optimum temperature for this reaction.
The decrease in yield with amplifying temperature is due to over
with respect to aldehyde is 97 and 99%, respectively. Therefore this
catalytic system is suitable for the oxidation of alcohols. A typical
reaction involving TBHP without benzyl alcohol was carried out and
the results were given in Table 2.
3.4.1. Effect of reaction period
◦
◦
◦
Fig. 4 shows the influence of reaction time on benzyl alcohol oxi-
dation. When the reaction time was increased from 1 to 10 h, the
benzyl alcohol conversion continuously increases and then remains
Fig. 4. Effect of time period on benzyl alcohol conversion and benzaldehyde selec-
tivity. Conditions: catalyst: 0.05 g, temp.: 80 C, molar ratio: (1:1).
Fig. 5. Effect of temperature on benzyl alcohol conversion and benzaldehyde selec-
tivity. Conditions: catalyst: 0.05 g, time: 6 h, molar ratio: (1:1).
◦

G.C. Behera, K.M. Parida / Applied Catalysis A: General 413–414 (2012) 245–253
249
OH
O
VPO
Benzaldehyde
Benzyl alcohol
O
O
OH
Benzaldehyde
Benzoicacid
O
OH
OH
O
O
+
Benzyl alcohol
Benzaldehyde
Benzyl benzoate
Scheme 1. Catalytic oxidation reaction.
Table 3
Effect of solvents on oxidation of benzyl alcohol .
oxidation of benzaldehyde to benzoic acid which subsequently
reacted with benzyl alcohol to form benzyl benzoate.
a
Solvent
Dipole moment (D) Conversion (%) Selectivityb (%) Yield (%)
Acetonitrile 3.92
Chloroform 1.04
97
48
75
99
90
99
96
43
74
3
.4.3. Effects of solvents
The results of oxidation of benzyl alcohol in different solvents
Toluene
0.37
were depicted in Table 2. It is evident from the fact that the behavior
of benzyl alcohol oxidation in various solvents is conspicuously dif-
ferent. Acetonitrile showed the best conversion results followed by
toluene. The observed lower benzyl alcohol conversion utility of the
catalyst in the presence of different solvents is mostly attributed to
the competitive adsorption between the solvents and benzyl alco-
hol on the catalyst and thereby occupying part of the active sites of
the catalyst by the adsorbed solvent molecules. However the lower
conversion value for chloroform is due to the presence of lone pair
of electrons on chlorine that attach to the strong Lewis acid sites of
a
◦
Conditions: catalyst: 0.05 g, temp.: 80 C, molar ratio: (1:1) (substrate:oxidant),
time: 6 h.
b
Benzaldehyde.
the VO(PO ) . In case of toluene the decrease in conversion value is
3
2
due to the low solubility of TBHP in a nonpolar solvent as a result of
which the reaction could not proceed. Acetonitrile readily dissolved
TBHP along with the benzyl alcohol as it is polar and having a very
high dielectric constant. This facilitates the adsorption of reactions
on the catalyst surface and increases the efficiency of the conver-
sion. The catalytic evaluation of VO(PO ) with different substrates
3
2
was also performed and the results are depicted in Table 3.
3.4.4. Effect of catalyst loadings
Fig. 6 shows the effect of catalyst loadings on benzyl alcohol
oxidation. Note that the variation was studied at 6 h of reaction time
since it was the optimum time period for this reaction. It has been
found that with the increase of catalyst amount the conversion and
yield increases. This may presumably due to the availability of more
active sites of the catalyst. Increasing the catalyst amount to 0.05 g
◦
Fig. 6. Effect of catalyst loadings. Conditions: time: 6 h, temp.: 80 C, molar ratio:
1:1) (substrate:oxidant).
(

2
50
G.C. Behera, K.M. Parida / Applied Catalysis A: General 413–414 (2012) 245–253
◦
Fig. 7. Effect of amount of catalyst on benzyl alcohol conversion with shorter time. Conditions: time: 2 h, temp.: 80 C, molar ratio: (1:1) (substrate:oxidant).
improved the conversion to 97% within 6 h of time. However the
conversion and yield remain nearly same upon further increasing
the catalyst amount to 0.07 g, which suggests that large amount of
catalyst is not needed to improve the reaction product. However
when the effect of amount of catalyst (0.01–0.07 g) was studied
verses the benzyl alcohol conversion for shorter reaction time, a
linear relation was obtained from which indicates that there was no
contribution of homogeneity in the reaction (Fig. 7). Again when it
was plotted from 0 to 0.07 g a non-monotonous conversion change
was obtained with shorter time.
3.5. Heterogeneity test
To determine whether the catalyst is functioning in a heteroge-
neous manner, a hot filtration test was performed in the oxidation
reaction. During the catalytic oxidation of benzyl alcohol, the solid
catalyst was separated from the reaction mixture by filtration
after 3 h of the reaction and the filtrate obtained was continuously
stirred under same reaction conditions for further 3 h. GC analy-
sis showed no increment in the conversion. ICP-OES (Optima 2100
DV, PerkinElmer) using a microwave pressure digestion (MDS 200;
CEM) with hydrofluoric acid and aqua regia at 9 bar was used to
analyze the chemical composition of fresh and used catalyst. The
sample was analyzed thrice and the results presented here are the
average values. The results are given in the Table 4. This fact sug-
gests that there is no loss of catalyst components during the course
3.4.5. Effect of molar ratio of substrate to oxidant
The activity of VO(PO3)2 catalyst in the oxidation of benzyl
alcohol was also evaluated using three different molar ratios of sub-
strate to oxidant. The effect of substrate oxidant molar ratio on the
oxidation of benzyl alcohol is depicted in Fig. 8. Conversion of 97%
was achieved at the substrate oxidant molar ratio 1:1 in 6 h when
of reaction which confirmed the heterogeneity of the catalyst. The
P/V ratio detected here indicates the presence of V4+ species in the
materials. From the literature it has been found that a P/V ratio > 1
is necessary for high catalytic performance [58]. It has also been
studied that at P/V ratios of less than 1.0, a number of vanadium
sites remain inactive but at the higher P/V ratios all surface sites
are active [59]. This is in good agreement with our results. Ele-
mental analysis of liquid after the reaction was also performed.
Vanadium leaching was very negligible during the reaction. The
vanadium concentration in the filtrate is less than 1 ppb as found
by ICP and also by AAS (Table 5).
3
0 mmol of benzyl alcohol reacted with 30 mmol of TBHP in ace-
◦
tonitrile medium at 80 C. Increasing the ratio to 1:2 improved the
conversion to 98%, while further increase of TBHP showed no such
improvement in conversion.
3.6. Recapability of the catalyst
The recapability performance of VO(PO ) for 4 cycles batch oxi-
3
2
dation reaction is illustrated in Fig. 9. After the reaction with benzyl
alcohol VPO was separated from the reaction mixture by centrifu-
gation, thoroughly washed with acetone and then reused as catalyst
for the next run under the same conditions. The catalyst did not
show any significant change in the activity after 24 h. The conver-
sion showed to stabilize in a range of between 95 and 97% with
benzaldehyde selectivity remaining fairly constant between 98 and
9
9%. The slight deactivation of the catalyst may presumably due to
the adsorption of large polar molecules that resulted from the by-
product reactions on the surface of the catalyst. The adsorption of
polar molecules on the catalyst surface is usually temporary and
can be resolved by calcination of the catalyst at high temperature
to recover its activity.
Fig. 8. Effect of molar ratio of substrate to oxidant.

G.C. Behera, K.M. Parida / Applied Catalysis A: General 413–414 (2012) 245–253
251
Table 4
a
Catalytic activity evaluation of VPO with various alcohols .
Entry
1
Time (h)
Substrate
Product
Conversion (%)
84
Yield (%)
83
Yield (%) of byproduct
Cl
Cl
6
1
2
3
O
OH
OH
O
O
2
3
6
6
89
92
86
88
S
S
OH
N
N
4
5
6
6
6
6
87
93
91
78
92
89
8
1
2
OH
O
OH
O
OH
O
OH
O
7
6
95
94
1
OH
O
8
9
4
4
86
90
85
89
1
1
OH
O
1
0
6
85
84
1
OH
O
Br
Br
OH
O
1
1
1
2
4
3
96
95
94
94
2
1
OH
OH
O
O
O
1
1
3
4
5
6
95
94
94
94
1
0
O
O
OH
O N
2
2
O N
1
1
5
6
5
5
88
96
88
95
0
1
OH
O
S
S
O
OH

2
52
Table 4 (Continued)
Entry Time (h)
G.C. Behera, K.M. Parida / Applied Catalysis A: General 413–414 (2012) 245–253
Substrate
Product
Conversion (%)
90
Yield (%)
90
Yield (%) of byproduct
0
N
OH
N
O
1
7
10
6
1
8
84
83
1
OH
o
O
a
◦
Conditions: catalyst: 0.05 g, temp.: 80 C, molar ratio: (1:2) (substrate:oxidant).
Table 5
Estimation of component of catalyst by ICP-OES.
Catalyst
V
P
P/V
Fresh
18.7
Used
Fresh
28.91
Used
VO(PO3)2
18.69
28.90
1.54
Conv.(%)
Sel.(%)
Acknowledgment
1
00
100
80
60
40
20
0
The authors are thankful to Prof. B.K. Mishra, Director, IMMT,
and Bhubaneswar for his interest, encouragement and kind per-
mission to publish this work.
8
0
6
0
References
[
1] C.J. Kiely, A. Burrows, S. Sajip, G.J. Hutchings, M.T. Sananes, A. Tuel, J.C. Volta, J.
Catal. 162 (1996) 31–47.
4
0
[
2] L. O’Mahony, T. Curtin, D. Zemlyanov, M. Mihov, B.K. Hodnett, J. Catal. 227
(
2004) 270–281.
2
0
[3] E.V. Murashova, N.N. Chudinova, Kristallografuya 39 (1994) 145–146.
[
[
[
4] V.V. Guliants, J.B. Benziger, S. Sundaresan, I.E. Wachs b, J.M. Jehng, J.E. Roberts,
Catal. Today 28 (1996) 275–295.
5] L. O’Mahony, T. Curtin, J. Henry, D. Zemlyanov, M. Mihov, B.K. Hodnett, Appl.
Catal. A: Gen. 285 (2005) 36–42.
6] H. Imai, Y. Kamiya, T. Okuhara, J. Catal. 255 (2008) 213–219.
0
1
2
3
4
No.of cycles
[7] V.V. Guliants, S.A. Holmes, J.B. Benziger, P. Heaney, D. Yates, I.E. Wachs, J. Mol.
Catal. A: Chem. 172 (2001) 265–276.
[
8] N. Ballarini, F. Cavani, C. Cortelli, M. Ricotta, F. Rodeghiero, F. Trifiro‘, C. Fuma-
galli, G. Mazzoni, Catal. Today 117 (2006) 174–179.
Fig. 9. Recapability performance of VO(PO3)2.
[
9] H. Kleimenov, M. Bluhm, A. Hävecker, A. Knop-Gericke, A. Pestryakov, D.
Teschner, J.A. Lopez-Sanchez, J.K. Bartley, G.J. Hutchings, R. Schlögl, Surf. Sci.
5
75 (2005) 181–188.
10] F.K. Hannour, A. Martin, B. Kubias, B. Lücke, E. Bordes, P. Courtine, Catal. Today
0 (1998) 263–272.
11] C.C. Toradi, J.C. Calabrese, Inorg. Chem. 23 (1984) 1308–1310.
[
4
. Conclusions
In summary, we have successfully synthesized vanadyl
4
[
[12] N. Hiyoshi, N. Yamamoto, N. Ryumon, Y. Kamiya, T. Okuhara, J. Catal. 221 (2004)
25–233.
13] J. Guan, H. Xu, S. Jing, S. Wu, Y. Ma, Y. Shao, Q. Kan, Catal. Commun. 10 (2008)
76–280.
[14] A. Martin, C. Janke, V.N. Kalevaru, Appl. Catal. A: Gen. 376 (2010) 13–18.
2
metaphosphate with a beautiful plate like morphology and proved
that this material can be used in liquid phase reaction. The cat-
alytic activity of the material was investigated by examining its
use in the selective oxidation of benzyl alcohol to benzaldehyde
using TBHP as oxidant. Excellent conversion and selectivity of this
catalyst towards the oxidation of benzyl alcohol was observed. The
material is also effective for the oxidation of other organic sub-
strates. The catalyst can be recycled several times without any loss
in conversion and selectivity. This suggests its reusability and sta-
bility. Easy product recovery and recycling efficiency along with
high selectivity of this material may be useful for the synthesis of
different chemicals under eco-friendly conditions. This cheap pro-
cess could be of great interest for selective oxidation of primary
alcohol. We anticipate that our findings will initiate attempts to
understand the detailed mechanism of oxygen activation at cata-
lyst surfaces, which might lead to commercial exploitation of the
[
2
[
15] F. Wang, J.L. Dubois, W. Ueda, J. Catal. 268 (2009) 260–267.
16] J.A. Lopez-Sanchez, R. Tanner, P. Collier, R.P.K. Wells, C. Rhodes, G.J. Hutchings,
Appl. Catal. A: Gen. 226 (2002) 323–327.
[
[17] B. Solsona, V.A. Zazhigalov, J.M. López Nieto, I.V. Bacherikova, E.A. Diyuk, Appl.
Catal. A: Gen. 249 (2003) 81–92.
[
18] H. Feng, J.W. Elam, J.A. Libera, M.J. Pellin, P.C. Stair, J. Catal. 269 (2010) 421–431.
19] M.P. Casaletto, L. Lisi, G. Mattogno, P. Patrono, G. Ruoppolo, G. Russo, Appl. Catal.
A: Gen. 226 (2002) 41–48.
[
[
[
20] R.A. Sheldon, I.W.C.E. Arends, A. Dijkman, Catal. Today 57 (2000) 157–166.
21] W.P. Griffith, J.M. Joliffe, in: L.L. Simandi (Ed.), Dioxygen Activation and Homo-
geneous Catalytic Oxidation, Elsevier, Amsterdam, 1991.
[22] H. Sugimoto, D.T. Sawyer, J. Org. Chem. 50 (1985) 1784–1786.
[
[
23] C. Sheu, D.T. Sawyer, J. Am. Chem. Soc. 112 (1990) 8212–9213.
24] N. Wonwoo, H. Raymond, S.J. Valentine, J. Am. Chem. Soc. 113 (1991)
7052–7054.
[25] C.Y. Lorber, J.A. Osborn, Tetrahedron Lett. 37 (1996) 853–856.
[26] R.W. Kaziro, J.K. Beattie, Aust. J. Chem. 42 (1989) 1273–1279.
27] R.S. Chandran, W.T. Ford, Chem. Soc. Chem. Commun. 46 (1988) 104–105.
28] H. Turk, W.T. Ford, J. Org. Chem. 53 (1988) 460–462.
29] S. Ivanov, R. Boeva, S. Tainelyan, J. Catal. 56 (1979) 150.
[
[
[
high catalytic activity of VO(PO ) . Further research will emphasize
additional catalytic application.
3
2

G.C. Behera, K.M. Parida / Applied Catalysis A: General 413–414 (2012) 245–253
253
[
30] M. Floor, A.P.G. Kieboom, H. van Bekkum, Recl. Trav. Chim. Pays-Bas 107 (1988)
62.
31] T.J. Pinnavia, M.S. Tzou, S.D. Landau, J. Am. Chem. Soc. 107 (1985) 4783–
785.
[45] G.J. Hutchings, C.J. Kiely, M.T. Sananes-Schulz, A. Burrows, J.C. Volta, Catal.
Today 40 (1998) 273–286.
[46] D. Brunel, F. Fajula, J.B. Nagy, B. Deroide, M.J. Verhoef, L. Veum, J.A. Peters, H.
van Bekkum, Appl. Catal. A 213 (2001) 73–82.
3
[
4
[
[
32] I.W.C.E. Arends, R.A. Sheldon, Appl. Catal. A: Gen. 212 (2001) 175–187.
33] M. Di Serio, M. Cozzolino, R. Tesser, P. Patrono, F. Pinzari, B. Bonellic, E. San-
tacesaria, Appl. Catal. A: Gen. 320 (2007) 1–7.
[47] A.M. Khenkin, R. Neumann, J. Org. Chem. 67 (2002) 7075–7079.
[48] B.Z. Zhan, M.A. White, T.K. Sham, J.A. Pincock, R.J. Doucet, K.V.R. Rao, K.N.
Robertson, T.S. Cameron, J. Am. Chem. Soc. 125 (2003) 2195–2199.
[49] V.R. Choudhary, P.A. Chaudhari, V.S. Narkhede, Catal. Commun. 4 (2003)
171–174.
[34] C. Carlini, P. Patrono, A.M.R. Galletti, G. Sbrana, V. Zima, Appl. Catal. A: Gen. 289
(
2005) 197–204.
[
[
35] Z.Y. Xue, G.L. Schrader, J. Phys. Chem. 103 (1999) 9459–9467.
36] Y. Suchorski, L. Rihko-Struckmann, F. Klose, Y. Ye, M. Alandjiyska, K. Sund-
macher, H. Weiss, Appl. Surf. Sci. 249 (2005) 231–237.
[50] T.L. Stuchinskaya, I.V. Kozhevnikov, Catal. Commun. 4 (2003) 417–422.
[51] G. Ferguson, A. Nait Ajjou, Tetrahedron Lett. 44 (2003) 9139–9142.
[52] R. Ganesan, B. Viswanathan, J. Mol. Catal. A: Chem. 181 (2002) 99–107.
[53] V.R. Choudhary, D.K. Dumbre, B.S. Uphade, V.S. Narkhede, J. Mol. Catal. A: Chem.
215 (2004) 129–135.
[37] S. Albonetti, F. Cavani, F. Trifiro, P. Venturoli, G. Calestani, M. Lopez Granados,
J.L. Fierro, J. Catal. 160 (1996) 52–64.
[
[
[
[
38] M. Abon, K.E. Bere, A. Tuel, P. Delishere, J. Catal. 156 (1995) 28–36.
39] P. Delishere, K.E. Bere, M. Abon, Appl. Catal. A: Gen. 172 (1998) 295–309.
40] F. Trifiro, Catal. Today 41 (1998) 21–35.
41] W.P.A. Jansen, M. Ruitenbeck, A.W.D. von der Gon, J.W. Geus, H.H. Brongersma,
J. Catal. 196 (2000) 379–387.
[54] A. Kockritz, M. Sebek, A. Dittmar, J. Radnik, A. Bruckner, U. Bentrup, H. Hugl, W.
Magerlein, J. Mol. Catal. A: Chem. 246 (2006) 85–99.
[55] M.H. Peyrovi, V. Mahdavi, M.A. Salehi, R. Mahmoodian, Catal. Commun. 6 (2005)
476–479.
[56] V.R. Choudhary, D.K. Dumbre, Appl. Catal. A: Gen. 375 (2010) 252–257.
[57] V.R. Choudhary, D.K. Dumbre, Ind. Eng. Chem. Res. 48 (2009) 9471–9478.
[58] F. Garbasi, J.C.J. Bart, F. Montino, G. Petrini, Appl. Catal. 16 (1985) 271–287.
[59] A. Satsuma, A. Hattori, K. Mizutani, A. Furuta, A. Miyamoto, T. Hattori, Y.
Murakami, J. Phys. Chem. 93 (1989) 1484–1490.
[
[
42] A. Bruckner, B. Kubias, B. Lücke, Catal. Today 32 (1996) 215–222.
43] J. Haber, V.A. Zazhigalov, J. Stoch, L.V. Bogutskaya, I.V. Batcherikova, Catal. Today
3
3 (1997) 39–47.
[44] M. Abon, J.M. Herrmann, J.C. Volta, Catal. Today 71 (2001) 121–128.