Studies on calcined cow bone and pyrolyzed wood, suitable supports for immobilizing hybrid nano particles of Co-Mn as new catalysts for oxidation of 2,6-diisopropyl naphthalene

Article abstract of DOI:10.1016/j.apcata.2013.02.013

Catalytic oxidation of 2,6-diisopropylnaphthalene (2,6-DIPN) to 2,6-naphthalene dicarboxylic acid (2,6-NDCA) was studied with two new catalysts prepared by immobilization of Co/Mn nano-hybrid particles over calcined cow bone, and pyrolyzed wood. The catalysts have the advantage of very cheap supports, and easy catalyst recovery. The effects of Co/Mn atomic ratio, reaction time and temperature, oxygen pressure, amount of catalyst, and the support on the conversion of 2,6-DIPN and product/intermediate yields were investigated. There was an interesting synergistic effect of cobalt and manganese catalysts. The maximum product (2,6-NDCA) yield was 100%, obtained at a Co/Mn atomic ratio of 10 supported on pyrolyzed wood. Lower cobalt concentration resulted the lower 2,6-NDCA yield, which was ascribed to the intermediate products formation. The catalysts were characterized in detail by SEM/EDS, BET surface area, and TEM measurements. Transmission electron microscopy (TEM) measurements indicated nanoparticles (diameter of about 2-5 nm) on the surface of the supports.

Full text of DOI:10.1016/j.apcata.2013.02.013

Applied Catalysis A: General 456 (2013) 51–58
Contents lists available at SciVerse ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Studies on calcined cow bone and pyrolyzed wood, suitable supports
for immobilizing hybrid nano particles of Co-Mn as new catalysts for
oxidation of 2,6-diisopropyl naphthalene
Atefeh Mardani Ghahfarrokhi, Parisa Moshiri, Mehran Ghiaci∗
Department of Chemistry, Isfahan University of Technology, P.O. Box 84156-83111, Isfahan, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Catalytic oxidation of 2,6-diisopropylnaphthalene (2,6-DIPN) to 2,6-naphthalene dicarboxylic acid (2,6-
NDCA) was studied with two new catalysts prepared by immobilization of Co/Mn nano-hybrid particles
over calcined cow bone, and pyrolyzed wood. The catalysts have the advantage of very cheap supports,
and easy catalyst recovery. The effects of Co/Mn atomic ratio, reaction time and temperature, oxygen
pressure, amount of catalyst, and the support on the conversion of 2,6-DIPN and product/intermediate
yields were investigated. There was an interesting synergistic effect of cobalt and manganese catalysts.
The maximum product (2,6-NDCA) yield was 100%, obtained at a Co/Mn atomic ratio of 10 supported
on pyrolyzed wood. Lower cobalt concentration resulted the lower 2,6-NDCA yield, which was ascribed
to the intermediate products formation. The catalysts were characterized in detail by SEM/EDS, BET
surface area, and TEM measurements. Transmission electron microscopy (TEM) measurements indicated
nanoparticles (diameter of about 2–5 nm) on the surface of the supports.
Received 29 October 2012
Received in revised form 27 January 2013
Accepted 13 February 2013
Available online xxx
Keywords:
Hybrid nanoparticles
Catalyst
Oxidation
Cow bone
Pyrolyzed wood
2,6-Diisopropylnaphthalene
© 2013 Elsevier B.V. All rights reserved.
1. Introduction
zeolites [2–4]. As mentioned, the most elegant route to 2,6-NDCA
might be the direct oxidation of 2,6-dimethylnaphthalene or 2,6-
Fibers and films produced from polyethylenenaphthalate have
improved strength and thermal properties relative to fibers and
films produced from polyethyleneterephthalate and are especially
useful in applications such as cords, magnetic tape backings and
hot-fill containers [1]. However, the use of 2,6-naphthalene dicar-
boxylic acid (2,6-NDCA) is inhibited by its relatively high cost,
which is due to the relative unavailability and high cost of the pre-
ferred feedstock, 2,6-dimethylnaphthalene, which can be readily
oxidized to 2,6-naphthalene dicarboxylic acid under conditions
that are conventional for the oxidation of alkylated aromatics under
liquid phase conditions, in a solvent, at elevated temperature and
pressure, by an oxygen containing gas, and in the presence of a
catalyst comprising cobalt, manganese and bromine components.
In this regards, effective utilization of 2,6-diisopropylnapht-
halene (2,6-DIPN) for more value-added products is also an
interesting proposition. Competitive processes for synthesis
of 2,6-NDCA by oxidation are mainly (a) various modi-
fied Henkel processes, (b) diiodonaphthalene carbonylation
by Eastman Chemicals and (c) various alkyl aromatic acyla-
tion, condensation, isomerization and alkylation reactions using
diisopropylnaphthalene according to the MC process (Mid-Century
Corp.). Oxidation of 2,6-DIPN with oxygen with homogeneous
cobalt and manganese containing catalysts has been reported [5,6].
However, these catalysts give rise to many problems such as cat-
alyst recovery and recycling. The classical synthetic laboratory
procedures preferably use stoichiometric oxidants such as per-
manganate or dichromate which are hazardous. In this context,
oxidation of alkyl aromatic compounds over heterogeneous cat-
alysts using oxygen as a cleaner oxidant is an especially attractive
goal.
Nowadays, most of the researches are focused on metal
nanoparticles [7,8]. Due to their large surface area to volume
ratio, they have unique properties such as magnetic, electronic,
optical and chemical behavior compared to bulk materials. High
activity of these catalysts in organic reactions is unique feature.
But the soluble metal nanoparticles have some problems such
as recycling and separation of these catalysts from reactions. To
solve these problems it would be better to immobilize them on
suitable supporting materials, and use them as heterogeneous
catalysts. Controlling the size of particles is an important fac-
tor in the preparation of heterogeneous catalysts. Therefore, most
of current researches have focused on modification of different
supports for immobilization of the active elements in nanoscale
size.
∗
Corresponding author. Tel.: +98 3113913254; fax: +98 3113912350.
E-mail addresses: mghiaci@cc.iut.ac.ir, mehranghiaci@gmail.com (M. Ghiaci).
0926-860X/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.apcata.2013.02.013

52
A. Mardani Ghahfarrokhi et al. / Applied Catalysis A: General 456 (2013) 51–58
Hydroxyapatite Ca10(PO4)6 (OH)2, is not only the main com-
ponent of the hard tissues such as bone, but is a material applied
as adsorbents and catalysts [9]. Bone consists of one firm organic
matrix that is invigorated with calcium and phosphate salts.
Bone inorganic composition (bone mineral) is formed from car-
bonated hydroxyapatite with lower crystallinity. Length of each
crystal is 40 nm, its thickness is between 1 and 3 nm and its
width is 10 nm. Hydroxyapatite is a phosphate mineral that hav-
ing stability and mirror structure, and interesting as biomaterials,
adsorbents and ion-exchangers [10]. Because of its high adsorp-
tion capacity, hydroxyapatite has been intrigued much attention
as support for transition metal catalysts in various reactions. Struc-
ture of pure hydroxyapatite is very similar to hydroxyapatite of
the bone but there are tiny differences between those due to
presence of other ions such as iron in structure of bone hydroxy-
apatite. Due to low price and porous structure, we thought that
bone could be a suitable support for immobilizing Co and Mn
nanoparticles.
This work is the first detailed report of the effect of bone
and wood as convenient and suitable supports on the Co/Mn
catalyst. The effect of varying the Co/Mn ratio, the Co/Mn/Br con-
centration on the 2,6-diisopropyl naphthalene consumption, on the
oxygen uptake, and on the distribution of intermediates is pre-
sented. Moreover in this study we have characterized the catalysts
using different techniques such as TEM, BET, MP-Plot, ICP-AES, and
SEM.
Fig. 1. Impregnation of bone into the solution of Co/Mn.
2.1. Preparation of the supported catalysts by different methods
2.1.1. Preparation of the bone supported catalyst by osmosis
method
2. Experimental
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 (Fig. 1).
After one week, the pieces of the bone were extracted from the solu-
tion. We expected that cobalt and manganese were loaded on the
support. Attained sample was dried at 100 ◦C, and finally calcined at
700 ◦C for 24 h (Co/Mn-BSO0.01). For preparation of a new supported
catalyst which has a lower concentration of the metals, Co/Mn-
BSO0.001, we repeated the above mentioned stages by using 450 mL
aqueous solution of Co(NO3)2·6H2O (0.001 M) that was added to
50 mL aqueous solution of Mn(NO3)2·6H2O (0.001 M).
The reactor and procedures have been previously described [11].
The source of chemicals is Merck chemical company. The cobalt and
manganese salts were the (+II) nitrate hexahydrates. The bromide
source was potassium bromide.
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
initial 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 2,6-diisopropyl naphthalene were con-
firmed by GC/MS (Fisons Instruments 8060, USA).
Scanning electron micrographs were obtained using
a
Cambridge Oxford 7060 scanning electron microscope (SEM)
connected to a four-quadrant backscattered 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 SEM method.
Particle size and morphology were evaluated from the trans-
mission 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 sam-
ple 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).
2.1.2. Preparation of the bone supported catalyst (0.01 M) by
impregnation method
For preparation of this catalyst, Co/Mn-BSI0.01, in the first step,
450 mL aqueous solution of Co(NO3)2·6H2O (0.01 M) was mixed
with 50 mL of an aqueous solution of Mn(NO3)2·6H2O (0.01 M).
Co/Mn molar ratio was 10:1 in the resultant solution. Bones were
cleaned, piecemealed and were put into the solution, and left for a
period of one week. After one week, the mass was heated on a hot
plate to dryness. Therefore, one expects that all of the cobalt and
manganese in the solution were loaded on the support, and finally
calcined at 700 ◦C for 24 h (Co/Mn-BSI0.01).
2.1.3. Preparation of the wood supported catalyst (0.01 M) by
osmosis method
For preparation of this catalyst (Co/Mn-WSOP0.01), in the first
step, 450 mL aqueous solution of Co(NO3)2·6H2O (0.01 M) was
mixed with 50 mL of an aqueous solution of Mn(NO3)2·6H2O
(0.01 M). Co/Mn molar ratio was 10:1 in the resultant solution.
Pieces of the wood were put into the solution for one week (Fig. 2).
After this period, the wood pieces were elicited from the solu-
tion, then dried in air, and pyrolyzed under nitrogen atmosphere.
During pyrolysis process, temperature was increased at a rate of
A PerkinElmer U.S.A., Optima 7300DV inductively coupled
plasma was used for elemental analysis of the catalysts.

A. Mardani Ghahfarrokhi et al. / Applied Catalysis A: General 456 (2013) 51–58
53
Fig. 3. Nitrogen adsorption–desorption isotherm of the Co/Mn-BSO0.01catalyst.
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
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 significant
for the adsorption of 2,6-diisopropylnaphthalene and desorption of
the product molecules such as 2,6-NDCA. SEM micrograph of the
Co/Mn-BSO0.01 catalyst is presented in Fig. 4. The image shows that
the sample is consisted of particles with diameter of 100–500 nm.
SEM/EDS mapping indicated a content of nanoparticles throughout
the catalyst pores that these were related to Co and Mn (Supple-
mentary data). Representative TEM images of the Co/Mn-BSO0.01
catalyst are demonstrated in Fig. 5. Formation of the Co and Mn
nanoparticles over the bone support was confirmed by TEM images.
The average size of the Mn and Co particles was estimated to be
Fig. 2. Impregnation of wood into the solution of Co/Mn.
50 ◦C/h (initial temperature was 250 ◦C and the final temperature
was 700 ◦C). Then the char was powdered and used as wood sup-
ported catalyst (Co/Mn-WSOP0.01).
2.1.4. Catalytic experiments
According to the optimized reaction conditions, the appropri-
ate amount of 2,6-diisopropyl naphthalene, glacial acetic acid as
solvent, solid catalyst and promoter (if needed) 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. Upon the completion of the reaction,
the reaction mixture was transferred to a flask and esterification
performed using H2SO4 according to a known method. This pro-
cess esterifies all the acidic species present. In the next step, the
solid precipitate which mainly consists of catalyst was separated
by centrifugation. The organic phase, which contains the esters
of acid products, unreacted 2,6-diisopropyl naphthalene and other
products was analyzed by GC and identified by GC–MS.
3. Results and discussion
Table 1
3.1. Characterization of the catalysts
Textural properties of the Co/Mn-BSO0.01and Co/Mn-WSOP0.01 catalysts.
Sample
Co/Mna
SBET (m2/g)b
dBJH (nm)c
Vtot (cm3/g)d
3.1.1. The Co/Mn immobilized on the cow bone by osmosis
method
Co/Mn-BSO0.01
Co/Mn-WSOP0.01
10/1
10/1
2.8
95
3.3
2.4
0.63
21.82
Nitrogen adsorption–desorption isotherm of the Co/Mn-BSO0.01
catalyst is demonstrated in Fig. 3. According to IUPAC catego-
rization [12–14], 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
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
pressure of 0.99.

54
A. Mardani Ghahfarrokhi et al. / Applied Catalysis A: General 456 (2013) 51–58
Table 2
Analytical data of the catalysts and supports.
Catalyst (1 g)
Analysis (mmol)
Ca
Na
Mg
Li
K
Sr
Fe
Se
B
Co
Mn
BSOa
7.77
0.26
0.24
0.068
0.021
0.015
0.013
0.010
0.007
0.000
0.169
0.000
0.011
0.000
0.017
0.000
0.001
Co/Mn-BSO0.01
WSOPb
0.96
0.07
0.09
0.03
0.02
0.002
0.005
0.002
0.000
Co/Mn-WSOP0.01
a
Calcined cow bone.
Pyrolyzed wood.
b
contents of the initial bone and the Co/Mn-BSO0.01 catalyst are
reported in Table 2.
Nitrogen adsorption–desorption isotherm of the Co/Mn-
WSOP0.01 catalyst is demonstrated in Fig. 6. The Co/Mn-WSOP0.01
catalyst shows Type
I behavior. However, inspection of the
isotherm reveals that a significant amount of additional adsorption
of adsorptive occurred at P/P0 > 0.8. No desorption measurements
were reported and therefore it is not possible to deduce whether
the further uptake at high P/P0 was due to multilayer adsorption,
capillary condensation or an irreversible change in the adsorption
system. In this figure, the hysteresis loop does not close. Evidently
this form of hysteresis cannot be attributed to capillary conden-
sation, and is instead indicative of a more complex change in the
adsorption system. We applied the t-method for detecting microp-
orosity (Supplementary data). Application of the t-method proves
presence of micropores in this catalyst [15].
BET measurements revealed a specific surface area of 95 m2 g−1
for the catalyst. The pore size distribution curve displays that
the Co/Mn-BSO0.01 catalyst contains mesopores (2 nm < pore
size < 50 nm) and the Co/Mn-WSOP0.01 catalyst contains meso-
pores and micropores (pore size < 2 nm). SEM micrograph of the
Co/Mn-WSOP0.01 catalyst is displayed in Fig. 7. Apparently there are
narrow channels in wood that are responsible for ions transporting
through it. Therefore, ion transporting causes the immobilization
of Co and Mn on wood pores. SEM/EDS images of the Co/Mn-
WSOP0.01 catalyst indicated nanoparticles that were related to Co
and Mn nanoparticles (Supplementary data). TEM was then utilized
as a perfecting technique to study inner structure of the cata-
lyst. Representative TEM images of the Co/Mn-WSOP0.01 catalyst
are demonstrated in Fig. 8. The average Mn and Co particles size
Fig. 4. SEM micrograph of the Co/Mn-BSO0.01 catalyst sample.
2–5 nm for the Co/Mn-BSO0.01 catalyst. The cobalt and manganese
contents of the bone and the supported catalyst sample were
determined by ICP-AES. The molar ratio of the measured Co and
Mn contents in the supported catalyst sample was 10:1. The ions
Fig. 5. TEM micrograph of the Co/Mn-BSO0.01 catalyst sample.
Fig. 6. Nitrogen adsorption–desorption isotherm of the Co/Mn-WSOP0.01catalyst.

A. Mardani Ghahfarrokhi et al. / Applied Catalysis A: General 456 (2013) 51–58
55
Fig. 9. TGA and DTG profiles of Co/Mn-WSOP0.01 catalyst.
Table 3. The oxidation of 2,6-DIPN over Co/Mn-WSOP0.01 improves
the conversion and selectivity of the reaction as compared with
other catalysts, and the best conversion (100%) and selectivity to
2,6-naphthalene dicarboxylic acid (100%) was achieved when we
used Co/Mn-WSOP0.01 as the catalyst (Scheme 2). These data are in
agreement with the results of the BET and TEM analysis which show
that the Co/Mn-WSOP0.01 has a larger surface area and smaller
nanosized catalysts than the other catalysts. Entry 13 shows the
result of the oxidation reaction in a homogeneous condition that
the selectivity decreased to 70%. Also, the catalytic activity of the
Co/Mn-WSOP0.01 was investigated as a function of temperature.
Table 4 shows the results of the oxidation at 423, 443, and 463 K. The
reaction temperature has a great influence on the progress of the
reaction. By increasing the reaction temperature to 463 K, the selec-
tivity increased remarkably. As shown in Table 4, a 20◦ increase
in the temperature affected the distribution of the products. The
selectivity of the 2,6-naphthalene dicarboxylic acid increased to
100% at 463 K, when the selectivity of the reaction for produc-
ing intermediate products decreased. By performing the reaction
at higher temperature (473 K), over-oxidation and probably ring
cleavage decreased the selectivity to a large extent. These results
suggested that the optimum temperature was 463 K.
Fig. 7. SEM micrograph of the Co/Mn-WSOP0.01 catalyst sample.
is estimated to be 2–5 nm for the Co/Mn-WSOP0.01 catalyst. The
cobalt and manganese contents of the Co/Mn-BSO0.01, and Co/Mn-
WSOP0.01 catalysts were determined by ICP-AES. The molar ratio of
measured Co and Mn contents in the both catalysts was 10:1. The
ion contents of the catalysts are reported in Table 2.
Thermogravimetric analyses of the best catalyst (Co/Mn-
WSOP0.01) were carried out in transient conditions in the range of
200–1000 ◦C under argon atmosphere in order to gain knowledge
about the stability of the catalyst in absence of O2. Fig. 9 presents
the evolution of the catalyst mass during sequential isothermal
introduction of Ar. During the process, a mass loss occurs. The data
signify that the mass loss in the range of 100–400 ◦C could be due to
loss of adsorbed water and coordinated water molecules, and the
mass loss in the range of 400–1000 ◦C might be due to removal of
the metal oxygen by the carbon support.
3.2. Catalytic studies
3.2.2. Effect of time and pressure of oxygen
Table 5 shows the effect of time and pressure on the 2,6-DIPN
oxidation with oxygen over the two best catalysts, i.e., Co/Mn-
WSOP0.01 and Co/Mn-BSO0.01. By increasing the reaction time,
the 2,6-DIPN conversion and selectivity to 2,6-naphthalene dicar-
boxylic acid increased, while the selectivity to the intermediate
products decreased. In the case of the Co/Mn-BSO0.01 catalyst, by
increasing the time of the reaction from 12 to 16 h, the selectiv-
ity decreased from 100% to 56%. Also, the catalytic activity of these
catalysts was investigated as a function of the pressure of oxygen.
Table 5 shows the results of the oxidation over Co/Mn-WSOP0.01 at
13, 15 and 17 bar. As shown in the table, the pressure of oxygen has
influence on the progress of the reaction. By increasing the pressure
to 17 bar, the selectivity increased considerably.
3.2.1. Effect of the catalyst composition and temperature
Oxidation of 2,6-DIPN was carried out over different catalysts
at 463 K for 12 h (Scheme 1). The results were summarized in
3.2.3. Effect of the amount of catalyst, the promoter and
mechanism of reaction
To study the effect of amount of the catalyst and promoter, oxi-
dation over the two best catalysts was carried out at 463 K. All
other parameters such as PO2 , time, and temperature were fixed,
and the results were summarized in Table 6. As seen, 0.8 g (con-
tains 8 × 10−2 mmol Co, and 0.88 × 10−2 mmol Mn) of the catalyst
was enough to increase appreciably the conversion of the reaction
(100%) and selectivity of 2,6-diisopropyl naphthalene (100%) for the
Co/Mn-WSOP0.01 catalyst. Also, we observed that in the absence of
the catalyst, conversion and 2,6-diisopropyl naphthalene selectiv-
ity was very poor.
Fig. 8. TEM micrograph of the Co/Mn-WSOP0.01 catalyst sample.

56
A. Mardani Ghahfarrokhi et al. / Applied Catalysis A: General 456 (2013) 51–58
Scheme 1. Oxidation of 2,6-DIPN to 2,6-NDCA.
Table 3
Data from oxidation of 2,6-DIPN in the presence of different catalysts.
Entry
Catalyst
Conversion (%)
Selectivity (%)
A
B
C
D
E
F
Others
1
2
3
4
5
6
7
8
9
10
11
12
13
BSO
Co-BSO0.01
Mn-BSO0.01
Co/Mn-BSO0.01
Co/Mn-BSO0.001
Co/Mn-BSI0.01
Co-BSO0.01 + Mn-BSO0.01
WSOP
12
100
100
100
100
95
97
18
98
25
42
54
84
30
30
39
50
44
–
24
23
8
11
–
–
2
7
11
–
33
–
17
2
70
66
9
11
17
70
–
–
6
2
–
–
–
2
–
–
–
–
–
–
18
29
19
3
–
4
48
30
28
30
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
2
–
–
–
–
–
Co-WSOP0.01
Mn-WSOP0.01
Co/Mn-WSOP0.01
Co-WSOP0.01 + Mn-WSOP0.01
100
100
97
100
–
70
–
–
–
–
8
–
1
100
21
a
Co/Mn0.01
100
Reaction conditions: 0.86 g (4 mmol) DIPN; 0.2 g KBr; T = 463 K; PO = 17 bar; 0.8 g catalyst; 12 h; glacial acetic acid (5 mmol).
2
a
Homogeneous condition.
Scheme 2. Products of 2,6-DIPN oxidation.
Table 4
Catalytic activity of the Co/Mn-WSOP0.01 on 2,6-DIPN oxidation.
Temperature (K)
Pressure (bar)
Time (h)
KBr (g)
Catalyst (g)
Selectivity (%)
Conversion (%)
Entry
463
463
463
463
463
463
463
443
423
463
463
17
17
17
17
17
15
13
17
17
17
17
12
12
12
12
12
12
12
12
12
9
0.1
0.1
0.1
0.2
0.3
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.4
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
34
30
42
100
45
–
93
83
97
100
100
70
60
100
90
100
81
1
2
3
4
5
6
7
8
9
–
34
14
48
37
10
11
6
Reaction conditions: 0.86 g (4 mmol) DIPN; glacial acetic acid (5 mmol).

A. Mardani Ghahfarrokhi et al. / Applied Catalysis A: General 456 (2013) 51–58
57
Table 5
Effect of time and pressure of oxygen on 2,6-DIPN oxidation.
Entry
Catalyst
T (h)
P (bar)
Conversion (%)
Selectivity (%)
A
B
C
D
E
F
Others
1
2
3
4
5
6
9
12
12
12
17
17
17
13
15
81
100
100
60
37
48
100
–
41
6
–
90
92
–
39
–
–
–
–
–
–
–
–
22
7
–
–
–
–
1
–
–
–
–
–
Co/Mn-WSOP0.01
10
7
70
–
6
7
8
9
6
12
12
16
17
17
19
17
59
100
100
100
59
84
50
56
40
11
23
14
–
2
–
–
–
–
–
–
1
3
14
15
–
–
12
15
–
–
1
–
Co/Mn-BSO0.01
Reaction conditions: 0.86 g (4 mmol) DIPN; 0.2 g KBr; T = 463 K; 0.8 g catalyst; glacial acetic acid (5 mmol).
Table 6
Effect of amount of the catalyst and promoter on 2,6-DIPN oxidation.
Entry
Catalyst
Amount of catalyst (g)
Promotor (KBr)
Conversion (%)
Selectivity (%)
A
B
C
D
E
F
Others
1
2
3
4
5
0.2
0.4
0.8
0.8
0.8
0.1
0.1
0.1
0.2
0.3
93
83
97
100
100
34
30
42
100
45
55
54
37
–
2
4
2
–
30
–
–
–
–
–
9
12
14
–
–
–
5
–
–
–
–
–
–
2
Co/Mn-WSOP0.01
12
11
6
7
8
0.8
0.8
0.8
0.005
0.2
0.4
100
100
98
17
84
49
3
11
10
55
2
26
–
–
–
23
3
4
–
–
–
2
–
11
Co/Mn-BSO0.01
Reaction conditions: 0.86 g (4 mmol) DIPN; T = 463 K; PO = 17 bar; 12 h; glacial acetic acid (5 mmol).
2
Table 7
The catalytic stability of the best catalyst Co/Mn-WSOP0.01 in the oxidation of 2,6-DIPN.
Catalyst
Conversion (%)
Selectivity (%)
A
B
C
D
E
F
Others
Co/Mn-WSOP0.01
aCo/Mn-WSOP0.01
100
89
100
72
–
22
–
–
–
–
–
6
–
–
–
–
a
Refreshed catalyst after the first cycle.
The effect of bromide ion on yields and selectivity is shown
in Table 6 where three experiments are compared with different
amounts of Br− for each catalyst. The diisopropyl naphthalene con-
version is nearly identical in these experiments but the selectivity
to 2,6-naphthalene dicarboxylic acid considerably changes with
increasing the amount of bromide ion. Thus, the presence of bro-
mide ion is associated with a significant increase in the selectivity
of the desired product.
up to 89%. This result and the data from the ICP measurements
(Table 2) revealed that the metals have leached from the support,
where their contribution in the total activity of the catalyst is very
important. This could be a big drawback for the catalyst, but if we
remember that the catalyst only contains 0.88 × 10−2 mmol Mn and
realizing that the oxidation in a homogeneous condition does not
show such a good selectivity, we might give a good credit to this
catalyst!
It is widely accepted that the oxidation of alkyl chain on the aro-
matic compounds follows a free radical chain mechanism [16–22]
that is initiated by Co(II). Co(II) is subsequently oxidized to Co(III)
by O2 and on its return to Co(II) it promotes the oxidation of Mn(II)
to Mn(III) [23].
Mn(III) subsequently converts bromide ion to bromide radical
on the way back to Mn(II). The oxidation of alkyl chain and in this
case is initiated upon removal of hydrogen atom from the benzylic
position of one of the isopropyl group of 2,6-dimethyl naphthalene
by this bromide radical [11].
4. Conclusions
In this paper structure of bone and wood as accessible and suit-
able supports for immobilization of Co-Mn nano hybrid particles
were investigated. Co/Mn supported catalysts are influencing cat-
alysts for oxidation of 2,6-DIPN, but the catalytic activity of both
single component cobalt and manganese samples is low. A con-
siderable increase in activity is established with the supported
catalyst that prepared from a mixed solution of Co/Mn (10:1 mole
ratio). These catalysts were found to be effective catalysts for the
oxidation of 2,6-diisopropyl naphthalene to 2,6-naphthalene dicar-
boxylic acid under desirable conditions.
3.2.4. Reusability of the catalysts
The catalytic stability of the best catalyst (Co/Mn-WSOP0.01) in
the oxidation of 2,6-diisoprpyl naphthalene is shown in Table 7.
By just separating the catalyst from the reaction mixture by cen-
trifugation, washing it with chloroform and drying at 100 ◦C, the
catalyst was used for a new run at the optimum reaction con-
ditions. The activity of the refreshed catalyst after the first cycle
for the Co/Mn-WSOP0.01 catalyst decreased, and conversion ended
Acknowledgements
Thanks are due to the Research Council of Isfahan University of
Technology and the Center of Excellency in the Chemistry Depart-
ment of Isfahan University of Technology for supporting this work.

58
A. Mardani Ghahfarrokhi et al. / Applied Catalysis A: General 456 (2013) 51–58
Appendix A. Supplementary data
[9] A. Mitsionis, T. Vaimakis, C. Trapalis, Appl. Catal. A: Gen. 106 (2011) 398–404.
[10] Y. Takeuchi, H. Arai, J. Chem. Eng. Jpn. 23 (1990) 75–80.
[11] M. Ghiaci, M. Mostajeran, A. Gil, Ind. Eng. Chem. Res. 51 (2012) 15821–15831.
[12] K.K. Unger, J. Roquerol, K.S.W. Sing, H. Kral (Eds.), Characterization of Porous
Solids, Elsevier, Amsterdam, 1988.
[13] F. Rodriguez-Reinoso, J. Roquerol, K.S.W. Sing, K.K. Unger (Eds.), Characteriza-
tion of Porous Solids II, Elsevier, Amsterdam, 1991.
Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/
j.apcata.2013.02.013.
[14] J. Roquerol, F. Rodriguez-Reinoso, K.S.W. Sing, K.K. Unger (Eds.), Characteriza-
tion of Porous Solids III, Elsevier, Amsterdam, 1994.
[15] G. Leofantia, M. Padovan, G. Tozzola, B. Venturelli, Catal. Today 41 (1998)
207–219.
[16] W. Partenheimer, Catal. Today 23 (1995) 69–158.
[17] Y. Kamiya, J. Catal. 33 (1974) 480–485.
[18] C. Hendriks, H. Beek, P. Heertjes, Ind. Eng. Chem. Prod. Res. Dev. 17 (1978)
256–264.
[19] M.P. Czytko, G.K. Bub, Ind. Eng. Chem. Prod. Res. Dev. 20 (1981) 481–486.
[20] N.M. Emanuel, D. Gal, Modeling of Oxidation Processes, Akademiai Kiado,
Budapest, Hungry, 1986.
[21] J.W. Kwak, J.S. Lee, K.H. Lee, Appl. Catal. A: Gen. 358 (2009) 54–58.
[22] J.S. Yoo, S.H. Jhung, K.H. Lee, Y.S. Park, Appl. Catal. A: Gen. 223 (2002) 239–251.
[23] S. Chavan, S. Halligudi, D. Srinivas, P. Rantnasamy, J. Mol. Catal. A: Chem. 161
(2000) 49–64.
References
[1] L.D. Lillwitz, Appl. Catal. A: Gen. 221 (2001) 337–358.
[2] A.D. Schmitz, C. Song, Catal. Today 31 (1996) 19–25.
[3] R. Brzozowski, W. Tecza, Appl. Catal. A: Gen. 166 (1998) 21–27.
[4] K. Smith, S.D. Roberts, Catal. Today 60 (2000) 227–233.
[5] T. Yamada, Y. Doko, K. Sugiura, Method for the preparation of naphthalene
dicarboxylic acids. Patent No. 4925977 (1990).
[6] A. Martin, U. Armbruster, P. Muller, E. Deuschle, J. Supercrit. Fluids 45 (2008)
220–224.
[7] J. Huang, L. Wang, Y. Liu, Y. Cao, H. Hea, K. Fan, Appl. Catal. B: Environ. 101
(2011) 560–569.
[8] H. Figueiredo, B. Silva, C. Quintelas, M.M.M. Raposo, P. Parpot, A.M. Fonseca,
A.E. Lewandowska, M.A. Ban˜ares, I.C. Neves, T. Tavares, Appl. Catal. B: Environ.
94 (2010) 1–7.