Hydroxylation of phenol over MeAPO molecular sieves synthesized by vapor phase transport

Article abstract of DOI:10.1134/S0036024416070116

In this study, MeAPO-25 (Me = Fe, Cu, Mn) molecular sieves were first synthesized by a vapor phase transport method using tetramethyl guanidine as the template and applied to hydroxylation of phenol. The zeolites were characterized by XRD, SEM, FT-IR, and

Full text of DOI:10.1134/S0036024416070116

ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2016, Vol. 90, No. 7, pp. 1326–1333. © Pleiades Publishing, Ltd., 2016.
CHEMICAL KINETICS
AND CATALYSIS
Hydroxylation of Phenol over MeAPO Molecular Sieves Synthesized
1
by Vapor Phase Transport
Hui Shao, Jingjing Chen, Xia Chen, Yixin Leng, and Jing Zhong
Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering,
Changzhou University, Changzhou, 213164, China
e-mail: shaohui200800@cczu.edu.cn
Received March 27, 2015
Abstract—In this study, MeAPO-25 (Me = Fe, Cu, Mn) molecular sieves were first synthesized by a vapor
phase transport method using tetramethyl guanidine as the template and applied to hydroxylation of phenol.
The zeolites were characterized by XRD, SEM, FT-IR, and DR UV–Vis. As a result, MeAPO-21 and
MeAPO-15 were synthesized by changing the Me/Al ratio. UV–Visible diffuse reflectance study suggested
incorporation of heteroatoms into the framework and FT-IR study also supported these data. Effects of het-
eroatoms, contents of Me in MeAPO-25, reaction temperature, phenol/H O mole ratios, reaction time and
2
2
concentration of catalyst on the conversion of phenol, as well as on the selectivity were studied. FeAPO-25
exhibited a high catalytic activity at the mole ratio of FeO and Al O equal to 0.1 in the synthesis gel, giving
2
3
the phenol conversion of 88.75% and diphenols selectivity of 66.23% at 60°C within 3 h [n(phenol)/n(H O ) =
2
2
0
.75, m(FeAPO-25)/m(phenol) = 7.5%]. Experimental results indicated that the FeAPO-25 molecular sieve
was a fairly promising candidate for the application in hydroxylation of phenol.
Keywords: heteroatom, MeAPO-25, vapor phase transport, phenol, hydroxylation
DOI: 10.1134/S0036024416070116
1
. INTRODUCTION
as the template to synthesize a hierarchical MeAPO-5
molecular sieve with mesopores and micropores.
Wang et al. [9] used tetramethylguanidine (TMG)
through conventional hydrothermal (CHT) method,
In the family of aluminophosphate molecular
sieves (AlPO -n), metal-containing aluminophos-
4
phate molecular sieves (MeAPOs) have received con-
siderable interest due to their modified acid sites
achieved by changing the metal amounts, large spe-
cific surface areas and great thermostability [1–3]. Up
successfully synthesized a typical AlPO -5. Neverthe-
4
less, friendly green templates have seldom been
reported.
Typically, using the CHT method is required for
separation between solvents and solid products, and
partially organic SDAs are inevitably preserved in the
liquid phase, resulting in the wastewater pollutants
and downstream purification system installation [10].
To further optimize the synthesis technology to fit the
principles of green chemistry, the synthesis of porous
materials by vapor-phase transport (VPT) was first
invented by Xu et al. [11]. Compared with CHT, VPT
has many advantages over CHT, including reducing
wastewater disposal, enhancing the efficiency of syn-
thesis reactors and minimizing template dosages [12],
resulting in lower production costs. In our previous
work [13], Me-substituted aluminophosphate molec-
ular sieves MeAPO-11 (Me = Cu, Fe, Zn, Mn) were
synthesized by the VPT method using diisopropyl-
amine as the template.
to now, AlPO -n molecular sieves have usually been
4
synthesized in the hydrothermal or solvothermal sys-
tems by using organic amines as templates. Organic
amines are toxic, inducing high production cost and
environmental problems arising from the thermal
decomposition of organic species [4]. Therefore, a lot
of efforts have been made to find an environmentally
friendly approach for the synthesis of crystalline alu-
minophosphates. Currently, an ionothermal synthesis
method was reported for preparing molecular sieves
using ionic liquids as both solvents and SDA, such as
1
-butyl-3-methylimidazolium bromide ([bmim]Br)
5], a mixture of choline chloride (ChCl) and pen-
taerythritol [6], 1-ethyl-3-methylimidazolium bro-
mide ([emim]Br) [7] etc. However, ionic liquids still
suffered from a complex synthesis process and expen-
sive cost. Low-toxic templates are urgently sought.
Zhou et al. [8] used glucose mixed with triethylamine
[
Hydroxylation of phenol with clean oxidants like
2
[14]. The products of hydroxylation of phenol can be
H O is a research topic of high industrial importance
2
1
The article is published in the original.
1326

HYDROXYLATION OF PHENOL OVER MeAPO MOLECULAR SIEVES SYNTHESIZED
1327
used as antioxidants, polymerization inhibitors [15], in the wavelength range of ~(200–800) nm on a
and photosensitive materials. Catalytic hydroxylation VARIAN CARY-500 equipment. BaSO was used as a
4
of diphenols has attracted large research attention reference.
[
16]. Heteropoly acid salts, metallic oxides and molec-
ular sieves containing heteroatoms had been used as
the catalysts for this reaction [17–19]. At present, the
uses of heteropoly acid salts depended on acetonitrile
as the solvent, which has high toxicity and difficult
2
.3. Catalytic Test
Hydroxylation of phenol was conducted in a
00 mL round-bottomed flask. The reaction condi-
1
recycling of catalysts. Although metal oxides have a tions were as follows: the reaction temperature was
low cost, convenient preparation and high stability, 60°C; the molar ratio of phenol to H O was 0.75 : 1
2
2
they were limited by a low selectivity. Hence,
MeAPO-25 molecular sieves could be a potential
competitor for the hydroxylation of Phenol.
(
with 2.0 g phenol in 12.0 mL distilled water for the
reaction); the mass of the catalyst was 0.1 g; and the
reaction time was 3 h. The reaction was monitored by
The objective of this work was to develop a new sampling periodically and analyzed using an EX-1600
method to synthesize MeAPO-25 (Me = Fe, Cu, Mn) series high performance liquid chromatography
by using the VPT method. Tetramethyl guanidine equipped with a C18 column (5 μm, 4.6 × 150 mm)
(
TMG) was used as a friendly green template. The and UV-detector (277 nm, 25°C).
characteristics of MeAPO-25 molecular sieves, such
as crystal structure and morphology, were studied.
The catalytic performance of these MeAPO-25
3
. RESULTS AND DISCUSSION
molecular sieves was evaluated in the reaction of phe- 3.1. Synthesis of MeAPO with Different Metal Contents
nols hydroxylation. Additionally, the phase transition
Figure 1 shows the XRD patterns of as-synthesized
between MeAPO-21 and MeAPO-15 molecular sieves
samples of MeAPO (Fig. 1a) and the calcined forms of
was observed by changing the metal content.
MeAPO (Fig. 1b). It clearly exhibits that the MeAPO-
2
1 molecular sieves synthesized with different
n(MeO)/n(Al O ) ratios (Me = Fe, Mn) in the range
2
3
2. EXPERIMENTAL SECTION
of ~(0.05–0.25) have a typical AWO structure. The
2.1. Synthesis of MeAPO-25
characteristic diffraction peak of the molecular sieves
is the strongest with a MeO/Al O ratio of 0.1. Then,
MeAPO-25 molecular sieves were synthesized by
using the VPT method. Mixtures with compositions of
2
3
the characteristic diffraction peak decreases with the
increase of the metal content. This result indicates that
the crystallinity decreases. The introduction of metal
heteroatoms changes the chemical microenvironment
near the crystal surfaces and affects the growth of the
crystal faces. In addition, with the increase of the met-
als content, the non-framework species content
increases. This changes the growth rate of the crystal
faces, resulting in the reduced crystallinity of the
molecular sieves [20]. The CuAPO-15 zeolite is syn-
thesized with a small metal content. When the
1
.3P O : 1.0Al O : xMeO : 1.0TMG : 100H O were
2 5 2 3 2
used as precursors, where x was selected as 0.05 (a),
.10 (b), 0.15 (c), 0.20 (d), or 0.25 (e). Pseudoboeh-
0
mite was added to the distilled water, and stirred until
a uniform gel was obtained. Phosphoric acid and
TMG were added successively to the gel, which was
stirred to a uniform reaction mixture. Then, cupric
acetate, iron(II) sulfate septhydrate or manganese ace-
tate tetrahydrate was added to the gel as the source of
different metals, respectively. The resulted hydrogel was
then dried at 80°C. The dry-gel powder was placed in a
sample holder located in the middle part of an auto-
clave. A mixture of TMG and water (1 : 20 (vol/vol))
CuO/Al O ratio reaches 0.25, the characteristic dif-
fraction peaks of CuAPO-15 disappear.
2
3
In the XRD patterns of calcined MeAPO-21(Me =
was placed at the bottom of the autoclave. The auto- Fe, Mn) samples, the peak position and intensity are
clave was then kept in the oven at 180°C for 24 h. The similar with the XRD patterns of AlPO -25 molecular
4
as-synthesized products were filtered, washed several
sieves [21]. This suggests that the calcination trans-
forms the MeAPO-21 molecular sieves into MeAPO-
times, dried and then calcined at 550°C.
2
5 molecular sieves with a ATV structure. A structural
unit of AlPO -21 molecular sieves has an AlO tetra-
4
4
2.2. Characterization
hedron, three PO tetrahedra, and two AlO trigonal
4
5
X-ray diffraction (XRD) experiments were per- bipyramids. Every two penta-coordinated aluminum
formed on a Rigaku D/max2500 instrument with ions result in an Al–O–Al connection, increasing the
CuK radiation (40 kV, 100 mA). Scanning electron energy of the system. Based on the principle that the
α
microscopy (SEM) images were collected on a S- skeleton structure should be formed in accordance
3
000N microscope at 30 kV. The FT-IR spectra of the with the minimum energy of the system [22], the
samples were recorded as KBr disks on a PROTÉGÉ penta-coordinated aluminum in the framework of
–1
4
60 spectrometer in the range of ~(4000–400) cm . AlPO -21 is transformed into a tetra-coordinated
4
The diffuse reflectance UV–Vis spectra were obtained form at high temperatures. Xiao et al. [23] pointed that
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A Vol. 90 No. 7 2016

1328
HUI SHAO et al.
n(FeO)/n(Al
2
O )
3
n(FeO)/n(Al
2
O )
3
(a)
0.25
(b)
0.25
0.20
0
.20
0
0
.15
0.15
0.10
0.05
.10
.05
0
5
5
5
10 15 20 25 30 35 40 45 505 10 15 20 25 30 35 40 45 50
θ, deg 2θ, deg
2
n(CuO)/n(Al
2
O )
3
n(CuO)/n(Al
2
O )
3
0
.25
.20
0
0.25
0
.15
0
.20
.15
0
.10
.05
0
0
.10
.05
0
0
10 15 20 25 30 35 40 45 505 10 15 20 25 30 35 40 45 50
θ, deg 2θ, deg
2
2 3
n(MnO)/n(Al O )
n(MnO)/n(Al
2
O )
3
0.25
0.25
0
.20
.15
0.20
0
0
.15
.10
0
.10
.05
0
0
0.05
10 15 20 25 30 35 40 45 505 10 15 20 25 30 35 40 45 50
θ, deg 2θ, deg
2
Fig. 1. XRD patterns of as-synthesized MeAPO (a) and calcined MeAPO (b) synthesized with different n(MeO)/n(Al O ).
2
3
the whole skeleton is transformed into AlPO -25 The FeAPO-25 with the 0.10 FeO/Al O ratio, the
4
2
3
molecular sieves without changing the main channel CuAPO-25 with the 0.25 CuO/Al O ratio and the
2
3
of the eight-membered ring.
MnAPO-25 with the 0.10 MnO/Al O ratio were
2 3
characterized and applied to hydroxylation of phenol.
In the case of CuAPO-15, the XRD patterns of the
CuAPO-15 molecular sieves after calcination do not
show the characteristic diffraction peaks, indicating
the presence of the amorphous state. It is consistent
with the conclusion reported in the literature that the
3.2. Characterization of MeAPO
SEM images of the as-synthesized and calcined
FeAPO, CuAPO, and MnAPO molecular sieves are
framework of AlPO -15 molecular sieve can be col-
4
lapsed after calcination [24]. The CuAPO-21 molecu- shown in Fig. 2. It shows that FeAPO-21 molecular
lar sieves are also transformed into CuAPO-25 molec- sieves are about 15 × 15 μm in size (Fig. 2a). After cal-
ular sieves. MeAPO-25 zeolites with a high crystallin- cination, the schistose crystals stack consists of irregular
ity were employed as catalysts in the following study. bulk particles. The CuAPO-21 molecular sieves (Fig. 2c)
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HYDROXYLATION OF PHENOL OVER MeAPO MOLECULAR SIEVES SYNTHESIZED
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2
5 μm
25 μm
5 μm
5 μm
(a)
(c)
(e)
(b)
(d)
(f)
5
μm
5
μm
Fig. 2. SEM of the as-synthesized and calcined (a, b) FeAPO, (c, d) CuAPO, and (e, f) MnAPO.
are fine and smooth flake crystals with the size of ~(5– samples. These bands were usually attributed to the
1
0) μm. The crystal size of CuAPO-25 is slightly larger oxides of Fe presented in the extra-framework state.
than that of CuAPO-21. MnAPO-21 molecular sieves The absorption peak disappeared in the calcined
are spherical crystals with a diameter of about 2 μm FeAPO-25 molecular sieves, indicating the introduc-
piled by thin and small flake crystals (Fig. 2e). It is tion of the heteroatoms into the frameworks. A char-
clear that the spherical crystals are destroyed after cal- acteristic band at ~(200–230) nm appeared in the
cination. This also indicates that the form of the spectra of both CuAPO-21 and CuAPO-25 due to the
molecular sieve has changed in the calcination pro- p–d electronic transition from the 2p electron of oxy-
cess.
gen atoms to empty d-orbital of the heteroatom [26].
In the range of ~(300–480) nm there were no charac-
teristic peaks, indicating that there were no hetero-
atom oxides in the extra-framework state of the as-
synthesized and calcined samples. No absorption peak
was observed for MnAPO-21 molecular sieves in the
range of ~(190–230) nm, indicating that Mn atoms
didn’t exist in the frameworks.
UV–Vis spectra were recorded for the as-synthe-
sized and calcined FeAPO, CuAPO, and MnAPO in
order to identify the existence of metal ions in the
framework or extra-framework of molecular sieves
(
Fig. 3). There was a very intense absorption band at
about 260 nm in the spectra of as-synthesized
FeAPO-21 as well as that of calcined FeAPO-25. This
band was associated with the charge-transfer from
ligand to metal [25]. This confirmed that Fe ions had
FT-IR spectra of the as-synthesized MeAPO-21
molecular sieves (shown in Fig. 4) showed a new
-1
been incorporated into the framework. Two bands at absorption band at 950 cm [27] compared with the
around 370–430 nm were observed for FeAPO-21 spectrum of AlPO
-21. It illustrated heteroatom iso-
4
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1330
HUI SHAO et al.
a)
(
(b)
CuAPO-25
CuAPO-21
FeAPO-25
FeAPO-21
2
00 300 400 500 600 700 800200 300 400 500 600 700 800
λ, nm
λ, nm
(c)
MnAPO-25
MnAPO-21
2
00 300 400 500 600 700 800
λ, nm
Fig. 3. DR UV–Vis spectra of the as-synthesized and calcined: (a) FeAPO, (b) CuAPO, and (c) MnAPO.
(a)
(b)
MnAPO-21
CuAPO-21
MnAPO-25
CuAPO-25
FeAPO-25
FeAPO-21
AlPO -25
4
AlPO -21
4
2000
1600
1200
800
400 2000
1600
1200
800
400
Wavenumber, cm−
1
Wavenumber, cm
−1
Fig. 4. FT-IR spectra of the as-synthesized MeAPO-21(a) and calcined MeAPO-25 (b).
morphous substitution of P or Al in the framework. On trum of the calcined MeAPO-25 molecular sieves led
the other hand, this absorption band had a red shift to a similar conclusion.
compared to that of AlPO -21. This was attributed to
4
the heavier atomic masses of Fe and Cu, compared
3
.3. Catalytic Test
with that of Al. With isomorphous substitution of Al
with Fe or Cu, the M–O bond length became longer,
leading to a red shift. But the spectrum of MnAPO-21
FeAPO-25, CuAPO-25, and MnAPO-25 molecu-
lar sieves were used as catalysts for hydroxylation of
–1
did not show the characteristic absorption at 950 cm , phenol. Their catalytic performances were illustrated
clearly indicating that Mn atoms were in the extra- in Fig. 5. FeAPO-25 showed a high activity in this
framework state. This was consistent with the conclu- reaction. At 60°C, the conversion of phenol reached
sion of the UV–Vis spectroscopy. The FT-IR spec- 90% after 3 h, with the 66.23% diphenols selectivity.
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HYDROXYLATION OF PHENOL OVER MeAPO MOLECULAR SIEVES SYNTHESIZED
1331
90
90
80
70
60
50
40
30
20
10
0
90
80
70
60
50
40
30
20
10
0
100
Conversion of phenol
Selectivity of diphenol
90
80
70
80
70
60
6
0
0
50
40
5
0
0.05 0.10 0.15 0.20 0.25 0.30 0.35
Mole ratio of FeO/Al
FeAPO-25
CuAPO-25
MnAPO-25
O
2 3
Fig. 5. The catalytic performance of MeAPO-25 in phenol
Fig. 6. Catalytic properties of FeAPO-25 with different
hydroxylation (conditions: phenol 2.0 g, phenol/H O
contents of Fe for phenol hydroxylation (conditions: phe-
2
2
molar ratio 3 : 4, water 12 mL, MeAPO-25 0.15 g, tem-
nol 2.0 g, phenol/H O molar ratio 3 : 4, water 12 mL,
2 2
FeAPO-25 0.15 g, temperature 60°C, time 3 h).
perature 60°C, time 3 h).
MnAPO-25 favored a high conversion of phenol but in the synthesis gel would lead to a better formation of
with a low selectivity. As mentioned in the UV–Vis tetrahedral Fe species in the framework. This was in
spectroscopy test, Mn species hardly enter into the agreement with the result of XRD analysis. The cata-
framework of the molecular sieves. After calcination, lytic activity decreased with the decrease of the zeolite
Mn atoms in the pore were transformed into MnO . It crystallinity. Accordingly, the appropriate metal con-
2
is generally accepted that MnO is the catalyst for the tent was needed for the reaction of phenol hydroxyl-
2
decomposition of H O to O . Therefore, MeAPO-25 ation.
2
2
2
was excessively active for the phenol hydroxylation,
diphenols were further oxidized and phenol was
directly oxidized into tar. In addition, it has been
reported that manganese oxides were excellent adsor-
bents for phenol [28]. The UV–Vis spectroscopy test
Table 1. Effect of reaction variables on the phenol hydrox-
ylation
Reaction
variable
XPhenol, % SCAT, % SHQ, % SCAT + HQ, %
3+
2+
also revealed that Fe and Cu ions entered the
framework to form active centers of phenol hydroxyl-
ation. This might be affiliated with the acidity increase
of catalysts after the modification with the metal.
However, the acid sites of FeAPO-25 and CuAPO-25
should be further explored by FR-IR spectra of pyri-
a
Phenol/H O ratio
2
2
0
.5
0.75
.0
.25
88.27
88.75
72.03
59.77
23.22
31.57
38.14
39.87
40.21
54.79
66.23
68.19
69.47
28.09
28.32
29.26
1
1
dine adsorption and NH -TPD for investigating the
3
difference between FeAPO-25 and CuAPO-25.
Reading these responses, further studies with different
metal contents were carried out with FeAPO-25
molecular sieves.
Temperature (°C)b
50
56.67
88.75
86.03
55.44
32.75
28.09
24.61
23.06
Time (h)c
40.00
72.75
66.23
60.59
57.29
60
38.14
35.98
34.23
The results of hydroxylation of phenol with different
FeAPO-25 molecular sieves were presented in Fig. 6.
It revealed that the phenol conversion and diphenol
selectivity reached the maximum when the molar ratio
of FeO and Al O was 0.10. In the acid-catalyzed
70
80
2
3
4
5
89.41
88.75
89.69
90.55
17.50
28.09
29.45
25.76
22.42
38.14
35.78
30.23
39.92
66.23
65.23
55.99
2
3
hydroxylation of phenol, the diphenols yield increased
with the increase of the Fe content. Generally, alumi-
nophosphate molecular sieves without any heteroat-
oms had few acid sites, which was useless for the phe-
nol hydroxylation. Indeed, the more Fe atoms led to
a
Phenol 2.0 g, water 12 mL, FeAPO-25 0.15 g, temperature 60°C,
time 3 h.
Phenol 2.0 g, phenol/H O molar ratio 3 : 4, water 12 mL,
FeAPO-25 (b) 0.15 g, time 3 h.
3+
more acid activity, according to the Fe atoms acted
as active centers in the MeAPO-25 catalyst. However,
Choi [29] had synthesized Fe-MCM-41 with varying
b
2
2
c
Phenol 2.0 g, phenol/H O molar ratio 3 : 4, water 12 mL,
2
2
amounts of Fe and it showed that small amounts of Fe FeAPO-25 (b) 0.15 g, temperature 60°C.
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1332
HUI SHAO et al.
Phenol
MeAPO-25
Pyrocatechol
H
H
e
Substitution
O
OO
O
H
Hydroquinone
Fig. 7. Schematic diagram of phenol hydroxylation over the MeAPO-25 catalyst.
•
The influence of other reaction conditions such as the reaction of OH and phenol which was lower than
the phenol/H O ratio, reaction temperature and
•
2
2
the decomposition of OH. Elevated temperatures
reaction time were studied by using FeAPO-25, and favored the reaction with a high activation energy.
the results were shown in Table 1. In general, the con-
The effect of the reaction time was studied in a
version of phenol decreased with the increase of the
range of ~(0–5) h. The conversion of phenol kept
phenol/H O ratio, but the diphenols selectivity
2
2
unchanged and the diphenols achieved a maximum
selectivity at 3 h. With further increasing of the reac-
tion time, diphenols were further oxidized to produce
the tar, due to a rapid decomposition of H O . There-
increased. Figure 7 illustrated the reaction mechanism
of phenol hydroxylation over the FeAPO-25 catalyst.
During the reaction, H O was first decomposed to
2
2
2
2
•
OH by the FeAPO-25 molecular sieve, then the OH
species reacted with phenol to produce catechol and
hydroquinone. The increase of the H O dosage led to
the increase of the OH concentration. Therefore, the
conversion of phenol increased with increasing the
amount of H O . However there was a competitive
fore, the optimal conditions of the reaction were: a
phenol/H O molar ratio of 0.75, temperature of 60°C
2
2
2
2
and reaction time of 3 h, respectively.
•
FeAPO-25 molecular sieves, ranging from 2.5 to
0% (mass ratio, FeAPO-25/Phenol), were added
1
2
2
into the solution of phenol. The catalytic results were
listed in Table 2. With the increase of FeAPO-25 load-
ing from 2.5 to 7.5%, the conversion of phenol
increased from 57.12 to 88.75%. However, with a fur-
•
reaction for OH: decomposition to H O and O . Fur-
2
2
ther oxidation of diphenols by oxygen leads to the
decrease of the diphenols selectivity.
The influence of the reaction temperature was ther increase in the amount of FeAPO-25, the conver-
studied in a range of ~(50–80)°C at an interval of sion of phenol decreased. This is due to suitable acidity
1
0°C. At 50°C, the conversion of phenol was very low that can promote the formation of OH and the conver-
compared with the conversion at 60°C. This might be sion of phenol. But if the acidity was too strong, the
•
due to the poor solubility of phenol. But Preethij [16] decomposition of OH accelerated, decreasing the
attributed this to the suppression of H O chemisorp- utilization of H O . Furthermore, after repeated use
2
2
2
2
tion. With the further increase of temperature, both for three times, still a 64.93% phenol conversion and
the conversion of phenol and diphenols selectivity 40.51% diphenols selectivity were observed.
decreased. It might be due to the activation energy of
CONCLUSIONS
Table 2. Effect of catalyst dosage on the phenol hydroxyl-
a
In conclusion, MeAPO-25 molecular sieves (Me =
Fe, Cu, Mn) were successfully synthesized by the VPT
method using TMG as the template. MeAPO-25
molecular sieve could act as a catalyst to efficiently
convert phenol to diphenols. The phenol conversion
and diphenols selectivity were greatly affected by het-
eroatom species, metal content, the ratio of phe-
nol/H O , reaction time, reaction temperature and
ation over the FeAPO-25 catalyst
w(FeAPO-
XPhenol, % SCAT, % SHQ, % SCAT + HQ, %
25 (b))
2
5
.5
57.12
76.69
88.75
51.08
35.94
31.51
28.09
20.63
44.04
40.32
38.14
31.02
79.98
71.83
66.23
51.65
7
.5
2
2
10
the amount of the catalyst. The results indicated that
3+
2+
a
Fe and Cu ions could be successfully incorporated
Phenol 2.0 g, phenol/H O molar ratio 3 : 4, water 12 mL, tem-
2
2
2+
into the framework of AlPO -25. But Mn ions
perature 60°C, time 3 h.
4
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HYDROXYLATION OF PHENOL OVER MeAPO MOLECULAR SIEVES SYNTHESIZED
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hardly entered into the framework. An appropriate 11. W.-Y Xu, J.-X Dong, J.-P Li, J.-Q Li, and Feng Wu,
J. Chem. Soc., Chem. Commun. 262, 177 (1990).
phenol conversion of 88.75% and diphenols selectivity
of 66.23% had been achieved over the FeAPO-25 cat- 12. C.-M. Song, Y. Feng, and L.-L. Ma, Microporous
Mesoporous Mater. 147, 205 (2012).
alyst. FeAPO-25 molecular sieve could be used as an
effective catalyst for the hydroxylation of phenol.
13. H. Shao, X. Chen, B. B. Wang, J. Zhong, and Y. Chao,
Shiyou Xuebao, Shiyou Jiagong 28, 933 (2012).
1
4. J.-N. Park, J. Wang, K. Y. Choi, W.-Y. Dong, S.-I. Hong,
ACKNOWLEDGMENTS
and C. W. Lee, J. Mol. Catal. A: Chem. 247, 73 (2006).
This work is supported by National Natural Sci- 15. L. Jian, C. Chen, F. Lan, S. Deng, W. Xiao, and
ence Foundation (no. 21276029), the Perspective
N. Zhang, Solid State Sci. 13, 1127 (2011).
Research Foundation of Production Study and 16. H. S. Abbo and S. J. Titinchi, Appl. Catal. A: Gen. 435,
148 (2012).
Research Alliance of Jiangsu Province of China
(
no. BY2014037-15). A Project funded by the Priority 17. M. E. L. Preethi, S. Revathi, T. Sivakumar, D. Man-
Academic Program Development of Jiangsu Higher
Education Institutions (PAPD) and the project of
ikandan, D. Divakar, A. V. Rupa, and M. Palanichami,
Catal. Lett. 120, 56 (2008).
overseas research plan for outstanding research group, 18. F. Shi, Y. Chen, L. Sun, L. Zhang, and J. Hu, Catal.
young teachers and principals in Jiangsu Province.
Commun. 25, 102 (2012).
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9. T. A. Alsalim, J. S. Hadi, E. A. AlNasir, H. S. Abbo,
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