Preparation of nano-SO4 2- /TiO2 catalyst and its application in esterification of sebacic acid with 2-ethyl hexanol

Article abstract of DOI:10.1134/S0023158411020224

A pure anatase phase nano-SO ₄ ^2- /TiO₂ catalysts were synthesized and their catalytic activities were tested. Nano-SO ₄ ^2- /TiO₂ shows high activity and effective re-usable when used as basic catalysts for the synthesis of dioctyl sebacate.

Full text of DOI:10.1134/S0023158411020224

ISSN 0023ꢀ1584, Kinetics and Catalysis, 2011, Vol. 52, No. 2, pp. 222–225. © Pleiades Publishing, Ltd., 2011.
2
–
Preparation of NanoꢀSO4 /TiO Catalyst and Its Application
2
1
in Esterification of Sebacic Acid with 2ꢀEthyl Hexanol
a,b
a,b
a
a
Xianbing Ji , Yinxia Chen , Xiaobo Wang , and Weimin Liu
a
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences,
Lanzhou, 730000 P.R. China
Graduate School of Chinese Academy of Sciences, Beijing, 100039 P.R. China
b
eꢀmail: wangxb@licp.cas.cn; jixb1981@hotmail.com
Received January 22, 2010
2
4
−
Abstract—A pure anatase phase nanoꢀSO /TiO2 catalysts were synthesized and their catalytic activities
2
4
−
were tested. NanoꢀSO /TiO2 shows high activity and effective reꢀusable when used as basic catalysts for the
synthesis of dioctyl sebacate.
DOI: 10.1134/S0023158411020224
D1uring the last few decades, SO4 /TiO2 solid acid two SO4 /TiO2 prepared with commercial titania was
2−
2−
has attracted great attention because of its high speꢀ also carried out under the same experimental condiꢀ
tions.
cific surface area, ordered pore structure, high selecꢀ
tivity, good catalytic activity, high thermal and
mechanical stabilities. Recently, many researchers then the synthesized TiO
have explored the synthesis and applications of (1 mol/l) by g/ml. After being stirred for 1 h, the soluꢀ
tion was calcined at 450 for 3 h [11, 12] to obtain
TiO
2
was prepared by solꢀgel method [10], and
was added into SO
H
2
2
4
2
−
°C
SO4 /TiO2 solid acid [1–5]. Several synthesis methods
2
−
2−
the nanoꢀSO /TiO2. NanoꢀSO4 /TiO ꢀP25 and
2
−
4
2
to prepare SO /TiO2 have been reported, including
4
2
−
nanoꢀSO /TiO2ꢀP were prepared by the same
4
solꢀgel and hydrothermal methods [6–9]. Jiang et al.
method using P25 and titania purchased from “Sinopꢀ
harm Chemical Reagent Co., Ltd” as raw materials,
correspondingly.
2
−
reported the preparation of mesoporous SO /TiO2 by
4
hydrothermal method. The good activity in esterificaꢀ
tion of salicylic acid with isoamyl alcohol and the conꢀ
densation of cyciohexanone with ethylene is due to the
higher specific surface area and mesoporous structure
Fourier transform infrared spectroscopy (FTꢀIR)
spectra analysis of catalysts is listed in Fig. 1. The band
at 3424 cm is assigned to the O–H stretching vibraꢀ
–1
[
8]. De Almeida et al. [9] reported the preparation of
–1
tion of the absorbed water, and the band at 1630 cm
SO4 /TiO2 by solꢀgel method and used it as catalyst in is the vibration of the absorbed water molecules [13].
transesterification reaction of vegetable oils. The relaꢀ Several absorption peaks in the 900–1300 cm region
2
−
–1
tion of structure and catalytic activity of the prepared are also observed on the spectra for the three catalysts,
2
4
–1
−
materials have been evaluated. However, to the best of
our knowledge, there are very few works reported on
which are aroused by combining of SO [6, 14]. The
absorption bands at 1226 and 1135 cm are the antiꢀ
2
−
the preparation and use of SO /TiO2 for the synthesis symmetric and symmetric S=O stretching vibrations,
4
–1
respectively, and the bands at 1040 and 983 cm indiꢀ
cate the antiꢀsymmetric and symmetric S–O stretchꢀ
of dicarboxylic acid esters. In this communication, we
have investigated the catalytic activities of the nanoꢀ
2
−
2
−
ing vibrations of the SO4 groups, respectively. Thereꢀ
fore, the FTꢀIR measurements suggest the formation
SO4 /TiO2 solid acid tested by the esterification of
sebacic acid with 2ꢀethyl hexanol (Scheme 1). On the
other hand, the comparison of catalytic activities of of SO
2
4
−
modified titania.
2
−
Xꢀray diffraction (XRD) and N2 physical adsorpꢀ
tion were performed in order to study the phase of the
catalysts and the specific surface area of the catalysts.
the prepared nanoꢀSO /TiO2 catalyst and the other
4
1
The article is published in the original.
222

2
–
PREPARATION OF NANOꢀSO4 /TiO CATALYST AND ITS APPLICATION
223
2
O
2–
nanoꢀSO4 /TiO2
HO
+
OH
OH
O
O
O
O
2
−
Scheme 1. Esterification of sebacic acid with 2ꢀethyl hexanol catalyzed by nanoꢀSO4 /TiO2.
3
2
1
4000
3500
3000
2500
2000
1500
1000
500
Wavenumber, cm−
1
Fig. 1. FTꢀIR spectra of the catalysts: 1—nanoꢀSO 24 /TiO ꢀP, 2—nanoꢀSO 24 −/TiO ꢀP25, 3—nanoꢀSO 42 −/TiO2.
−
2
2
Figure 2 shows the XRD patterns of the catalysts.
2
−
As shown in Fig. 2a, the nanoꢀSO /TiO catalyst
4
2
exhibits the characteristic peaks of anatase phase at
= 25°, 38°, 48°, 54°, 63°, 70°, and 75°. This proves
3
2
2
θ
2
−
that the nanoꢀSO /TiO catalyst is pure anatase
4
2
2
−
phase. While the XRD patterns of nanoꢀ SO /TiO2ꢀ
4
2
−
P25 and nanoꢀSO /TiO ꢀP catalysts show that the
4
2
2
4
−
1
phase of the nanoꢀSO /TiO ꢀP25 and nanoꢀ
2
2
−
SO /TiO ꢀP catalysts is a mixture of anatase and
4
2
1
0
20
30
40
50
60
70
80
, deg
rutile. The relative fraction of rutile in the crystalline
2
θ
2
−
phases of the nanoꢀSO /TiO ꢀP25 and nanoꢀ
4
2
Fig. 2. XRD patterns of the catalysts:
SO 24 /TiO2,
SO 24 /TiO ꢀP.
1—nanoꢀ
−
—nanoꢀSO 24 −/TiO ꢀP25,
2
−
2
3—nanoꢀ
SO4 /TiO ꢀP is 15.6 and 27.7%, respectively, which
2
2
−
was calculated by the Rao equation [15].
2
KINETICS AND CATALYSIS Vol. 52
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224
XIANBING JI et al.
1
00
0
0
0
0
0
0
0
.8
.7
.6
.5
.4
.3
.2
(a)
(
b)
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
Adsorption
Desorption
0.1
0
–0.1
0
0.2
0.4
0.6 0.8
Relative pressure,
1.0
p/
p0
0
10 20 30 40 50 60 70 80
Pore diameter, nm
Fig. 3. Nitrogen adsorption–desorption (a) and pore size distribution curve isotherms (b) of the nanoꢀSO 24 /TiO2.
−
The specific surface areas of the catalysts are listed
in table. The specific surface area of the nanoꢀ
2−
hexanol ratio of 1 : 3. NanoꢀSO4 /TiO results in the
2
most active catalyst with a conversion of 87% after 2 h.
2
−
SO4 /TiO catalyst is much higher than that of nanoꢀ
2−
2
In comparison the nanoꢀSO4 /TiO ꢀP25 catalyst
2
2
−
2−
SO /TiO ꢀP25 and nanoꢀSO4 /TiO ꢀP. Figure 3 gives reaches a conversion of 50% after the same time,
4
2
2
the nitrogen adsorption–desorption isotherms and the
2−
whereas nanoꢀSO4 /TiO ꢀP shows a much lower conꢀ
pore size distribution curve of the nanoꢀSO /TiO . As version just 32%. The different catalytic performance
2
2
−
4
2
shown in Fig. 3a, the nitrogen adsorption isotherms of of the three catalysts is probably attributed to the fact
2
−
that they have different specific surface area (see
table). Another reason may be that the rutile phase of
titania deteriorates the catalytic activity of the cataꢀ
the nanoꢀSO4 /TiO catalyst shows IV type isotherms.
2
Pore size distribution obtained from nitrogen adsorpꢀ
tion experiments in Fig. 3b indicates the nanoꢀ
2
−
2
−
lysts. The nanoꢀSO /TiO is pure anatase phase of
4
2
SO4 /TiO catalyst has narrow pore size distribution
and the average pore size of the catalyst is 4.2 nm.
2
titania, while the other two catalysts are the mixture of
anatase and rutile phases of titania. The higher the catꢀ
alyst contains rutile phase of titania, the lower the catꢀ
alyst catalytic performance is.
The catalytic performance of the catalysts was
investigated for the esterification of sebacic acid with
ꢀethyl hexanol at 95° with a sebacic acid : 2ꢀethyl
2
Recycling tests were carried out in order to study
2
−
the stability of nanoꢀSO /TiO . In this study, nanoꢀ
4
2
100
2−
SO4 /TiO was used as a test catalyst at a temperature
2
of 160° instead of 95° in order to accelerate the proꢀ
cess. After each run, the solid catalyst was separated
from the reaction mixture by filtration, washing sevꢀ
eral times with methanol and drying it at 80° for the
next cycle. Figure 4 shows that by regenerating the catꢀ
alyst after each run, only a slight deactivation was
detected. After five cycles, the conversion of the prodꢀ
80
60
40
20
0
2
−
uct catalyzed by nanoꢀSO /TiO still can reach 94%,
4
2
only 5% decrease of the conversion. This may be due
2
−
to the leaching of a small amount of the anchored SO4
and the inevitable loss of catalyst during the recycling
test in the batch reactor. Thus, we can conclude that
1
2
3
4
5
Reuse times
2
−
the nanoꢀSO /TiO prepared by solꢀgel and wet
4
2
impregnation methods is a suitable catalyst for appliꢀ
cation in esterifacation of sebacic acid with 2ꢀethyl
2
4
−
Fig. 4. Stability of the nanoꢀSO /TiO catalyst.
2
KINETICS AND CATALYSIS Vol. 52
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2011

2
–
PREPARATION OF NANOꢀSO4 /TiO CATALYST AND ITS APPLICATION
225
2
Specific surface area (BET), average pore diameter (BJH)
and pore volume
3. Choo, S.T., Nam, I.S., Ham, S.W., and Lee, J.B.,
Korean J. Chem. Eng, 2003, vol. 20, p. 273.
4
. Jung, S.M. and Grange, P., Catal. Today, 2000, vol. 59,
p. 305.
Specific
surface pore diamꢀ volume,
Average
Pore
Catalysts
2
3
5. Navarrete, J., Lopez, T., Gomez, R., and Figueras, F.,
area, m /g eter, nm
cm /g
Langmuir, 1996, vol. 12, p. 4385.
2
–
NanoꢀSO4 /TiO2
152.4
44.0
2.0
4.2
29.2
9.5
0.21
6. Wang, X.C., Yu, J.C., Liu, P., Wang, X.X., Su, W.Y., and
Fu, X.Z., J. Photochem. Photobiol., A, 2006, vol. 179,
p. 339.
2
4
–
NanoꢀS
NanoꢀS
O
O
/TiO ꢀP25
2
0.34
7
. Tian, G.H., Pan, K., Fu, H.G., Jing, L.Q., and Zhou, W.,
J. Hazard. Mater., 2009, vol. 166, p. 939.
2
4
–
/TiO ꢀP
2
0.0044
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9
. de Almeida, R.M., Noda, L.K., Goncalves, N.S.,
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hexanol. The higher specific surface area and pure
anatase phase of titania yield the higher catalytic activꢀ
ity of the catalysts.
1
0. Fu, X.Z., Clark, L.A., Zeltner, W.A., and Anderꢀ
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ACKNOWLEDGMENTS
1
1. Yang, H., Lu, R., and Wang, L., Mater. Lett., 2003,
This work is supported by the Ministry of Science
and Technology (973 grant no. 2007CB607606 and
vol. 57, p. 1190.
1
2. Lopez, T., Bosch, P., Tzompantzi, F., Gomez, R.,
Navarrete, J., LopezꢀSalinas, E., and Llanos, M.E.,
Appl. Catal., A, 2000, vol. 197, p. 107.
863 grant no. 2007AA05Z420).
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KINETICS AND CATALYSIS Vol. 52
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2011