Preparation of ammonium cerium phosphate via low-heating solid state reaction and its catalysis for benzyl acetate synthesis

Article abstract of DOI:10.1002/cjoc.201090082

Ammonium cerium phosphate was prepared with (NH₄)₃PO₄?3H₂O and Ce(SO₄)₂?4H₂O as raw materials and PEG-400 as surfactant via a solid state reaction at low-heating temperature. The characterization result of XRD indicates that the molecular formula of the product was (NH₄)₂Ce(PO₄)₂?H₂O. The synthesis of benzyl acetate was carried out with H₂SO₄/ammonium cerium phosphate as catalyst, and uniform experimental design as well as data mining technology was applied to the experiments, in which the effect of the reaction time, the molar ratio of acid to alcohol and the amount of catalyst on the conversion yield of acetic acid were studied. When benzalcohol was 0.10 mol, under the optimal reaction conditions, i.e. reaction time of 174 min, 2.02 of molar ratio of acid to alcohol and 0.5 g of catalyst, the esterification rate of acetic acid was 97.9%. The ammonium cerium phosphate had potential for industry application since it not only was feasible and simple in synthesis technics, but also had good catalysis activity for the synthesis of benzyl acetate.

Full text of DOI:10.1002/cjoc.201090082

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FULL PAPER
Preparation of Ammonium Cerium Phosphate via Low-heating
Solid State Reaction and Its Catalysis for Benzyl Acetate
Synthesis
Liao, Sen*(廖森)
Chen, Zhipeng(陈智鹏)
Wang, Tianshun(王天顺)
Liu, Gang(刘刚)
Tian, Xiaozhen(田晓珍)
Wu, Wenwei(吴文伟)
School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi 530004, China
Ammonium cerium phosphate was prepared with (NH4)3PO4•3H2O and Ce(SO4)2•4H2O as raw materials and
PEG-400 as surfactant via a solid state reaction at low-heating temperature. The characterization result of XRD in-
dicates that the molecular formula of the product was (NH4)2Ce(PO4)2•H2O. The synthesis of benzyl acetate was
carried out with H2SO4/ammonium cerium phosphate as catalyst, and uniform experimental design as well as data
mining technology was applied to the experiments, in which the effect of the reaction time, the molar ratio of acid to
alcohol and the amount of catalyst on the conversion yield of acetic acid were studied. When benzalcohol was 0.10
mol, under the optimal reaction conditions, i.e. reaction time of 174 min, 2.02 of molar ratio of acid to alcohol and
0.5 g of catalyst, the esterification rate of acetic acid was 97.9%. The ammonium cerium phosphate had potential for
industry application since it not only was feasible and simple in synthesis technics, but also had good catalysis ac-
tivity for the synthesis of benzyl acetate.
Keywords supported catalyst, ammonium cerium phosphate, benzyl acetate, solid-state reaction, data mining
technology
Introduction
prepare benzyl acetate.12-14 In continuation of our ongo-
ing program to synthesize functional inorganic materials
via solid-state reaction at low-heating temperature,15-20
we describe in this paper, the synthesis of the ammo-
nium cerium phosphate via solid-state reaction at
low-heating temperature and its catalysis for synthesis
of benzyl acetate.
In recent decade, the use of natural phosphate (NP)
in the organic transformation has been under atten-
tion10-5 because this solid is cheap, readily available,
stable, non-toxic, not a pollutant and recoverable and
reusable. Recently, Sebti and his co-workers6-11 reported
that the basic and acidic activities of NP could be im-
proved when it was doped with zinc chloride (ZnCl2/NP)
or potassium fluoride (KF/NP). It has been reported that
ZnCl2/NP was used as excellent acidic catalyst for
transesterification reaction, Friedel-Crafts alkylation,
1,3-dipolar cycloaddition, acyclonucleoside synthesis
and 3,4-dihydropyrimidin-2(1H)-one synthesis. KF/NP
catalyzed efficiently transesterification reaction, nitrile
hydration, Michael addition, Knoevenagel condensation,
flavanone synthesis, nucleobase alkylation, nucleoside
synthesis and transesterification reaction. Na/NP, as
strong basic catalyst, could promote Knoevenagel con-
densation, alkene epoxidation, Claisen-Schmidt con-
densation and Michael addition.
Experimental
Reagent and apparatus
All chemicals were of reagent-grade purity. X-ray
powder diffraction (XRD) was performed at a scanning
ratio of 0.02 (°)•s－ from 5° to 65° for 2θ using a Ri-
1
gaku D/max 2500 V diffractometer equipped with a
graphite monochromator and a Cu target. Fourier trans-
form infrared (FTIR) spectroscopy was performed on an
Ahimadzu IR450 spectrometer in the wavelength range
of 400 — 4000 cm－ 1 on KBr pellets.
Preparation and characterization of (NH4)2Ce-
(PO4)2•H2O
The main component of NP is calcium phosphate.
The properties of the rare earth ions are similar with
those of calcium ion, suggesting that rare earth phos-
phates have the similar catalyst activity as NP.
(NH4)3PO4•3H2O (40.0 mmol, 8.1256 g) and
Ce(SO4)2•4H2O (20.0 mmol, 8.0862 g) according to 2.0
of P/Ce molar ratio were mixed with 0.5 mL of
Recently, various catalysts have been reported to
*
E-mail: liaosen@qxu.edu.cn; Tel.: 0086-0771-3225152; Fax: 0086-0771-3225152
Received June 22, 2009; revised September 4, 2009; accepted October 27, 2009.
Project supported by the Key Laboratory of New Processing Technology for Nonferrous Metals and Materials, Ministry of Education, Guangxi University (No.
GXKFZ-02) and Guangxi Science Fund (Nos. 0991108, 0832111).
378
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Preparation of Ammonium Cerium Phosphate
PEG-400 in a mortar, and ground for 30 min. The reac-
tion mixture was sealed and kept at 80 ℃ for 2 h,
washed with water to remove soluble inorganic salts
until SO24－ ions could not be detected by a 0.5 mol•
L－ 1 BaCl2 solution, then washed with a small amount of
anhydrous ethanol and dried at 80 ℃ for 4 h. The re-
sulting material was subsequently determined to be the
crystal phase of (NH4)2Ce(PO4)2•H2O. All diffraction
peaks of the product in Figure 1 could be indexed to be
in agreement with the orthorhombic system structure of
(NH4)2Ce(PO4)2•H2O from PDF card 52-0336.
Table 1 Factors and levelsa
t/min
30
n
w/g
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
1
2
3
4
5
6
7
8
9
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
50
70
90
110
130
150
170
190
210
10
a
t (reaction time): 30— 210 min, n (acid/alcohol molar ratio):
0.4— 2.2, w (the amount of catalyzer): 0.5— 2.75 g.
Table 2 Experimental project of uniform design and resultsa
t/min
30
n
w/g
2.00
1.00
2.75
1.75
0.75
2.50
1.50
0.5
Y/%
1
2
3
4
5
6
7
8
9
1.2
2.2
1.0
2.0
0.8
1.8
0.6
1.6
0.4
1.4
81.19
85.86
70.51
83.13
72.42
85.66
84.85
88.99
81.72
90.91
50
70
90
110
130
150
170
190
210
Figure 1 XRD patterns of the product.
2.25
1.25
Preparation of H2SO4/(NH4)2Ce(PO4)2•H2O
10
a
50 mL of 1.5 mol/L H2SO4 and 10 g of
(NH4)2Ce(PO4)2•H2O were mixed in a 100 mL beaker
and kept at room temperature for 24 h, then vacuum
filtrated and dried for 2 h at 100 ℃ to obtain
H2SO4/(NH4)2Ce(PO4)2•H2O.
t (reaction time): 30— 210 min, n (acid/alcohol molar ratio):
0.4— 2.2, w (the amount of catalyzer): 0.5— 2.75 g.
cator. The percentage of esterification of benzalcohol
was calculated according to the amount of acetic acid
remaining. Every experiment was repeated three times
to get average result. The mixture was subsequently
washed with water, dilute solution of sodium carbonate
and water, then dried with anhydrous Na2SO4. The
products were obtained by distilling the dried mixture
with a bit of boric acid, in which boric acid made ben-
zalcohol transformed into high boiling point benzyl bo-
rate. The product was analyzed by GC-MS.
Experiment design of catalysis of esterification reac-
tion
The results of preparative experiments showed that
H2SO4/(NH4)2Ce(PO4)2•H2O had catalysis activity for
esterification, but the catalysis activity disappeared
without loading H2SO4. So, all catalysis experiments of
esterification were carried out with H2SO4/(NH4)2Ce-
(PO4)2•H2O as catalyzer. The amount of benzalcohol
was 0.10 mol (10.50 mL) for every reaction. The factors
and their levels of the experiments are shown in Table 1.
The uniform design project21 of the experiments is
shown in Table 2, in which the conversion yield of es-
terification (Y) was used as the response value.
Results and discussion
Modeling with stepwise regression analyses
The equation relating the coefficients obtained from
stepwise regression analyses21 with the data of Table 2
is as follows [Eq. (1)]:
General procedure for the esterification reaction
The experiments were carried according to direction
of the uniform design project in Table 2. A mixture of
glacial acetic acid, benzalcohol, and H2SO4/(NH4)2-
Ce(PO4)2•H2O was refluxed while being stirred. Reac-
tion temperature of the liquid pot was kept at 120 ℃.
After the reaction ending, the mixture was filtered, and
the residual acetic acid was neutralized with standard-
ized NaOH solution, using phenolphthalein as an indi-
Y
86.6578 0.05217(t 120) 3.8454(n 1.3)2
＝
＋
－
－
－
－
6.2836(w 1.625)2 4.5471(n 1.3)(w 1.625)
－
－
－
－
＋
16.5791(n 1.3)(w 1.625)2
(1)
－
－
F＝245.11, R＝0.9984, S＝0.5616. The values of Fi are
F1＝284.75, F2＝27.47, F3＝208.41, F4＝60.00 and
F5＝722.72 (F is equation F-statistic; Fi are equation
Chin. J. Chem. 2010, 28, 378— 382
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F-statistic variable items; R is the correlation coefficient
of equation; S is the standard deviation of residuals of
equation). The results of the F significance test showed
that the coefficients of the equation and the equation all
passed the F significance test at confidence level of α＝
0.01.
Static data mining
The optimal reaction conditions got from optimiza-
tion of the Eq. (1) with a grid method21 are as follows:
t＝174 min, n＝2.02, w＝0.5 g and Y＝98.32%.
Dynamic data mining
The Eq. (1) could be conversed as following three
equations that expressed the relation between single
factor and the response, in which the optimal reaction
conditions obtained from the static data mining were
used as benchmark:
Figure 2 Effect of reaction time t on the conversion yield of
esterification.
Y
Y
Y
95.5025 0.05217(t 120)
(2)
＝
＝
＝
＋
－
81.5222 26.0984(n 1.3) 3.8454(n 1.3)2 (3)
＋
－
－
－
87.4813 3.2739(w 1.625) 5.6534(w
－
－
＋
－
1.625)2
(4)
The Eqs. (2)—(4) were used to draw figures of X-Y and
Figures 2—4 were obtained according to direction of
the method in the Ref. 21. Figure 2 shows that the effect
of reaction time on the conversion yield of esterification
is a line, while the value of the conversion yield of es-
terification increases with reaction time. The esterifica-
tion is a reversible reaction, so the reaction is carried out
forward to increase the conversion yield of esterification
with the increasing reaction time, when the water
formed from the reaction is continuously removed by
manifold. Figure 3 shows that the effect of n
(acid/alcohol molar ratio) on Y is the left of a parabola
with opening downwards, while the Y value increases
with increasing the acid/alcohol molar ratio. The result
of the Figure 3 agrees with the principles of chemical
equilibrium that the reaction will be carried out forward
with increasing the concentration of the reactant. Figure
4 shows that the effect of w (The amount of catalyzer)
on Y is a parabola opening upwards without a part of the
right, while the Y value decreases with increasing the
amount of catalyzer. The result of the Figure 4 implys
that the by-reaction increases with increasing the
amount of catalyzer. The etherification does not con-
sume acetic acid, so it is possible that the by-reaction is
the etherification.
Figure 3 Effect of acid/alcohol molar ratio (n) on the conver-
sion yield of esterification
Figure 4 Effect of dosage of catalyzer (w) on the conversion
yield of esterification.
Verification experiment with the optimal reaction
conditions
Characterization of the esterification product
The infrared spectrum of the esterification product is
shown in Figure 5. The band observed at 3066 cm－ 1 was
attributed to ArH stretching. The strong absorption
Three parallel verification experiments were carried
with the optimal reaction conditions: t＝174 min, n＝
2.02, w＝0.5 g, and the obtained average value Y＝
97.9% was very close to the optimal value 98.32%.
peaks observed at 1747 and 1233 cm－ indicate that
1
380
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Preparation of Ammonium Cerium Phosphate
Figure 5 IR spectrum of the esterification product.
Figure 8 Mass spectrum of peak No. 5.
there is an acyl group in the product molecule. The ab-
sorption bands observed at 1505, 1457, 1382 and
Conclusion
1347.55 cm－ were all assigned to the various vibration
1
We have successfully prepared the ammonium ce-
rium phosphate via solid-state reaction at low-heating
temperature and tested its catalysis for synthesis of
benzyl acetate.
(1) When (NH4)3PO4•3H2O and Ce(SO4)2•4H2O
were used as starting materials, crystal phase of
(NH4)2Ce(PO4)2•H2O was obtained via a solid-state re-
action at low-heating temperature.
(2) The (NH4)2Ce(PO4)2•H2O had no catalysis activ-
ity toward esterification in the synthesis of benzyl ace-
tate.
(3) The H2SO4/(NH4)2Ce(PO4)2•H2O was proved to
behave as an excellent heterogeneous catalyst in the
synthesis of benzyl acetate.
modes of phenyl group.
The total ion chromatogram of the product is shown
in Figure 6. It can be seen from the Figure 6 that the
component content of peaks Nos. 2 and 5 is 99.67% in
total content, while the component content of peak No.
2 is 98.92% and is the main product. Mass spectra of
peaks Nos. 2 and 5 are shown in Figures 7 and 8, re-
spectively, which can be attributed to be in agreement
with benzyl acetate at matching rate 94% and methoxy-
benzene at 90%, respectively. So, it is obvious that there
is very little other impurity in the product from Figure 6.
When benzalcohol was 0.10 mol, under the optimal
reaction conditions, i.e. reaction time of 174 min, 2.02
of molar ratio of acid to alcohol and 0.5 g of catalyst,
the esterification rate of acetic acid was 97.9%. The
ammonium cerium phosphate had potential for indus-
trial application since it was not only feasible and sim-
ple in synthesis technics, but also had good catalysis
activity for the synthesis of benzyl acetate.
Figure 6 Total ion chromatogram of the ester product.
References
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5
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Sebti, S.; Rhihil, A.; Saber, A.; Laghrissi, M.; Boulaajaj, S.
Tetrahedron Lett. 1996, 37, 3999.
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Abrouki, Y.; Zahouily, M.; Rayadh, A.; Bahlaouan, B.;
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Figure 7 Mass spectrum of peak No. 2.
Chin. J. Chem. 2010, 28, 378— 382
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