Glycerol catalytic cyclocondensation with ethanediamine to pyrazinyl compounds over the modified SiO2-Al2O3

Article abstract of DOI:10.1002/hc.21026

The Fe, Zn, and Mn-modified SiO₂-Al₂O₃ catalysts for the glycerol vapor-phase cyclocondensation with ethanediamine (ED) to 2-pyrazinemethanol (2-PMol) and 2-methylpyrazine (2-MP) in a fixed-bed system were prepared by coprecipitation and characterized by N₂ adsorption-desorption, X-ray powder diffraction, and NH₃ temperature-programmed desorption (NH₃-TPD) in the present work. The results showed that the Mn-modified SiO₂-Al₂O₃ catalyst with a SiO₂/Al₂O₃ molar ratio 15.84 and 6% Mn gave the highest catalytic activity for formation of 2-PMol (53.1%) and 2-MP (42.9%). Mn species could cause the modulation of the acidic species of catalysts, improving the glycerol cyclocondensation with ED to 2-PMol, and also acted as the catalytic centers for the hydrodehydration of 2-PMol to 2-MP. However, too many strong acidic sites could lead to ED self-cyclocondensation to form a by-product pyrazine. The optimum temperature was tested to be 380°C for the cyclocondensation over a 6%Mn-SiO₂-Al₂O ₃ catalyst.

Full text of DOI:10.1002/hc.21026

Heteroatom Chemistry
Volume 00, Number 0, 2012
Glycerol Catalytic Cyclocondensation with
Ethanediamine to Pyrazinyl Compounds over
the Modified SiO -Al O
2 2 3
Chuanqi Liu, Chenghua Xu, Tongwei Xia, Yan Guo, and Jianying Liu
Air Environmental Modeling and Pollution Controlling Key Laboratory of Sichuan Higher
Education Institutes, Chengdu University of Information Technology, Chengdu, Sichuan 610225,
People’s Republic of China
Received 20 February 2012
INTRODUCTION
ABSTRACT: The Fe, Zn, and Mn-modified SiO2-
Al2O3 catalysts for the glycerol vapor-phase cy-
clocondensation with ethanediamine (ED) to 2-
pyrazinemethanol (2-PMol) and 2-methylpyrazine
(2-MP) in a fixed-bed system were prepared by co-
precipitation and characterized by N2 adsorption–
desorption, X-ray powder diffraction, and NH3
temperature-programmed desorption (NH3-TPD) in
the present work. The results showed that the Mn-
modified SiO2-Al2O3 catalyst with a SiO2/Al2O3 mo-
lar ratio 15.84 and 6% Mn gave the highest catalytic
activity for formation of 2-PMol (53.1%) and 2-MP
(42.9%). Mn species could cause the modulation of
the acidic species of catalysts, improving the glycerol
cyclocondensation with ED to 2-PMol, and also acted
as the catalytic centers for the hydrodehydration of
2-PMol to 2-MP. However, too many strong acidic
sites could lead to ED self-cyclocondensation to form
a by-product pyrazine. The optimum temperature was
tested to be 380◦C for the cyclocondensation over a
With the gradual exhaustion of resources and an in-
crease in demand of oil, human beings are facing
a serious energy crisis and the biodiesel as a kind
of renewable and clean energy has attracted more
and more attention. However, a large quantity of
by-product glycerol will come forth during biodiesel
manufacturing [1]. Therefore, the reasonable uti-
lization of glycerol is very important to develop the
biodiesel industry. It has been reported that glycerol
can be catalytically hydrogenated to propanediols
[2–5], dehydrated to acrolein [6–9], and converted
to hydrogen or syngas through the steam reforming
[10–12].
From the recent studies [13–17], it is found that
two adjacent hydroxyl groups in glycols such as 1,2-
propanediol and glycol can be cyclocondensed with
two adjacent amino groups in ethanediamine (ED)
to pyrazinyl compounds. Glycerol consists of three
adjacent OH groups; thereby, it can also be cyclo-
condensed with ED to form 2-pyrazinemethanol
(2-PMol) as shown in Scheme 1. Sarkari et al. [18]
have studied this reaction over ZnCr2O4 as a cata-
lyst and discovered that the obtained main product
is 2-methylpyrazine (2-MP) due to further hydrode-
hydration of 2-PMol. Anyway, both pyrazinyl com-
pounds are the key intermediates for pyrazinamide,
an effective antitubercular drug. The present work
mainly aims to utilize the metal-modified SiO2-Al2O3
mixed oxides as catalysts to carry out the simulta-
neous synthesis of 2-PMol and 2-MP through the
ꢀ
C
6%Mn-SiO2-Al2O3 catalyst.
2012 Wiley Periodicals,
Inc. Heteroatom Chem 00:1–6, 2012; View this article on-
line at wileyonlinelibrary.com. DOI 10.1002/hc.21026
Correspondence to: Chenghua Xu; e-mail: xch@cuit.edu.cn.
Contract grant sponsor: Youth Science and Technology Foun-
dation of Sichuan Province in People’s Republic of China.
Contract grant number: 2012JQ0047.
2012 Wiley Periodicals, Inc.
c
ꢀ
1

2
Liu et al.
CH2OH
CH2OH
N
N
CH2OH
+ H2
CH3
+H2O
N
N
N
NH2
NH2
HO
HO
Catalyst
Catalyst
+
+ 2H2O + 3H2
N
SCHEME 1
SCHEME 2
vapor-phase catalytic cyclocondensation of glycerol
with ED. The used typical bifunctional catalysts are
characterized by N2 adsorption–desorption, X-ray
powder diffraction (XRD), and NH3 temperature-
programmed desorption (NH3-TPD). In addition, the
effects of catalyst composition and cyclocondensa-
tion temperature on the glycerol vapor-phase cyclo-
condensation with ED in the fixed-bed system are
also investigated in detail.
generated by the deamination of ED through self-
cyclocondensation [19]. 2-PMol is from the cyclo-
condensation between two adjacent hydroxyl groups
in glycerol and two amino groups of ED as described
in Scheme 1. Another main product 2-MP is from the
hydrodehydration of 2-PMol with active hydrogen
produced during formation of 2-PMol as described
in Scheme 2.
From Fig. 1, it can also be observed that the
by-product Py in products is reduced with increas-
ing SiO2 amount in catalysts. It is probably because
that an increase in the SiO2 amount leads to a de-
crease in the strong acidic sites provided by alu-
mina species on the catalyst surface, which inhibits
the self-cyclocondensation of the strongly adsorbed
ED. The NH3-TPD results of the SiO2-Al2O3 catalysts
(Fig. 2a) show that the SiO2-Al2O3 catalyst with a
SiO2/Al2O3 molar ratio 10.56 gives two NH3 desorp-
tion peaks at about 90◦and 200–450◦C, which are
assigned to the weak and strong acidic sites, re-
spectively. In addition, it can also be observed that
strong acidic site intensities decrease with increas-
ing SiO2 amount in catalysts. The NH3 adsorption
on the SiO2–Al2O3 catalyst with a higher SiO2/Al2O3
ratio (26.4) mainly occurs on the weak acidic sites,
and the NH3 desorption peak shifts to the high tem-
perature with increasing SiO2/Al2O3 ratio in the cat-
alyst, indicating that they exhibit a stronger acidity.
Therefore, the self-cyclocondensation of ED to a by-
product Py can be deduced to carry out on the strong
acidic sites located on the catalyst surface, which is
not helpful to utilization of glycerol.
On the other hand, it is also found from Fig. 1
that the 2-MP formation first increases and then de-
creases with increasing SiO2 amount in catalysts and
gives the highest value at the SiO2/Al2O3 molar ratio
15.84, and however the 2-PMol content has no ob-
vious change. It is due to the fact that the presence
of SiO2 in the catalyst can provide more surface hy-
droxyl groups [20], which will probably provide the
Brønsted acidic sites. However, a further increase
in SiO2 in the catalyst will excessively decrease the
acidic sites and the Lewis acidic sites mainly pro-
vided by Al2O3 species, which are disadvantageous
to the ED adsorption. According to the NH3-TPD re-
sults, it can be concluded that the proper SiO2/Al2O3
RESULTS AND DISCUSSION
Selection of SiO2/Al2O3 Ratio
The effect of the SiO2/Al2O3 molar ratio on the
catalytic properties of SiO2-Al2O3 catalysts (Fig. 1)
in glycerol cyclocondensation with ED is investi-
gated under the conditions of liquid hourly space
velocity (LHSV) 4.5 h−1 and temperature 380◦C. It
can be found that the glycerol cyclocondensation
with ED on the SiO2-Al2O3 catalysts gives two main
products including 2-PMol and 2-MP, as well as
a small amount of pyrazine (Py). Py is probably
100
98
96
94
92
90
100
98
96
94
92
90
50
45
40
35
30
25
20
15
10
5
50
45
40
35
30
25
20
15
10
5
ED conversion
Glycerol conversion
2-PMol
2-MP
Py
0
0
5
10
15
20
25
30
SiO2/Al2O3 molar ratio
FIGURE 1 Effect of the SiO2/Al2O3 molar ratio on catalytic
properties of SiO2-Al2O3 in the glycerol cyclocondensation
with ED.
Heteroatom Chemistry DOI 10.1002/hc

Glycerol Catalytic Cyclocondensation with Ethanediamine to Pyrazinyl Compounds over the Modified SiO2-Al2O3
3
ratio is probably due to a decrease in the absolute
2-PMol amount from cyclocondensation. Therefore,
during the glycerol cyclocondensation with ED, the
Lewis acidic sites of catalyst first adsorb one of the
amino groups in ED molecules, the Brønsted acidic
sites give rise to dehydroxylation of glycerol to pro-
duce carbocation, which can attack another amino
group of ED to carry out the nucleophilic reaction,
resulting in cyclocondensation of glycerol with ED to
2-PMol (Scheme 3).
(a)
40 mV
SiO2/Al2O3 = 26.4
SiO2/Al2O3 = 15.84
SiO2/Al2O3 = 10.56
Metal Modification
(b)
40 mV
As described in Schemes 1 and 2, the cyclization,
dehydrogenation, and hydrodehydration are mainly
involved in the glycerol cyclocondensation with ED
to 2-PMol and 2-MP. It has been reported that some
transition metal species (such as Fe, Mn, Zn, and Cu)
exhibit a good catalytic activity on glycol cyclocon-
densation with ED to pyrazinyl compounds [13,16].
Therefore, the effect of the modification with transi-
tion metal ions (such as 5% of Fe3+, Zn2+, or Mn2+)
on the catalytic properties of SiO2-Al2O3 (SiO2/Al2O3
molar ratio 15.84) catalyst in glycerol cycloconden-
sation with ED is also investigated under the con-
ditions of reaction temperature 380◦C and LHSV
4.5 h−1. The results (Fig. 3) show that the modifica-
tion of Zn2+ and Fe3+ will lead to a little decrease
in 2-PMol formation along with 2-MP increase
over SiO2-Al2O3 catalysts. It indicates that Zn2+ and
Fe3+ exhibit a catalytic reducibility, resulting in the
2-PMol hydrodehydration to 2-MP, which is consis-
tent with the results in the cyclization of propylene
glycol with ED to 2-MP as reported [15–17]. How-
ever, glycerol conversion decreases significantly,
which is probably because the Zn2+ and Fe3+ ions
are located on the silica species leading to the atten-
uation of glycerol dehydroxylation to carbocation.
In addition, it is also found from Fig. 3 that the Mn
modification can result in an obvious increase in the
2-PMol formation (61.0%) with a slight decrease in
2-MP, indicating that the Mn2+modification is
8% Mn
6% Mn
4% Mn
2% Mn
0% Mn
100
200
300
400
500
600
700
800
Temperature (oC)
FIGURE 2 NH3-TPD curves for SiO2-Al2O3 with a differ-
ent SiO2/Al2O3 molar ratio (a) and Mn-SiO2-Al2O3 (SiO2/
Al2O3 = 15.84) catalysts with a different Mn amount (b).
ratio will give rise to the simultaneous production
of a proper number of Brønsted and Lewis acidic
sites on the surface of catalyst. It will be helpful
to the simultaneous adsorption of ED and glycerol,
and the presence of the Brønsted acidic sites can
also lead to the dehydroxylation on 2-C sites of glyc-
erol to carbocation. A slight decrease in 2-MP for-
mation over the catalysts with a higher SiO2/Al2O3
HO
HO
NH2
NH2
OH
HO
CH2OH
N
N
H
O
OH
–H2O
–H2
–H2O
O
NH2
Al
NH2
Al
O
Si
Si
O
O
O
O
O
SCHEME 3
Heteroatom Chemistry DOI 10.1002/hc

4
Liu et al.
tent in products first decreases and then increases
with increasing Mn amount, which is opposite to
the change in trend in 2-MP. It indicates that the
Mn species in catalysts also exhibit a catalytic ac-
tivity on the hydrodehydration of 2-PMol to 2-MP.
In addition, the conversions toward both glycerol
and ED increase to some extent with increasing Mn
amount and reach up to the highest values at the Mn-
modified amount of 6%. It adequately shows that
the Mn species in catalysts play an important role in
glycerol catalytic cyclocondensation with ED.
The N2 absorption–desorption results (data
omitted here) reveal that the surface area (213 m2
g−1) of the SiO2-Al2O3 catalyst (SiO2/Al2O3 molar ra-
tio 15.84) is decreased to 170–190 m2 g−1 after the
Mn modification. From the XRD patterns (Fig. 5)
of Mn-SiO2-Al2O3 catalysts, it can be observed that
the Mn-SiO2-Al2O3 catalysts with a low Mn amount
give some distinct AlOOH characteristic diffraction
peaks (Pdf no. 17-940) at 2θ = 14.5◦, 28.2◦, 38.5◦,
49.0◦, 65.1◦, and 73.2◦, respectively. However, with
an increase in Mn amount (>3%), the AlOOH species
in catalysts generates a crystal-phase transforma-
tion to γ -Al2O3 (Pdf no: 1-1303) along with the gen-
eration of a small amount of new species such as
Mn7O8(SiO4) (Pdf no. 89-5664). And, no apparent
SiO2 characteristic diffraction peaks are observed for
all the catalysts, indicating that the SiO2 species in
the catalysts were amorphous.
100
90
80
70
60
50
40
30
20
10
0
Catalyst types
FIGURE 3 Effect of metal ion modification on catalytic prop-
erties of SiO2-Al2O3 ED conversion, Glycerol con-
version , 2-PMol , 2-MP, Py.
helpful to the glycerol cyclocondensation with ED
to 2-PMol over SiO2-Al2O3.
Selection of Mn-Modified Amount
The effects of Mn-modified amount on the cat-
alytic properties of the Mn-SiO2-Al2O3 catalysts
(SiO2/Al2O3 molar ratio 15.84) are investigated in de-
tail. The results (Fig. 4) show that the 2-PMol con-
From NH3-TPD curves (Fig. 2b) of Mn-SiO2-
Al2O3 catalysts, the Mn-SiO2-Al2O3 catalysts with
Mn amount of 2% is found to give two strong NH3
100
AlO(OH)
r-Al2O3
95
ED conversion
Glycerol conversion
Mn7O8(SiO4)
90
2-PMol
2-MP
Py
85
80
60
(1)
(2)
(3)
50
40
30
20
10
0
(4)
(5)
(6)
(7)
10
20
30
40
50
60
70
80
0
1
2
3
4
5
6
7
8
9
10
2θ/ (o)
Mn amount (wt%)
FIGURE 4 Effect of Mn-modified amount on catalytic prop-
erties of Mn-SiO2-Al2O3 in glycerol cyclocondensation with
ED.
FIGURE 5 XRD patterns of Mn-SiO2-Al2O3 with a differ-
ent Mn amount of (1) 0.2%; (2) 1.0%; (3) 2.0%; (4) 3.0%;
(5) 4.0%; (6) 6.0%; and (7) 8.0%.
Heteroatom Chemistry DOI 10.1002/hc

Glycerol Catalytic Cyclocondensation with Ethanediamine to Pyrazinyl Compounds over the Modified SiO2-Al2O3
5
desorption peaks at 90◦ and 250–350◦C, respectively.
100
80
They are assigned to the weak and strong acidic sites.
No obvious change in the peak intensity of NH3 des-
orption occurred on the weak acidic sites, which can
be observed after the SiO2-Al2O3 catalyst is modi-
fied by Mn. However, when Mn amount is increased
from 2% to 6%, the intensities of the NH3 desorption
peak are weakened at about 250–350◦C. In combina-
tion with the XRD results, it can be concluded that
the acidic sites are mainly provided by AlOOH or
γ -Al2O3 species and the Mn oxide species are prob-
ably located on the surface of aluminum oxide
species, resulting in a slight decrease in Lewis acidic
sites and can provide Brønsted acidic sites similar
to the Si-OH groups, which are helpful to glycerol
conversion. However, the presence of excessive Mn
leads to formation of Mn7O8(SiO4) composite ox-
ides in catalyst, probably resulting in a decrease in
the Brønsted acidic sites. From the catalytic results
(Fig. 4), the SiO2-Al2O3 catalyst with Mn amount of
6% exhibits the best catalytic property; it is mainly
because of the simultaneous existence of proper
Brønsted and Lewis acidic sites. In other words,
the modification with a proper Mn can modulate
the acidic species over the surface of catalysts. The
glycerol catalytic cyclocondensation with ED occurs
between the carbocations from glycerol and the ad-
sorbed ED on Lewis acidic sites to 2-PMol and H2,
and whereafter the 2-MP formation will be carried
out by the hydrodehydration of 2-Pmol, which can
be improved by the presence of Mn in catalysts.
ED conversion
Glycerol conversion
2-PMol
2-MP
Py
60
40
20
9
8
7
6
340
360
380
400
420
Reaction temperature (oC)
FIGURE 6 Effect of reaction temperature on catalytic prop-
erties of 6%Mn-SiO2-Al2O3 in glycerol cyclocondensation
with ED.
self-cyclocondensation and the difficulty in glycerol
conversion on Brønsted acidic sites of the catalyst
surface. 380◦C should be the optimum reaction tem-
perature for the glycerol cyclocondensation with ED
in the fixed-bed system, which is the same as that
for the synthesis of the other pyrazinyl compounds
as reported [17]. The investigation on the catalytic
stability of 6%Mn-SiO2-Al2O3 in the glycerol cyclo-
condensation with ED (Fig. 7) shows that the con-
versions of glycerol and ED are at the stable levels of
about 95% and 97%, respectively. And the content of
2-PMol (∼60%) and 2-MP (∼35%) in products also
has not decreased after 48 h. It indicates that this
catalyst displays a stable catalytic property in the
glycerol cyclocondensation with ED.
Effect of Reaction Temperature
The effect of reaction temperature on the catalytic
property of 6%Mn-SiO2-Al2O3 in the glycerol cyclo-
condensation with ED is investigated under LHSV
4.5 h−1. From Fig. 6, the by-product Py in prod-
ucts increases gradually with increasing reaction
temperature, it indicates that the high temperature
is helpful to ED self-cyclocondensation on the cat-
alyst surface. The product 2-PMol first decreases
and then increases; however, 2-MP formation gives
an adverse trend with increasing reaction temper-
ature. It is mainly because the increase in temper-
ature is advantageous to the hydrodehydration of
2-PMol; however too high a temperature can make
the produced 2-PMol escape from the catalyst sur-
face quickly. As far as conversions toward glycerol
and ED are concerned, they increase first and then
decrease with the increasing reaction temperature
and the highest conversions come forth at 380◦C.
Moreover, a decrease in the glycerol conversion in
the high-temperature region is also found to be much
more than that of ED, which is mainly because of ED
EXPERIMENTAL
Catalyst Preparation
SiO2-Al2O3 catalysts were synthesized as follows: A
desired amount of pseudoboehmite (AlO(OH)·xH2O,
68%–72% Al2O3) and tetraethyl orthosilicate was
successively added in urea solution under the vig-
orous stirring for 20 min at room temperature. The
obtained white slurry was then heated at 70◦C under
stirring for another 1.5 h to carry out the homoge-
neous coprecipitation. The white precipitates were
filtrated, washed, dried, and calcined at 500◦C for 5 h
to obtain the SiO2-Al2O3 catalysts. The metal mod-
ification of SiO2-Al2O3 catalysts was carried out by
the impregnation using the nitrates of Zn2+, Fe3+, or
Heteroatom Chemistry DOI 10.1002/hc

6
Liu et al.
100
(0.38–0.83 mm, apparent volume 2 mL) was sand-
wiched between quartz wool layers in a quartz tube
reactor and was activated in a flow of dry air at 400◦C
for 4 h prior to catalytic runs. The catalysts were then
flushed with 30 mL min−1 of dry N2 and cooled to the
desired temperature. The aqueous liquid reactants
with a molar composition of 0.1 glycerol : 0.1 ED :
1 H2O were fed into the reactor by a PDB-FT-2505
syringe feed pump (Jing-Wei Good Friends Beijing,
Tech Development Co., Beijing, China) at a rate of
9 mL h−1. The liquid products collected in an ice-
cooled condenser were analyzed by a GC-2000 gas
chromatograph (Chongqing Chuanyi Analyzer Co.,
Chongqing, China) equipped an OV-101 column and
a flame ionization detector.
98
96
94
92
ED conversion
Glycerol conversion
2-PMol
2-MP
Py
90
60
40
20
0
0
5
10 15 20 25 30 35 40 45 50
Time on stream (h)
REFERENCES
[1] Fangrui, M.; Milford A. Bioresour Technol 1999, 70,
1–15.
FIGURE 7 Catalytic stability of 6%Mn-SiO2-Al2O3 in glyc-
erol cyclocondensation with ED at LHSV 4.5 h−1, reaction
temperature 380◦C, N2 as a carrier gas.
[2] Dasari, M. A.; Kiatsimkul, P. P.; Sutterlin, W. R.; Sup-
pes G. J. Appl Catal A 2005, 281, 225–231.
[3] Meher, L. C.; Gopinath, R.; Naik, S. N.; Dalai A. K.
Ind Eng Chem Res 2009, 48, 1840–1846.
[4] Guo, X. H.; Li, Y.; Shi, R. J.; Liu, Q. Y.; Zhan, E. S.;
Shen, W. J. Appl Catal A 2009, 371, 108–113.
[5] Montasssir, C.; Menezo, J. C.; Hoang, L. C.; Renaud,
C.; Barbier, J. J Mol Catal 199l, 70, 99–110.
[6] Chai, S. H.; Wang, H. P.; Liang, Y.; Xu, B. Q. Green
Chem 2007, 9, 1130–1136.
Mn2+ as a precursor. After impregnation, the sam-
ples were calcined at 400◦C for 1 h after drying.
Catalyst Characterization
The specific surface areas of catalysts were mea-
sured by the N2 adsorption–desorption isotherms
at –196◦C using an SSA-4200 micromeritics instru-
ment (Builder Co., Beijing, China). XRD patterns
of catalysts were recorded on a DX-2700 powder
diffractometer (Dandong Fangyuan Instrument Co.,
Dandong, China) operated at 30 kV and 20 mA,
using Cu Kα radiation. The compositions were de-
termined using a XRF-1800 X-ray fluorescence spec-
trometer (Shimadzu Co., Japan). The surface acidity
of catalysts was tested by NH3-TPD on a TP-5080 ad-
sorption instrument (Tianjin Xianquan Instrument
Co., Tianjin, China): 0.2 g samples (0.38–0.83 mm)
was loaded and pretreated with N2 at 600◦C for 1 h to
remove the adsorbed water. The adsorption of NH3
and the removal of the physically adsorbed NH3 on
the catalyst surface were carried out at room tem-
perature. The desorption of the chemically adsorbed
NH3 was carried out by heating it from 20 to 900◦C
(at a heating rate of 10◦C min−1) in 30 mL min−1 of
Ar gas; the desorbed NH3 amount was detected by
the thermal conductivity detector.
[7] Chai, S. H.; Wang, H. P.; Liang, Y.; Xu, B. Q. J Catal
2007, 250, 342–349.
[8] Ning, L. L.; Ding, Y. J.; Chen, W. M.; Gong, L. F.;
Lin, R. H.; Yuan, L.; Xin, Q. Chin J Catal 2008, 29,
212–214.
[9] Tsukuda, E.; Sato, S.; Takahashi, R.; Sodesawa, T.
Catal Commun 2007, 8, 1349–1353.
[10] Valliyappan, T.; Ferdous, D.; Bakhshi N. N. Top Catal
2008, 49, 59–67.
[11] Wen, G. D.; Xu, Y. P.; Ma, H. J.; Xu, Z. S.; Tian, Z. J.
Int J Hydrogen Energy, 2008, 33, 6657–6666.
[12] Wawrzetz, B.; Peng, B.; Hrabar, A.; Jentys, A.;
Lemonidou, A. A.; Lercher, J. A. J Catal 2010, 269,
411–420.
[13] Basak, J.; Hardia, N.; Saxena, S.; Dixit, R.; Dwivedi,
R.; Bhadauria, S.; Prasad, R. Ind Eng Chem Res 2007,
46, 7039–7044.
[14] Anand, R.; Hegde, S. C.; Rao, B. S.; Gopinath, C. S.
Catal Lett 2002, 84, 265–272.
[15] Anand R.; Rao, B. S. Catal Commun 2002, 3, 29–35.
[16] Park, N.; Lee, J. H.; Rhee, Y. Y.; Han, Y. H.; Kim, H.
R. Appl Catal A 2003, 253, 249–255.
[17] Jing, F. L.; Chu, W.; Zhang, Y. Y.; Chen, Y. Q.; Luo,
S. Z. Chin Chem Lett 2008, 19, 752–755.
[18] Sarkari, R.; Anjaneyulu, C.; Krishna, V.; Kishore, R.;
Sudhakar, M.; Venugopal, A. Catal Commun 2011,
12, 1067–1070.
[19] Latha, B. M.; Sadasivam, V.; Sivasankar, B. Catal
Commun 2007, 8, 1070–1073.
[20] Xu, C. H.; Jin, T. H.; Jhung, S. H.; Chang, J. S.;
Hwang, J. S.; Park, S. E. Catal Today 2006, 111, 366–
372.
Catalytic Test
Glycerol cyclocondensation with ED was performed
in a fixed-bed reactor under atmospheric pressure at
the temperature range of 340-420◦C. 1.5 g of catalysts
Heteroatom Chemistry DOI 10.1002/hc