Synthesis of dimethyl carbonate from ethylene carbonate and methanol over nano-catalysts supported on CeO2-MgO

Article abstract of DOI:10.1166/jnn.2015.11248

A series of CeO₂(X)-MgO(1-X) (X = 0, 0.25, 0.5, 0.75, and 1.0) nano-catalysts were prepared by a co-precipitation method for use in the synthesis of dimethyl carbonate from ethylene carbonate and methanol. Among the CeO₂(X)-MgO(1-X) catalysts, CeO₂(0.25)-MgO(0.75) nano-catalyst showed the best catalytic performance. Alkali and alkaline earth metal oxides (MO = Li₂O, K₂O, Cs₂O, SrO, and BaO) were then supported on CeO₂(0.25)-MgO(0.75) by an incipient wetness impregnation method with an aim of improving the catalytic performance of CeO₂(0.25)-MgO(0.75). Basicity of the catalysts was determined by CO₂-TPD experiments in order to elucidate the effect of basicity on the catalytic performance. The correlation between catalytic performance and basicity showed that basicity played an important role in the reaction. Yield for dimethyl carbonate increased with increasing basicity of the catalysts. Among the catalysts tested, Li₂O/CeO₂(0.25)-MgO(0.75) nano-catalyst with the largest basicity showed the best catalytic performance in the synthesis of dimethyl carbonate.

Full text of DOI:10.1166/jnn.2015.11248

Article
Journal of
Nanoscience and Nanotechnology
Vol. 15, 8330–8335, 2015
Copyright © 2015 American Scientific Publishers
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Printed in the United States of America
Synthesis of Dimethyl Carbonate from Ethylene
Carbonate and Methanol Over Nano-Catalysts
Supported on CeO2–MgO
Jin Oh Jun, Joongwon Lee, Ki Hyuk Kang, and In Kyu Song∗
School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University,
Shinlim-dong, Kwanak-ku, Seoul 151-744, South Korea
A series of CeO2ꢀXꢁ–MgO(1 −X) (X = 0, 0.25, 0.5, 0.75, and 1.0) nano-catalysts were prepared
by a co-precipitation method for use in the synthesis of dimethyl carbonate from ethylene carbonate
and methanol. Among the CeO2ꢀXꢁ–MgO(1 − X) catalysts, CeO2(0.25)–MgO(0.75) nano-catalyst
showed the best catalytic performance. Alkali and alkaline earth metal oxides (MO = Li2O, K2O,
Cs2O, SrO, and BaO) were then supported on CeO2(0.25)–MgO(0.75) by an incipient wetness
impregnation method with an aim of improving the catalytic performance of CeO2(0.25)–MgO(0.75).
Basicity of the catalysts was determined by CO2-TPD experiments in order to elucidate the effect
of basicity on the catalytic performance. The correlation between catalytic performance and basicity
showed that basicity played an important role in the reaction. Yield for dimethyl carbonate increased
Delivered by Publishing Technology to: University of Waterloo
with increasing basicity of the catalysts. Among the catalysts tested, Li2O/CeO2(0.25)–MgO(0.75)
IP: 74.216.185.194 On: Thu, 05 Nov 2015 12:59:34
nano-catalyst with the largest basicity showed the best catalytic performance in the synthesis of
Copyright: American Scientific Publishers
dimethyl carbonate.
Keywords: Dimethyl Carbonate, Transesterification, Ethylene Carbonate, Methanol, Basicity.
1. INTRODUCTION
problems, this reaction process is restricted by thermody-
namic equilibrium limitation.1ꢀ10 On the other hand, syn-
thesis of DMC via transesterification of ethylene carbonate
with methanol has been recognized as a promising pro-
cess because of its environmentally benign nature and high
yield for DMC.
Dimethyl carbonate (DMC) has attracted recent attention
as a green chemical due to its clean and non-polluting
nature.1 DMC is mainly used as a methylation and car-
bonylation agent to replace highly toxic and corrosive
gases such as phosgene and dimethyl sulfate. DMC can
also be used as an ideal fuel additive due to its high oxygen
content.2ꢀ3 In addition, DMC has been used as a precur-
sor for polycarbonate resins and an electrolyte for lithium
batteries.4ꢀ5
DMC has been conventionally produced by various
processes including phosgenation of methanol, oxida-
tive carbonylation of methanol, and carbonylation of
methylnitrite.1 However, these processes involve toxic,
corrosive, flammable, and explosive gases such as phos-
gene, nitric oxide, and carbon monoxide.6–9 Therefore,
there have been many efforts to develop environmen-
tally compatible processes for the production of DMC.
Although direct synthesis of DMC from methanol and
carbon dioxide has been investigated to overcome these
Figure 1 shows the mechanism for the production of
DMC via transesterification of ethylene carbonate with
methanol. Methanol is activated to methoxy species on
the base sites of the catalyst. Methoxy carbonate anion
is then formed by the reaction of methoxy species with
carbonyl carbon of ethylene carbonate. Methoxy carbon-
ate anion further reacts with another methanol to produce
2-hydroxyethyl methyl carbonate, which is an interme-
diate of the reaction. Further nucleophilic substitution
of 2-hydroxyethyl methyl carbonate by methoxy species
occurs to produce DMC and ethylene glycol anion. Finally,
ethylene glycol is generated by proton exchange between
ethylene glycol anion and methanol.11 Thus, it can be
inferred that base sites of the catalyst may play an impor-
tant role in the synthesis of DMC via transesterification of
ethylene carbonate with methanol.
∗Author to whom correspondence should be addressed.
8330
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1533-4880/2015/15/8330/006
doi:10.1166/jnn.2015.11248

Jun et al.
Synthesis of DMC from Ethylene Carbonate and Methanol Over Nano-Catalysts Supported on CeO2–MgO
O
O
Catalyst
O–
CH3O–
+
O
O
CH3OH
H3CO
O
Ethylene Carbonate
CH3OH
O
OH
CH3O–
+
H3CO
O
2-Hydroxyethyl Methyl Carbonate
O
O–
CH3OH
OH
CH3O–
+
H3CO
Dimethyl Carbonate
OCH3
+
HO
HO
Ethylene Glycol
Figure 1. Catalytic mechanism for the synthesis of DMC from ethylene carbonate and methanol over base catalyst.
In this work, a series of CeO2ꢁXꢂ–MgO(1 − X) (X =
0, 0.25, 0.5, 0.75, and 1.0) nano-catalysts were prepared
by a co-precipitation method for use in the synthesis of
dimethyl carbonate from ethylene carbonate and methanol.
Among the CeO2ꢁXꢂ–MgO(1−X) catalysts, CeO2(0.25)–
MgO(0.75) showed the best catalytic performance. Based
on this result, alkali and alkali earth metal oxides (MO =
MO/CeO2(0.25)–MgO(0.75) (MO = Li2O, K2O, Cs2O,
SrO, and BaO) nano-catalysts were prepared by an
incipient wetness impregnation method using an aque-
ous solution of lithium nitrate (LiNO3, Sigma-Aldrich),
potassium nitrate (KNO3, Sigma-Aldrich), cesium nitrate
(CsNO3, Sigma-Aldrich), strontium nitrate (Sr(NO3ꢂ2,
Sigma-Aldrich), and barium nitrate (Ba(NO3ꢂ2, Junsei).
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Li2O, K2O, Cs2O, SrO, and BaO) were then supported on
The loading of metal oxide on CeO (0.25)–MgO(0.75)
IP: 74.216.185.194 On: Thu, 05 Nov 2015 12:59:34
2
CeO (0.25)–MgO(0.75) by an incipient wetness impregna-
Copyright: American Scientific Publishers
was fixed at 3 wt% in all cases. After impregnation,
MO/ꢀCeO2(0.25)–MgO(0.75) nano-catalysts were dried at
2
tion method with an aim of improving the catalytic perfor-
mance of CeO2(0.25)–MgO(0.75). The prepared catalysts
were applied to the synthesis of DMC from ethylene car-
bonate and methanol in a batch reactor. CO2-TPD experi-
ments were conducted to investigate the effect of basicity
on the catalytic performance of CeO2ꢁXꢂ–MgO(1−X) and
MO/CeO2(0.25)–MgO(0.75) (MO = Li2O, K2O, Cs2O,
SrO, and BaO) nano-catalysts. A correlation between cat-
alytic performance and basicity of the catalysts was then
established and discussed.
ꢀ
100 C overnight and calcined at 550 C for 3 h in an air
stream.
2.2. Characterization of Catalysts
To investigate crystalline phases of CeO2ꢁXꢂ–MgO(1−X)
and MO/CeO2(0.25)–MgO(0.75) (MO = Li2O, K2O,
Cs2O, SrO, and BaO) nano-catalysts, X-ray diffrac-
tion measurements were obtained with a diffractome-
ter (Rigaku, D-MAX2500-PC) operated at 50 kV and
150 mA under Cu Kꢃ radiation (ꢄ = 1ꢅ541 Å). Basicity
of the catalysts was measured by CO2-TPD (temperature-
programmed desorption) experiments (BELCAT-B, BEL
Japan). Each catalyst (0.06 g) was charged into the
reactor of the conventional TPD apparatus. It was pre-
treated at 200 ꢀC for 1 h under a flow of helium
(50 ml/min) to remove any physisorbed organic molecules.
CO2 (50 ml/min)ꢀ was then periodically introduced into
the reactor at 50 C, until base sites of the catalyst were
saturated with CO2. The physisorbed CO2 was removed
2. EXPERIMENTAL DETAILS
2.1. Preparation of Catalysts
CeO2ꢁXꢂ–MgO(1 − X) (X = 0, 0.25, 0.5, 0.75, and 1.0)
nano-catalysts were prepared by a co-precipitation method
with a variation of CeO2 content (X, mol%). Known
amounts of cerium nitrate (Ce(NO3ꢂ3 · 6H2O, Samchun)
and magnesium nitrate (Mg(NO3ꢂ3 · 6H2O, Junsei) were
dissolved in ethanol. Oxalic acid solution was then added
into the mixed solution containing cerium and magnesium
precursors. After stirring the mixed solution at room tem-
perature for 3 h, a precipitate was obtained. The resultant
ꢀ
at 150 C for 1 h under a flow of helium (50 ml/min).
After the sample was cooled to room temperature, fur-
nace temperature was increased from room temperature to
900 ꢀC at a heating rate of 5 ꢀC/min under a flow of helium
(30 ml/min). The desorbed CO2 was detected by using a
TCD (thermal conductivity detector).
ꢀ
was filtered and dried at 100 C overnight. After grind-
ꢀ
ing the solid product, it was finally calcined at 550 C
for 3 h in an air stream to yield CeO2ꢁXꢂ–MgO(1 − X)
nano-catalysts.
J. Nanosci. Nanotechnol. 15, 8330–8335, 2015
8331

Synthesis of DMC from Ethylene Carbonate and Methanol Over Nano-Catalysts Supported on CeO2–MgO
Jun et al.
Table I. Crystallite size and basicity of CeO2ꢁXꢂ–MgO(1−X) (X = 0,
0.25, 0.5, 0.75, and 1.0) and MO/CeO2(0.25)–MgO(0.75) (MO = Li2O,
K2O, Cs2O, SrO, and BaO) nano-catalysts.
2.3. Synthesis of DMC from Ethylene
Carbonate and Methanol
Synthesis of DMC from ethylene carbonate and methanol
was carried out in a stainless steel autoclave reactor
(200 ml) under CO2 atmosphere. 28.7 ml of methanol,
8 ml of ethylene carbonate, and 1 g of catalyst were
charged into the reactor. The reactor was then purged with
CO2. After heating the reactor to the reaction tempera-
Crystallite
size (nm)a
Basicity
(mmol CO2/g-catalyst)b
Catalyst
CeO2
16.7
12.3
11.2
10.8
–
39.1
13.7
13.0
11.3
12.6
0.199
0.223
0.469
0.825
0.378
1.929
1.091
0.841
0.706
0.556
CeO2(0.75)–MgO(0.25)
CeO2(0.5)–MgO(0.5)
CeO2(0.25)–MgO(0.75)
MgO
Li2O/CeO2(0.25)–MgO(0.75)
K2O/CeO2(0.25)–MgO(0.75)
Cs2O/CeO2 (0.25)–MgO(0.75)
BaO/CeO2 (0.25)–MgO(0.75)
SrO/CeO2(0.25)–MgO(0.75)
ꢀ
ture (110 C), pressure of the reactor was raised up to
10 bar using CO2. The catalytic reaction was carried at
ꢀ
110 C for 3 h. After the reaction, the reactor was cooled
to room temperature and depressurized. Reaction products
were analyzed using a gas chromatograph (HP 5890 II)
equipped with a flame ionization detector (FID) and a cap-
illary column (HP-5MS). Yield for DMC was calculated as
the ratio of moles of DMC formed with respect to moles
of ethylene carbonate introduced.
Notes: aCalculated by the Scherrer equation from CeO2 (111) diffraction
peak broadening (2ꢆ = 28ꢅ5ꢀ) in Figures 2 and 5; bDetermined by CO2-TPD
measurement.
catalysts were in the range of 10–20 nm, indicating that
all the catalysts were nanoscale materials.
3. RESULTS AND DISCUSSION
3.1. DMC Synthesis Over CeO2ꢁXꢂ–MgO(1 −X)
Catalysts
Synthesis of DMC from ethylene carbonate and
methanol was preliminarily conducted in the absence of
catalyst at 110 ꢀC for 3 h. It was revealed that yield
for DMC in the absence of catalyst was less than 1%,
indicating that a suitable catalyst should be required for
high yield for DMC in the reaction. Figure 3 shows
the catalytic performance of CeO2ꢁXꢂ–MgO(1 − X)
Figure
2 shows the XRD patterns of CeO2ꢁXꢂ–
MgO(1 −X) (X = 0, 0.25, 0.5, 0.75, and 1.0) nano-
catalysts. All the CeO2ꢁXꢂ–MgO(1 − X) nano-catalysts
showed the individual or the mixed peaks of CeO2 and
MgO without a shift of diffraction angle. No solid solu-
nano-catalysts in the synthesis of DMC from ethylene
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tion between CeO2 and MgO was observed. This indicates
IP: 74.216.185.194 On: Thu, 05 Nov 2015 12:59:34
carbonate and methanol. In the catalytic reaction, yield
for DMC over CeO2ꢁXꢂ–MgO(1 − X) nano-catalysts
showed a volcano-shaped curve with respect to CeO2
content. This indicates that an optimal amount of CeO2
was required for maximum production of DMC over
CeO2ꢁXꢂ–MgO(1 − X) nano-catalysts. The catalytic per-
formance of CeO2ꢁXꢂ–MgO(1−X) decreased in the order
of CeO2(0.25)–MgO(0.75) > CeO2(0.5)–MgO(0.5) >
MgO > CeO2(0.75)–MgO(0.25) > CeO2. Among the
CeO2ꢁXꢂ–MgO(1 − X) catalysts, CeO2(0.25)–MgO(0.75)
nano-catalyst showed the best catalytic performance in
that CeO ꢁXꢂ–MgO(1 − X) nano-catalysts were success-
Copyright: American Scientific Publishers
2
fully prepared as a form of mixed metal oxides.12–14 In
order to identify the scale of all catalysts, crystallite sizes
were calculated by the Scherrer equation from CeO2 (111)
diffraction peak broadening (2ꢆ = 28ꢅ5ꢀ) in Figure 2 as
listed in Table I. It was revealed that crystallite sizes of the
MgO
CeO2
MgO
70
60
50
40
30
20
10
CeO2(0.25)-MgO(0.75)
CeO2(0.5)-MgO(0.5)
CeO2(0.75)-MgO(0.25)
CeO2
0
0.25
0.5
0.75
1.0
20
30
40
50
60
70
80
X in CeO2(X)-MgO(1-X)
2 Theta (degree)
Figure 3. Catalytic performance of CeO2ꢁXꢂ–MgO(1 − X) (X = 0,
0.25, 0.5, 0.75, and 1.0) nano-catalysts in the synthesis of DMC from
ethylene carbonate and methanol.
Figure 2. XRD patterns of CeO2ꢁXꢂ–MgO(1 − X) (X = 0, 0.25, 0.5,
0.75, and 1.0) nano-catalysts.
8332
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Jun et al.
Synthesis of DMC from Ethylene Carbonate and Methanol Over Nano-Catalysts Supported on CeO2–MgO
MgO
CeO2
the synthesis of DMC from ethylene carbonate and
methanol.
Figure 4 shows the CO2-TPD profiles of CeO2ꢁXꢂ–
MgO(1 − X) (X = 0, 0.25, 0.5, 0.75, and 1.0) nano-
catalysts. Basicity of CeO2ꢁXꢂ–MgO(1 − X) catalysts
calculated from CO2-TPD peak area is summarized in
Table I. Basicity of the catalysts decreased in the order of
CeO2(0.25)–MgO(0.75)> CeO2(0.5)–MgO(0.5)> MgO >
CeO2(0.75)–MgO(0.25) > CeO2. It should be noted that
the trend of basicity was well consistent with the
trend of catalytic performance of CeO2ꢁXꢂ–MgO(1 − X)
nano-catalysts (Fig. 3). Yield for DMC over CeO2ꢁXꢂ–
MgO(1 − X) nano-catalysts increased with increasing
basicity of the catalysts. This clearly indicates that the
catalytic performance was closely related to the basic-
ity of CeO2ꢁXꢂ–MgO(1 − X) nano-catalysts. Among the
CeO2ꢁXꢂ–MgO(1 − X) catalysts, CeO2(0.25)–MgO(0.75)
catalyst with the largest basicity showed the best cat-
alytic performance. According to the literature,13 crystal-
lite growth of MgO can be suppressed by the addition
of CeO2, which increases the amount of surface lattice
oxygen of the catalyst. On the basis of XRD and CO2-
TPD results, therefore, it is inferred that CeO2(0.25)–
MgO(0.75) with the smallest crystallite size might retain
the largest amount of surface lattice oxygen which serves
as a base site.
Li2O/CeO2(0.25)-MgO(0.75)
K2O/CeO2(0.25)-MgO(0.75)
Cs2O/CeO2(0.25)-MgO(0.75)
BaO/CeO2(0.25)-MgO(0.75)
SrO/CeO2(0.25)-MgO(0.75)
CeO2(0.25)-MgO(0.75)
20
30
40
50
60
70
80
2 Theta (degree)
Figure 5. XRD patterns of MO/CeO2 (0.25)–MgO(0.75) (MO = Li2O,
K2O, Cs2O, SrO, and BaO) nano-catalysts.
Figure 5 shows the XRD patterns of MO/CeO2(0.25)–
MgO(0.75) (MO = Li2O, K2O, Cs2O, SrO, and BaO)
nano-catalysts. It is noticeable that no characteristic
diffraction peaks for MO (alkali and alkali earth metal
oxides) were observed in the MO/CeO2(0.25)–MgO(0.75)
nano-catalysts. This indicates that alkali and alkali earth
metal oxides were finely dispersed on the surface of
CeO (0.25)–MgO(0.75) nano-catalyst.17–21 In particular,
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2
IP: 74.216.185.194 On: Thu, 05 Nov 2015 12:59:34
Li2O/CeO2(0.25)–MgO(0.75) showed strong and sharp
XRD peaks compared to the other catalysts due to
3.2. DMC Synthesis over MO/CeO (0.25)–MgO(0.75)
2Copyright: American Scientific Publishers
(MO = Li2O, K2O, Cs2O, SrO, and
thermal instability of Li-containing oxide during the high-
temperature calcination process.22ꢀ23 Furthermore, crystal-
lite sizes were determined using the Scherrer equation
from CeO2 (111) diffraction peak broadening (2ꢆ = 28ꢅ5ꢀ)
in Figure 5 as listed in Table I, indicating that the size of
catalysts was in the range of 10–40 nm.
BaO) Catalysts
It has been reported that alkali and alkali earth metal
oxides supported on metal oxides can modify the basic-
ity of the support.15ꢀ16 In this work, therefore, alkali and
alkali earth metal oxides (MO = Li2O, K2O, Cs2O, SrO,
and BaO) were supported on CeO2(0.25)–MgO(0.75),
with an attempt to enhance the base property of
CeO2(0.25)–MgO(0.75).
Figure
6
shows the catalytic performance of
MO/CeO2(0.25)–MgO(0.75) (MO = Li2O, K2O, Cs2O,
SrO, and BaO) nano-catalysts in the synthesis of DMC
from ethylene carbonate and methanol. It is noticeable
that alkali metal oxide catalysts (Li2O, K2O, and Cs2O)
supported on CeO2(0.25)–MgO(0.75) showed a better
performance than CeO2(0.25)–MgO(0.75) nano-catalyst.
However, alkaline earth metal oxide catalysts (BaO
and SrO) supported on CeO2(0.25)–MgO(0.75) showed
a poor activity compared to CeO2(0.25)–MgO(0.75)
nano-catalyst. This indicates that the catalytic perfor-
mance of MO/CeO2(0.25)–MgO(0.75) nano-catalysts
was strongly affected by the identity of metal oxide.
The catalytic performance decreased in the order
of Li2O/CeO2(0.25)–MgO(0.75) > K2O/CeO2(0.25)–
MgO(0.75) > Cs2O/CeO2(0.25)–MgO(0.75) > BaO/
CeO2(0.25)–MgO(0.75) > SrO/CeO2(0.25)–MgO(0.75).
Among the catalysts tested, Li2O/CeO2(0.25)–MgO(0.75)
nano-catalyst showed the best catalytic performance in the
synthesis of DMC from ethylene carbonate and methanol.
MgO
CeO2(0.25)-MgO(0.75)
CeO2(0.5)-MgO(0.5)
CeO2(0.75)-MgO(0.25)
CeO2
100
200
300
400
500
600
700
800
900
Temperature (ºC)
Figure 4. CO2-TPD profiles of CeO2ꢁXꢂ–MgO(1 − X) (X = 0, 0.25,
0.5, 0.75, and 1.0) nano-catalysts.
J. Nanosci. Nanotechnol. 15, 8330–8335, 2015
8333

Synthesis of DMC from Ethylene Carbonate and Methanol Over Nano-Catalysts Supported on CeO2–MgO
Jun et al.
80
ion (alkali metal ion) in the MgO matrix generates the
O− anions to maintain electroneutrality. The formed O−
anions act as base sites by abstracting a hydrogen atom
from methanol to form methoxy species. In particular,
substitution of Mg2+ by Li+ in the MgO lattice may easily
occur because the ionic radius of Li+ is similar to that
75
70
65
60
55
50
of Mg2+ 24
For this reason, Li2O/CeO2(0.25)–MgO(0.75)
.
nano-catalyst with the largest basicity showed the best
catalytic performance among the catalysts tested.
3.3. Correlation Between Catalytic Performance and
Basicity of the Catalysts
According to Figure 1, the reaction requires base sites of
the catalyst. Methanol is activated to methoxy species on
the base sites of the catalyst. The reaction of methoxy
species with carbonyl carbon of ethylene carbonate leads
to a formation of methoxy carbonate,10 which is respon-
sible for the production of DMC from ethylene carbonate
and methanol. Therefore, large amount of base sites can
facilitate the synthesis of DMC from ethylene carbonate
and methanol.
Figure 8 shows the correlation between catalytic per-
formance and basicity of CeO2ꢁXꢂ–MgO(1 − X) and
MO/CeO2(0.25)–MgO(0.75) (MO = Li2O, K2O, Cs2O,
SrO, and BaO) nano-catalysts. The correlation clearly
shows that the catalytic performance was closely related to
Figure 6. Catalytic performance of MO/CeO2(0.25)–MgO(0.75)
(MO = Li2O, K2O, Cs2O, SrO, and BaO) nano-catalysts in the synthesis
of DMC from ethylene carbonate and methanol.
Figure 7 shows the CO2-TPD profiles of MO/
CeO2(0.25)–MgO(0.75) (MO = Li2O, K2O, Cs2O, SrO,
and BaO) nano-catalysts. Basicity of MO/CeO2(0.25)–
MgO(0.75) nano-catalysts calculated from CO2-TPD
peak area is listed in Table I. Basicity of the catalysts
decreased in the order of Li2O/CeO2(0.25)–MgO(0.75) >
K2O/CeO2(0.25)–MgO(0.75) > Cs2O/CeO2(0.25)–MgO
(0.75) > BaO/CeO (0.25)–MgO(0.75) > SrO/CeO (0.25)–
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MgO(0.75). This trend was in good agreement with
the basicity of the catalysts. Yield for DMC over the cat-
2
2
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alysts increased with increasing basicity of the catalysts.
Among the catalysts, Li2O/CeO2(0.25)–MgO(0.75) nano-
catalyst with the largest basicity showed the best catalytic
performance in the synthesis of DMC from ethylene car-
bonate and methanol. Thus, large basicity of the catalyst
was favorable for the formation of DMC from ethylene
carbonate and methanol.
Copyright: American Scientific Publishers
the trend of catalytic performance of MO/CeO2(0.25)–
MgO(0.75) nano-catalysts (Fig. 6). Yield for DMC over
MO/CeO2(0.25)–MgO(0.75) nano-catalysts increased with
increasing basicity of the catalysts. This also implies
that the catalytic performance was closely related to the
basicity of MO/CeO2(0.25)–MgO(0.75) nano-catalysts.
Substitution of a divalent ion (Mg2+ꢂ by a monovalent
80
Li2O/CeO2(0.25)-MgO(0.75)
K2O/CeO2(0.25)-MgO(0.75)
Cs2O/CeO2(0.25)-
MgO(0.75)
CeO2(0.25)-
MgO(0.75)
60
40
20
BaO/CeO2(0.25)-MgO(0.75)
SrO/CeO2(0.25)-MgO(0.75)
CeO2(0.5)-MgO(0.5)
Li2O/CeO2(0.25)-MgO(0.75)
MgO
K2O/CeO2(0.25)-MgO(0.75)
Cs2O/CeO2(0.25)-MgO(0.75)
CeO2(0.75)-MgO(0.25)
CeO2
BaO/CeO2(0.25)-MgO(0.75)
SrO/CeO2(0.25)-MgO(0.75)
0
0.4
0.8
1.2
1.6
2.0
2.4
Basicity (mmolCO2/g-catalyst)
100 200 300 400 500 600 700 800 900
Temperature (ºC)
Figure 8. A correlation between catalytic performance and basic-
ity of CeO2ꢁXꢂ–MgO(1 − X) (X = 0, 0.25, 0.5, 0.75, and 1.0) and
MO/CeO2(0.25)–MgO(0.75) (MO = Li2O, K2O, Cs2O, SrO, and BaO)
nano-catalysts.
Figure 7. CO2-TPD profiles of MO/CeO2 (0.25)–MgO(0.75) (MO =
Li2O, K2O, Cs2O, SrO, and BaO) nano-catalysts.
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J. Nanosci. Nanotechnol. 15, 8330–8335, 2015

Jun et al.
Synthesis of DMC from Ethylene Carbonate and Methanol Over Nano-Catalysts Supported on CeO2–MgO
4. CONCLUSIONS
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CeO2ꢁXꢂ–MgO(1 − X) (X = 0, 0.25, 0.5, 0.75, and 1.0)
nano-catalysts were prepared by a co-precipitation method
with a variation of CeO2 content (X, mol%). The pre-
pared catalysts were applied to the synthesis of dimethyl
carbonate from ethylene carbonate and methanol. Among
these catalysts, CeO2(0.25)–MgO(0.75) nano-catalyst was
found to be the most efficient catalyst. Based on this
result, alkali and alkali earth metal oxides (MO = Li2O,
K2O, Cs2O, SrO, and BaO) supported on CeO2(0.25)–
MgO(0.75) were prepared by an incipient wetness impreg-
nation method. CO2-TPD experiments were conducted to
elucidate the effect of basicity on the catalytic perfor-
mance of CeO2ꢁXꢂ–MgO(1 − X) and MO/CeO2(0.25)–
MgO(0.75) (MO = Li2O, K2O, Cs2O, SrO, and BaO).
A correlation between catalytic performance and basicity
of the catalysts revealed that yield for DMC was closely
related to the basicity of the catalysts. Yield for DMC
increased with increasing basicity of the catalysts. Among
the catalysts tested, Li2O/CeO2(0.25)–MgO(0.75) catalyst
showed the highest yield for DMC. It is concluded that
basicity of the catalysts served as an important factor deter-
mining the catalytic performance in the synthesis of DMC
from ethylene carbonate and methanol.
Acknowledgments: The authors acknowledge the sup-
port from KPX Green Chemicals.
20. J. Tantirungrotechai, S. Thepwatee, and B. Yooskuk, Fuel 106, 279
Delivered by Publishing Technology(t2o01:3U).niversity of Waterloo
IP: 74.216.185.194 On: Thu, 05 Nov 2015 12:59:34
Copyright: American S2c1i.enSt.ifIiwcamPoutob,liRs.hTearksahashi, and M. Inoue, Appl. Catal. B-Environ.
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Received: 23 June 2014. Accepted: 2 December 2014.
J. Nanosci. Nanotechnol. 15, 8330–8335, 2015
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