The value-added utilization of glycerol for the synthesis of glycerol carbonate catalyzed with a novel porous ZnO catalyst

Article abstract of DOI:10.1039/c6ra14288e

In the carbonylation reaction, a novel porous ZnO was prepared by a calcination method, and the raw material Zn glycerolate platelets were prepared via the glycerol approach, which could make use of a by-product of glycerol. To elucidate their composition, morphology, and properties, the resulting materials were characterized by FT-IR, XRD, SEM, BET, XPS, TPD and TG. The results showed that the catalyst was porous and irregularly shaped with appropriate acid and base properties; moreover, it displayed better catalytic performance for the synthesis of glycerol carbonate. The highest glycerol carbonate yield reached 85.97% of ZnO from zinc glycerolate under the optimal reaction conditions of 5.0 wt% of catalyst, 1:1.5 molar ratio of glycerol to urea and reacting at 140 °C for 6 h under 1 kPa. Comparing the three catalysts ZnO, zinc glycerolate and ZnO from zinc glycerolate, the maximum glycerol carbonate yield was 85.97% with the ZnO from zinc glycerolate as the catalyst under optimized operating conditions. Compared with the conventional ZnO, the as-prepared catalyst embodied in its porosity, acidity and basicity. The catalyst maintained excellent catalytic performance after 5 cycles with almost no loss of catalytic activity. This study revealed that ZnO from a zinc glycerolate catalyst is highly active, highly recyclable, remarkably stable, and environmental friendly for industrial applications. Overall, this new material overcomes the limitation of glycerol application and will have a good potential for industrial application.

Full text of DOI:10.1039/c6ra14288e

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The value-added utilization of glycerol for synthesis of glycerol
carbonate catalyzed with a novel porous ZnO catalyst
Received 00th January 20xx,
Accepted 00th January 20xx
*
*
Pingbo Zhang , Lihua Liu, Mingming Fan , Yuming Dong and Pingping Jiang
DOI: 10.1039/x0xx00000x
In the carbonation reaction, novel porous ZnO was prepared by calcination method and the raw material Zn glycerolate
platelets were prepared via the glycerol approach, which could make use of byproduct glycerol. To elucidate their
composition, morphology and properties, the resulting materials were characterized by using: FT-IR, XRD, SEM, BET, XPS,
TPD and TG respectively. The results showed that the catalyst with porous and irregularly shaped with appropriate acid
and base properties had better catalytic performance to synthesis of glycerol carbonate. The highest glycerol carbonate
yield reached 85.97% of ZnO from zinc glycerolate under the optimal reaction conditions: 5.0 wt.% of catalyst adding, 1:1.5
www.rsc.org/
o
of the molar ratio of glycerol to urea and reacting at 140 C for 6 h under 1KPa. Compared with three catalysts ZnO, zinc
glycerolate and ZnO from zinc glycerolate, the maximum glycerol carbonate yield 85.97% with the ZnO from zinc
glycerolate as the catalyst under optimizing operating conditions was obtained. Compared with the conventional ZnO, as-
prepared catalyst embodied in its porosity, acidity and basicity. The catalyst maintained excellent catalytic performance
after 5 cycles, almost no loss of catalytic activity. The study revealed that the ZnO from zinc glycerolate catalyst with high
activity, highly recyclable, remarkably stable, and environmental friendly is appropriately applied in industrialization.
Overall, this new material overcomes the limitation of glycerol application and would have a good potential for industrial
application.
hydroxyl group, and as an electrophile through its ring carbon
atoms. Glycerol carbonate can be used as solvents, beauty &
personal care, chemical intermediates, polymers such as
1
. Introduction
The sharp increase in demand for fuels and the increase in
environmental problems, coupled with reduction of crude oil
reserves, have attracted people's attention about renewable
hyperbranched polyethers, polycarbonates, polyurathanes and
non-isocyanate polyurethanes. Glycerol carbonate have a lot
of potential applications in manufacturing useful materials
such as carrier in pharmaceutical preparations, carrier in
lithium and lithium-ion batteries, solid laundry detergent
1
energy . Biodiesel as renewable energy has developed very
2
well in recent years . In fact, the production of biodiesel is still
relatively far away from the intended target which due to the
high cost of production. In order to maintain the balance of
the glycerol existing market, improve the added value of
glycerol and promote the development of biodiesel industry,
many researchers focus on the study of valued-added glycerol
derivatives. So the glycerol as biodiesel by-product is the viable
9
compositions .
It is carried out to synthesis glycerol carbonate directly
1
0
11
from glycerol and subcritical CO
2
using Cu/La
catalysts. Glycerol carbonate can be
synthesized through the reaction of glycerol with CO and O in
2
the presence of PdCl (phen)/KI catalysts . Glycerol carbonate
2 3 2
O , nBu SnO ,
1
2
2 2 3
La O CO -ZnO
2
1
3
3
-5
method to reduce the cost of biodiesel production
.
could be synthesized with several different synthetic routes
such as the transesterification reaction of glycerol and
Conversion process of glycerol as a renewable and cheap
raw chemical to high value-added products which have
6
attracted more and more people's attention . Glycerol
1
4
15
dimethyl carbonate or diethyl carbonate using K
2
CO
3
, CaO
1
and hydrotalcite and the carbonylation reaction of glycerol
6
carbonate is a small molecule with a bifunctional compound:
7
dioxolane ring and hydroxyl group
1
7-18
-8
and urea in the presence of catalyst such as metal oxides
21
,
. The bifunctional
1
9
20
WO
3 2
/SnO , ionic liquids , lanthanum compounds , gypsum
compound as reactive sites make glycerol carbonate as a raw
material to synthesis chemical intermediates achievable.
Glycerol carbonate can react both as a nucleophile through its
2
based catalyst , Zn-Al mixed-oxide catalyst , WO
2
23
24
2
/TiO ,
3
2
5
tantalum in henteropoly tungstate catalysts , γ-zirconium
2
6-28
29
calcined Zn hydrotalcite , Co
30
/ZnO ,
phosphate
,
3
O
4
31-32
gypsum and gold-based catalysts
. CO and phosgene don’t
a.
The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education,
School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122,
P. R. China. E-mail: pingbozhang@126.com, fanmm2000@126.com
meet with the requirements of sustainable development. The
use of carbon dioxide as carbonating agent required high
Electronic Supplementary Information (ESI) available: [details of any temperature and high pressure and the yield for glycerol
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
carbonate was too low for practical purpose.
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In our work, a novel solid catalyst was used for catalyzing The specific surface area and pore diameter of the catalysts
glycerol and urea to synthesize the high value-added glycerol was measured according to the Brunauer-Emmet-Teller (BET)
carbonate. Attempts are being focused on using urea due to its method with nitrogen adsorption-desorption with ASAP 2020
cheaper cost and safe handling. Furthermore, ammonia instrument (Micromeritics, USA).
2 2
formed can be easily converted to urea since the urea Temperature programmed desorption of CO (CO -TPD) was
synthesis performed from ammonia and carbon dioxide. The measured for basicity and base intensity distribution of the
performances of three catalysts ZnO, zinc glycerolate and ZnO catalysts. The sample was pretreated under helium flow 300 °C
from zinc glycerolate were compared under optimizing for 1 h. Subsequently, it was cooled to 50 °C to adsorb CO
operating conditions. The catalyst was also characterized by After adsorption CO 30min, the catalyst was pretreated under
FT-IR, XRD, SEM, BET, TPD, XPS and TG. In addition, the helium flow 100 °C for 1 h to remove the adsorbed CO from
2
.
2
2
combination of a weak Lewis acid and Lewis base was found in sample surface. Desorption curve was recorded from 100 °C to
the carbonate formation. In the reaction, glycerol can be used 800 °C at 10 °C /min.
not only as the reactant but also as the catalyst precursor.
3 3
Temperature programmed desorption of NH (NH -TPD) was
performed for acidity and acid intensity distribution of the
catalysts. The sample was pretreated under helium flow 300 °C
2
. Experimental Section
for 1 h. Subsequently, it was cooled to 50 °C to adsorb NH
After adsorption NH 30min, the catalyst was pretreated under
helium flow 100 °C for 1 h to remove the adsorbed NH from
3
.
3
2.1 Materials
3
Anhydrous glycerol of high purity (>99%), urea (>99%), sample surface. Desorption curve was recorded from 100 °C to
absolute ethanol (>99%), acetic acid (99%), zinc nitrate 800 °C at 10 °C /min.
hexahydrate Zn(NO
Zn(CH COO) ·2H
hydroxide KOH (99%) and zinc chloride (99%) were obtained photoelectron spectrometer with Al Kα line as the excitation
3
)
2
2
·6H O (99%), zinc acetate dihydrate X-ray photoelectron spectroscopy (XPS) analysis was
3
2
2
O (99%), oxalic acid (99%), potassium conducted using an ESCALAB 250 Xi (Thermo, USA) X-ray
from Sinopharm Chemical Reagent Co, Ltd, China.
source (hv = 1484.6 eV) and adventitious carbon (284.6 eV for
binding energy) was used as reference to correct the binding
energy of sample.
2.2 Catalyst preparation
Zn(CH COO) ·2H O (2g) was mixed with glycerol (20g) at 160 °C TG analysis was performed with a STA409 instrument in dry air
3
2
2
under reflux for 5h. The resulting mixture was transferred into at a heating rate of 20 °C/min.
a Teflon-lined stainless steel autoclave and kept at 150 °C for
2
.4 Catalytic reaction
18 h. The product mixture was filtered, washed with distilled
water, and dried at 80 °C in air overnight. Then, the obtained The carbonation reaction was carried out in a 100mL three-
white fine powder was Zn glycerolate. The as-prepared necked flask provided with magnetic stirrer. 25 mmol glycerol,
samples were labeled as ZMG and was heated with different 37.5 mmol urea and a certain amount of prepared catalysts (5
thermal produres (heating rate). Finally, the synthesized wt. % to glycerol) were added into flask. Carbonation reaction
precursor ZMG was decomposed to ZnO by calcination at 450 was performed at 140 °C for 6h under stirring, under reduced
°
C in an N
2
flow for 2 h (heating temperature rate was set to pressure of under 1kPa. After reaction completion, the
.5 °C/min). The optimal thermal method were as follows: mixtures were cooled to ambient temperature. Added 15 ml of
50°C, 0.5 °C/min.
methanol washed the catalyst. Subsequently, the reaction
0
4
In the 0.5mol/L zinc nitrate solution, potassium hydroxide was mixtures were separated from the catalyst by centrifugation
added to prepare zinc hydroxide. The synthesized precursor and dried 12 hours. The supernatant was used for gas
Zn(OH)
for 2 h.
2
was decomposed to ZnO by calcination at 450 °C in air chromatography analysis. The washed catalyst was used in the
next circulation.
2.3 Catalyst characterization
2.5 Product analysis
As to the solid catalyst, 1mg sample and 200mg KBr were The supernatant was analyzed by gas chromatography 9790II.
ground completely and pressed into thin disks. Subsequently, A quantitative analysis method of glycerol and glycerol
the FT-IR of sample were tested by FTLA2000 type Fourier carbonate by SE-54 capillary column gas chromatography with
transform infrared spectrometer of the Canadian ABB FID detector and using tetraglycol as internal standard was
-
1
33-36
company with scanning range 4000 ~ 500 cm .
X-ray diffraction (XRD) patterns were examined with a Bruker Temperature programming which increased from 60 C to 260
applied
. The injection volume of sample is 0.2 μL.
o
o
D8 Advance powder diffractometer using Cu Kα radiation
C and using of silyl reagent were adopted in the analysis. Silyl
3
was composed of the 4 mL DMF, 4 mL dioxane
7-38
source (λ= 1.5406 Å) at 40 kV and 40 mA from 10° to 90° with a agent
scan rate of 4° min .
-1
amine hexamethyldisilazane and 0.1 mL trimethylchlorosilane.
The morphology of the catalyst was evaluated by field Pipette 100 μL of sample, followed by adding silyl reagent in
emission scanning electron microscopy (FE-SEM) on a Hitachi tube. Subsequently, the tube was vibrated for 1 min and
S-4800.
allowed to stand. The supernatant was analyzed by gas
chromatography.
2
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3
. Results and discussion
(c)
3
.1 Characterization of catalysts
.1.1. FT-IR analysis
3
Before the detailed results with the three solid catalysts are
presented, the activity of several heterogeneous catalysts were
compared. The yield to glycerol carbonate was <100%, mainly due
to the formation of byproduct. From the test results, ZnO from ZMG
had the better catalytic activity due to porous structure. The results
were displayed in Fig. 1. The FTIR spectra of ZnO, ZMG and ZnO
from ZMG catalysts were showed in Fig.1. Zn glycerolate platelets
(
b
)
(a)
were obtained via the glycerol-mediated synthesis utilizing a
4000
3500
3000
2500
2000
1500
1000
500
o
3
COO)
2
in glycerol that was heated to 150 C. At
Wavenumber/cm 1
Fig. 2. FTIR spectra of three catalyst: (a) ZMG; (b)ZnO from ZMG; (c) ZnO
-
solution of Zn(CH
o
about 120 C the solution became turbid which indicates the
precipitation of solid Zn glycerolate. Infrared spectra (FT-IR) of the
as-prepared ZMG with platelike structure was also in complete glycerolate. The XRD pattern for the solid catalyst presented
agreement with reference data of Zn glycerolate. The narrowing of characteristic peaks located at 2θ=11.08°, 17.03°, 20.9°,
the glycerol bands in Zn glycerolate was due to the crystalline 27.79°, 36.67°, 38.83°, according to the JCPDS File No. 23-
nature of the material. The characteristic signals of the alcoholic C- 1975, which are assigned to the crystal phase of Zn glycerolate
-
1
32-35
O stretching mode were present at 1054 and 1124 cm . The peaks (Zn(C H O ))
.Upon subsequent heating of the sample to
43
3
o
6 3
-1
at 1468 and 1675 cm were attributed to the O-H bending mode. 450 C, the evolution of ZnO phase (JCPDS File No. 65-3411)
-1
The broad absorption peak at 3443 cm was attributed to the - occured, as seen in Fig. 3(b). Fig. 3(b) depicted the diffraction
OH group, such as water molecules in catalyst interlayer profile of the calcined sample, and all the peaks were well
region, glycerol O-H stretching mode and hydrogen bonding. indexed to the ZnO phase (JCPDS File No. 65-3411) Fig. 3(b).
-1
The band at 1943 cm assigned to C-O stretching mode, where the The ZnO which was calcined from ZMG with platelet-like had
oxygen atom is involved in hydrogen bond, proves the existence of the larger surface area. ZnO obtained from Zn(OH)2 was
zinc glycerolate phase. The characteristic signals of the Zn-O in zinc identified as the ZnO phase (JCPDS File No. 65-3411) in Fig.
-
1
glycerolate were present at 650.89 cm in Fig. 2(a), indicated the 3(c). However, the morphology of ZnO obtained from Zn(OH)2
presence of Zn-O bond in the sample. The peak of ZnO from ZMG was inferior to ZnO obtained from ZMG.
was consistent with ZnO. In fact, ZnO from ZMG and ZnO had 3.1.3 SEM analysis
-1
characteristic signals in 650.89 cm . The surface of ZnO sample had
bending and stretching vibration peak of hydroxyl group at 1632.78
The morphology of precursor ZMG before and after calcination
by scanning electron microscopy, a representative picture
were listed in Fig. 4. Surface morphologies of the ZMG samples
were recorded using field emission scanning electron
microscopy (FE-SEM) analysis, and the images were shown Fig.
-1
-1
cm and 1115.46 cm in Fig. 2(b) and Fig. 2(c). In the air, the
sample surface adsorbed water, resulting in the formation of the
hydroxyl peak.
3.1.2 XRD analysis
4
(a-b). It can be clearly seen that a large number of plate-like
The three different solid base catalysts about XRD patterns microcrystals of zinc glycerolate were formed. In addition,
was shown in Fig. 3. The XRD profile of the synthesized ZMG according to SEM images the morphology of ZMG were plate-
with typical of layered compounds showed an intense basal like, irregular and polygon. From the figure we can see, after
diffraction attributed to the first basal peak in the region of 11° calcination the sample had the porous layer structure Fig. 4(c-
at 2θ values. From Fig. 3(b), compared with standard card, the
prominent crystalline phase ZMG catalysts are attributed to Zn
ZnO
ZnGly
(
c)
(
b)
(
a)
1
0
20
30
40
50
60
2
Theta/degree
Fig. 1. Comparison of reusability of three catalysts (Reaction conditions:
Fig. 3. XRD patterns of three solid catalysts (a): ZnO obtained from ZMG; (b): ZMG; (c)
o
glycerol/urea=1:1.5, catalyst dosage 5.0 wt.%, 140 C, 6 h, 1KPa)
ZnO
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and regular pore structure can handle larger molecules or
groups and improve the diffusion rate of the reactants. BET
results are consistent with the results of SEM. The porous
structure of catalyst which makes the catalyst a promising
candidate for the industrial production of glycerol carbonate.
3
.1.5. Acid and base properties of catalysts
CO -TPD and NH -TPD was adopted to measure the basicity
2
3
and the acidity of the catalysts. Largely, the catalytic
performance of catalyst was affected by basicity and acidity of
Fig. 4. SEM of three solid catalysts (a-b): ZMG; (c-d): ZnO from ZMG; (e-f): ZnO
catalyst in Fig. 5(a) and Fig. 5(b). The CO desorption capacity is
2
proportional to the amount of base and the CO desorption
2
d). We speculate that the major change in morphology of the
sample can be explained due to the loss of organic ligands
results in phase transition from ZMG to ZnO at high
temperature which was consistent with the XRD analysis as
temperature represents the strength of basic sites. The CO2
desorption curve was shown in Fig. 5(a). The ZnO catalyst
o
exhibited a broad desorption peak in 400 C. These desorption
peaks are related to the weak basic sites in the catalyst.
Whereas the ZnO from ZMG catalyst also presented a broad
o
desorption peak in 400 C. The integral area of the ZnO from
3
9
described earlier . At the same time, the micrographs reveal
that most of them are porous, irregularly shaped. The
precursor ZMG after calcination transformed into ZnO. ZMG
with plate-like morphology, its layered structure resulted in
poor catalytic performance due to the non-porous in plate.
Precursor ZMG after calcination had the porous layer structure
contributed to the excellent catalytic performance.
Comparison showed that, the morphology of ZnO displayed
that sample were stacked together lead to nonporous and
poor catalytic performance in Fig. 4(c-d).
ZMG catalyst was 4041.614. While, the integral area of the
ZnO catalyst was 2916.536. Thus, from the integral area, the
ZnO from ZMG catalyst had a high peak area which showed a
stronger basicity.
The NH desorption capacity is proportional to the amount of
3
acid and the NH3 desorption temperature represents the
strength of acid sites. For acidity, the NH desorption curve
3
was shown in Fig. 5(b). The ZnO catalyst exhibited a broad
o
desorption peak in the range of 250-350 C. These desorption
3.1.4. BET analysis
Three different catalysts were analyzed by BET in Table 1. The peaks are related to the weak acid sites in the catalyst.
specific surface area and pore size was described by the N
Whereas the ZnO from ZMG catalyst also presented two broad
2
o
o
adsorption isotherm. Structural features improved significantly desorption peak respectively in 200-500 C and 550-800 C.
o
due to calcination, which may be attributed to improved These desorption peaks in 200-500 C are related to the weak
o
crystalline phase of catalyst. Based on pore size, catalyst is acid sites in the catalyst and desorption peaks in 550-800 C
divided into microporous, mesoporous and macroporous. are related to the strong acid sites in the catalyst. The NH3
Moreover, the high absorption at low relative pressure desorption integral area of the ZnO from ZMG catalyst was
represents the microporous nature of materials. Among the 5413.714. While, the NH desorption integral area of the ZnO
3
three catalysts, the ZnO from ZMG catalyst possess the largest catalyst was 3132.736. Thus, from the integral area, the ZnO
pore diameter and specific surface area. As seen from BET, the from ZMG catalyst had a high peak area which showed a
pore size of ZnO from ZMG catalyst was 48.156nm which stronger acidity. It can been seen from integral area that the
matched with the characteristics of mesoporous materials, acid property was nearly close to base property for ZnO from
suggested that the catalyst was composed of mesoporous ZMG. In the carbonylation reaction, lewis acid catalyst
structures. It was observed that the surface area of ZMG was activated urea carbonyl group, hydroxyl group of glycerol was
less than ZnO from ZMG, which could be attributed to the activated conjugated basic sites. The results showed that with
porous structure. The specific surface area and pore volume of adequate combination of a weak Lewis acid and a Lewis base
2
ZnO obtained from Zn(OH) was poor in Table.1. Mesoporous plays an important role in the high yield of glycerol carbonate.
materials with relatively large specific surface area, pore size The base amount and acid amount of ZnO was inferior to ZnO
Tab. 1. BET surface area, pore volume and pore diameter of three catalysts
3
Catalyst
BET surface area
pore volume (cm /g)
pore diameter (nm)
2
(m /g)
ZnO from ZMG
ZMG
13.71
3.698
0.04531
0.03752
48.15
16.15
ZnO
1.178
0.004923
7.568
4
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(a)
800000
600000
400000
200000
0
ZnO
ZnO From ZMG
0
200
400
600
800
1000
1200
Binding energy(eV)
100
200
300
400
500
600
700
800
Temperature/o
C
(b)Zn2p3/2
Fig. 5(a). TPD of CO
2
profiles of two catalysts: ZnO and ZnO from ZMG solid catalysts
Zn2p1/2
ZnO
1020
1030
1040
1050
1060
ZnO From ZMG
Binding energy(eV)
(c)
O1s
100
200
300
400
500
600
700
800
Temperature/o
C
3
Fig. 5(b). TPD of NH profiles of two catalysts: ZnO and ZnO from ZMG solid
catalysts
from ZMG.
3.1.6. XPS analysis
5
25
530
535
540
545
To gain more information about the ZnO nanoparticle, XPS was
Binding energy(eV)
Fig. 6. XPS of ZnO from ZMG solid catalysts
4
4
performed . Fig. 6(a) exhibited the XPS survey spectrum of
ZnO nanoparticle. The Fig. 6(a) indicated that XPS consist of Zn,
O and trace amount of carbon in the results was mainly
attributed to adventitious hydrocarbon from XPS itself. Fig 6(b)
showed that the peaks of the Zn2p were found to be at
organic compounds, weight loss rate of 37.28% in Fig. 7. From
DTG curves of Zn glycerolate, there existed maximum weight
o
loss of Zn glycerolate at 412 C. Namely, at this temperature
1
021.68 eV and 1044.3 eV for Zn2p1/2 and Zn2p3/2,
the decomposition of Zn glycerolate was fastest. This value
matched exactly when assuming a thermal decomposition of
Zn glycerolate in air under formation of ZnO. As can be seen
4
5
respectively . We obtained binding energy of ZnO in the
experiment were consistent with previously reported in the
literature about Zn2p for ZnO. No obvious shift of the Zn2p
peaks is observed and peak positions are closely matching with
the standard value for ZnO, indicating that Zn atoms are in the
o
from TG analysis and a temperature of 450 C required for
complete decomposition. Meanwhile, to prepare the catalyst
with excellent hole-shaped morphology we need to control the
calcination rate. High temperature and the high calcination
rate will lead to the catalyst sintering. Therefore, Zn
4
6
2
+ oxidation state . In Fig. 6(c), the peak of O1s were located
at about 530.45 eV. The peak at 530.45 eV could be attributed
to the bond formation between O and Zn. Namely, the peak at
o
glycerolate was calcined at 450 C with calcination rate at 0.5
o
C/min.
2
-
47
30.45 eV was attributed to O ions in ZnO .
5
3.1.7. TG-MS
Thermal decomposition of Zn glycerolate had only a significant 3.2. Catalytic activity
weight loss stage which correspond to the decomposition of
3
.2.1. Effect of reaction temperature
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wt.% with respect to glycerol amount), whereas the other
1
00
reaction conditions were fixed, the molar ratio glycerol/urea of
o
:1.5, reaction temperature of 140 C, 1KPa and reaction time
0
.00
1
9
8
7
6
5
0
0
0
0
0
TGA
DTG
of 6h in Fig. S4. According to Fig. S4, it is clear that the addition
of catalyst ameliorated the yield of GC.
-
0.05
0.10
3.3 Catalyst stability tests
The stability of the catalyst ZnO from ZMG with porous,
irregularly shaped was examined by testing the reusability of
catalyst. The recyclability of catalyst is very important for
industrial and technological applications. The catalyst recycling
is an important step as it minimizes the cost of the process.
The ZnO catalyst in each reaction separated by separator,
washed with methanol and dried fully before reutilization. The
stability of catalyst was investigated, as shown in Fig. 8. The
glycerol carbonate yield could remain 70.85% after the catalyst
was repeatedly used for five times. Recycling experiments was
executed by employing it in the consecutive reaction for 6
times under the same conditions. After each reaction, the
catalyst was fully washed with methanol over again and dried
in oven overnight. In order to further explore the superiority of
the ZnO catalyst on the catalytic performance, a comparison of
ZnO, pure ZnO and ZMG had been made in repeatability. The
retained performance illustrated that the activity of catalyst
still exist after the circulation. The catalyst still showed
excellent catalytic performance without significantly weaking.
The particle size of porous ZnO catalyst maintained between
-
0
100 200 300 400 500 600 700 800
o
Temperature / C
o
Fig. 7. Thermogravimetry of Zn glycerolate (total weight: 8mg, heating rate: 20 C/min)
Reaction temperature as one of the most important factors
was investigated which could largely affect the carbonation
reaction. The catalytic activities of the ZnO catalysts were
studied with the reaction temperatures varying from 120 to
o
60 C. The yield of glycerol carbonate were shown in Fig. S1 in
1
supporting information. Increasing reaction temperature
would improve catalytic reactivity. The results showed that the
yields of glycerol carbonate firstly increased with the increase
of reaction temperature and then decreased with further
heating with a turning point 140 °C. In summary, the optimum
reaction temperature is 140 °C. Chemical equilibrium constant
calculations show the high temperature and low pressure is
appropriate to synthesis glycerol carbonate by glycerol and
urea.
2
20nm to 235nm. The polydispersibility of porous ZnO catalyst
3
.2.2. Effect of urea-to-glycerol molar ratio
was less than ZnO which demonstrated the excellent
dispersion performance of catalyst (seen from Fig. S5). As
acknowledged by XRD characterization aforementioned, the
structure of the catalyst was essentially maintained during the
recycling tests, and it was helpful with the good recycling
performance. Therefore, porous ZnO catalyst with high activity,
highly recyclable, remarkably stable, and environmental
friendly is appropriately applied in industrialization.
It is well known that the carbonation reaction is an equilibrium
reaction and that the excess amount of glycerol can drive the
equilibrium toward product formation. In this reaction,
glycerol reacted with urea in molar ratio 1:1.5 at 140 °C in the
presence of a catalyst and usually under vacuum to shift the
thermodynamic equilibrium by removing continuously the
ammonia formed. Carbonation reaction was performed by
varying the urea to glycerol molar ratios from 1:1 to 3:1 and at
o
40 C till the completion of reaction (See Fig. S2 in supporting
1
information). In the first stage, the yields of glycerol carbonate 4. Conclusions
gradually increased until the maximum values. Further
In short, the heterogeneous catalysts by prepared can be
increase in the molar ratio of urea-to-glycerol beyond its
optimum value would decrease the yield of glycerol carbonate.
Hence, 1.5:1 molar ratio of urea to glycerol was selected for
optimizing urea-to-glycerol molar ratio parameters.
applied for synthesis glycerol carbonate in industrial
3.2.3. Effect of reaction time and dosage of catalyst
The reaction time was known to be one of the important
parameters which could affect the fame yield. In my
experiment, the glycerol carbonate yields of the reaction time
varying from 3 to 7 h were investigated. As shown in Fig. S3 in
supporting information, the maximum yield of glycerol was
obtained at 6 h. As depicted, the formation of GC proceeds in
two consecutive steps. The carbamate formed in the first step
4
8
of the reaction and the glycerol carbonate was end-product .
With further increase of the reaction time, the generated
glycerol carbonate would decompose into glycidol. Hence, the
optimal reaction time for glycerol carbonate production was 6
Fig. 8. Comparison of reusability of three catalysts (Reaction conditions:
o
h. The catalyst amount varied between 0.023-0.253 g (1–11 glycerol/urea=1:1.5, catalyst dosage 5.0 wt.%, 140 C, 6 h, 1KPa)
6
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production. Compared with different catalysts, the maximum 15 J.-R. Ochoa-Gómez, O.-A. Gómez-Jiménez-Aberasturib and
B .Maestro-Madurgab, et al. Appl. Catal. A-Gen., 2009, 366
glycerol carbonate yield 85.97% with the ZnO from ZMG as the
(
6 A. Takagaki, K. Iwatani, S. Nishimura and K. Ebitani. Green
2), 315-324.
catalyst under optimizing operating conditions was obtained.
Reaction test indicated that the catalysts with appropriate acid
1
Chem., 2010, 12, 578-581.
and base properties were favorable to the synthesis of glycerol 17 Y. Patel, J. George, S.-M. Pillaic and P. Munshi. Green Chem.,
carbonate. The catalyst still has excellen
t
catalytic
2009, 11, 1056-1060.
1
1
8 M.-G. Alvarez, M.-S. Anna, S. Contreras and J.-E. Sueiras.
Chem. Eng. J., 2010, 161(3): 340-345.
9 M. Srinivas, G. Raveendra, G. Paramesw, P.-S. Sai Prasad, S.
performance after 5 cycles, almost no loss of catalytic activity.
The study revealed that the ZnO catalyst having the
advantages of high activity, highly recyclable, remarkably
Loridant and N. Lingaiah. J. Chem. Sci., 2015, 127(5), 897-908.
stable, and environmental friendly is appropriately applied in 20 J.-J. Chen, C. Wang, B. Dong, W.-G. Leng, J. Huang, R. Ge and
industrialization. A green cogeneration of high purity of zinc
glycerolate( ZMG) and glycerol carbonate( GC) was established
Y.-N. Gao. Chinese J. Catal., 2015, 36, 5336-343.
1 D.-F. Wang, X.-L. Zhang, C.-L. Liu and T.-T. Cheng. React. Kinet.
Mech. Cat., 2015, 115, 597-609.
2 N.-A. Zuhaimi, V.-P. Indran, M.-A. Deraman, N.-F. Mudrikah,
G.-P. Maniam, Y.-H. Taufiq-Yap, M.-H. Rahim. Appl. Catal. A-
Gen., 2015, 502, 312-319.
2
2
by using glycerol as the main raw material．In this study,
glycerol can be relevant for applications such as reactants and
as raw material to prepare the catalyst. Furthermore, the
reaction product of ammonia can also be used in the next 23 Y.-B. Ryu, J.-S. Kim, K.-H. Kim, Y. Kim and M.-S. Lee. Res. Chem.
Intermediat, 2016, 42, 83-93.
reaction to synthesize urea. We hope that our work can make
2
2
4 K. Jagadeeswaraiah, C. Ramesh Kumar, A. Rajashekar, A.
Srivani and N. Lingaiah. Catal. Lett., 2016,146, 692-700.
5 M. Sharath Babu, A. Srivani, G. Parameswaram, G.
Veerabhadram and N. Lingaiah. Catal. Lett., 2015, 145, 1784-
1791.
contribution to the industrialization of glycerol carbonate.
Acknowledgements
2
2
2
2
3
3
3
3
6 Y.-Y. Wang and X.-J. Cao. Bioresource Technol., 2011, 102(22),
1
The financial supports from the National Natural Science
Foundation of China (NSFC) (No. 21306063), the Fundamental
Research Funds for the Central Universities (JUSRP51623A),
the Key Research and Development Program of Jiangsu
Province (Industry Outlook and Common Key Technologies)
0173-10179.
7 L.-B. Li, W.-Y. Zhang, N. Zhao, W. Wei, Y.-H. Sun. Catal. Today,
2006, 115(1-4), 111-116.
8 M. Aresta, A. Dibenedetto, F. Nocito and C. Ferragina. J.
Catal., 2009, 268(1), 106-114.
9 M.-J. Climent, A. Corma, P.-D. Frutos, S. Iborra, M. Noy, A.
Velty and P. Concepción. J.Catal., 2010, 269(1), 140-149.
0 F. Rubio-Marcos, V. Calvino-Casilda, M.-A. Bañares and J.-F.
Fernandez. J. Catal., 2010, 275(2), 288-293.
1 C. Hammond, J.-A. Lopez-Sanchez, M. H. A. A. Rahim and N.
Dimitratos., et al. Dalton T., 2011, 40, 3927.
2 N. A. S. Zuhaimi, V. P. Indran, M. A. Deraman and N. F.
Mudrikah, et al. Appl. Catal. A-Gen, 2015, 502, 312-319.
3 H.-J. Wang and P.-F. Lu. J. Chem. Eng. Data., 2012, 57, 582-
589.
(BE2015204), the Fundamental Research Funds for the Central
Universities (JUSRP51507), and MOE & SAFEA for the 111
Project (B13025) are gratefully acknowledged.
References
1
2
3
4
5
6
7
8
9
A.-R. Go, Y.-R. Lee and Y.-H. Kim, et al. Enzyme. Microb. Tech.,
013, 53(3), 154-158.
H.-S. Jung, Y.-R. Lee and D. Kim, et al. Enzyme. Microb. Tech.,
012, 51(3), 143-147.
N.-T. Nguyen and Y. Demirel. Int. J. Chem. React. Eng., 2011,
2
34 L.-Y. Wang, Y. Liu, C.-L. Liu, R.-Z. Yang and W.-S. Dong. Sci.
China Chem., 2013, 56, 10.
35 Y. Wang, C.-L. Liu, J.-H. Sun, R.-Z. Yang and W.-S. Dong. Sci.
China Chem., 2015, 58, 4.
36 G. Rokicki, P. Rakoczy, P. Parzuchowski and M Sobiecki. Green
Chem., 2005, 7, 529-539.
37 J.-L. Hua, J.-J. Li, Y.-L. Gua and Z.-H. Guan, et al. Appl. Catal.
A-Gen., 2010, 386, 188-193.
38 P.-F. Lu, H.-J. Wang, K.-K. Hu. Chem. Eng. J., 2013, 228, 147-
154.
39 J. Das and D. Khushalani. J. Phys. Chem. C, 2010, 114(17),
8114-8114.
40 D.-M. Reinoso, D.-E. Damiani and G.-M. Tonetto. Appl. Catal.
B-Environ., 2014, 144, 308-316.
41 S. Fujita, Y. Yamanishi and M. Arai. J. Catal., 2013, 297, 137-
141.
2
9
.
M.-M. Fan, J. Yang, P.-P. Jiang, P.-B. Zhang and S.-S. Li. RSC
Adv., 2013, , 752.
F.-X. Yang, M.-A. Hanna and R.-C. Sun. Biotechnol Biofuels,
012, , 13
3
2
5
W.-K. Teng, G.-C. Ngoh, R. Yusoff, M.-K. Aroua. Energ.
Convers. Manage., 2014, 88, 484-497.
M.-O. Sonnati, S. Amigoni and E.-P. Givenchy, et al. Green
Chem., 2013, 15, 283.
A. Dibenedetto, A. Angelini and M. Aresta, et al. Tetrahedron,
2011, 67, 1308-1313.
J. Ochoa-Gómez, O. Gómez-Jiménez-Aberasturi, C. Ramírez-
López, and M. Belsué. Org. Process Res. Dev., 2012, 16, 389- 42 F.-S. Lisboa, F.-R. Silva, L.-P. Ramos and F. Wypych. Catal.
3
99.
Lett., 2013, 143, 1235-1239.
43 X. Collard, A. Comès and C. Aprile. Catal. Today, 2015, 241,
33-39.
44 N.-K. Divya and P.-P. Pradyumnan. Mat. Sci. Semicon. Proc.,
2016, 41, 428-435.
45 K. Ravichandran, K. Subha and N. Dineshbabu. J. Alloy.
Compd., 2016, 656, 332-338.
46 M. Shatnawi, A.-M. Alsmadi, I. Bsoul and B. Salameh, et al. J.
Alloy. Compd., 2016, 655, 244-252.
1
1
0 J. Zhang, D.-H. He. J. Colloid Interf. Sci., 2014, 419, 31-38.
1 J. George, Y. Patel, S.-M. Pillai and P. Munshi. J. Mol. Catal. A-
Chem, 2009, 304, 1-7.
2 H.-G. Li, D.-Z. Gao, P. Gao, F. Wang and N. Zhao, et al. Catal.
Sci. Technol., 2013,
3 J.-L. Hua, J.-J. Li, Y.-L. Gua, Z.-H. Guan, W.-L. Mo, et al. Appl.
Catal. A-Gen., 2010, 386, 188-193.
4 G. Rokicki, P. Rakoczy, P. Parzuchowski and M. Sobiecki. Green
1
1
1
3
, 2801.
Chem., 2005, 7, 529-539.
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4
4
4
7 H.-R. Madan, S.-C. Sharma, U.-D. Suresh and Y.-S. Vidya, et al.
Spectrochim. Acta A, 2016, 152, 404-416.
8 L.-G. Wang, Y.-B. Ma, Y. Wang, S.-M. Liu, Y.-Q. Deng. Catal.
Commun., 2011, 12(15), 1458-1462.
9 Q.-B. Li, W.-Y. Zhang, N. Zhao, W. Wei and Y.-H. Sun. Catal.
Today, 2006, 115, 111-116.
8
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