POSS-derived solid acid catalysts with excellent hydrophobicity for highly efficient transformations of glycerol

Article abstract of DOI:10.1039/c5cy01240f

Novel excellent hydrophobic POSS-derived solid acid catalysts were successfully synthesized through free radical copolymerization of polyhedral oligomeric vinylsilsesquioxanes (POSS) with sodium p-styrene sulfonate (POSS-x-SO₃H), and characterized by several physicochemical methods. Green routes toward valorization of glycerol via acetalization with benzaldehyde and esterification of glycerol with acetic acid have been proposed. The as-prepared catalysts showed very high activities and selectivities toward glycerol derivatives within a short reaction time, which were even higher than that of homogeneous H₂SO₄. The POSS-2-SO₃H catalyst was recycled up to five times without any significant loss of activity. The excellent performance of these solid acid catalysts is mostly attributed to the combination of superior hydrophobicity and large specific surface area.

Full text of DOI:10.1039/c5cy01240f

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POSS-derived solid acid catalysts with excellent hydrophobicity
for highly efficient transformations of glycerol
Received 00th January 20xx,
Accepted 00th January 20xx
a
a
a
a
Yan Leng *, Jiwei Zhao , Pingping Jiang , Dan Lu
Novel excellent hydrophobic POSSꢀderived solid acid catalysts were successfully synthesized through free radical
DOI: 10.1039/x0xx00000x
3
copolymerization of polyhedral oligomeric vinylsilsesquioxanes (POSS) with sodium pꢀstyrene sulfonate (POSSꢀxꢀSO H),
www.rsc.org/
and characterized by several physicochemical methods. The green routs toward valorization of glycerol via acetalization
with benzaldehyde and esterification of glycerol with acetic acid have been proposed. The asꢀprepared catalysts showed
very high activities and selectivity toward glycerol derivatives within a short reaction time, which are even higher than that
2 4
of homogeneous H SO . The catalyst was recycled up to five times without any significant loss in the activity. The excellent
performance of these solid acid catalysts is mostly attributed to their combination of superior hydrophobicity and large
specific surface area.
transformation of glycerol, including zeolites, heteropolyacids,
1
5ꢀ17
Introduction
amberlyst, supported ionic liquids, and others.
However, their
activities are normally lower than those of the homogeneous mineral
liquid acids because of the lower degree of exposure of active sites
to the reactants. Moreover, the hydrophilic frameworks of these solid
catalysts largely influence their catalytic activities because water
usually acts as a byproduct in many acidꢀcatalyzed reactions, which
easily coadsorbs near the acid centers, resulting in their partial
As the petroleum reserves deplete and concerns about
environmental issues increase, the preparation of biofuels from
1
,2
biomass is stimulating growing interest.
Glycerol is an
unavoidable side product of the biodiesel production process,
and so recent increases in the adoption of biodiesel have led to
3
,4
a concurrent rise in glycerol stocks. It would therefore be
desirable to develop methods of transforming glycerol into
valueꢀadded chemicals in order to increase the profitability of
biodiesel manufacture. Many new catalytic routes for the
transformation of glycerol have been developed, such as
18,19
deactivation due to competition with the reactant species.
Thus, a
waterꢀtolerant solid acid catalyst is essential for the acetalization and
esterication of glycerol, where the active components of the catalyst
will remain intact even in a highly polar reaction mixture.
5
6
7
8
oxidation,
acetalization, and carbonylation.
glycerol derivatives, the conversion of glycerol into cyclic nanostructures with formula R
acetals and glyceryl acetate by acid catalytic reaction has core (Si 12) is surrounded by organic moieties at the eight
hydrogenolysis,
9
dehydration,
esterification,
Polyhedral oligomeric silsesquioxanes (POSS), an intriguing class
10
Among the different of organicꢀinorganic hybrid materials, exist as cageꢀtype
Si 12, in which the central inorganic
O
8
8
O
8
2
0,21
received much attention because these compounds are widely vertices.
Owning to the features of unique starꢀshaped
applied in the pharmaceutical, cosmetics, polymer, food nanostructures and chemical properties, such as facile chemical
additives, and tobacco industries, in addition to their role as modification, good pH tolerance, high temperature and oxidation
1
1,12
biodiesel additives.
Traditionally, the acetalization and esterication of glycerol were constructing multiꢀfunctional materials by introducing functional
resistance properties, POSS is an ideal building block for
2
2ꢀ24
generally carried out by using mineral acids as homogeneous groups and elements.
The recent studies have shown that POSS
catalysts. However, these processes are usually accompanied by can function as a carrier or activity promoter for developing highly
25
several technical and environmental drawbacks such as catalyst efficient heterogeneous catalytic systems. Also noticeably, the
separation, product purity, reactor corrosion, and effluent hydrophobicity provided by the inorganic core (Si
O
12) in POSS has
8
13,14
26
disposal.
The challenge was to replace them with solid acid been demonstrated to be favorable for the organic transformations.
catalysts which possess the advantages of reductive corrosion, easy Accordingly, it is reasonable to design and prepare a POSSꢀbased
separation and good recyclability, and green chemical processes. solid acid catalyst for acid catalyzed transformations.
There are some solid acid catalysts that are reported for the
Herein, we demonstrate a successful preparation of SO
functionalized solid acids catalysts by copolymerization of octavinyl
POSS with sodium pꢀstyrene sulfonate (POSSꢀxꢀSO H). The
obtained POSSꢀxꢀSO H products have tunable BET surface areas,
adjustable active site concentrations, and excellent hydrophobicity.
Catalytic tests have shown that POSSꢀxꢀSO H exhibit extraordinary
3
Hꢀ
3
a.
The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education,
3
School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122,
China. Fax: +86-510-85917763; Tel: +86-510-85917090; E-mail:
lengyan1114@126.com.
3
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catalytic activities and recyclability in acetalization of glycerol with
3
Excellent hydrophobic copolymer POSSꢀxꢀSO H (where x stand
benzaldehyde (PhCHO) and esterification of glycerol with acetic for the molar ratio of sodium pꢀstyrene sulfonate with POSS) were
acid, which are even higher than that of H
2
SO
4
.
synthesized through free radical copolymerization of octavinyl
POSS with sodium pꢀstyrene sulfonate. As a typical run for the
3
synthesis of POSSꢀ2ꢀSO H, 1.266 g of octavinyl POSS was added
into 30 mL of THF, followed by addition of 25 mL of methanol,
Experimental Details
then 0.824 g of sodium pꢀstyrene sulfonate was introduced. After
Reagents and analysis
o
stirring at 60 C for 0.5 h, 0.05 g of AIBN was added, then the
All chemicals were analytical grade and used as received. FTꢀIR
spectra were recorded on a Nicolet 360 FTꢀIR instrument (KBr
discs) in the 4,000–400 cm region. SiꢀNMR spectra were
measured with a Bruker DPX 400 spectrometer at ambient
o
mixture was treated at 65 C. The solid product POSSꢀ2ꢀSO
3
Na was
filtered, washed with THF and methanol for three times, dried under
ꢀ
1
29
o
3
vacuum at 60 C for 8 h. The obtained POSSꢀ2ꢀSO Na sample was
further ionꢀexchanged using 1 M sulfuric acid. 1.0 g of POSSꢀ2ꢀ
3
temperature in CDCl using TMS as internal reference. TG analysis
SO Na was dispersed into 20 mL of 1 M sulfuric acid. After stirring
3
was carried out with a STA409 instrument in dry air at a heating rate
of 10°C/min. Nitrogen adsorption/desorption were measured at
liquid nitrogen temperature, using an ASAP 2020 gas sorption
analyzer (Micromeritics, USA). Before analysis, the samples were
degassed under vacuum condition at 120 C for 3 h. The Brunauerꢀ
EmmettꢀTeller (BET) surface areas were calculated based on the
for 24 h at room temperature, the sample was treated by
centrifugation and washed with water until the supernatant was
neutral. After drying at 80°C for 12 h, POSSꢀ2ꢀSO H was obtained.
3
Other samples POSSꢀ1ꢀSO H, POSSꢀ3ꢀSO H, POSSꢀ4ꢀSO H, and
o
3
3
3
PhꢀSO H were prepared in the same way.
3
linear part of the BET plot (P/P
0
< 0.30). Water repellency was Typical procedure for catalytic experiments
checked by the contact angle of a pure water droplet using a contact
angle meter of OCA 40. SEM images were performed on a
HITACHI Sꢀ4800 fieldꢀemission scanning electron microscope.
TEM images were obtained with JEOL JEMꢀ2100 electron
microscope operated at 200 Kv. The CHNS elemental analysis was
performed on an elemental analyzer Vario EL cube. The acid
exchange capacities of the catalysts were determined by acid−base
titration with standard NaOH solution.
Acetalization of glycerol with PhCHO
The acetalization of glycerol with PhCHO was carried out under
batch conditions. In a roundꢀbottomed flask equipped with a
magnetic stirrer and a reflux condenser, were placed glycerol (2.76
g, 0.03 mol), PhCHO (3.50 g, 0.033 mol) and catalyst POSSꢀ2ꢀSO H
3
(
0.05 g, 0.05 mmol). The mixture was reacted at 30°C with vigorous
stirring under atmospheric pressure, and kept at this temperature for
h to ensure completeness of the reaction. After reaction, the solid
2
Catalyst preparation
catalyst can be recovered by centrifugation, and the liquid phase was
detected by GCꢀMS. For the acetalization of glycerol with acetone
and PhCHO with ethylene glycol, the test was carried out
accordingly.
Preparation of octavinyl POSS
Octavinyl POSS was prepared according to the previous
2
7,28
literature.
Typically, in a 250 mL flask, vinyltriethoxysilane
Esterification of glycerol with acetic acid
(19 g, 0.1 mol) was dissolved in 50 mL anhydrous ethanol.
In a typical esterification reaction, glycerol (2.76 g, 0.03 mol),
acetic acid (14.4 g, 0.24 mol), the catalyst (0.1 g, 0.1 mmol) and 10
mL toluene were added to a flask with a water segregator. The
reaction was refluxed at the heating temperature 120°C of the oil
bath for 2 h with vigorous stirring. After reaction, the resultant
mixture was filtered off, extracted using ethanol and the monoꢀ, diꢀ
(1,2ꢀdiacetylglyceride) and triacetylglyceride products were
identified by GCꢀMS, along with their ratios. For other esterification
reactions, the test was carried out accordingly. Exceptionally, for the
esterifications using nꢀbutanol as a reactant, no waterꢀcarrying agent
Then 10 mL hydrochloric acid and 8 mL deionized water were
added into the above solution with vigorous stirring. The above
reaction mixture was allowed to react for 48 h at room
temperature. On completion, the white crystalline powder was
filtered, washed with anhydrous ethanol, recrystallized in
tetrahydrofuran/methanol (volume ratio: 1:3) mixture solvent
2
9
and dried in vacuum at 80°C for 10 h. Si NMR (400 MHz,
CDCl , TMS) δ (ppm) = 80.19 (see Figure S1 in Supporting
3
Information (SI)).
Preparation of POSSꢀxꢀSO
3
H
was used. To test the catalytic recyclability of POSSꢀ2ꢀSO H, after
3
3
Figure 1. Schematic illustration outlining the preparation and structure for the solid catalysts POSSꢀxꢀSO H.
2
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Table 1. Elemental analysis and BET surface areas of samples
POSSꢀxꢀSO H.
3
(a)
(
b)
Acid sites
S
BET
2
Sample
C%
H%
S%
(
mmol/g) (m /g)
(c)
POSSꢀ1ꢀSO
POSSꢀ2ꢀSO
POSSꢀ3ꢀSO
3
3
3
H
H
H
35.25
38.36
3.91 3.72
3.99 6.24
1.16
1.63
109.9
149.3
(d)
40.51
42.17
4.05 7.96
4.09 9.16
1.97
2.55
74.1
27.6
1008
1036
1178
3
POSSꢀ4ꢀSO H
1126
1800
1600
1400
1200
1000
800
600
-1
Wavenumber (cm )
−
1
Figure 2. FTꢀIR spectra of (a) POSSꢀ
1
ꢀSO H, (b) POSSꢀ
2ꢀ
1036, and 1178 cm , assignable to the stretching vibration of
ν(O=S=O)sym, ν(CꢀS), and ν(O=S=O)asym, respectively. These results
suggest the successful introduction of sulfonic groups onto the
network of POSS polymers through the copolymerization route. The
3
SO H, (c) POSSꢀ
3
ꢀSO H, and (d) POSSꢀ
4
ꢀSO H.
3
3
3
−1
small increase in the intensity of the bands at 1008 and 1036 cm
may result from the increase of the content of the SO H in the
copolymers.
3
1
00
9
8
7
6
5
4
0
0
0
0
0
0
TG analysis in Figure 3 shows that the prepared catalysts POSSꢀxꢀ
SO H have superior thermal stability with decomposition starting at
3
about 300°C, which is even higher than that of the conventional
organic polymers. The small weight loss of 2% before 300°C results
from the loss of the adsorbed water. The weight loss of nearly 8ꢀ20%
in the range 300ꢀ400°C is due to the decomposition of sulfonic
(a)
c)
(b)
(
29
groups. The further weight loss in 400ꢀ600°C and is attributed to
(
d)
the destruction of the polymer network. The composition of POSSꢀxꢀ
SO H was also examined by CHNS elemental analysis, and the
3
1
00
200
300
400
500
600
700
800
results in Table 1 indicate that the molar ratio of POSS to PhꢀSO H
o
3
Temperature ( C)
for POSSꢀxꢀSO H was approximate 1:1, 1:2, 1:3, and 1:4,
3
respectively. Moreover, the sulfur content of POSSꢀxꢀSO H samples
in Table 1 indicates adjustable acidic concentration between 1.16ꢀ
3
Figure 3. TG curves of (a) POSSꢀ
1
3
ꢀSO H, (b) POSSꢀ2ꢀ
SO H, (c) POSSꢀ ꢀSO H, (d) POSSꢀ4ꢀSO H.
3
3
3
3
2
.55 mmol/g.
Figure 4 presents the SEM and TEM images of the samples
reaction, the catalyst was separated by filtration, washed with POSSꢀxꢀSO
H. SEM images of POSSꢀ1ꢀSO H and POSSꢀ2ꢀSO H
3 3
3
ethanol, dried in vacuum at 80°C for 6 h, and then used for the next show the abundant wormholeꢀlike morphology with micrometer size.
run without adding any fresh catalyst.
However, when the molar ratio of PhꢀSO H to POSS increased to
3
4
:1, the morphology of POSSꢀ4ꢀSO H changed to blocks with a
3
relative smooth surface (Figure 4D). In the TEM images of POSSꢀxꢀ
Results and Discussion
SO H (Figure 4Eꢀ4H), the observed dark micelles (nanoparticles
3
with small size of 5ꢀ20 nm) indicates that the POSS has been
uniformly dispersed in the copolymer network. It is proposed that
the POSS units act as the crossꢀlinking node, which intertwined with
Preparation and characterization of catalysts
The preparation of the POSSꢀderived solid acid catalysts was
carried out according to the procedures shown in Figure 1. In brief,
the octavinyl POSS units were first prepared by hydrolyzation of
vinyltriethoxysilane. Then, the copolymers POSSꢀxꢀSO Na were
synthesized by free radical copolymerization of octavinyl POSS with
the PhꢀSO H to form a highly cross linked framework. Notably, as
3
the PhꢀSO H/POSS molar ratio increased, the POSS micelles tend to
3
be sparse and the particle size of which increased. This is mostly due
3
to that the higher content of PhꢀSO H may be not benefit for the
3
formation of crossꢀlinked framework structure with highly dispersed
POSS particles. The results of the Brunauer−Emmett−Teller (BET)
sodium pꢀstyrene sulfonate in THF and methanol mixed solvent at
65°C, and subsequent treatment of the copolymers with H SO to
2 4
surface areas in Table 1 shows that the optimum specific surface
give the crossꢀlinked copolymers POSSꢀxꢀSO H.
3
2
area 149.3 m /g is obtained when the molar ratio of PhꢀSO H to
3
Figure 2 shows the FTꢀIR spectra of POSSꢀxꢀSO H samples. All
spectra shows a broad band at around 1126 cm , which is attributed
to the asymmetric vibration of SiꢀOꢀSi on the POSS. In addition, the
3
POSS is 2:1. The high molar ratio of PhꢀSO H to POSS leads to low
−
1
3
surface areas, for example, when the PhꢀSO H/POSS molar ratio is
3
characteristic vibration bands for the PhꢀSO H are observed at 1008,
3
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(
a)
(b)
(b)
(c)
CA=132°
CA=121°
CA=104°
(d) CA=92°
(e) CA=39°
A
(
a)
(c)
(c)
(e)
(d)
CA
＜
10°
CA
＜
10°
CA＜
10°
10°
CA=13°
CA=11°
CA=18°
B
(
a)
(
b)
(d)
(e)
CA
＜
10°
CA
＜
10°
CA
＜
CA=10°
C
Figure 5. (A) Water droplets, (B) benzaldehyde droplets,
and (C) acetic acid droplets on the surface of catalysts (a)
POSSꢀ
POSSꢀ
1
4
ꢀSO
ꢀSO
3
H, (b) POSSꢀ
H, and (e) PhꢀSO
2
ꢀSO
3
H, (c) POSSꢀ
3ꢀSO
3
H, (d)
3
3
H.
Figure 4. SEM images of (A) POSSꢀ
SO H, (C) POSSꢀ SO H, (D) POSSꢀ
images of (E) POSSꢀ SO H, (F) POSSꢀ
POSSꢀ SO H, (H) POSSꢀ SO H.
1
-
SO
3
H, (B) POSSꢀ
2-
3
3
-
3
4
-
SO
3
H, and TEM
1
-
3
2
-
SO
3
H, (G)
3
-
3
4-
3
2
2
3
:1 and 4:1, the BET surface area are only 74.1 m /g and 27.6 m /g,
Figure 6. Control experiments for acetalization of glycerol with
respectively.
It is well known that the hydrophobicity of inorganic nuclear in
POSS units can significantly affect the surface wettability of
PhCHO.
Reaction conditions: glycerol (0.03 mol), PhCHO (0.033
mol), catalyst POSSꢀ2ꢀSO H (0.05 mmol), 30°C, 2 h.
3
30
polymer materials. To understand the wettability of these solid
catalysts POSSꢀxꢀSO H, we carried out the CA tests. As can be seen
in Figure 5A, when a water droplet is brought in contact with the
3
o
surface of POSSꢀ1ꢀSO
excellent hydrophobicity. However, the CAs tend to decrease as the seen that the liquid H
molar ratio of PhꢀSO
H to POSS increased, and the CA for POSSꢀ with 98% combined selectivity to 1,3ꢀdioxolane and 1,3ꢀdioxane,
free sample PhꢀSO
hydrophobicity is attributable to the surface chemistry change due to major product. POSSꢀfree sample PhꢀSO
the increasing of hydrophilcity SO
H groups in the solid catalysts. reactants but dissolvable with produced water. In this case, the
3
H, it yields a CA of 132 , demonstrating its reaction temperature. The results are shown in Figure 6. It can be
SO offers a relative low conversion of 72.8%
2
4
3
o
H is measured to be 39 . The weakened and the kinetically favoured product 1,3ꢀdioxolane is formed as
H was insoluble in
3
3
3
With benzaldehyde and acetic acid as the testing droplet, the CAs are reaction is a liquidꢀliquid biphasic system, showing also a low
measured to be less than 18° for all samples (Figure 5B and 5C), conversion of 79%. Interestingly, the POSSꢀderived solid acid
demonstrating excellent surface wettability for organic substrates. catalysts POSSꢀxꢀSO
Moreover, the CA test for glycerol is not workable because of its exhibit 92ꢀ95% conversions with excellent combined selectivity.
H are all insoluble in the reaction system, and
3
high viscosity.
Nevertheless, the typical solid catalysts, heteropolyacid H PW12O
3 40
dissolved in the reaction system gives a conversion of 93%, and the
acidic ion exchange resin Amberliteꢀ732 leads to a solidꢀliquid
Acetalization of glycerol with PhCHO
Acetalization of glycerol with PhCHO produces two main heterogeneous catalysis, but offers only 69% conversion. The
products: 1,3ꢀdioxolane and 1,3ꢀdioxane, whose relative formation catalytic activity and selectivity of POSSꢀxꢀSO for the
depends on the acetalization position within the glycerol molecule. acetalization of glycerol with PhCHO are much greater than those of
H
3
The catalytic activities of synthesized catalysts POSSꢀxꢀSO
3
H were the previously reported heterogeneous catalysts, such as SBAꢀ15
assessed in comparison to various control catalysts with 30 C supported alumina, anchored silicotungstates, aluminosilicateꢀ
o
4
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Table 2. Results of different acetalizations and esterifications
a
3
over POSSꢀ2ꢀSO H .
b
c
Molar
ratio
T
C
t
Con
Sel
Entry
Substrates
o
(
)
(h)
(%)
(%)
Glycerol +
Acetone
Benzaldehyde +
Glycol
Acetic acid +
Butanol
Lactic acid +
Butanol
Oleic acid +
Butanol
Citric acid +
Butanol
Acetic acid +
Benzyl alcohol
Acetic acid +
Cyclohexanol
1
2
3
4
5
6
7
1:1.2
1:1
30
2
72
92
90
1.5
90
99
96
96
85
97
81
98
100
100
100
99
1:1.2
1:2
120 1.5
120 1.5
1:5
130
130
120
120
4
3
1
3
1:5
Figure 7. Control experiments for esterfication of glycerol with
acetic acid.
1:1.2
1:1.2
100
99
Reaction conditions: glycerol (0.03 mol), acetic acid (0.24
o
8
mol), catalysts (0.1 mmol), 120 C, 2 h.
a
Reaction conditions: catalyst (0.06 mmol), carboxylic acid (30
mmol).
b
3
1ꢀ33
Conversions for entries 1 and 2 are based on alcohol, and
supported iron oxide nanoparticles
, as well as the homogeneous
c
34
entries 3ꢀ8 are based on carboxylic acid. Selectivity for
the products.
acidic ionic liquids with a shorter reaction time of 2 h.
Notably, during the reaction, glycerol is immiscible with PhCHO,
when POSSꢀxꢀSO
liquidꢀsolid thriphase reaction system. The results of catalytic
kinetics of POSSꢀxꢀSO H and PhꢀSO H illustrate that the reaction
rates gradually decreased as the molar ratio x increased (See Figure
S2 and Table 1 in SI). This variation is in consistent well with their
surface hydrophobicity as suggested by CA in Figure 5, the
comparatively high hydrophobicity favor higher catalytic rate. We
thus proposed that the waterꢀtolerant catalyst structure should have
supplied a unique microenvironment for the catalysts to involve both
3
H were used as the catalysts, it caused liquidꢀ
3
3
exhibited 89% conversion. Acidic ion exchange resin Amberliteꢀ732
was insoluble in the reaction system, but only gave a 70%
conversion. In contrast, all the heterogeneous catalysts POSSꢀx-
3
SO H present high conversions above 95% with outstanding
combined selectivity to the DAG and TAG (above 99%). Due to the
equal activity of two terminal alcoholic groups, the MAG was
almost not observed, and there was no dehydration products acetol
and acrolein detected in the product mixture. Additionally, DAG was
found to be the major product under the investigated reaction
3
the glycerol and PhCHO, which allows the SO H groups in the bulk
of catalysts to give full play as catalytic centers. Moreover, it looked
like a micro reactor equipped with a micro waterꢀremoving device,
which could separate out the produced water from the organic phase
in time to shift the reaction to products side. In contrast, when the
conditions, with the exception of the use of H
SO was more selective to the TAG. Notably, the results of
catalytic kinetics of POSSꢀxꢀSO H and PhꢀSO H in the esterification
2 4
SO as a catalyst,
H
2
4
3
3
2 4 3
liquid H SO , hydrophilic PhꢀSO H and Amberliteꢀ732 were used as
of glycerol with acetic acid (see Figure S3 and Table 1 in SI)
demonstrate that catalytic activities of catalysts are reasonably
related to their surface areas, and the comparatively high surface
area favor higher catalytic rate. In comparison to the reported solid
the catalyst, they were mostly retained in the glycerol and water
phase, thus giving low conversions due to the less accessibility of
PhCHO substrate molecules to active sites.
34,35
Esterification of glycerol with acetic acid
catalysts,
3
POSSꢀxꢀSO H catalyzed esterification of glycerol with
acetic acid was demonstrated to be superior with respect to acetic
acid molar ratio, reaction time, and simple preparation of catalyst.
The esterification of glycerol with acetic acid is another attractive
pathway for their valueꢀadded chemicals, in which the obtained
products include glyceryl monoacetate (MAG), glyceryl diacetate Catalytic activity in various acetalization and esterification
DAG) and glyceryl triacetate (TAG). Among these products, DAG reactions
and TAG are the most favorable ones due to their versatile
(
3
5,36
3
We extended the used of POSSꢀ2ꢀSO H to the acetalizations of
applications as biofuel additives.
performance of various catalysts in the esterification of glycerol. The
traditional homogeneous H SO and H 40 showed almost
00% glycerol conversion with 99 % combined selectivity to DAG
Figure 7 illustrates the catalytic
glycerol with acetone and PhCHO with ethylene glycol, and various
exterifications of carboxylic acids with alcohols. The results are
summarized in Table 2. Solidꢀliquid biphasic heterogeneous
catalysis systems were observed in these reactions, and good to
excellent catalytic activities were obtained. These results further
2
4
3
PW12O
1
3
and TAG. PhꢀSO H also caused a homogeneous catalysis and
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ARTICLE
Journal Name
Table
3
3. Catalytic reusability of POSSꢀ2ꢀSO H for the
acetalization of glycerol with PhCHO and esterification of
glycerol with acetic acid.
(a)
Glycerol/Acetic
Glycerol/Benzaldehyde
acid
(b)
Entry
Con
%)
1,3ꢀ
1,3ꢀ
(c)
Con
(%)
DAG
(%)
TAG
(%)
Dioxolane Dioxane
(
(
%)
(%)
36.5
32.3
34.7
30.8
32.7
1
2
3
4
5
94.2
93.7
93.4
93.6
92.5
55.7
59.4
58.6
62.1
60.3
100
98.6
98.4
98.5
97.7
87.2
88.3
84.2
87.5
85.6
12.4
11.2
14.9
11.7
13.8
1
008
1
178
1
1211036
1800
1600
1400
1200
1000
800
600
-1
Wavenumber (cm )
Figure 8. (a) fresh POSSꢀ
ꢀSO H, and (c) five recycled POSSꢀ2ꢀSO H.
3
2ꢀSO H, (b) two recycled POSSꢀ
3
a
2
3
Reaction conditions: catalyst (0.06 mmol), carboxylic acid (30
mmol).
Acknowledgements
3
indicate the applicability of POSSꢀxꢀSO H as solid acidic catalysts
The authors thank the National Natural Science Foundation of
China (No. 21206052) and MOE & SAFEA for the 111 Project
for the esterification and acetalization reactions.
Catalyst reusability
(No. B13025).
3
Finally, the reusability of the catalyst POSSꢀ2ꢀSO H was
evaluated on the acetalization of glycerol with PhCHO and
esterification of glycerol with acetic acid, respectively. After each
cycle, the catalyst was separated from the reaction system by
filtration, washed with ethanol, dried and reused for the next run
without adding any fresh catalyst. As shown in Table 3, the catalyst
did not show any appreciable deactivation even after fiveꢀrun tests in
acetilization and esterification, respectively, revealing a quite steady
reusability of the present new catalyst. The recycled POSSꢀ2ꢀSO H
3
showed nearly no obvious decreases in both acidic concentration and
sulfur content as compared with that of the fresh one. Furthermore,
Notes and references
1
2
3
K. Matthew, M. K. Weschler, W. J. Barr, W. F. Harper, A. E.
Landis, Bioresource Technol. 2014, 153, 108.
I. Rawat, K. R. Ranjith, T. Mutanda, F. Bux, Appl. Energy. 2013,
1
03, 444.
K. Y. Nandiwale, S. E. Patil, V. V. Bokade, Energy Technol. 2014,
, 446.
2
4
5
M. Martín, I. E. Grossmann, Appl. Energy. 2014, 135, 108.
C. G. Heck, B. G. Janesko, G. E. Scuseria, N. J. Halas, S. Wong, ACS
Catal. 2013, 3, 2430.
6
F. Maurielloa, H. Arigab, M. G. Musolinoa, R. Pietropaoloa, S.
Takakusagib, K. Asakura, Appl. Catal. B: Environmental. 2015,
166-167, 121.
3
the IR spectrum for the recovered POSSꢀ2ꢀSO H in Figure 8 was
well consistent with that of the fresh one, demonstrating a durable
catalyst structure accounting for the steadily catalytic reuse.
7
8
B. Katryniok, S. Paul, F. Dumeignil, ACS Catal. 2013, 3, 1819.
S. H. Zhu, Y. L. Zhu, X. Q. Gao, T. Mo, Y. F. Zhu, Y. W. Li,
Bioresource Technol. 2013, 130, 45.
T. E. Souza, M. F. Portilho, P. M. T. G. Souza, P. P. Souza,
9
1
1
Conclusions
ChemCatChem. 2014, 6, 2961.
0
1
F. Rubio-Marcos, V. Calvino-Casilda, M. A. Bañares, J. F.
Fernandez, J. Catal. 2010, 275, 288.
B. Mallesham, P. Sudarsanam, B. M. Reddy, Ind. Eng. Chem. Res.
In summary, a novel kind of hydrophobic SO Hꢀbased solid
3
acid catalysts (POSSꢀ
xꢀSO H) synthesized by free radical
3
copolymerization of octavinyl POSS with sodium
p
ꢀstyrene
2
014, 53, 18775.
sulfonate were successfully applied to catalyze the acetalization 12 M. S. Khayoon, S. Triwahyono, B. H. Hameed, A. A. Jalil, Chem.
Eng. J. 2014, 243, 473.
of glycerol with PhCHO and esterification of glycerol with
1
1
3
4
G. S. Nair, E. Adrijanto, A. Alsalme, I. V. Kozhevnikov, D. J. Cooke,
D. R. Brown, N. R. Shiju, Catal. Sci. Technol. 2012, , 1173.
M. V. Kirillova, A. M. Kirillov, D. Mandelli, W. A. Carvalho, A. L.
acetic acid, plus the advantages of convenient recovery and
steady reusability. The great catalytic performance and the
highly viable recycling process are largely attributed to the
2
Pombeiro, G. B. Shulpin, J. Catal. 2010, 272, 9.
special properties of the catalysts, such as hydrophobicity and 15 B. Mallesham, P. Sudarsanam, G. Raju, B. M. Reddy, Green
Chem. 2013, 15, 478.
wettability for various organic substrates, and high surface
1
1
6
7
M. C. Cerón-García, M. D. Macías-Sánchez, A. Sánchez-Mirón, F.
García-Camacho, E. Molina-Grima, Appl. Energy. 2013, 103, 341.
J. L. Xu, H. Y. Zhang, Y. F. Zhao, B. Yu, S. Chen, Y. B. Li, L. D. Hao,
Z. M. Liu, Green Chem. 2013, 15, 1520.
areas. These features should allow the design and development
of a wide variety of solid catalysts for the conversion of organic
compounds.
6
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
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Page 7 of 8
Catalysis Science & T hno
Please do not adjust me ca rgin sl ogy
View Article Online
DOI: 10.1039/C5CY01240F
Journal Name
ARTICLE
1
1
2
2
2
2
2
8
9
0
1
2
3
4
J. Feng, W. Xiong, B. Xu, W. D. Jiang, J. B. Wang, H. Chen, Catal.
Commun. 2014, 46, 98.
T. Z. Li, C. Fu, J. S. Qi, J. Pan, S. H. Chen, J. J. Lin, Reac. Kinet.
Mech .Cat. 2013, 109,117.
Q. H. Zhang, X. Huang, X. L. Wang, X. D. Jia, K. Xi, Polymer. 2014,
5
5
, 1282.
D. Gnanasekaran, K. Madhavan, B. S. R. Reddy, J. Sci. Ind. Res.
009, 68, 437.
H. B. He, B. Li, J. P. Dong, Y. Y. Lei, T. L. Wang, Q. W. Yu, Y. Q.
Feng, Y. B. Sun, ACS Appl. Mater. Inter. 2013, , 8058.
K. Tanaka, F. Ishiguro, Y. Chujo, J. Am. Chem. Soc. 2010, 132
7649.
2
5
,
1
C. K. Mayfair, V. R. Mark, N. M. Michael, H. K. Harold, Chem.
Comm. 2014, 50, 3262.
2
2
5
6
K. Tanaka, Y. A. Chujo, J. Mater. Chem. 2012, 22, 1733.
R. Goseki, A. Hirao, M. Kakimoto, T. Hayakawa, ACS Macro. Lett.
2013, 2, 625.
2
7
B. H. Yang, J. R. Li, J. F. Wang, H. Y. Xu, S. Y. Guang, C. Li, J. Appl.
Pol. Sci. 2009, 111, 2963.
2
2
8
9
W. P. Wang, X. X. Jie, M. Fei, H. Jiang, J. Pol. Res. 2011, 18, 13.
F. J. Liu, W. P. Kong, C. Z. Qi, L. F. Zhu, F. S. Xiao, ACS Catal. 2012,
2
, 565.
J. Z. Li, Z. Zhou, L. Ma, G. X. Chen, Q. F. Li, Macromolecules. 2014,
, 5739.
N. Narkhede, A. Patel, RSC Adv. 2014,
G. Gonzalez-Arellano, R. A. D. Arancon, R. Luque, Green Chem.
014, 16, 4985.
C. Gonzalez-Arellano, S. Deb, R. Luque, Catal. Sci. Technol. 2014,
, 4242.
B. Wang, Y. Shen, J. Sun, F. Xu, R. Sun, RSC Adv. 2014.
S. Singh, A. Patel, Ind. Eng. Chem. Res. 2014, 53, 14592.
3
0
47
3
3
1
2
4, 19294.
2
3
3
4
3
3
3
4
5
6
4, 18917.
W. N. R. W. Isahak, Z. A. C. Ramli, M. Ismail, M. A. Yarmo, Ind.
Eng. Chem. Res. 2014, 53, 10285.
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Graphical Abstract
POSS-derived solid acid catalysts with excellent hydrophobicity for
highly efficient transformations of glycerol
a
a
a
a
Yan Leng *, Jiwei Zhao , Pingping Jiang , Dan Lu
a
The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and
Material Engineering, Jiangnan University, Wuxi 214122, China. Fax: +86-510-85917763; Tel: +86-510-85917090;
E-mail: lengyan1114@126.com
New POSS-derived acid catalysts are synthesized and proved to be highly efficient and steadily
reused for glycerol transformations.