Selective dehydration of fructose to 5-hydroxymethylfurfural catalyzed by mesoporous SBA-15-SO3H in ionic liquid BmimCl

Article abstract of DOI:10.1016/j.carres.2012.01.003

Mesoporous SBA-15 materials functionalized with propylsulfonic acid groups (SBA-15-SO₃H) were synthesized through a conventional one-pot route. It was used as a catalyst for the selective synthesis of 5-hydroxymethylfurfural (HMF) from the dehydration of fructose using BmimCl as solvent. Reaction time, temperature and fructose concentration were investigated during the HMF synthesis procedure. The catalyst SBA-15-SO₃H exhibits high fructose conversion (near 100%) and HMF selectivity (about 81%) with good stability in the HMF synthesis. It was a suitable catalyst to produce HMF from renewable carbohydrates in potential industrial process.

Full text of DOI:10.1016/j.carres.2012.01.003

Carbohydrate Research 351 (2012) 35–41
Contents lists available at SciVerse ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Selective dehydration of fructose to 5-hydroxymethylfurfural catalyzed by
mesoporous SBA-15-SO H in ionic liquid BmimCl
3
⇑
Xingcui Guo, Quan Cao, Yijun Jiang, Jing Guan, Xiaoyan Wang, Xindong Mu
Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Article history:
Mesoporous SBA-15 materials functionalized with propylsulfonic acid groups (SBA-15-SO H) were syn-
thesized through a conventional one-pot route. It was used as a catalyst for the selective synthesis of
3
Received 16 November 2011
Received in revised form 4 January 2012
Accepted 6 January 2012
5
-hydroxymethylfurfural (HMF) from dehydration of fructose using BmimCl as solvent. Reaction time,
temperature and fructose concentration were investigated during the HMF synthesis procedure. The cat-
alyst SBA-15-SO H exhibits high fructose conversion (near 100%) and HMF selectivity (about 81%) with
Available online 17 January 2012
3
good stability in the HMF synthesis. It was a suitable catalyst to produce HMF from renewable carbohy-
drates in potential industrial process.
Keywords:
5
-Hydroxymethylfurfural (HMF)
Ó 2012 Elsevier Ltd. All rights reserved.
Fructose
Dehydration
Acid catalysts
Ionic liquids
1
. Introduction
mentioned heterogeneous catalysts were not readily regener-
1
6
ated. Thus, more research is being conducted to find more effi-
cient solid catalysts for fructose dehydration. Karam et al.
Biomass is a promising alternative for sustainable supply of
1
7
precious intermediates and platform chemicals to the chemical
industry.
5
3
reported that the mesoporous structure of SBA-SO H was pre-
1
,2
Amongst many possible biomass derived chemicals,
served after five catalytic runs for the reaction of indole with benz-
aldehyde in water. The drop in the yield can be attributed to a
-hydroxymethylfurfural (5-HMF) can be used as valuable inter-
mediate for fine chemicals, pharmaceuticals and furan-based poly-
mers. It is considered to have the potential to be a sustainable
substitute for petroleum-based building blocks.3–5
3
decrease of the acid strength of SBA-SO H caused by a solvation
of the catalytic sites by water. SBA-15 is a promising candidate
for the catalyst supports due to its unique mesoporous structure
and high thermal stability, which can be functionalized with differ-
ent catalytic active groups. It has been reported that the mono-
functionalized organo-sulfonic acid modified ordered mesoporous
silica materials showed relative high performance for many heter-
ogeneous acid-catalyzed reactions such as the dehydration of
Acid catalyzed dehydration of D-fructose is the most convenient
and efficient method for preparing HMF. Due to the increased
interest and demand for industrial application, many efficient cat-
6
alytic systems were recently developed. It is no doubt that devel-
oping a cheap, non-toxic or low-toxic, easily handled catalytic
system is highly desirable but challenging. Many types of acid cat-
1
8
monoaccharides. Crisci synthesized a supported bifunctional acid
catalyst and silica-supported alkylsulfonic acids for the selective
conversion of carbohydrates which are efficient and selective fruc-
tose dehydration catalysts under batch conditions, the co-con-
densed material suffered loss of its mesopore ordering and most
of its functional groups during the secondary derivatization
7
,8
alysts have been used in this process, such as mineral acids,
9–11
12,13
strong acid cation exchange resins,
H-form zeolites
and
supported heteropolyacids.14 Among these acid catalysts, hetero-
geneous acid catalysts offer the advantage of easy separation from
the reaction products and can be recycled, thus appearing as the
most suitable catalysts for a potential industrial process. However,
up to now, the performances of different heterogeneous acid cata-
lysts are still unsatisfactory. A progressive decrease of selectivity to
HMF has been observed with time, due to the formation of formic
and levulinic acids as well as of polymeric by-products, such as
insoluble humins, as shown in Scheme 1.1 Furthermore, the above
1
9,20
step.
Both catalyst and solvent are crucial in the conversion of fruc-
tose into HMF. In an effort to achieve a high HMF yield, a great deal
of work has been reported in the literature, using various media,
2
1,22
23,24
such as water,
uids.
highly polar organic solvents,
and ionic liq-
5
25–29
Environmental concerns favor water as a solvent for the
reaction, but water is not very selective for the production of HMF
and many by-products comprising insoluble polymeric compounds
⇑
Corresponding author. Tel.: +86 532 8066 2723; fax: +86 532 8066 2724.
E-mail address: muxd@qibebt.ac.cn (X. Mu).
(
i.e. humins) and soluble polymers are often formed, leading to a
0
008-6215/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2012.01.003

3
6
X. Guo et al. / Carbohydrate Research 351 (2012) 35–41
2
2
2
2
+
2
2
2
Scheme 1. Acid-catalyzed synthesis of HMF from fructose and possible by-products.
comparably low HMF yield.30 Although high yields of HMF can be
achieved in some high-boiling point organic solvents such as di-
methyl sulfoxide (DMSO) and dimethylacetamide (DMA), the dis-
advantage of using those solvents is the high energy
consumption during separation.
PO70EO20, Aldrich), tetraethoxysilane (TEOS) and (3-mercapto-
propyl) trimethoxysilane (MPTMS) were purchased from Aladdin
Reagent Limited Company (China). Deionized water was used for
the preparation of aqueous solutions. 1-Butyl-3-methylimidazo-
lium chloride (BmimCl) (99%) was purchased from Shanghai Chen-
gjie Chemical Co., Ltd.
Ionic liquids are a group of salts that exist as liquids at low
temperatures (<100 °C). They have many attractive properties,
including chemical and thermal stability, nonflammability, and
immeasurably low vapor pressure, which is favorable for a cata-
2
.2. Catalyst preparation
3
1
lytic reaction. Some authors studied the dehydration of fructose
in ionic liquids. Zhao et al.32 reported that chromium(II) chloride
was found to be uniquely effective, leading to the conversion of
glucose to HMF with a yield near 70%, but the toxicity and recov-
ery of the ionic liquids was not clear. Moreau et al., have demon-
The preparation procedures of ordered mesoporous silica SBA-
1
3
5 functionalized with sulfonic acid groups (SBA-15-SO H) were
3
6
similar to those reported by Zheng et al. Briefly, 4 g of Pluronic
23 (EO20PO70EO20, Mav = 5800) was dissolved in 105.2 g of
1
deionized water at 40 °C by stirring, and then 24.42 g of hydrochlo-
ric acid (37 wt %) was added. After that, tetraethyl orthosilicate
strated that neutral ionic liquids such as [Bmim]PF
Bmim]BF can act as a suitable reaction medium for the dehydra-
tion of fructose to HMF in the presence of the acidic catalyst,
6
and
[
4
(
TEOS) was added for prehydrolysis, and then a certain amount
3
3
of 3-mercaptopropyltrimethoxysilane (MPTMS) was slowly added.
The resulting mixture was stirred for 24 h at 40 °C followed by
aging at 100 °C for another 24 h under static conditions. The molar
composition of the mixture was (1 ꢀ x/100) TEOS:(x/100) MPT-
Amberlyst-15. Recently, metal chlorides in neutral ionic liquid
Emim]Cl have been found to be effective catalysts for converting
[
fructose and glucose to HMF. The water generated from the dehy-
dration of fructose is diluted in the IL phase thus avoiding the
important deactivation of catalytic sites. These results suggest
that ionic liquids as solvents or catalysts can play a positive role
in the development of effective processes for the dehydration of
2
MS:6.1 HCl:0.017 P123:165 H O, where x = (MPTMS/(TEOS + MPT-
MS)) ꢁ 100 varied from 0 to 20. The solid product was then filtered
and subsequently washed with deionized water. The template was
removed from the synthesized material by washing with ethanol
under reflux for 24 h.
Oxidation of thiol to sulfonic acid groups was carried out
according to the following procedures: 0.15 g SBA-15-SH was dis-
3
4,35
hexose to HMF.
In summary, many attempts have been made to develop new
catalytic processes, mainly basing on heterogeneous catalysis, for
the transformation of fructose and fructose-precursors into HMF.
Although multiple solvents have been reported for the production
of HMF, we indicated that HMF can be produced in high yields by
the acid-catalyzed dehydration of fructose in BmimCl.
In this work, functional propyl-sulfonic acid groups were
grafted onto the pore surface of mesoporous SBA-15. The structure
of the materials was investigated with electron microscopic and
2 2
solved in 20 g 2 M HCl aqueous solution, and 0.75 g 30 wt % H O
was then added. After stirring for 5 min at ambient temperature,
the mixture was transferred into an autoclave and then statically
treated for 6 h at 100 °C. Finally, the solid product was filtered,
washed with deionized water and ethanol, and air-dried at 80 °C
overnight to obtain sulfonic acid functionalized SBA-15 (denoted
3
7,38
3
as SBA-15-SO H-x).
Scheme 2.
The whole procedure is illustrated in
3
BET surface area techniques etc. Furthermore, the SBA-15-SO H,
was first used as a heterogeneous solid acid catalyst for the selec-
tive synthesis of 5-hydroxymethylfurfural (HMF) from dehydration
of fructose in ionic liquids.
2
2
. Experimental
3
2
SO3H SO3H
.1. Materials
2
2
SO3H SO3H
1
1
3
3
1
3
Fructose (99%), 5-hydroxymethylfurfural (99%) and HCl
(
37 wt %) were purchased from Sigma–Aldrich and were used
Scheme 2. Formation of mesoporous materials SBA-15-SO
3
H by co-condensation.
without further purification. Triblock copolymer P123 (EO20-
R
1
, R and R represent CH -, SH-CH -CH -CH - and CH -CH -, respectively.
2
3
3
2
2
2
3
2

X. Guo et al. / Carbohydrate Research 351 (2012) 35–41
37
2
.3. Catalyst characterization
The catalyst was characterized by X-ray diffraction (XRD),
transmission electron microscopy (TEM) and BET surface area
techniques. XRD measurements were done on a Bruker D8 Advance
X-ray diffractometer, using Cu Ka radiation (k = 1.5404 Å) at 40 kV
and 20 mA in the 2h range of 0.5° to 5°. TEM measurements were
performed on a Hitachi H-7650 at an accelerating voltage of
a
b
c
d
e
1
20 kV under a low electron dose. The specific surface area was
calculated by the BET method and the pore size distribution was
calculated by the Barrett–Joyner–Halenda (BJH) method with an
ASAP 2000 (Micromeritics) analyzer. The Brönsted acidity on the
samples was determined by the ion-exchange capacity, using
aqueous solutions of sodium chloride as exchange agents. The
method for the Agilent GC/MS system consisted of an Agilent
1
2
3
4
5
o
2
θ ( )
Figure 1. XRD powder patterns of the catalyst samples: (a) SBA-15, (b) SBA-
7
890A GC (Agilent Technologies, Shanghai, China) fitted with a
Polyethylene Glyco capillary column (30 m ꢁ 0.25 mm i.d. and
.25 m film thickness), coupled to an Agilent 5975C mass-selec-
15-SO
3
H-5, (c) SBA-15-SO
3
H-10, (d) SBA-15-SO
3
H-15, (e) SBA-15-SO
3
H-20.
0
l
tive detector (Agilent Technologies, Santa Clara, CA, USA). The
detector was operated in electron impact (EI) ionisation mode
3
2
000
000
a
(
electron energy 70 eV). Helium with a purity of 99.999% from
Qingdao Ruifeng Gas Co., Ltd (Qingdao, China) was used as the car-
rier gas. The oven temperature programme was 313 K (held for
5
min) to 503 K at 10 K/min (held for 2 min).
2
.4. General procedure for the conversion of fructose to 5-HMF
Dehydration of fructose was performed in a sealed pressure-
1000
0
stable glass tube charged with fructose, catalyst, ionic liquids and
a magnetic stirrer. In a typical reaction, a 25 mL reaction tube
was charged with 2 g ionic liquids (such as BmimCl), 0.2 g fructose
and 0.02 g catalyst in a glovebox and then sealed. The tube with
the reaction mixture was placed in a pre-heated oil bath employed
with a temperature controller for a specified time under stirring
0.2
0.4
0.6
0.8
1.0
Relative pressure (P/Po)
12
8
b
(
reaction time were measured after a stable oil bath temperature
had been reached). After the reaction, the tube was removed from
the oil bath and cooled to room temperature before a sample was
taken for analysis.
Sample analyses were performed by HPLC using Waters 2424
and Waters 2489 systems. Fructose conversion was monitored
4
with an NH
using a mobile phase CH
.0 mL/min, with an ELSD 2424 detector of drift tube temperature
at 80 °C and gas pressure at 0.59 MPa. HMF was quantified with a
Zorbax Eclipse XDB-C18 (150 ꢁ 4.6 mm, 5 m) reverse phase col-
umn, using a mobile phase CH OH–H O (1:4) at a flow rate of
.6 mL/min with a UV/vis 2489 Detector (284 nm) and a column
temperature of 35 °C.
2
P-50 4E (250 ꢁ 4.6 mm) column (Shodex Asahipak),
3
CN–H O (78:22) at a flow rate of
2
1
0
4
8
12
16
l
Pore diameter (nm)
3
2
0
Figure 2. Nitrogen adsorption/desorption isotherms (a) and pore size distribution
b) of SBA-15-SO H materials prepared at different n(MPTMS)/n(TEOS + MPTMS)
ratios: (5) SBA-15, (}) SBA-15-SO
s) SBA-15-SO H-20.
(
3
3
H-5, (4) SBA-15-SO
3 3
H-10, (h) SBA-15-SO H-15,
(
3
3
3
. Results and discussion
.1. Characterization of the catalyst
The powder XRD patterns of SBA-15-SO
2
ꢀ1
higher BET surface area (631.9–737.3 m g ), big pore volume
3
ꢀ1
3
H samples are shown
(0.95–1.06 cm g ), as well as large N
2
adsorbed amount. More-
in Figure 1. All samples show one intense peak of (100) and two
weak diffraction peaks of (110) and (200). The XRD patterns of
SBA-15-SO H indicate that the crystallographic order of mesopores
3
is preserved after the incorporation of MPTMS into SBA-15. The
well resolved (110) and (200) reflections for the samples reveal
3
highly ordered mesopores in the SBA-15-SO H materials. However,
when x = 20, the reflections (110) and (200) are less resolved and
less intense. The results show that the mesoporous order decreases
with higher concentrations of MPTMS.
over, the BET surface area and pore volume of the SBA-15-SO H
3
materials gradually decreased with increasing MPTMS content in
the synthesis gel (Table 1). The isotherms are of type IV with a nar-
row hysteresis loop indicating the existence of mesoporous struc-
ture. The position of hysteresis loops shifts slightly to lower
relative pressure and the step becomes less steep with the increase
of MPTMS/(MPTMS + TEOS) ratio. Furthermore, the BJH pore size
distribution broadened. This further suggested that the mesopor-
ous structure order decreased with the increase of x. However,
even at the highest MPTMS content (MPTMS/(MPT-
The nitrogen adsorption–desorption isotherms of SBA-15-SO
3
H
samples are shown in Figure 2a. SBA-15-SO H materials exhibited
3
3
MS + TEOS) = 0.2), the SBA-15-SO H still exhibited considerably

3
8
X. Guo et al. / Carbohydrate Research 351 (2012) 35–41
Table 1
3
Textural parameters of SBA-15-SO H samples
2
3
H+ contenta (mmol/g)
Sample
Sulfur content (wt %)
S
BET (m /g)
d
100 (nm)
V
p
(cm /g)
p
D (nm)
SBA-15
0
806.0
737.3
688.6
690.3
631.9
11.20
10.20
10.00
9.81
1.17
1.09
1.06
0.96
0.95
8.90
7.25
5.92
5.77
5.73
—
SBA-15-SO
SBA-15-SO
SBA-15-SO
SBA-15-SO
3
3
3
3
H-5
2.40
3.84
4.45
5.06
0.47
0.83
0.92
1.16
H-10
H-15
H-20
9.86
a
H+ content determined by titration.
Figure 3. TEM images of SBA-15-SO
3
H with different MPTMS concentrations in the initial mixture: (a) 0%, (b) 10%, (c) 15%, and (d) 20%.
high BET surface area and pore volume,37,38 which satisfies the
requirements for the catalytic reaction.
Nevertheless, the TEM micrographs confirm that the SBA-15-
3
SO H materials contain well-ordered, one-dimensional pore struc-
Table 2
Catalytic activities of various catalysts for dehydration of fructose under BmimCl
Entry
Catalyst
Catalytic performance
Conv. (%) Yield (%)
ture, similar to that of the extracted pure SBA-15 (Fig. 3). The dis-
tance between two consecutive centers of hexagonal pores is
1
2
3
4
5
6
H
2
SO
4
100.0
89.2
98.2
99.2
98.5
97.4
82.3
41.9
74.9
81.0
80.4
79.3
SBA-15
1
1 nm estimated by the TEM images. The average thickness of
the wall is 4–5 nm and the pore diameter is around 6 nm, which
is in agreement with the results measured by N adsorption.
The thiol groups of MPTMS were in situ oxidized to sulfonic acid
groups with H under acidic condition. The accessibility of the
SBA-15-SO
SBA-15-SO
SBA-15-SO
SBA-15-SO
3
3
3
3
H-5
H-10
H-15
H-20
2
Reaction conditions: m(ionic liquids)/m(fructose)/m(catalyst) = 100:10:1, reaction
temperature: 120 °C, reaction time: 1.0 h.
2 2
O
sulfonic acids in the materials was determined by ion-exchange
capacities with aqueous solutions of sodium chloride (NaCl), and
the results are shown in Table 1. The acid capacities of the materi-
+
Pure silica SBA-15 material has no acid sites42 and indicates that
acid is not required as catalyst for the dehydration of fructose in
BmimCl. This has been proven by previous work, which found fruc-
tose can be dehydrated to form HMF in acidic ionic liquids that act
als ranging between 0.48 and 1.16 mmolH /g SiO
the increase in MPTMS contents in the initial mixture.
2
increased with
3
9–41
3
.2. Catalytic activities of various catalysts under BmimCl
2
5,43
as both solvent and catalyst.
However, highest HMF yields of
H materials
The reaction results of fructose dehydration to HMF using
81% can be obtained through catalysis by SBA-15-SO
3
different catalysts are presented in Table 2. The yield of HMF
reached a value as high as 41.9% when SBA-15 is used as a catalyst.
(entry 4 in Table 2) and it is very close to that of sulfuric acid,
82.3% (entry 1 in Table 2). As we have known, sulfuric acid was

X. Guo et al. / Carbohydrate Research 351 (2012) 35–41
39
an efficient homogenous catalyst in this reaction, but with some
serious drawbacks in the process. This result showed that the cat-
alysts of SBA-15-SO H possessed a very high activity and selectiv-
3
3
SO H. At the same time, higher temperatures may bring on serious
side reactions and speed up the loss of active components.
The effect of reaction time on the dehydration of fructose cata-
ity in this catalytic system, indicating that a catalyst with suitable
acid base properties is essential for the formation of HMF under
these conditions. Compared with sulfuric acid, SBA-15-SO H ap-
3
peared more suitable for industry process and is worth researching
further.
3
lyzed by SBA-15-SO H is also shown in Figure 4. It was found that
the yield of HMF increased gradually during the reaction from 0.5
to 1.0 h. When the time was extended to 1.5 h and longer, the yield
of HMF showed almost no increased due to the accompanying de-
crease in HMF selectivity. These results showed that the optimal
reaction time was 1 h in the dehydration of fructose in BmimCl.
SBA-15-SO
has similar activities for the dehydration of fructose to HMF, and
SBA-15-SO H-10 showed the highest selectivity and mass yield
3
H materials with x = 5–20 (entries 3–6 in Table 2)
3
3.4. The effect of the initial fructose concentration
for HMF of 81%. The GC-MS analysis results show it is found that
the HMF is the main product, and neither levulinic acid nor formic
acid is found, indicating that the hydrolysis reaction do not take
place in current catalytic system.
Table 2 shows that the sulfonic acid functionalized materials
are very active and selective in the synthesis of HMF from dehydra-
tion of fructose. The yield of HMF reached 74.9, 81.0, 80.4, and
A high substrate concentration is usually preferred in terms of
process economics. Although a number of HMF production strate-
gies have been available, few of them have satisfactory selectivity
4
5
and/or yield at high fructose concentrations. Qi et al. achieved
54% HMF yield when 20 wt % fructose was treated at 150 °C for
5 min in the presence of an ion-exchange resin in an acetone/water
4
6
7
9.3 mol % over SBA-15-SO
3
H-5, SBA-15-SO
3
H-10, SBA-15-SO
3
H-
2
mixture. Dumesic performed the same reaction in H O–salt–or-
1
5 and SBA-15-SO H-20, respectively. The selectivities for HMF
3
ganic solvent systems with 30 wt % fructose at 180 °C and attained
55–66% HMF yield.
Our experiments with initial fructose concentrations at 10–
60 wt %, according to the results in Figure 5, near 69.5% HMF yield
can be achieved with 50 wt % fructose concentration when SBA-15-
7
was all found more than 74% at 120 °C for 1 h. The observed results
could be rationalized by the fact that the larger surface areas in the
mesoporous catalysts can promote the activity and sufficient acidic
sites easily accessible for the reactants were responsible for the
stabilization of the cationic intermediate formed during the reac-
tion, and also to be more easily accessible for the reactants. How-
ever, the catalytic performance of SBA-15-SO H depended on both
the sulfonic group content and the integrality of mesoporous struc-
ture. The mesopore ordering of SBA-15-SO H decreased with the
3
SO H is added. As fructose concentration reaches 60 wt %, as high
4
4
as z 60.8% HMF yield is obtained. We can always keep higher fruc-
tose conversion and satisfied HMF yield with increasing initial
fructose concentration. The amount of by-products is not increased
even at higher initial fructose concentrations according to HPLC
analysis. Obviously, our strategy offers an opportunity to use a high
fructose concentration under mild conditions without significantly
compromising the HMF yield. Because a higher substrate concen-
tration can greatly reduce solvent use, this method is expected to
have great potential in terms of improved process economics and
environmental friendliness. The reported conditions with short
reaction time at high concentrations may allow for high space-time
yields, which may be of interest for the development of efficient
continuous processes for the conversion of carbohydrates into
HMF.
3
3
increase of propylsulfonic acid amounts in the catalyst. Higher pro-
pylsulfonic acid content does not give better catalytic results.
3
.3. Effect of reaction temperature and time
The effects of reaction temperature and time on dehydration of
3
fructose to HMF were examined with SBA-15-SO H-10 as catalyst
and the results are given in Figure 4. High temperature did favor
for acid-catalyzed dehydration of fructose to HMF. When the dehy-
dration of fructose was performed at a relatively low temperature
of 90–140 °C, by-product formation was negligible. At tempera-
tures lower than 100 °C, no significant effect on HMF yield oc-
curred. HMF yield increased almost linearly with reaction
temperature reaching an optimum of 81%, at 120 °C. However,
with further increasing the reaction temperature up to 140 °C,
the HMF yield was at the same level. Therefore, a temperature of
3
3.5. Stability and recycling of SBA-15-SO H-BmimCl catalytic
system
3
The stability of the SBA-15-SO H-BmimCl catalytic system was
studied. The SBA-15-SO H-BmimCl catalytic system was reused
3
1
20 °C was proper for fructose dehydration to HMF over SBA-15-
successively for three times under the same reaction conditions.
It was found that the whole system could be recycled several times
9
8
7
6
0
0
0
0
100
8
7
6
5
4
0
0
0
0
0
9
0
Fructose conversion
HMF yield
80
70
0
.5
1.0
1.5
2.0
1
0
20
30
40
50
60
Reaction time (h)
Fructose (wt%)
Figure 4. Effect of reaction time and temperature on HMF yield. }, 90 °C; 4, 100 °C;
, 120 °C; s, 140 °C. (Reaction conditions: 2.4 g BmimCl, 0.6 g fructose, 0.03 g
catalyst.)
5
Figure 5. Effect of fructose concentration on HMF yield (4) and conversion of
fructose (h). (Reaction conditions: 2.4 g BmimCl, 0.03 g catalyst, 120 °C, 1.0 h.)

4
0
X. Guo et al. / Carbohydrate Research 351 (2012) 35–41
3
that of sulfuric acid. The activity of SBA-15-SO H may be ascribed
1
9
9
9
9
00
85
80
75
70
65
to the materials with suitable acidic sites as the active centers and
the unique surface textural properties. The separation of HMF was
successfully achieved in a THF/BmimCl biphasic system. These
made this simple SBA-15-SO H-BmimCl system a promising choice
3
for fructose dehydration to HMF.
8
6
Fructose conversion
HMF yield
4
Acknowledgments
2
The authors are grateful for the financial support of the National
High Technology Research and Development Program of China (No.
90
2
009AA05Z410), the National Natural Science Foundation of China
1
2
3
4
(
No. 20803038), the Natural Science Foundation of Shandong Prov-
Cycle
ince, China (No. O92003110C) and the Knowledge Innovation Pro-
gram of the Chinese Academy of Sciences (No. KSCX2-YW-G-075-
1
Figure 6. Stability of SBA-15-SO
2
3
H upon catalyst recycling. (Reaction conditions:
.4 g BmimCl, 0.6 g fructose, 0.03 g catalyst, 120 °C, 1.0 h.)
3).
3
without using any additional SBA-15-SO H catalyst. The HMF
product was extracted after each run, and fructose was added di-
rectly for the next run. The fructose conversion stabilized at 97–
References
1.
Ilgen, F.; Ott, D.; Kralisch, D.; Reil, C.; Palmberger, A.; König, B. Green Chem.
2009, 11, 1948–1954.
1
00% (Fig. 6), a slight decrease in the selectivity of HMF was ob-
2
3
.
.
Tong, X.; Ma, Y.; Li, Y. Appl. Catal. A 2010, 385, 1–13.
Hu, S. Q.; Zhang, Z. F.; Song, J. L.; Zhou, Y. X.; Han, B. X. Green Chem. 2009, 11,
served. These results clearly showed that the heterogeneous cata-
lysts were active in the dehydration of fructose and can be reused
without significant decrease in the catalytic activity and with al-
most similar selectivity after three recycles.
1746–1749.
4. Yong, G.; Zhang, Y. G.; Ying, J. Y. Angew. Chem., Int. Ed. 2008, 47, 9345–9348.
5
.
.
Tong, X.; Li, M.; Yan, N.; Ma, Y. J.; Dysonb, P.; Li, Y. Catal. Today 2011, 175, 524–
27.
Qu, Y.; Huang, C.; Zhang, J.; Chen, B. Bioresour. Technol. 2011. doi:10.1016/
j.biortech.2011.11.069.
5
6
3
.6. Separation of HMF by THF (tetrahydrofuran) extraction
7
8
9
.
.
.
Román-Leshkov, Y.; Chheda, J. N.; Dumesic, J. A. Science 2006, 312, 1933–1937.
Chheda, J. N.; Román-Leshkov, Y.; Dumesic, J. A. Green Chem. 2007, 9, 342–350.
Mercadier, D.; Rigal, L.; Gaset, A. J. Chem. Tech. Biotechnol. 1981, 31, 497–502.
Separation of HMF from the reaction system is another chal-
lenge. Extraction is widely applied in the separation and purifica-
10. Halliday, G. A.; Young, R. J.; Grushin, V. V. Org. Lett. 2003, 5, 2003–2005.
2
5,37,47,48
tion of HMF
as the solubility of HMF in several organic
11. Moreau, C.; Durand, R.; Razigade, S. Appl. Catal. A 1996, 145, 211–224.
12. Rivalier, P.; Duhamet, J.; Moreau, C. Catal. Today 1995, 24, 165–171.
13. Moreau, C.; Durand, R.; Aliès, F. Ind. Crops Prod. 2000, 11, 237–242.
14. Schwegler, M. A.; Vinke, P.; Van der Eijk, M.; Van Bekkum, H. Appl. Catal. A
1992, 80, 41–57.
solvents is high. To be used as an extracting reagent, the organic
solvent must not only be immiscible with the reactive catalytic
system but also possess a low boiling point, which will facilitate
its separation from the extracted HMF via evaporation. THF with
1
1
5. Shimizu, K.; Uozumi, R.; Satsuma, A. Catal. Commun. 2009, 10, 1849–1853.
6. Benvenuti, F.; Carlini, C.; Patrono, P.; Galletti, A. M. R.; Sbrana, G.; Massucci, M.
A.; Galli, P. Appl. Catal. A 2000, 193, 147–153.
3
its boiling point of only 66 °C, the BmimCl/fructose/SBA-15-SO H
system was most reactive at 120 °C, a temperature far above the
boiling point of THF, was reported to be a good choice in the
extraction of HMF. So THF was screened as an HMF extraction sol-
vent in this work.
17. Karam, A.; Alonso, J. C.; Gerganova, T. I.; Ferreira, P.; Bion, N.; Barrault, J.;
Jérôme, F. Chem. Commun. 2009, 45, 7000–7002.
18. Dias, A. S.; Pilinger, M.; Valente, A. A. J. Catal. 2005, 229, 414–423.
19. Crisci, A. J.; Tucker, M. H.; Lee, M. Y.; Jang, S. G.; Dumesic, J. A.; Scott, S. L. ACS
Catal. 2011, 1, 719–728.
20. Crisci, A. J.; Tucker, M. H.; Dumesic, J. A.; Scott, S. L. Top. Catal. 2010, 53, 1185–
The extraction method was operated with the similar procedure
4
9
1192.
as described previously. After the reaction, some THF was added
into the reaction systems, the semi continuous process for the con-
21. Watanabe, M.; Aizawa, Y.; Iida, T.; Nishimura, R. Appl. Catal. A 2005, 295, 150–
156.
version of fructose to HMF in a THF-BmimCl/SBA-15-SO
biphasic system. The lower phase contains BmimCl, fructose and
SBA-15-SO H, whereas the upper phase contains THF. HMF is ex-
3
H/fructose
22. Asghari, F. S.; Yoshida, H. Ind. Eng. Chem. Res. 2006, 45, 2163–2173.
2
3. Qi, X.; Watanabe, M.; Aida, T. M.; Smith, R. L. Ind. Eng. Chem. Res. 2008, 47,
234–9239.
4. Binder, J. B.; Raines, R. T. J. Am. Chem. Soc. 2009, 131, 1979–1985.
9
3
2
tracted into the THF phase and separated through an evaporation
step. Fructose and THF were added to the system at the beginning
of each consecutive bath of the operation.
25. Moreau, C.; Finiels, A.; Vanoye, L. J. Mol. Catal. A Chem. 2006, 253, 165–169.
2
2
2
6. Qi, X.; Watanabe, M.; Aida, T. M. ChemSusChem 2009, 2, 944–946.
7. Tong, X.; Li, Y. ChemSusChem 2010, 3, 350–355.
8. Zhang, Z.; Wang, Q.; Xie, H.; Liu, W.; Zhao, Z. ChemSusChem 2011, 4, 131–138.
The amounts of the residual HMF and fructose in the reaction
phase were analysed using HPLC. In the whole process operation,
a total of 99.4% of the fructose was reacted and the selectivity to-
wards HMF was 81.1% and corresponding to 93% of the HMF pro-
duced during the whole process was isolated by the THF
extraction.
29. Tong, X.; Ma, Y.; Li, Y. Carbohydr. Res. 2010, 345, 1698–1701.
30. Hu, S.; Zhang, Z.; Zhou, Y.; Han, B. Green Chem. 2008, 10, 1280–1283.
31. Zhu, S.; Wu, Y.; Chen, Q.; Yu, Z.; Wang, C.; Jin, S.; Ding, Y.; Wu, G. Green Chem.
2006, 8, 325–327.
32. Zhao, H.; Holladay, J. E.; Brown, H.; Zhang, Z. C. Science 2007, 316, 1597–1600.
3
3
3. Lansalot-Matras, C.; Moreau, C. Catal. Commun. 2003, 4, 517–520.
4. Cao, Q.; Guo, X. C.; Yao, S. X.; Guan, J.; Wang, X. Y.; Mu, X. D.; Zhang, D. K.
Carbohydr. Res. 2011, 346, 956–959.
At suitable temperatures, the high HMF yield, low catalyst cost
35. Ray, D.; Mittal, N.; Chung, W. J. Carbohydr. Res. 2011, 346, 2145–2148.
3
3
3
3
6. Zheng, Y.; Li, J. P.; Zhao, N.; Wei, W.; Sun, Y. H. Micropor. Mesopor. Mater. 2006,
3
and toxicity make this simple SBA-15-SO H-BmimCl system a
9
2, 195–200.
promising choice for fructose dehydration.
7. Margolese, D.; Melero, J. A.; Christiansen, S. C.; Chmelka, B. F.; Stucky, G. D.
Chem. Mater. 2000, 12, 2448–2459.
8. Yang, L. M.; Wang, Y. J.; Luo, G. S.; Dai, Y. Y. Micropor. Mesopor. Mater. 2005, 84,
4
. Conclusions
SBA-15-SO H as a heterogeneous catalyst exhibits excellent
275–282.
9. Wang, X. G.; Cheng, S.; Chan, J. C. C. J. Phys. Chem. C 2007, 111, 2156–2164.
3
40. Mbaraka, I. K.; Radu, D. R.; Lin, V. S. Y.; Shanks, B. H. J. Catal. 2003, 219, 329–
36.
1. Yang, Q. H.; Liu, J.; Yang, J.; Kapoor, M. P.; Inagaki, S.; Li, C. J. Catal. 2004, 228,
65–272.
3
performance in the selective synthesis of HMF from dehydration
of fructose. It is tolerant to high concentration fructose and can
be reused. High fructose conversion (near 100%) and HMF selectiv-
ity (about 81%) were obtained, which almost was the same with
4
2
42. Li, Y.; Zhang, W. H.; Zhang, L.; Yang, Q. H.; Wei, Z. B.; Feng, Z. C.; Li, C. J. Phys.
Chem. B 2004, 108, 9739–9744.

X. Guo et al. / Carbohydrate Research 351 (2012) 35–41
46. Qi, X.; Watanabe, M.; Aida, T. M. Green Chem. 2008, 10, 799–805.
41
4
4
4
3. Bao, Q. X.; Qiao, K.; Tomida, D.; Yokoyama, C. Catal. Commun. 2008, 9, 1383–
388.
4. Amarasekara, A. S.; Williams, L. D.; Ebede, C. C. Carbohydr. Res. 2008, 343,
021–3024.
5. Chheda, J. N.; Huber, G. W.; Dumesic, J. A. Angew. Chem., Int. Ed. 2007, 46, 7164–
183.
1
47. Román-Leshkov, Y.; Barrett, C. J.; Liu, Z. Y.; Dumesic, J. A. Nature 2007, 447,
982–985.
48. Chan, J. Y. G.; Zhang, Y. ChemSusChem 2009, 2, 731–734.
49. Cao, Q.; Guo, X. C.; Mu, X. D.; Zhang, D. K. Appl. Catal. A 2011, 403, 98–103.
3
7