Graphene oxide catalyzed dehydration of fructose into 5- hydroxymethylfurfural with isopropanol as cosolvent

Article abstract of DOI:10.1002/cctc.201301067

The design of green heterogeneous catalysts for the efficient conversion of biomass into platform molecules is a key aim of sustainable chemistry. Graphene oxide prepared from Hummers oxidation of graphite was proven to be a green and efficient carbocatalyst for the dehydration of fructose into 5-hydroxymethylfurfural (HMF) in some three-carbon and four-carbon alcohol mediated solvent systems. HMF was obtained in up to 87 % yield in 90vol % isopropanol-mediated DMSO solvent. Some control experiments and analytical data showed that a small number of sulfonic groups and abundance of oxygen-containing groups (alcohols, epoxides, carboxylates) have an important synergic effect in maintaining the high performance of graphene oxide. GO-ing all the way: Graphene oxide is demonstrated to be a green heterogeneous catalyst for the selective dehydration of fructose into 5-hydroxymethylfurfural (HMF) in a cost efficient and environmentally benign isopropanol-mediated solvent system. A small number of sulfonic groups with the synergic effect of oxygen-containing groups (alcohols, epoxides, carboxylates) make graphene oxide an efficient acid catalyst.

Full text of DOI:10.1002/cctc.201301067

CHEMCATCHEM
COMMUNICATIONS
DOI: 10.1002/cctc.201301067
Graphene Oxide Catalyzed Dehydration of Fructose into
5-Hydroxymethylfurfural with Isopropanol as Cosolvent
Hongliang Wang,[a, b] Qingqiang Kong,[a] Yingxiong Wang,[c] Tiansheng Deng,[a]
Chengmeng Chen,[a] Xianglin Hou,*[a] and Yulei Zhu*[a, c]
The design of green heterogeneous catalysts for the efficient
conversion of biomass into platform molecules is a key aim of
sustainable chemistry. Graphene oxide prepared from Humm-
ers oxidation of graphite was proven to be a green and effi-
cient carbocatalyst for the dehydration of fructose into 5-hy-
droxymethylfurfural (HMF) in some three-carbon and four-
carbon alcohol mediated solvent systems. HMF was obtained
in up to 87% yield in 90 vol% isopropanol-mediated DMSO
solvent. Some control experiments and analytical data showed
that a small number of sulfonic groups and abundance of
oxygen-containing groups (alcohols, epoxides, carboxylates)
have an important synergic effect in maintaining the high per-
formance of graphene oxide.
Catalysts with either Brønsted or Lewis acid sites were
proven to be capable of dehydrating fructose into HMF.[4] On
the way to green and sustainable chemistry, it is of critical im-
portance to make continuing efforts in searching for new cata-
lysts that are nontoxic, sustainable, and of high activity for the
conversion of renewable hydrocarbon sources.[1a,2a,5] The devel-
opment of novel solid heterogeneous catalysts for the replace-
ment of environmentally hazardous liquid Brønsted and Lewis
acid catalysts is currently an active area of research.[3,6] In this
respect, catalysts developed from elemental carbon are of spe-
cial interest, as they are not only made from an inexhaustible
resource with environmental acceptability, but they also have
tailorable physical and chemical properties that endow them
with tunable catalytic performance for different reactions.[5a,7]
Graphene has been the focus of attention in carbocatalysis
and nanoscience recently, for it can be used either as a support
to immobilize active species or as a metal-free catalyst owing
to its outstanding electrical, electrochemical, and mechanical
properties.[7,8] Graphene oxide (GO) primarily functions as a pre-
cursor to reduced graphene oxide, and it is rich in a variety of
oxygen-containing functionalities (e.g., alcohols, epoxides, car-
boxylates, sulfate groups), which makes it a green solid acid
catalyst. Dreyer et al. confirmed GO as a convenient carbocata-
lyst for hydration reactions.[9] Dhakshinamoorthy et al. demon-
strated GO to be an efficient acid catalyst for the ring opening
of epoxides and the acetalization of aldehydes.[10] Recently, we
discovered that GO could be used as a facile catalyst for the
etherification of HMF with ethanol to produce 5-ethoxymethyl-
furfural.[11]
There has been strong political and technical focus to obtain
transportation fuels and platform chemicals from biomass re-
sources, because the threats of fossil resource exhaustion and
worldwide environmental problems are becoming more seri-
ous.[1] In this context, the production of furan compounds, es-
pecially 5-hydroxymethylfurfural (HMF), from the dehydration
of carbohydrates is considered to have particularly high poten-
tial, as HMF can be selectively transformed into a variety of
2,5-disubstituted furan derivatives that can serve as promising
alternatives for chemicals derived from petroleum.[2] There are
many factors that have a remarkable influence on the yield of
HMF during the dehydration of carbohydrates. Relative to
other feedstocks, the production of HMF from fructose is
much easier because of the fact that the fructofuranoic struc-
ture is more reactive to dehydration. Therefore, fructose has
always been chosen as an ideal model substrate to evaluate
the performance of catalytic systems for biomass conversion.[3]
Besides the design of novel catalysts, searching for green
and economical solvent systems is another key point in bio-
mass conversion. Various solvents including water,[4b,6b,12] ionic
liquids,[13] and aprotic organic solvents, especially dimethyl sulf-
oxide (DMSO),[14] have been employed as reaction media in the
dehydration of carbohydrates to HMF. However, all of these
solvents suffer from some limitations that prevent practical ap-
plications. Water holds great advantages owing to its ecologi-
cal superiority and technological convenience. Unfortunately, it
is inefficient for HMF production as a result of the formation of
an abundance of byproducts, including levulinic acid, formic
acid, and humins. Ionic liquids are promising solvents with
high selectivity in biomass conversion; however, they are not
desirable for industrial-scale processes, as the cost is presently
too high. DMSO has been discovered to be an effective solvent
for HMF production from sugars. High yields (up to 100%) of
HMF have been obtained in DMSO,[15] but the separation of
the product is quite difficult because the boiling point of
[a] Dr. H. Wang, Q. Kong, Dr. T. Deng, Dr. C. Chen, Prof. X. Hou, Prof. Y. Zhu
Institute of Coal Chemistry, Chinese Academy of Sciences
Taiyuan, 030001 (P.R. China)
Fax: (+86)351-4041153
E-mail: houxl@sxicc.ac.cn
zhuyulei@sxicc.ac.cn
[b] Dr. H. Wang
Graduate University of the Chinese Academy of Sciences
Beijing 100039 (P.R. China)
[c] Dr. Y. Wang, Prof. Y. Zhu
State Key Laboratory of Coal Conversion
Institute of Coal Chemistry
Chinese Academy of Sciences
Taiyuan, 030001 (P.R. China)
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201301067.
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 2014, 6, 728 – 732 728

CHEMCATCHEM
COMMUNICATIONS
www.chemcatchem.org
DMSO is high (1968C), which necessitates energy-intensive iso-
lation procedures that cause serious loss of HMF. One of the
possible solutions for mitigating the undesirable impact of
DMSO processes is the use of green and cost-efficient cosol-
vents to substitute a reasonable amount of DMSO. For exam-
ple, Qi et al. utilized 7:3(w/w) acetone/DMSO solvent mixtures
as a reaction medium for the dehydration of fructose to HMF,
and they found the addition of acetone had little impact on
the results.[14b] However, the capacity of acetone to dissolve
sugars is very low, which limited its further substitution to
DMSO. Recently, alcohol-mediated solvent systems were suc-
cessfully applied in the production of HMF from sugars.[16] Al-
cohols, as easy-to-use solvents, not only have high solubility to
sugars,[16c] but they also have a minimal impact on the
environment.
Table 1. Dehydration of fructose into HMF over GO under different
conditions.[a]
Catalyst Amount of Amount of Fructose
HMF
HMF
loading
[mg]
iPrOH
[vol%]
DMSO
[vol%]
conversion[b] selectivity[b] yield
[%]
[%]
[%]
8
8
8
8
8
8
0
5
10
20
0
20
50
90
95
100
90
90
90
90
100
80
50
10
5
100
100
100
98
97
92
87
97
99
100
93
90
89
89
73
46
54
84
86
78
93
90
89
87
71
42
47
82
85
78
0
10
10
10
10
[a] Reaction conditions: Fructose (0.5 mmol) with a specific amount of GO
mixed in DMSO/isopropanol (2 mL) at 1208C for 6 h. [b] Conversion and
selectivity were determined by using HPLC. The product was confirmed
by using an authentic sample and NMR spectroscopy.
On the basis of previous reports, we report herein that gra-
phene oxide can be used as an efficient carbocatalyst and iso-
propanol can be used as a green cosolvent for the dehydration
of fructose into HMF. GO used in the study was prepared by
Hummers’ method, which was based on the exhaustive oxida-
tion of graphite under strongly acidic conditions followed by
exfoliation of graphite oxide under ultrasonic conditions (a de-
tailed procedure for the preparation of GO is available in the
Supporting Information). The GO sample obtained by the tradi-
tional Hummers method was conveniently prepared and did
not require any additional hazardous treatments.[10b,17] Isopro-
panol was found to be an outstanding cosolvent for the sub-
stitution of DMSO. Up to 90% (volume fraction) of DMSO was
substituted by isopropanol without a significant decrease in
the yield of HMF, which thus minimizes the undesirable impact
of the DMSO process.
tion reaction. To verify this proposal, the reaction was per-
formed in a 9:1 isopropanol/DMSO mixture without GO, and
HMF was obtained in 47% yield. DMSO has an important posi-
tive effect on the reaction mainly because of the following sev-
eral aspects. First, it facilitates the formation of the furanoid
form of fructose, which can be easily dehydrated to HMF.[18]
Second, DMSO can act as both an electron acceptor and an
electron donator to improve the dehydration of the sugars.[3b]
Third, DMSO can prevent the formation of byproducts such as
levulinic acid and humins from HMF.[14a] Moreover, as a versatile
polar aprotic solvent, DMSO can dissolve both polar and non-
polar compounds, which makes it an effective solvent for
sugars and the products.
Initially, the dehydration of fructose was performed in pure
DMSO, which was discovered to be an efficient solvent for the
production of HMF. In a typical procedure, fructose (90 mg,
0.5 mmol) was dissolved in DMSO (2 mL), and the mixture was
heated at 1208C for 6 h in the presence of GO (8 mg). After
the reaction, the yield of HMF was found to be as high as
93%, which was in agreement with the literature.[14a,16b] Subse-
quently, isopropanol was gradually added and used as a partial
substitution for DMSO. As listed in Table 1, the addition of iso-
propanol did not decrease the yield of HMF clearly, even if the
content of isopropanol was increased to as high as 90 vol%.
The HMF yield remained acceptable (71%) up to an isopropa-
nol-for-DMSO substitution level of 95%. The main byproduct
was found to be 5-isopropoxymethylfurfural (PMF), which was
formed from etherification of HMF with isopropanol, and its
yield increased as the ratio of isopropanol was increased. If
100% isopropanol was used as the solvent, the yield of HMF
significantly dropped to approximately 42%. Additionally, PMF
was formed in 9% yield in pure isopropanol, and a small
amount of insoluble product, namely, humins, was also ob-
served. All these results indicate that isopropanol can be used
as an efficient cosolvent with DMSO for the dehydration of
fructose. However, DMSO plays a very important role in the re-
action. Addition of 5% DMSO significantly increased the yield
of HMF from 42 to 71%. This result indicates that DMSO may
act as a cocatalyst and not just as a cosolvent in this dehydra-
The catalytic performance of GO with different loadings was
investigated. As mentioned above, it seems that the conver-
sion of fructose into HMF can proceed with or without catalyst
in isopropanol/DMSO solution, and the addition of an appro-
priate amount of GO can efficiently improve the yield of HMF.
In the presence of GO (5 mg), HMF was obtained in 82% yield,
and after adding more catalyst (i.e., 8 mg), the yield of HMF
further increased to 87%. However, increasing the amount of
GO to 10 mg caused a small decrease in the yield of HMF
(85%), and a further increase in the catalyst loading to 20 mg
resulted in a decrease in the yield of HMF to 78%. This result
may be attributed to the high loadings of GO, which can not
only promote the dehydration of fructose to HMF but also fa-
cilitate the degradation and polymerization of HMF to byprod-
ucts and humins. Notably, the formation of humins that could
be absorbed on the surface of GO may cause serious catalyst
deactivation.
Figure 1 shows the influence of reaction temperature and
time on fructose dehydration to HMF catalyzed by GO. It was
found that the reaction temperature was another important
factor in the dehydration of fructose to HMF. The yield of HMF
increased slowly to 68% at 1008C after a reaction time of 6 h.
Even if the reaction time was prolonged to 16 h, HMF was ob-
tained in only approximately 78% yield. However, if the reac-
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 2014, 6, 728 – 732 729

CHEMCATCHEM
COMMUNICATIONS
www.chemcatchem.org
Figure 1. Effect of reaction temperature and time on the yield of HMF from
the dehydration of fructose catalyzed by GO. Reaction conditions: fructose
(90 mg), GO (8 mg), isopropanol (1.8 mL), DMSO (0.2 mL).
Figure 2. Effect of different solvents mixed with DMSO on the production of
HMF from fructose catalyzed by GO. Reaction conditions: fructose (90 mg),
GO (8 mg), solvent (1.8 mL), DMSO (0.2 mL), T=1208C, t=6 h.
tion temperature was increased to 110 or 1208C, HMF was ob-
tained in 78 or 85% yield, respectively, within a reaction time
of approximately 4 h, and this indicates that raising the reac-
tion temperature efficiently improves the rate of fructose dehy-
dration to HMF. However, higher reaction temperatures were
not favorable for this reaction, as not only did this promote
the dehydration of fructose, but it also accelerated the etherifi-
cation reaction and the formation of humins, which thus de-
creased the yield of HMF. The maximum yield of HMF was
87%, which was achieved at 1208C after a reaction time of 6 h.
Further prolongation of the reaction at 1208C led to a slight
decrease in the yield of HMF. In addition, the stability of HMF
in the solvent system without fructose was examined. In a con-
trol experiment, HMF (0.63 mg) and GO (0.8 mg) were added
to a mixture of isopropanol (1.8 mL) and DMSO (0.2 mL) in the
absence of fructose. After 6 h at 1208C, 94% of HMF was re-
covered, and the main product was found to be PMF (no
humins was found), which indicates that HMF was stable in
the isopropanol/DMSO solvent system in the absence of fruc-
tose. The formation of humins and rehydration products such
as levulinic acid and formic acid could be suppressed
effectively.
much low than that obtained with the use of isopropanol. The
low selectivities towards HMF in methanol and ethanol are at-
tributed to the formation of HMF–alcohol ether products, as
the reaction conditions are also suitable for the etherification
reaction, and these results are in accordance with previous
studies.[11,16c,19] Upon using 1-propanol, isopropanol, 1-butanol,
isobutanol, and tert-butanol as cosolvents, the yield of HMF
was significantly higher than that obtained with the use of
methanol and ethanol. The high selectivities towards HMF in
these alcohols are probably due to their bulkiness and steric
hindrance, which can reduce the activity of the etherification
reaction. The highest yield of HMF was obtained upon using
isopropanol as the cosolvent, and this is likely related to the
higher solubility of fructose in this solvent and its lower etheri-
fication reactivity with HMF.
Subsequently, the active sites present in GO were assessed
by some control experiments. Initially, glacial acetic acid, p-tol-
uenesulfonic acid, concentrated sulfuric acid, and Amberlyst-15
were used as catalysts in their optimum amounts under similar
conditions (see Table S1, Supporting Information). It was found
that all of the acidic catalysts could facilely promote the dehy-
dration reaction except glacial acetic acid, which indicates that
the active sites of GO are probably the sulfonic groups rather
than the carboxylic groups. It was also found that, with their
optimum loadings, the yield of HMF (87%) was clearly higher
if GO was used as the catalyst instead of Amberlyst-15 (HMF
yield of 71%). The difference in the two is that GO contains
a diverse array of oxygen-containing groups, such as hydroxy,
epoxy, and carboxyl groups, as detected by FTIR spectroscopy
(see Figure S1), whereas Amberlyst-15 contains sulfonic groups
only. Thus, it can be deduced that other oxygen-containing
functionalities on the surface of GO play an important role in
the dehydration of fructose into HMF. To obtain an explanation
for this phenomenon, affinities of different catalysts to fructose
and HMF were evaluated by adsorption experiments. It was
Afterwards, several different solvents were tested as the co-
solvent with DMSO for the production of HMF under the opti-
mized reaction conditions. As it can be seen in Figure 2, water
was not an effective cosolvent, as it gave HMF in a low 8%
yield, and this is probably because water can induce serious
side reactions such as the rehydration and polymerization of
HMF. In addition, water is another main product in the dehy-
dration reaction; thus, it is not favorable to shift the equilibri-
um towards the production of HMF. Acetone, an environmen-
tally friendly solvent with a molecular structure similar to that
of DMSO, was also tested as the cosolvent in the reaction, and
a moderate yield of HMF (54%) was obtained. Nearly complete
conversion of fructose was found upon using methanol and
ethanol as the cosolvents; however, the yield of HMF was
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 2014, 6, 728 – 732 730

CHEMCATCHEM
COMMUNICATIONS
www.chemcatchem.org
discovered that the adsorption of fructose on GO was much
higher than that on Amberlyst-15 (see Table S2). The higher af-
finity of GO to fructose should be due to the presence of the
surface oxygen-containing groups, which can form strong hy-
drogen-bonding interactions with the hydroxy groups existing
in fructose. Moreover, a larger amount of ether product was
formed if Amberlyst-15 was used as the catalyst, and this is
probably due to its stronger acidity. Therefore, it could be con-
cluded that GO has appropriate acidity and strong adsorption
towards fructose, and these factors may account for its higher
catalytic performance.
disappeared rapidly. At a temperature of 2158C, almost all of
the signals between 2500 and 3600 cmÀ1 disappeared. These
results are consistent with the results of TG–MS, as GO is un-
stable above 2008C; most of the oxygen-containing groups
that account for the majority of the acid sites are removed.
However, the sulfate groups on GO are still stable even after
heat treatment at 2158C, as indicated in Figure 3 (1050 to
1150 cmÀ1). Moreover, after heat treatment at different temper-
atures GO was used as a catalyst for the reaction (see
Table S3). It was found that the catalytic activity declined rapid-
ly after GO was treated above 2008C, and it remained almost
unchanged if GO was treated below 1508C. Thus, this once
again suggests that the oxygen-containing groups on GO play
a very important role in maintaining the high catalytic activity
of GO for the fructose dehydration reaction.
To further detect the acid sites on GO and assess the ther-
mal stability of these active sites, GO was thermally treated at
different temperatures and was characterized by diffuse reflec-
tance Fourier transform infrared spectroscopy (DRIFT) and ther-
mogravimetry/mass spectrometry (TG–MS). It is known that
heat treatment of GO can result in the removal of some
oxygen-containing groups to reconstitute graphene.[20] TG
analysis of GO showed that there were two main stages of
mass loss (see Figure S2). The mass loss at approximately
1008C corresponds to partial interlayer water and surface-ad-
sorbed water of GO. The large mass loss at approximately
2108C is attributed to the loss of the abundant oxygen-con-
taining groups. Notably, the loss of sulfur content was not
clear, even at a temperature of 2208C, as indicated by MS.
On the basis of the results of TG–MS analysis, DRIFT was ap-
plied to monitor the changes in the acid sites of GO after treat-
ment at different temperatures. The bands at approximately
3600 cmÀ1 are attributed to OÀH stretching.[21] The bands at
3280, 3010, and 2860 cmÀ1 can be assigned to NH4+, which is
formed by the reaction of NH3 with some Brønsted acid sites
on GO. The band at 1780 cmÀ1 is attributed to NH3 coordinat-
ed to the Lewis acid sites on GO. The three bands in the range
from 1480 to 1660 cmÀ1 are ascribed to some synthetic factors,
including amide stretching and ammonium bending.[22] As de-
picted in Figure 3, at relatively low temperature treatments
(below 1508C), the main acid sites of GO remain stable. How-
ever, if GO was treated above 2008C, some Brønsted acid sites
Finally, the reusability of GO was investigated (see Figure S4).
It was observed that the catalytic activity of GO dropped
slightly after four runs, which is similar to a previous report.[11]
This result was mainly due to the loss of some oxygen-contain-
ing groups during the long thermal treatment. However, it is
easy to recover the full catalytic activity of GO by handling the
reused GO under the conditions of Hummers’ method (see
Figure S4).
In conclusion, graphene oxide prepared by Hummers’
method was used as an efficient carbocatalyst for the dehydra-
tion of fructose into HMF in some three-carbon and four-
carbon alcohol mediated solvent systems. These alcohols can
be used as green cosolvents for the partial substitution of
DMSO to minimize its negative effects. The highest yield of
HMF (87%) was obtained with the use of 90 vol% isopropanol
as the cosolvent. Both the reaction temperature and the load-
ing of GO had a remarkable influence on the yield of HMF. In
addition, some control experiments and analytical data
showed that a small number of sulfonic groups should account
for the active sites, whereas an abundance of oxygen-contain-
ing groups (alcohols, epoxides, carboxylates), which can form
strong hydrogen-bonding interactions with fructose, have an
important synergic effect in maintaining the high performance
of GO. Moreover, GO was found to be stable after heat treat-
ment below 1508C, whereas most of the oxygen-containing
groups were removed upon treatment above 2108C. Given
that GO can be readily functionalized, it is envisaged that
many more new carbocatalysts with engineered morphology
or functionality will emerge and play an important role in
green and sustainable chemistry in the near future.
Experimental Section
Materials
Fructose (99%) and HMF (99%) were purchased from Amresco and
J&K Scientific Company, respectively. Graphite powder was pur-
chased from Aladdin Chemistry Co., Ltd. (Shanghai, China). DMSO,
1-propanol, isopropanol, 1-butanol, and all other chemicals (analyt-
ical grade) were purchased from Sinopharm Chemical Reagent Co.,
Ltd., China. All reagents were used as received without further
purification.
Figure 3. DRIFT spectra of NH3-adsorbed GO after thermal treatment at
different temperatures.
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 2014, 6, 728 – 732 731

CHEMCATCHEM
COMMUNICATIONS
www.chemcatchem.org
sky, J. van der Schaaf, J. C. Schouten, T. A. Nijhuis, ChemSusChem 2012,
5, 1812–1819; c) J. P. Lange, E. van der Heide, J. van Buijtenen, R. Price,
ChemSusChem 2012, 5, 150–166.
Preparation of GO
Typically, graphite powder (8000 mesh, 5 g) suspended in sulfuric
acid (115 mL, 98 wt%) was oxidized by the addition of NaNO3
(2.5 g), KMnO4 (15 g), and H2O2 (30 wt%, 50 mL) in sequence. After
that, the mixture was washed by HCl (1m, 1 L) and a large amount
of distilled water. Then, the graphite oxide suspension was ultraso-
nicated to form graphene oxide. Finally, the GO suspension was
dried to obtain the GO powder. More detailed procedures and the
characterization data are available in the Supporting Information.
[3] a) Z. Huang, W. Pan, H. Zhou, F. Qin, H. Xu, W. Shen, ChemSusChem
2013, 6, 1063–1069; b) R. Liu, J. Chen, X. Huang, L. Chen, L. Ma, X.-J. Li,
Green Chem. 2013, 15, 2895–2903.
[4] a) T. S. Hansen, J. Mielby, A. Riisager, Green Chem. 2011, 13, 109–114;
b) J. N. Chheda, Y. Roman-Leshkov, J. A. Dumesic, Green Chem. 2007, 9,
342–350; c) T. Wang, Y. J. Pagan-Torres, E. J. Combs, J. A. Dumesic, B. H.
Shanks, Top. Catal. 2012, 55, 657–662.
[5] a) D. S. Su, S. Perathoner, G. Centi, Chem. Rev. 2013, 113, 5782–5816;
b) Y. C. Lee, C. T. Chen, Y. T. Chiu, K. C. W. Wu, ChemCatChem 2013, 5,
2153–2157; c) D. R. Dreyer, C. W. Bielawski, Chem. Sci. 2011, 2, 1233–
1240; d) D. W. Boukhvalov, D. R. Dreyer, C. W. Bielawski, Y. W. Son, Chem-
CatChem 2012, 4, 1844–1849.
Experimental procedure for reactions
In a typical experiment, fructose (90 mg), GO (8 mg), isopropanol
(1.8 mL), and DMSO (0.2 mL) were charged in a 10 mL stainless
app:ds:steel microautoclave with a Teflon lining and sealed by
a screw cap. The autoclave was then heated to 1208C and main-
tained at 1208C for 6 h. The autoclave was fitted with a magnet
stir bar and filled with air under ambient pressure. After the reac-
tion, the autoclave was cooled to room temperature and GO was
separated by filtration. The reaction mixture was diluted with 95%
ethanol and filtered with a 0.45 mm syringe filter prior to analysis.
The yield of HMF was determined by using a Shimadzu high-pres-
sure liquid chromatograph (LC-10AT) equipped with a UV detector
[6] a) A. H. Jadhav, H. Kim, I. T. H. Wang, Bioresour. Technol. 2013, 132, 342–
350; b) C. Tian, C. Bao, A. Binder, Z. Zhu, B. Hu, Y. Guo, B. Zhao, A. S. Dai,
Chem. Commun. 2013, 49, 8668–8670.
[7] a) C. Su, K. P. Loh, Acc. Chem. Res. 2013, 46, 2275–2285; b) H. P. Jia, D. R.
Dreyer, C. W. Bielawski, Adv. Synth. Catal. 2011, 353, 528–532; c) D. R.
Dreyer, K. A. Jarvis, P. J. Ferreira, C. W. Bielawski, Macromolecules 2011,
44, 7659–7667.
[8] a) C. Huang, C. Li, G. Shi, Energy Environ. Sci. 2012, 5, 8848–8868;
b) B. F. Machado, P. Serp, Catal. Sci. Technol. 2012, 2, 54–75; c) J. H. Yun,
Y. H. Ng, R. J. Wong, R. Amal, ChemCatChem 2013, 5, 3060–3067.
[9] D. R. Dreyer, H. P. Jia, C. W. Bielawski, Angew. Chem. Int. Ed. 2010, 49,
6813–6816; Angew. Chem. 2010, 122, 6965–6968.
[10] a) A. Dhakshinamoorthy, M. Alvaro, M. Puche, V. Fornes, H. Garcia,
ChemCatChem 2012, 4, 2026–2030; b) A. Dhakshinamoorthy, M. Alvaro,
P. Concepcion, V. Fornes, H. Garcia, Chem. Commun. 2012, 48, 5443–
5445.
[11] H. Wang, X. Hou, T. Deng, Y. Wang, X. Mu, Y.-l. Zhu, Green Chem. 2013,
15, 2379–2383.
[12] T. Deng, X. Cui, Y. Qi, Y. Wang, X. Hou, Y. Zhu, Chem. Commun. 2012, 48,
5494–5496.
[13] a) Y. Li, H. Liu, C. Song, X. Gu, H. Li, W. Zhu, S. Yin, C. Han, Bioresour.
Technol. 2013, 133, 347–353; b) C. Lansalot-Matras, C. Moreau, Catal.
Commun. 2003, 4, 517–520; c) H. B. Xie, Z. K. Zhao, Q. Wang, ChemSu-
sChem 2012, 5, 901–905.
and an evaporative light-scattering detector.
A 4.6 mm idꢁ
250 mm Kromstar C18 reverse-phase column was used. The mobile
phase consisted of deionized water and acetonitrile with a volume
ratio of 7:3 at a flow rate of 0.6 mLminÀ1. For the analysis of fruc-
tose, a 4.6 mmꢁ250 mm Shodex sugar column (SC1011) was used,
and distilled water was used as the mobile phase at a flow rate of
1.0 mLminÀ1. The column temperature was maintained at 358C.
The yield of HMF and the conversion of fructose were calculated
on the basis of external standard curves constructed with authen-
tic standards.
[14] a) R. M. Musau, R. M. Munavu, Biomass 1987, 13, 67–74; b) X. Qi, M. Wa-
tanabe, T. M. Aida, R. L. Smith, Jr., Ind. Eng. Chem. Res. 2008, 47, 9234–
9239; c) Y.-Y. Lee, K. C. W. Wu, Phys. Chem. Chem. Phys. 2012, 14, 13914–
13917.
[15] K.-i. Shimizu, R. Uozumi, A. Satsuma, Catal. Commun. 2009, 10, 1849–
1853.
[16] a) J. Liu, Y. Tang, K. Wu, C. Bi, Q. Cui, Carbohydr. Res. 2012, 350, 20–24;
b) M. Benoit, Y. Brissonnet, E. Guelou, K. D. O. Vigier, J. Barrault, F.
Jerome, ChemSusChem 2010, 3, 1304–1309; c) L. Lai, Y. Zhang, ChemSu-
sChem 2011, 4, 1745–1748.
Acknowledgements
This work was financially supported by the National Key Basic
Research Program of China (973 Program) (no.2012CB215305)
and the Science Foundation of Shanxi (2013011010-6). The au-
thors would also like to acknowledge financial support from the
Natural Science Foundation of China (No. 21106172)
[17] W. S. Hummers, R. E. Offeman, J. Am. Chem. Soc. 1958, 80, 1339–1339.
[18] F. W. Lichtenthaler, S. Rçnninger, J. Chem. Soc. Perkin Trans. 2 1990,
1489–1497.
[19] H. L. Wang, T. S. Deng, Y. X. Wang, Y. Q. Qi, X. L. Hou, Y. L. Zhu, Bioresour.
Technol. 2013, 136, 394–400.
Keywords: biomass
heterogeneous catalysis · sustainable chemistry
· carbocatalysis · graphene oxide ·
[1] a) E. L. Kunkes, D. A. Simonetti, R. M. West, J. C. Serrano-Ruiz, C. A. Gart-
ner, J. A. Dumesic, Science 2008, 322, 417–421; b) J. Q. Bond, D. M.
Alonso, D. Wang, R. M. West, J. A. Dumesic, Science 2010, 327, 1110 –
1114; c) J. N. Chheda, G. W. Huber, J. A. Dumesic, Angew. Chem. Int. Ed.
2007, 46, 7164–7183; Angew. Chem. 2007, 119, 7298–7318; d) J. C. Ser-
rano-Ruiz, R. Luque, A. Sepulveda-Escribano, Chem. Soc. Rev. 2011, 40,
5266–5281.
[20] D. Chen, H. Feng, J. Li, Chem. Rev. 2012, 112, 6027–6053.
[21] X. Yang, B. Zhao, Y. Zhuo, Y. Gao, C. Chen, X. Xu, Environ. Sci. Technol.
2011, 45, 1147–1151.
[22] D. Liu, P. Yuan, H. M. Liu, J. G. Cai, Z. H. Qin, D. Y. Tan, Q. Zhou, H. P. He,
J. X. Zhu, Appl. Clay Sci. 2011, 52, 358–363.
[2] a) R. J. van Putten, J. C. van der Waal, E. de Jong, C. B. Rasrendra, H. J.
Heeres, J. G. de Vries, Chem. Rev. 2013, 113, 1499–1597; b) V. V. Ordom-
Received: December 13, 2013
Published online on February 12, 2014
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 2014, 6, 728 – 732 732