Conversion of concentrated sugar solutions into 5-hydroxymethyl furfural and furfural using Br?nsted acidic ionic liquids

Article abstract of DOI:10.1039/c5cy00858a

Catalytic amounts of recyclable Br?nsted acidic ionic liquids (BAILs) yielded HMF (73%) and furfural (81%) with high selectivity from highly concentrated solutions of d-fructose (40 wt%) and d-xylose (3 wt%), respectively. With a 6 wt% d-xylose solution, 73% yield was observed. An activity-property correlation of BAIL is established.

Full text of DOI:10.1039/c5cy00858a

View Article Online
View Journal
Catalysis
Science &
Technology
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: B. M. Matsagar, M.
M. Munshi, A. A. Kelkar and P. L. Dhepe, Catal. Sci. Technol., 2015, DOI: 10.1039/C5CY00858A.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/catalysis

Please do not adjust margins
Catalysis Science & Technology
Page 1 of 5
View Article Online
DOI: 10.1039/C5CY00858A
Journal Name
COMMUNICATION
Conversion of concentrated sugar solutions in to 5‐hydroxymethyl
furfural and furfural using Brönsted acidic ionic liquids
B. M. Matsagar,a M. K. Munshi,b A. A. Kelkar,*,b and P. L. Dhepe*,a
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
Catalytic amount of recylable Brönsted acidic ionic liquids (BAILs) [EMIM][Cl] and [EMIM][HSO4].24‐29 In the synthesis of HMF from
24,
yielded HMF (73%) and furfural (81%) with high selectivity from either fructose or glucose, use of several catalysts such as, CrCl3,
highly concentrated solutions of D‐fructose (40 wt%) and D‐xylose
SnCl4,26 HCl,34 PTSA,35 Amberlyst‐15,35 WCl6, lanthanide
30‐33
36
(3 wt%), respectively. With 6 wt% D‐xylose solution, 73% yield was chlorides,37 boric acid38 and along with ILs as solvent are reported.
observed. Activity‐property correlation of BAIL is established.
Since the main purpose of using ILs in these reactions is to dissolve
the substrate it has been used in very high quantities (1‐5 times to
that of substrate). Use of ILs along with mineral acid (HCl) to yield
dehydration products is also known.39 Additionally, use of
homogeneous organic acids (citric, malonic and oxalic) or insoluble
organic acid resins (Amberlyst‐15) together with ILs [EMIM][HSO4]
as solvent in fructose dehydration reaction into HMF is also
reported.40 In yet another report, use of [BMIM][HSO4] for fructose
conversion into HMF in the presence of metal chloride as a catalyst
is shown.41 Few more reports also show possibility of use of
imidazolium based ionic liquids for the synthesis of HMF from
fructose or glucose under varying reaction conditions.42, 43
The furan derivatives, 5‐hydroxymethyl furfural (HMF) and furfural
are of great importance since those have many industrial
applications and their further conversion can yield range of
industrially important chemicals.1‐7 In view of the importance of
furans, acid catalyzed methods are being developed for their
synthesis from C5 and C6 sugars.8‐12 The use of several solid acid
catalysts such as, acidic resins (Dowex 50wx8‐100, acetone/DMSO;
14
Amberlyst‐15,
DMF),13,
heteropolyacids
(Keggin‐type
heteropolyacids (H3PW12O40, H4SiW12O40 and H3PMo12O40),
16
DMSO),15,
zeolites (del‐Nu‐6(1), water/toluene),17 sulfated
zirconia (SO42‐/ZrO2, acetone/water),18 etc. are investigated for the
Though, use of ILs in these reactions (primarily as solvent) is shown
to be beneficial, but due to their high cost and high viscosity
(limited interaction between catalyst and substrate) those cannot
be used on higher scales. To overcome these disadvantages, it
would be desirable to use ILs in small quantities dissolved in water
or water‐organic solvent systems. Moreover, it is advantageous if
use of metal salts is avoided. Considering these points, it was
anticipated that ILs with acidic characteristics might prove to be
standalone catalysts (without an addition of extra catalyst) to
catalyze dehydration reactions in the biphasic solvent system.
Further, most of the earlier studies have been carried out using low
substrate concentrations (2‐3.5 wt%) since at higher
concentrations, the formation of undesired products is seen.44
However, industry demands use of concentrated systems to make
the overall process economical and hence efforts should be taken
to develop methods with high substrate concentrations.
synthesis of HMF. Synthesis of furfural from xylose using few of the
19, 20
above mentioned catalysts is also known.17,
However, it is
difficult to achieve higher furan yields since furans are prone to
undergo polymerization and degradation reactions to yield humins,
levulinic and formic acid etc.9 Few of the studies use aprotic high
boiling solvents such as DMSO and DMF to achieve higher yields of
furans but separation of products from these high boiling solvents is
very difficult.14 To overcome the problem associated with high
boiling solvents and to improve the yields of furans, use of bi‐phasic
solvent systems is reported in the literature.21‐23
Recently, use of ionic liquids (ILs) as a solvent and/or catalyst is
increasing due to their unique tunable properties such as low vapor
pressure, stability, polarity, recyclability etc. The conversion of
cellulose, starch and inulin to yield glucose, HMF and furfural is
reported using ILs (as solvents) such as, [EMIM][BF4], [BMIM][Cl],
After understanding the various aspects mentioned above, in this
report, we describe the method for the dehydration of fructose and
xylose into HMF and furfural (ESI†, Scheme S1), respectively using
standalone (without using any additional catalysts) Brönsted acidic
ionic liquids (BAILs) such as, 1‐methyl‐3‐(3‐sulfopropyl)‐imidazolium
a. Catalysis and Inorganic Chemistry Division CSIR‐National Chemical Laboratory.
Pune 411008, India. E‐mail: pl.dhepe@ncl.res.in; Fax +91‐2025902633; Tel: +91‐
20 25902024
b. Chemical Engineering and Process Development Division CSIR‐National Chemical
Laboratory. Pune 411008, India. E‐mail: aa.kelkar@ncl.res.in; Fax +91‐20‐
25902620; Tel: +91‐20‐25902544
4‐methylbenzenesulfonate
(IL1),
1‐methyl‐3‐(3‐sulfopropyl)‐
† Footnotes relaꢀng to the ꢀtle and/or authors should appear here.
Electronic Supplementary Information (ESI) available. See
DOI: 10.1039/x0xx00000x
imidazolium hydrogensulfate (IL2), and 1‐methyl‐3‐(3‐sulfopropyl)‐
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1‐3 | 1
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 2 of 5
COMMUNICATION
Journal Name
imidazolium chloride (IL3) as catalysts (Fig. S1; ESI†, section 1.). The calculated ratio of presence of HMF in MIBK and water layers was,
View Article Online
activity of BAILs was compared with neutral IL, 1‐butyl‐3‐ 4.21 while it was 0.45 in case of toluene aDnOdI:w1a0t.1e0r3.9T/hCi5sCsYu0g0g8e5s8tAs
methylimidazolium chloride (IL4), solid acid catalysts (HMOR that MIBK is efficient in extracting HMF from water than toluene
(Si/Al=10), HUSY (Si/Al=15), Hβ (Si/Al=19)) and homogeneous and hence higher HMF yields are obtained with the water+MIBK
mineral acid (H2SO4) under similar reaction conditions. As discussed system. Subsequently, effect of water+MIBK solvent ratio was
above, higher substrate concentrations (fructose, 10 wt%; xylose, 6 studied and it was seen that with increase in MIBK solvent in water,
wt%) were used during the evaluation of catalysts.
enhancement in the HMF yields is possible (water+MIBK (v/v) = 1:1,
The NMR (13C, H) and elemental analysis (ESI†, section 1.2 & 1.3 12%; 1:2, 24%; 1:3, 40%; 1:5, 73%). However, further increase in
and Fig. S2‐S4) confirmed the synthesis of ILs in pure form. The ratio 1:7 (v/v) did not show increase in HMF yield.
Hammett acidity function (Ho) was determined by UV‐Vis
spectrophotometry (ESI†, section 1.6 and Table S1) and it is
understood that as the Ho value decreases, acid strength increases
and we observed following order of increase in acid strength for
synthesized ILs, H2SO4 and solid acid catalysts.
1
HUSY (0.97) > Amberlyst‐15 (1.09) > HMOR (1.31) > H2SO4 (1.68) >
IL2 (2.08) > IL1 (2.33) > IL3 (2.47).
Fructose dehydration reactions (10 wt% solutions) were carried out
with different ILs at 150 °C for 30 min using water+MIBK (1:5 v/v)
solvent system (ESI†, section 2) and the catalytic results are
presented in Fig. 1. As seen, with IL2 as a catalyst, maximum HMF
yield of 73% was obtained with 87% selectivity. The other acidic ILs
also showed higher HMF yields (IL1, 55% yield with 65% selectivity;
IL3, 50% yield with 66% selectivity) compared to neutral IL (IL4, 3%
yield with 8% selectivity). Under similar reaction conditions, in the
absence of a catalyst, though 9% conversion was seen, no HMF
formation was observed, which means that fructose is yielding
some side products which were not detected on GC. A careful look
at the data (Fig. 1) suggests that although with all the catalysts,
except with IL4, 80 ± 5% conversion of fructose is observed, the
difference in the HMF yields is notable. This implies that for
achieving higher selectivity for HMF, IL2 is the best catalyst. This
phenomenon can be explained based on the difference in the acid
amount (IL1, 2.65 mmol/g; IL2, 6.61 mmol/g; IL3, 4.15 mmol/g) as
same quantity (0.025 g) of ILs is charged. To substantiate this
possibility, reactions with IL1 and IL3 were carried out using 0.05 g
of catalyst (S/C=10 wt/wt) instead of 0.025 g (S/C=20 wt/wt) at 150
°C for 30 min. The increase in HMF yield of 72% with IL1 (76%
selectivity) and 73% with IL3 (77% selectivity) along with slight
improvement in selectivity was achieved. Since with IL1 and IL3
catalysts we observed an increase in HMF yields after carrying out
reactions with low S/C (10 wt/wt) ratio, the IL2 catalyst was also
evaluated under the same condition. Nevertheless, we observed,
lower HMF yield (61%) after 30 min due to the formation of side
products (dark colour solution with char formation). These results
imply that though yields can be increased by maintaining an almost
same concentration of H+ in all the ILs, but to achieve the highest
selectivity, IL2 is necessary. Also It is observed that IL2 (Ho, 2.08)
has higher acid strength than IL1 (Ho, 2.33) and IL3 (Ho, 2.47) and
this may be helping to achieve higher yield/selectivity.
Fig. 1 Dehydration of fructose to HMF using different ILs. Reaction conditions: Fructose,
0.5 g; Catalyst, 0.025 g; water+MIBK, 30 mL (1:5 v/v); 150 °C; 30 min.
Typically reactions were carried out with S/C ratio of 20 (wt/wt)
(fructose, 0.5 g; IL, 0.025 g). In order to study the effect of catalyst
concentration, reactions were carried out with S/C (wt/wt) = 10, 20
and 40 (ESI†, Fig. S6) after keeping solvent (30 mL) and substrate
(0.5 g) quantity constant in all reactions. When S/C ratio was
maintained at 10 (IL2, 0.05 g), IL2 catalyst gave 61% HMF yield (67%
selectivity) after 30 min. However, when S/C ratio was maintained
at 20 (wt/wt), an increase in yield to 73% (87% selectivity) was seen.
Further increase in S/C ratio to 40 (IL2, 0.0125 g), yielded 50% HMF
(70% selectivity). The decrease in yield at higher S/C ratio of 40
(wt/wt) is due to the insufficient catalyst in the system. Further, by
keeping catalyst (0.025 g) and solvent (water+MIBK=30 mL)
quantity constant, fructose concentration was altered and reactions
were done for 30 min at 150 °C. When the reaction was done using
5 wt% of fructose solution (0.25 g), 53% yield (60% selectivity) for
HMF was observed. On the contrary when 10 wt% fructose solution
(0.5 g) was used, 73% yield was seen. But with the increase in
fructose concentration to 20 wt% (1 g), decrease in HMF yield (53%,
68% selectivity) was observed. Further increase in fructose
concentration to 40 wt% (2 g) showed almost similar HMF yield
(52%, 74% selectivity). When with 40 wt% solution, reaction was
continued to achieve 93% conversion (1 h), almost similar yield
(73%) with 78% selectivity for HMF was seen. Similar to S/C ratio
study, in case of substrate concentration study also optimum
substrate concentration (10 wt%) is required to achieve highest
yields (73%) with high selectivity (87%). With 5 wt% solution, lower
selectivity was seen due to possibility of side reactions catalyzed by
excess catalyst (same catalyst quantity is used (0.025 g) in all runs).
Since water+MIBK solvent system proved to be better in case of
HMF, xylose dehydration reaction was carried out using same
solvent system at 170 °C for 4 h with IL2 catalyst and we observed
55% furfural yield. From our previous experience on the conversion
of hemicellulose into furfural it was learnt that water+toluene is the
Since IL2 catalyst showed best yields (73%) with high selectivity
(87%), influence of solvent system on the HMF synthesis was
studied with water, water+MIBK (1:5 v/v) and water+toluene (1:5
v/v) (ESI†, Fig. S5). The reacꢀons were carried out at 150 °C for 30
min and it was observed that the maximum HMF yield (73%) was
obtained with water+MIBK solvent system. While with the
water+toluene solvent system, 39% HMF yield, and with only water
as a solvent, 17% HMF yield (60% selectivity) were observed. The
2 | J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 5
Catalysis Science & Technology
Please do not adjust margins
Journal Name
COMMUNICATION
best solvent system23 and therefore further reactions were carried be that fructose resembles xylulose and xylose resembles glucose
View Article Online
out using water+toluene solvent system. Under these conditions, as a substrate. In case of glucose, it takesDloOnI:g1e0r.10ti3m9e/Ct5oCYa0c0h8ie58vAe
with IL2 catalyst we obtained 73% yield (selectivity, 76%) (Fig. 2). good yields of HMF compared to fructose since the first step;
While with IL1 (70%; selectivity, 74%) and IL3 (63%; selectivity, 69%) isomerization of glucose to fructose is difficult. Similarly, the first
catalysts slightly lower yields were obtained, the furfural yield for a step of xylose to xylulose might be difficult to proceed over
non‐catalytic reaction was only 36%.
Brönsted acid catalysts. Nevertheless, the apparent activation
energies calculated for mineral acid catalyzed fructose and xylose
dehydration reactions are almost same.46 It is also mentioned that
the apparent activation energy of degradation reactions of xylose is
lower compared to dehydration reaction.47 These factors might be
responsible for deciding the selectivity for furfural and HMF.
Comparative studies on the catalytic activities of BAILs with solid
acid catalysts [Hβ (Si/Al=19), HMOR (Si/Al=10) and HUSY (Si/Al=15)]
in the fructose dehydration reactions were done (ESI†, Table S2),
most of the solid acid catalysts showed lower yields compared with
BAILs. The higher HMF yield (68%) obtained with Amberlyst‐15
catalyst was either due to leaching of –SO3H groups in the solution
during the reaction or due to very high acid amount (4.65 mmol/g)
compared with other catalysts (ESI†, Table S2). However, during
recycling study with Amberlyst‐15, decrease in HMF yield (59%) was
seen, which suggests that during first reaction, ‐SO3H groups were
leached in the solution. The other solid acid catalysts used have
lower acidity (HMOR, 0.06 mmol H+/0.05 g; HUSY, 0.027 mmol
H+/0.05 g) compared to IL2 (0.165 mmol H+/0.025 g) and hence
lower activity was expected. To overcome this, reactions were
carried out with HMOR catalyst by maintaining similar H+
concentration (0.165 mmol H+, 0.14 g) as like IL2 and in this reaction
6% HMF yield with 36% fructose conversion was observed after 30
min reaction. To boost the yield, reaction was carried out at 160 °C
instead of 150 °C and 13% HMF yield with 44% fructose conversion
was achieved (ESI† Table S2). However, the results obtained with
IL2 (73%) are better than HMOR having similar H+ concentration.
The inferior performance of HMOR than IL2 is due to potential
diffusion constraints in the monodimensional pore network of MOR
(6.7 x 7 Å), which may restrict access of substrate to acid sites and
the difference in Ho between HMOR and IL2.
Fig. 2 Dehydration of xylose to furfural using different ILs. Reaction condition: xylose,
0.6 g; catalyst, 0.08 g; water+toluene, 60 mL (1:5 v/v); 170 °C; 4 h.
The difference in yield with water+MIBK and water+toluene solvent
system might be due to following reasons. Since HMF and furfural
are extracted in organic phase and as MIBK has higher miscibility in
water (19.1 g/L at 20‐25 °C) than toluene has in water (0.47 g/L at
20‐25 °C), it is possible for furans to again come in contact with
water and catalyst when MIBK is used. This phenomenon is more
predominant in case of furfural than HMF since, reaction time for
furfural (4 h) is longer than HMF (0.5 h). However, literature
suggests that for furfural synthesis, water+MIBK system is better.45
The reason for a discrepancy in our results and earlier work is that
we have used a batch mode reaction system whereas, in earlier
work, reactions are done in a continuous flow mode. As explaine
above, compared to a batch mode in continuous mode, contact
time is very less so the effect of solvent (miscibility) would be
different. However, it would be really interesting to study the effect
of mode of reaction on the yields and solvent system.
As presented in Table S2 (ESI†), H2SO4 with varying quantities
(varying H+ concentrations) was used to carry out the dehydration
reactions. With 0.05 g of H2SO4 (1.02 mmol H+) very low yield of
HMF (33%) was seen compared with IL2 catalyst (73%, 0.165 mmol
H+). It was thought that due to higher concentration of H+ in H2SO4
reaction, formation of degradation products would be predominant
and thus lower yield was obtained. Hence, reactions were carried
out using 0.510 (59%) and 0.165 (47%) mmol of H+ to improve the
yields of HMF. Still, IL2 (73%) showed better yield of HMF compared
with H2SO4 (47%) when similar H+ concentrations are used.
Since in xylose reactions also IL2 catalyst showed better yields
among all the catalysts, to boost the yields of furfural further,
reaction with IL2 was done for longer time (5 h) at 170 °C. However,
almost similar furfural yield (74%, 76% selectivity) was seen as was
obtained after 4 h reaction. By achieving similar yield and
selectivity, it is also proved that under reaction conditions, furfural
is stable. With the decrease in reaction temperature to 160 °C, it
was expected that yields may improve because of suppression of
the side reactions, but lower yield (66%) was observed.
Subsequently, decrease in yield (59%) was also seen when a higher
concentration of catalyst was used (S/C ratio = 5 (wt/wt)). But, with
3 wt% xylose solution, improvement in the yield (81%) was seen.
As seen from the results, with 40 wt% fructose solution, 73% HMF
yield (78% selectivity) was obtained, which is similar (73%, 87%
selectivity) with 10 wt% fructose solution. However, lower yield of
furfural (73%) with 6 wt% xylose solution was seen compared to
81% obtained with 3wt% solution. It is suggested that difference in
time (30 min and 4 h) and temperature (150 °C and 170 °C) may
play role in deciding the course of reaction and thus selectivity for
furans formation. Another reason behind this phenomenon might
The better yields obtained with BAIL compared to H2SO4 can be
attributed to the possibility of ion‐dipole type interaction between
ions of ionic liquids and hydroxyl groups of substrate (cation of IL
interacting with ‘O’ of –OH group and anion of IL interacting with
‘H’ of –OH group) as is reported earlier in hemicelluloses
49
reactions.48,
The similar type of interaction is not possible
between mineral acid and hydroxyl groups of substrate, which may
decrease the probability of interaction of the substrate and catalyst.
It is suggested that the lower yields observed with solid acid
catalysts compared with BAILs are due to the diffusion limitations
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1‐3 | 3
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 4 of 5
COMMUNICATION
Journal Name
14 G. Sampath and S. Kannan, Catal. Commun., 2013, 37, 41‐44.
(difficulty in accessing all the active sites present on the catalyst for
substrate molecules to interact with) faced with solid acids.
15 C. Fan, H. Guan, H. Zhang, J. Wang, S. Wang andVXie.wWArtaicnlegO, nline
DOI: 10.1039/C5CY00858A
Biomass Bioenergy, 2011, 35, 2659‐2665.
16 A. S. Dias, M. Pillinger and A. A. Valente, Appl. Catal., A,
2005, 285, 126‐131.
The comparative study was also done for xylose dehydration
reaction with solid acid catalysts at 170 °C for 4 h (ESI†, Table S2).
The results showed that with IL2, 73% furfural yield was obtained
whereas with solid acid catalysts like, Amberlyst‐15, HUSY and
HMOR furfural yield obtained were only 64%, 60% and 57%,
respectively. This clearly shows that IL2 is better catalyst.
17 S. Lima, M. Pillinger and A. A. Valente, Catal. Commun., 2008,
9, 2144‐2148.
18 X. Qi, M. Watanabe, T. M. Aida and R. L. Smith, Catal.
Commun., 2009, 10, 1771‐1775.
19 C. Moreau, R. Durand, D. Peyron, J. Duhamet and P. Rivalier,
To confirm the stability and reusability of the BAILs, recycle studies
of the IL2 catalyst in both the reactions were carried out (ESI†,
section 2.3). In fructose dehydration reaction, with IL2 as a catalyst,
HMF yield of 73‐66% [73% (1st run), 73% (2nd run), 70% (3rd run),
68% (4th run), 66 (5th run) and 66 (6th run)] was achieved. Similarly,
IL2 catalyst was also recycled in the xylose dehydration reaction to
yield furfural. In the first reaction, 74% furfural yield was obtained
and in the subsequent runs 73‐64% yields were observed [73% (1st
run), 72% (2nd run), 69% (3rd run) 66% (4th run) 66 (5th run) and 64
(6th run)]. The slight decrease in yields in recycle runs are probably
due to loss of IL during recovery process. The efficiency of BAILs in
recycling experiment and use of concentrated sugar solutions (40
wt% fructose) can make this process economical compared to
known methods, which either do not show reproducible activity or
use lower substrate concentrations.
Ind. Crops Prod., 1998, 7, 95‐99.
20 A. S. Dias, M. Pillinger and A. A. Valente, J. Catal., 2005, 229
,
414‐423.
21 Y. Román‐Leshkov, J. N. Chheda and J. A. Dumesic, Science
(New York, N.Y.), 2006, 312, 1933‐1937.
22 S. Dutta, S. De, B. Saha and M. I. Alam, Catal. Sci. Technol.,
2012, 2, 2025‐2036.
23 P. Bhaumik and P. L. Dhepe, RSC Adv., 2013, 3, 17156.
24 S. Lima, P. Neves, M. M. Antunes, M. Pillinger, N. Ignatyev
and A. A. Valente, Appl. Catal., A, 2009, 363, 93‐99.
25 C. Li, Z. Zhang and Z. K. Zhao, Tetrahedron Lett., 2009, 50
5403‐5405.
,
26 S. Hu, Z. Zhang, J. Song, Y. Zhou and B. Han, Green Chem.,
2009, 11, 1746‐1749.
27 F. Jiang, Q. Zhu, D. Ma, X. Liu and X. Han, J. Mol. Catal. A:
Chem., 2011, 334, 8‐12.
28 F. Tao, H. Song and L. Chou, J. Mol. Catal. A: Chem., 2012,
357, 11‐18.
In summary, this report discusses the possibility of the use of
standalone BAILs in the synthesis of furans from concentrated
fructose and xylose solutions. It is noteworthy that the BAILs are
used in the catalytic amount to achieve high yields (73% HMF, 87%,
selectivity and 73% furfural, 76% selectivity) with IL2 catalyst. Even
with 40 wt% solution of fructose high yield of HMF (73%) was seen.
The detailed studies on S/C ratio, substrate concentration reveal
that both, acid strength and acid amount play an important role.
Moreover, easy recyclability of the catalyst (6 runs) with almost
similar yields for furans suggests good stability of IL2 catalyst.
29 F. Tao, H. Song and L. Chou, Carbohydr. Res., 2011, 346, 58‐
63.
30 H. Zhao, J. E. Holladay, H. Brown and Z. C. Zhang, Science
(Washington, DC, U. S.), 2007, 316, 1597‐1600.
31 B. Kim, J. Jeong, D. Lee, S. Kim, H.‐J. Yoon, Y.‐S. Lee and J. K.
Cho, Green Chem., 2011, 13, 1503‐1506.
32 G. Yong, Y. Zhang and J. Y. Ying, Angew. Chem. Int. Ed., 2008,
47, 9345‐9348.
33 J. B. Binder, J. J. Blank, A. V. Cefali and R. T. Raines,
ChemSusChem, 2010, 3, 1209‐1209.
34 M. Chidambaram and A. T. Bell, Green Chem., 2010, 12
,
1253‐1262.
References
35 C. Lansalot‐Matras and C. Moreau, Catal. Commun., 2003,
517‐520.
4,
1
2
P. Gallezot, Chem. Soc. Rev., 2012, 41, 1538‐1558.
R. Sahu and P. Dhepe, React. Kinet., Mech. Catal., 2014, 112
173‐187.
R.‐J. van Putten, J. C. van der Waal, E. de Jong, C. B.
Rasrendra, H. J. Heeres and J. G. de Vries, Chem. Rev., 2013,
113, 1499‐1597.
36 J. Y. G. Chan and Y. Zhang, ChemSusChem, 2009, 2, 731‐734.
,
37 T. Stahlberg, M. G. Sorensen and A. Riisager, Green Chem.,
2010, 12, 321‐325.
38 T. Stahlberg, S. Rodriguez‐Rodriguez, P. Fristrup and A.
Riisager, Chem.‐Eur. J., 2011, 17, 1456‐1464.
3
39 C. Li, Z. K. Zhao, A. Wang, M. Zheng and T. Zhang, Carbohydr.
Res., 2010, 345, 1846‐1850.
4
5
6
7
M. E. Zakrzewska, E. Bogel‐Łukasik and R. Bogel‐Łukasik,
Chem. Rev., 2010, 111, 397‐417.
40 S. Lima, M. M. Antunes, M. Pillinger and A. A. Valente,
A. Corma, S. Iborra and A. Velty, Chem. Rev., 2007, 107
,
ChemCatChem, 2011, 3, 1686‐1706.
2411‐2502.
41 S. Eminov, J. D. E. T. Wilton‐Ely and J. P. Hallett, ACS
Sustainable Chem. Eng., 2014, , 978‐981.
42 X. Tong and Y. Li, ChemSusChem, 2010, , 350‐355.
43 Q. Bao, K. Qiao, D. Tomida and C. Yokoyama, Catal.
Commun., 2008, , 1383‐1388.
44 V. Choudhary, S. I. Sandler and D. G. Vlachos, ACS Catal.,
2012, , 2022‐2028.
45 C. Aellig, D. Scholz, P. Y. Dapsens, C. Mondelli and J. Perez‐
Ramirez, Catal. Sci. Technol., 2015, , 142‐149.
J. Wu, Y. Shen, C. Liu, H. Wang, C. Geng and Z. Zhang, Catal.
Commun., 2005, , 633‐637.
2
6
3
A. S. Mamman, J.‐M. Lee, Y.‐C. Kim, I. T. Hwang, N.‐J. Park, Y.
K. Hwang, J.‐S. Chang and J.‐S. Hwang, Biofuels Bioprod.
9
Biorefin., 2008, 2, 438‐454.
8
9
A. A. Rosatella, S. P. Simeonov, R. F. M. Frade and C. A. M.
Afonso, Green Chem., 2011, 13, 754‐793.
M. J. Climent, A. Corma and S. Iborra, Green Chem., 2011, 13
520‐540.
2
,
5
46 B. Cinlar, T. Wang and B. H. Shanks, Appl. Catal., A, 2013,
450, 237‐242.
10 J. N. Chheda, Y. Roman‐Leshkov and J. A. Dumesic, Green
Chem., 2007, , 342‐350.
9
47 R. Weingarten, J. Cho, J. W. C. Conner and G. W. Huber,
Green Chem., 2010, 12, 1423‐1429.
11 D. M. Alonso, J. Q. Bond and J. A. Dumesic, Green Chem.,
2010, 12, 1493‐1513.
48 J. Zhang, H. Zhang, J. Wu, J. Zhang, J. He and J. Xiang, Phys.
Chem. Chem. Phys., 2010, 12, 1941‐1947.
49 B. M. Matsagar and P. L. Dhepe, Catal. Sci. Technol., 2015,
531‐539.
12 W. D. Jong and G. Marcotullio, Int. J. Chem. React. Eng.,
2010, 8, 1542‐6580.
5
,
13 X. Qi, M. Watanabe, T. M. Aida and R. L. Smith, Jr., Green
Chem., 2008, 10, 799‐805.
4 | J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 5
Catalysis Science & Technology
View Article Online
DOI: 10.1039/C5CY00858A
Title
Conversion of concentrated sugar solutions in to 5-hydroxymethyl furfural and furfural using Brönsted
acidic ionic liquids
Using recyclable and green ionic liquids in catalytic amount renewable sugars are
dehydrated in to furans with high yields.