Conversion of fructose, glucose and sucrose to 5-hydroxymethyl-2-furfural over mesoporous zirconium phosphate catalyst

Article abstract of DOI:10.1016/j.apcata.2014.10.020

5-Hydroxymethyl-2-furfural (HMF) is considered an important platform chemical among other intermediates derived from biomass. In this study, we have used mesoporous zirconium phosphate as a catalyst for the conversion of sugars into HMF. The catalyst was synthesized using a hydrothermal method and was characterized using powder XRD, FT-IR spectroscopy and FESEM. The as-prepared catalyst showed porous structure and a very high surface area. Mesoporous zirconium phosphate exhibited excellent catalytic activity for the formation of HMF, from fructose, glucose and sucrose. The effect of various factors such as reaction time, temperature and reaction systems on formation of HMF has been investigated.

Full text of DOI:10.1016/j.apcata.2014.10.020

Accepted Manuscript
Title: Conversion of fructose, glucose and sucrose to
5-hydroxymethyl-2-furfural over meso-porous zirconium
phosphate catalyst
Author: Archana Jain Andrew M. Shore Subash C.
Jonnalagadda Kandalam V. Ramanujachary Amos Mugweru
PII:
S0926-860X(14)00633-4
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.apcata.2014.10.020
APCATA 15052
To appear in:
Applied Catalysis A: General
Received date:
Revised date:
Accepted date:
11-8-2014
3-10-2014
10-10-2014
Please cite this article as: A. Jain, A.M. Shore, S.C. Jonnalagadda, K.V. Ramanujachary,
A. Mugweru, Conversion of fructose, glucose and sucrose to 5-hydroxymethyl-2-
furfural over meso-porous zirconium phosphate catalyst, Applied Catalysis A, General
(2014), http://dx.doi.org/10.1016/j.apcata.2014.10.020
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Research highlights:
• Mesoporous zirconium phosphate was used as a catalyst
• Glucose fructose and sucrose efficiently converted to HMF.
• High HMF yield up to 80% was achieved.
• Catalyst synthesized using hydrothermal method.
• Catalyst reusable after regeneration through heating.
Page 1 of 22

Conversion of fructose, glucose and sucrose to 5-
hydroxymethyl-2-furfural over meso-porous zirconium
phosphate catalyst
Archana Jain, Andrew M. Shore, Subash C. Jonnalagadda, Kandalam V. Ramanujachary and
Amos Mugweru*
Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028
*Corresponding Author. Tel.: +1-856-256-5454.
E-mail address: mugweru@rowan.edu
Abstract
5-hydroxymethyl-2-furfural (HMF) is considered an important platform chemical among other
intermediates derived from biomass. In this study, we have used mesoporous zirconium
phosphate as a catalyst for the conversion of sugars to HMF. The catalyst was synthesized using
a hydrothermal method and was characterized using powder XRD, FT-IR spectroscopy and
FESEM. The as prepared catalyst showed porous structure and a very high surface area.
Mesoporous zirconium phosphate exhibited excellent catalytic activity for the formation of
HMF, from fructose, glucose and sucrose. The effect of various factors such as reaction time,
temperature and reaction systems on formation of HMF has been investigated.
Keywords
Mesoporous zirconium phosphate, 5-Hydroxymethyl-2-furfural, Glucose, Sucrose and Fructose.
Page 2 of 22

1. Introduction
Diminishing natural recourses and their growing prices, have lead to extensive efforts focused on
the wasted biomass for production of chemicals and fuels [1-4]. Biomass is inexpensive,
renewable and abundant in nature. 5-hydroxymethyl-2-furfural (HMF) is considered an
important signature chemical among other chemical intermediates derived from the biomass [5-
7]. Other useful intermediates, including, the bio-based polymers (2,5-diformylfuran and 2,5-
furandicarboxylic acid), fuels (2,5-dimethylfuran) and solvents such as, levulinic acid can be
prepared by the selective oxidation, reduction and rehydration of HMF respectively [8, 9]. HMF
is synthesized from the dehydration of mono-/di-/polysaccharides (such as fructose, glucose,
sucrose, cellobiose and cellulose etc.) [10-13]. The use of fructose as substrate is not economical
because of its low availability and high cost. Glucose which is the main component of biomass
has been considered more desirable substrate. The formation of HMF from glucose requires an
initial isomerization to fructose, followed by the dehydration of fructose. The synthesis of HMF
from hexose has been performed using a variety of acid catalysts such as inorganic materials [3,
14], organic acids [15] and metal chlorides[16], and heterogeneous catalysts e.g. zeolites[17, 18]
, ion-exchange resins[19, 20], heteropoly acid salts[21] sulfated[22] and phosphoric acid treated
metal oxides[23]. Extensive efforts have been made to improve the yield of HMF by adopting
different kind of reaction methods and solvent systems such as ionic liquids or
aqueous/bi/multiphase organic solvent systems [10, 11]. Metal phosphates (such as Al, Ti, Zr
and Nb) have also been employed as heterogeneous acid catalysts for the conversion of sugars to
HMF due to the presence of the Lewis (metal sites) and Brønsted (protonated phosphate group)
acidic sites [24]. It has been reported that, the Lewis acidic sites on the solid catalyst, promotes
the isomerization of glucose to fructose, via intermolecular hydride shift, while the Brønsted
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acidic sites helps in the dehydration of fructose to HMF [25-27]. Benvenuti et. al.[28] performed
a comparative study of the catalytic activity of various form of Zr-/Ti-phoshates (layered and
cubic forms) for the conversion of fructose to HMF in aqueous media and suggested cubic
zirconium pyrophosphate and γ-titanium phosphate as the best catalysts among the investigated
samples. On the other hand, Asghari et. al. [29] investigated the catalytic performance of the
crystalline and amorphous forms of zirconium phosphate under sub-critical water conditions for
the dehydration of fructose to HMF. To the best of our knowledge, the use of the meso-porous
zirconium phosphate as catalyst in the preparation of HMF from hexoses has not been reported
so far.
In this work, the catalytic activity of mesoporous zirconium phosphate (ZrP) for the formation of
HMF from fructose, glucose and sucrose was investigated. This material was prepared by
hydrothermal method at low temperature using CTAB as a cationic pore directing agent. It has a
mesoporous structure with a very high surface area (407 m2/g). Due to the high surface area, this
catalyst exhibited excellent catalytic performance for hexose transformation to HMF with high
yield. We have also studied the effect of various factors such as solvents, reaction time,
temperature and reaction systems on its catalytic activity in the formation of HMF. The catalyst
was regenerated by heat treatment and exhibited acceptable performance after re-use.
2. Experimental
2.1 Chemicals: All chemicals required for the synthesis of catalyst and catalytic reactions were
purchased from Alfa Aesar, Acros Organics, Sigma Aldrich and BDH companies.
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2.2 Catalyst synthesis: The zirconium phosphate (ZrP) catalyst was synthesized according to a
literature procedure with slight modification[30]. Briefly, hydrothermal treatment involving an
in-situ generated zirconium carbonate complex, di-ammonium hydrogen ortho-phosphate, and
hexadecyl trimethyl ammonium bromide (CTAB) in a basic medium was carried out. CTAB is a
micelle forming agent that is used in the process to add porosity to the catalyst. The white
zirconium carbonate was precipitated out upon mixing of a dilute aqueous solutions of
ammonium carbonate (Alfa Aesar, ACS, NH3 30.0 +%) (3 g dissolved in 200 mL DI H2O) and
zirconium oxychloride (Alfa Aecar, 98%) under continuous stirring. After complete
precipitation, the solid residue was collected by repeated centrifugation and washings with water
until the complete removal of chloride ions. The chloride free precipitate was mixed in an
aqueous solution of ammonium carbonate and vigorously stirred until a clear solution was
obtained. Finally, this solution was diluted to 175 mL using distilled water. A 50 ml aqueous
solution of 6.5506 g di-ammonium hydrogen orthophosphate, [(NH4)2HPO4] (ACS, 98% min.)
was added to the clear solution at a fixed flow rate (5 ml min−1) to make a 225 mL solution of
1% (w/v). The aqueous solutions containing CTAB (Amresco, high purity grade) was placed in a
1000 mL thick-wall glass bottle and stirred continuously for 12 h at room temperature, then at
80°C for 2 days and finally at 90°C for 1 day in the same glass bottle. The reaction mixture was
left for another day in a teflon lined stainless steel reactor (Parr bomb) that was kept in a pre-
heated hot air oven at 135°C. After cooling, the white precipitate reaction mass was centrifuged,
washed thoroughly with distilled water and dried in a hot air oven at 80°C for 12 h. The dried
samples were calcined in a high temperature furnace at 550°C for 6 h to get pure mesoporous
3−
zirconium phosphate. Synthesis was carried out using molar ratio of Zr4+/PO4 /CTAB/H2O:
1:2:0.25:1000.
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2.3 Instrumentation
Powder X-ray diffraction analysis of the catalyst was carried out using Panalytical Empyrean
Diffraction System with an operating voltage set to 40 kV and current of 45 mA using Cu Kα
radiations (λ = 1.542 Å). X-ray diffraction patterns were recorded at 0.01 deg/min step in 5-90
degree range using 8 seconds residence time. Fourier transform infrared (FT-IR) spectra of
zirconium phosphate and pyridine absorbed sample were recorded on Perkin Elmer (Model
spectrum 100). The Field-emission scanning electronic microscope (FESEM) images were
collected on FEI Quanta 3D FEG operated at an accelerating voltage of 5kV. The specific
surface area and pore volumes were obtained by means of N2 adsorption and desorption studies
on a Nova 2200 operated at 77 K. The specific surface area was determined by using Brunauer-
Emmette-Teller (BET) method and the pore volume by John-teller method. The catalyst was
degassed at 300 °C for 16 h prior to the surface area measurements.
2.4 Synthesis of HMF
The reactions were performed in a thick-walled glass pressure tube. In a typical experiment,
sugar, catalyst, aqueous phase (saturated NaCl solution), and diglyme were placed in the glass
reactor vessel respectively. The aqueous phase and diglyme were used in the volume ratio of 1:3.
The glass reactor vessel was sealed and placed in a pre-heated oil bath at a set temperature with
continuous stirring. After the set time, the reaction mixture was cooled down in an ice bath and
then transferred into a centrifuged tube. The reaction mixture was separated from the catalyst by
centrifuging it. The solid catalyst was washed with water and acetone respectively and dried in a
hot air oven at 100°C. The analysis of liquid layer was performed by means of high performance
Page 6 of 22

liquid chromatography (HPLC) using a Agilent 1100 series instrument and C18 reverse phase
column of dimensions 250 mm x 4.6 mm x 5.0 µm. The product solution containing HMF was
run using a mobile phase of acidic water and methanol (0.05% H2SO4 (10%) + MeOH (90%)) at
a flow rate of 1mL min-1. The HMF peak was identified by its retention time in comparison with
the standard sample. The actual concentration of HMF was determined from the calibration plot
(see supplementary data, Fig. S1). The results are tabulated (Table 1). The HPLC chromatograms
are shown for a few selective reactions in supplementary data (Figs. S2-S4). The proton NMR of
the crude product in the case of the dehydration reaction of fructose to HMF (entry # 3 in table 1)
is also shown as a reference in fig. S5.
3. Results and discussion
3.1 Catalyst characterization
The powder XRD pattern of the calcined ZrP sample shows two broad peaks in 2θ ranges of 10-
40° and 40-70° and suggests its amorphous nature (Fig. 1a). The FT-IR spectra of the sample
before and after calcination are shown in Fig. 2a. The as-synthesized sample exhibits a broad
peak at 1000-1200 cm-1 that is due to –PO4 stretching vibration and shifts towards higher wave
numbers (ca. 55-65 cm-1) after calcination. The bands at 3375 and 1630 cm-1 are attributed to the
asymmetric OH stretching and bending of water molecule, respectively. The bands at 1471 and
2800-3000 cm-1 are due to the C-H stretching of the surfactant that disappear after calcinations.
A similar pattern of powder XRD and FT-IR of mesoporous zirconium phosphate has been
reported by Sinhamahapatra et al [31]. The surface acidity of ZrP has been determined by FT-IR
using pyridine as a probe molecule. Pyridine forms pyridinium ions with proton (Brønsted acid
sites) and is coordinated to electron-deficient metal centers (Lewis acid centers)[31]. Fig. 2b
shows the FT-IR of zirconium phosphate before and after adsorption of pyridine. The band at
Page 7 of 22

~1545 cm-1 is assigned to pyridinium ion, confirming presence of Brønsted acid sites. The
Brønsted acidity arises as a result of presence of geminal P(OH) groups [32]. A peak at around
~1445 cm-1 is due to the pyridine attached to a Lewis acid center. The band at 1490 cm-1 is a
combination band between two separates bands at 1545 and 1445 cm-1, corresponding to
Brønsted and Lewis acid sites respectively.
The specific surface area of calcined mesoporous zirconium phosphate was found to be 407
m2/g, as analyzed, using multilayer BET method. Figure 1b shows the nitrogen adsorption-
desorption isotherm of calcined m-ZrP. The isotherm of ZrP is of type IV according to IUPAC
which is of characteristics of mesoporous materials. The pore size distribution plot (Fig. 1b inset)
derived from this isotherm using non local density functional theory (NLDFT) show a very
narrow pore size distribution. The field-emission scanning electronic microscopic images of
calcined zirconium phosphate reveals spherical nature as well as agglomeration of the particles
containing rough surfaces (Fig. S6 ).
3.2 Catalytic reactions
Previous reports indicate, mesoporous ZrP as an efficient catalyst for the xylose conversion to
furfurals as a result of a large surface area, as well as presence of Lewis and Bronsted acidic sites
[33]. In the present study, the catalytic activity of synthesized mesoporous ZrP was examined in
the conversion of fructose, glucose and sucrose to HMF under various reaction conditions. In the
first set of experiments, the effect of solvents on HMF yield was investigated. The dehydration
of fructose was performed in different solvent systems under conventional refluxing conditions.
The following reaction conditions were used: 1000 mg fructose, 500 mg ZrP catalyst,
water/organic solvent (saturated with NaCl, 1:3 v/v) (40 mL), and at 150 °C for 4 h. The highest
Page 8 of 22

HMF yield was obtained in water-dyglyme solvent system (Fig. 3). We also compare the yield of
HMF from reactions done in different conditions. Conventional refluxing system, sealed reactor
system were compared while studying the conversion of fructose to HMF. The following
reaction conditions were used. 100 mg fructose, 50 mg ZrP catalyst, water/diglyme solvent (1:3
v/v, saturated with NaCl), and at 150 °C. The yield of HMF was found to be 80% in just 1 h in
the case of reaction done in a sealed reactor (Entry #3 in table 1), as compared to 61% HMF
yield in 4 h from the reaction done under refluxing conditions (Entry #20 in table 1). It can be
clearly seen that the heating in a sealed reactor helps in maximizing the HMF yield and also
reduces the reaction time.
In further study, the effect of catalyst and salt as co-catalyst on the HMF yield was investigated.
The reactions were performed in water-diglyme solvent system in presence of both catalyst ZrP
and co-catalyst NaCl or in absence of one of them using fructose, glucose, and sucrose as
substrates (Entries #3, 8, 9, 12-14, and 17-19 in table 1 respectively) in a sealed reactor. A higher
HMF yield as measured using HPLC was observed, when the catalyst and co-catalyst were used
together (Fig. 4).
Table 1: HMF synthesis from fructose, glucose and sucrose in a sealed reactor using ZrP
catalyst
Entry Substrate (mg) Catalyst
(mg)
Solvents
(4 mL)
Time
(h)
T(°C) HMF yield
(mol %)
1
2
3
4
Fructose, 100
Fructose, 100
Fructose, 100
Fructose, 100
ZrP, 50
ZrP, 50
ZrP, 50
ZrP, 50
H2O-diglyme
H2O-diglyme
H2O-diglyme
H2O-diglyme
2
150
150
150
150
77
78
80
50
1.5
1
0.5
Page 9 of 22

5
Fructose, 100
Fructose, 100
Fructose, 100
Fructose, 100
Fructose, 100
Glucose, 100
Glucose, 100
Glucose, 100
Glucose, 100
Glucose, 100
Glucose, 100
Sucrose, 100
Sucrose, 100
Sucrose, 100
Sucrose, 100
Fructose, 1000
ZrP, 50
ZrP, 50
ZrP, 50
ZrP, 50
-
H2O-diglyme
H2O-diglyme
H2O-diglyme
H2O-diglymea
H2O-diglyme
H2O-diglyme
H2O-diglyme
H2O-diglyme
H2O-diglymea
H2O-diglyme
H2O-diglymeb
H2O-diglyme
H2O-diglyme
H2O-diglymea
H2O-diglyme
H2O-diglyme
1
1
180
120
100
150
150
150
180
180
180
180
180
180
180
180
180
150
73
43
38
36
7
6
7
1
8
1
9
1
10
11
12
13
14
15
16
17
18
19
20c
ZrP, 50
ZrP, 50
ZrP, 50
ZrP, 50
-
2.5
2
45
61
63
31
3
3
2
2
ZrP, 50
ZrP, 50
ZrP, 50
ZrP, 50
-
2
56
52
53
22
1
1
2
2
1
ZrP, 500
4
61
H2O-diglyme = 1:3 (v/v) saturated with salt (NaCl); a without salt (NaCl); b solvent = 2 mL;
c reaction done in RB flask equipped with refluxing condenser using 40 mL H2O-diglyme solvent
mixture.
In the absence of co-catalyst (NaCl), HMF yield, reduced by ~30-50%. The addition of sodium
chloride to the aqueous phase leads to increased HMF yields because of the improvement of the
partitioning of HMF into the extracting phase by means of the salting out effect [34]. In blank
reaction (without catalyst), very low yield of HMF was observed (Entries #8, 13 and 19 in table
1).
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The effects of reaction time on HMF yield were also studied for the conversion of fructose to
HMF under the same reaction conditions in sealed reactor (Entries # 1-4 in table 1). Fig. 5 shows
the effect of time on the HMF yield. In prolonged reaction time, a slight decrease in the HMF
yield was observed, most likely due to the minor transformation of HMF to other products[35] .
The effect of reaction temperature, on the HMF yield was also investigated. The yield obtained
in temperature range from 100 to180 °C using ZrP (50 mg) as solid catalyst are shown in table 1.
It was found that the HMF yield increased on increasing temperature from 100 °C to 150 °C
(Fig. 6). Further increase in temperature decreases the HMF yield drastically. This may be
attributed to the side reactions occurring at higher temperatures.
The reusability of the catalyst was tested for the conversion of fructose to HMF under the
conditions of 100 mg fructose, 50 mg ZrP catalyst, water/diglyme solvent (saturated with NaCl,
1:3 v/v) (4 mL), and at 150 °C for 1 h in a sealed glass reactor. The catalyst was collected by
repeated centrifugation and washing with water and acetone for several times after each cycle.
The catalyst as obtained was brownish in color, due to deposition of organic by-products. The
catalyst was successfully regenerated by heating at 500 °C for 2 h in air in a furnace and then
used for the fresh reaction. As shown in Fig. 7, the catalyst was re-used for five times, and only
a slight decrease in HMF yield was observed.
4. Conclusions
In this study, the catalytic activity of synthesized ZrP was examined in the conversion of
fructose, glucose and sucrose to HMF under various reaction conditions. The effect of various
factors such as reaction time, temperature and reaction systems on HMF yield was also
investigated. It was found that the heating for longer time and at high temperature had negative
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impact on HMF yield due to the formation of side products. The catalyst recycled five times
showed negligible reduction in activity as observed in HMF yield.
Acknowledgement
We are grateful to NATCO Company, Hyderabad for the financial support of this research.
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Figure captions
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Figure 1: (a) Powder X-ray diffraction pattern and (b) N2 adsorptin-desorption isotherm and
corresponding pore size distribution curve (inset) of calcined msoporous zirconium phosphate
Figure 2: FT-IR spectra of (a) as synthesized and calcined m-ZrP and, (b) calcined m-ZrP before
and after adsorption of pyridine
Figure 3: Effect of different biphasic solvents on HMF yield
Figure 4: Effect of catalyst and co-catalyst on HMF yield
Figure 5: Effect of the reaction time on HMF yield
Figure 6: Effect of the reaction temperature on HMF yield
Figure 7: Re-use of the catalyst for the conversion of fructose to HMF (Reaction conditions:
fructose: 100 mg, catalyst ZrP: 50 mg; H2O-diglyme: 4 mL in volume ratio of 1:3, saturated with
NaCl; time:1 h; and temp.: 150°C; sealed reactor)
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*Graphical Abstract (for review)
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Figure 1
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Figure 2
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Figure 3
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Figure 4
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Figure 5
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Figure 6
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Figure 7
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