Production and upgrading of 5-hydroxymethylfurfural using heterogeneous catalysts and biomass-derived solvents

Article abstract of DOI:10.1039/c2gc36536g

High yields of HMF from glucose can be achieved using biomass-derived solvents and a combination of solid Lewis and Bronsted catalysts in a salt-free reaction system. The HMF produced in this system can be oxidized to FDCA or hydrogenated to DMF, both being high-value chemicals.

Full text of DOI:10.1039/c2gc36536g

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COMMUNICATION
Production and upgrading of 5-hydroxymethylfurfural
using heterogeneous catalysts and biomass-derived
solvents†
Cite this: DOI: 10.1039/c2gc36536g
Received 28th September 2012,
Accepted 26th October 2012
DOI: 10.1039/c2gc36536g
Jean Marcel R. Gallo, David Martin Alonso, Max A. Mellmer and James A. Dumesic*
www.rsc.org/greenchem
High yields of HMF from glucose can be achieved using biomass-
derived solvents and a combination of solid Lewis and Brønsted cata-
lysts in a salt-free reaction system. The HMF produced in this system
can be oxidized to FDCA or hydrogenated to DMF, both being high-
value chemicals.
Fig. 1 Conversion of glucose to HMF by a combined isomerization/dehy-
dration reaction pathway.
The conversion of renewable biomass resources into chemicals
and fuels traditionally obtained from petroleum is strategically
important to improve the sustainability of the chemical
industry. Lignocellulosic biomass is the non-edible portion of
biomass, and extensive research has been carried out in
its conversion into platform molecules. The platform molecule
7
,11,16
higher than 90%;
however, the separation and purifi-
cation of HMF from these solvents are complicated.
While glucose can be obtained from cellulose by hydrolysis
with yields of 98–100%, isomerization of glucose to fructose
is economically limited to 42%, requiring additional and
expensive separation steps. As a consequence, the final market
price of fructose is significantly higher than that of glucose. In
order to obtain HMF in high yields from glucose, recent
studies have aimed to use one-pot isomerization reactions to
produce fructose by using a Lewis acid or Lewis base, followed
by Brønsted acid-catalyzed dehydration of fructose to HMF
Fig. 1).
Zhao et al. first reported HMF yields of 68–70% from
glucose in the ionic liquid 1-ethyl-3-methyl-imidazolium chlor-
ide using CrCl2 as the Lewis acid catalyst. In subsequent
studies with ionic liquids, HMF was produced from glucose
1
7
5
-hydroxymethylfurfural (HMF), produced from the Brønsted
acid catalyzed dehydration of C sugars (hexoses), is con-
6
1
sidered to be one of the top value-added chemicals. Mechan-
istic studies have shown that HMF is formed from the
dehydration of the hexoses in the furanose form (5-member
2
–4
ring).
Although glucose is the most abundant and least
(
expensive hexose, it presents low amounts of furanose isomer
1
1
5
in solution (1% in water ), and its dehydration into HMF thus
6
takes place with low selectivity. In contrast, fructose, which
5
presents 21.5% of the furanose form in aqueous solution, can
be dehydrated to HMF in higher yields using monophasic
or biphasic solvent systems and using homogeneous and het-
1
8
with yields higher than 90%. However, ionic liquids are not
7
–13
14,15 yet suitable for large scale applications due to their high cost
erogeneous Brønsted acids.
Dumesic and co-workers
7
and deactivation by small amounts of water. Binder and
Raines reported that a system using dimethylacetamide
DMA), NaBr, and CrCl resulted in HMF yields of 81%, being
employed a biphasic system consisting of an aqueous layer
saturated with NaCl and containing fructose and HCl or
H SO as catalysts, in combination with an extracting organic
2 4
1
2
(
2
as effective as ionic liquid systems. Other authors have
layer to protect HMF from degradation reactions. Several alco-
hols, ketones, and ethers were used as extracting organic
layers, and yields for HMF as high as 70% were observed.
In monophasic solvent systems using dimethyl sulfoxide or
ionic liquids as solvents, HMF can be obtained with yields
1
9
explored biphasic systems. Huang et al. reported a 63% HMF
4,15 yield in a biphasic reactor system with a two-step process invol-
ving the isomerization of glucose to fructose in the presence of
glucose isomerase and borate ions, followed by the HCl-
catalyzed dehydration of fructose to HMF. Dumesic and co-
1
6
workers reported 62% yield of HMF from glucose using a
biphasic reactor consisting of AlCl ·6H O and HCl as catalysts
3 2
in water saturated with NaCl, in contact with sec-butylphenol.
In all of these systems, the main goal was to maximize HMF
yield, while the upgrading and purification of HMF and the
Department of Chemical and Biological Engineering, University of Wisconsin-
Madison, 1415 Engineering Drive, Madison, WI 53706, USA.
E-mail: dumesic@engr.wisc.edu; Fax: +1-608-262-5434; Tel: +1-608-262-109
†
Electronic supplementary information (ESI) available: Experimental Section,
Fig. S1, Fig. S2 and Table S1. See DOI: 10.1039/c2gc36536g
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Table 1 Conversion of glucose or fructose to HMF in a biphasic system with
a
γ-lactones, THF, and SBP as the extracting organic layer
%
HMF % HCl
Organic Time/ Conv./ Selec./ in org.
in org.
layer
Feed
layer
min
%
%
layer
Fructose GVL
20
40
40
40
40
—
40
94
88
88
89
92
80
91
84
70
65
65
54
71
68
94
94
92
92
83
93
97
30
30
20
10
0
30
0
Glucose
Glucose
Glucose
Glucose
Glucose
Glucose
GVL
GHL
GOL
GUL
THF
SBP
b
b
a
Reaction conditions: 1.5 g of NaCl-saturated aqueous feed
−1
(5 wt% glucose, or fructose, 5.0 mmol L AlCl
L
3
, and 3.17 mmol
−
1
b
HCl); 3.0 g of organic solvent; temperature 170 °C. Results
from ref. 6.
employed biphasic systems similar to those reported pre-
Fig. 2 Pathways for the production of THF, GVL and other γ-lactones from
(
*)
biomass. 2- and 3-pentenoic acid are also formed in the isomerization, viously where THF and sec-butylphenol were used as the
6
however, the consecutive reaction takes place with the 4-pentenoic acid isomer.
organic layers. In biphasic reactors, monosaccharide de-
hydration takes place in the aqueous layer, followed by the
extraction of HMF by the organic layer, where it is protected
sustainability of the process remained as secondary problems. from the catalysts, minimizing side reactions. The aqueous
For example, reutilization of homogeneous catalysts can be an layer has to be saturated with NaCl to diminish the solubility
issue, and these catalysts lead to corrosion problems that of both the organic solvent and HMF, improving the efficiency
require expensive materials of construction. Moreover, the of the organic extracting layer. Aluminium chloride is used as
replacement of these homogeneous catalysts with hetero- isomerization catalyst, while dehydration is catalyzed by HCl.
geneous catalysts is not possible in the presence of salts, due
As seen in the results presented in Table 1, the selectivity
to exchange of protons on the catalyst with cations in solution, for conversion of glucose to HMF using the γ-lactones in a
leading to deactivation of the heterogeneous catalyst. Further- biphasic system (with the exception of GUL) are comparable
more, the sustainability of biomass conversion process would with systems using THF and SBP as the extracting solvent.
be improved by the use of biomass-derived solvents, alleviating However, as observed previously with THF, γ-lactones extract
the need to purchase and transport petroleum-derived solvents part of the HCl from the aqueous layer, which not only affects
to the biomass conversion site. These solvents must operate in HMF separation or upgrading, but also increases process cost,
presence of solid catalysts at reaction conditions favorable for because the aqueous layer has to be re-acidified and the
glucose or fructose dehydration, and they must be compatible organic layer has to be neutralized. For example, the molar
with upgrading processes, which typically involve oxidation, ratio of HMF formed to HCl lost is approximately 200 when
hydrogenation, or hydrogenolysis reactions.
using THF and GVL as the extracting solvents. The use of SBP
Herein, we present an integrated process using solid acid appears to be the most promising solvent for these biphasic
catalysts and biomass-derived solvents, γ-lactones and tetra- systems, due to high HMF selectivity and negligible extraction
hydrofuran (THF), for the conversion of glucose to HMF, fol- of HCl; however, the high toxicity of this solvent could limit its
lowed by the subsequent upgrading of HMF by hydrogenation application.
or oxidation. As depicted in Fig. 2, γ-valerolactone (GVL) can
Of the solvents listed in Table 1, THF, GVL, and GHL can
be obtained from hydrogenation of levulinic acid, a platform form a monophasic mixture with water. THF and GVL are com-
molecule derived from monosaccharide dehydration. In pletely miscible in water, while GHL can dissolve 7–10 wt% of
addition, GVL is an important platform molecule used for water. The use of monophasic solvent systems alleviates poten-
2
0,21
the production of chemicals and fuels.
Other γ-lactones tial mixing problems that may be encountered when scaling
with higher molecular weights can be obtained from GVL, up biphasic systems. Accordingly, we next studied the pro-
2
2,23
as described elsewhere,
or by ring closing of unsaturated duction of HMF from glucose in a solvent system consisting of
acids. Thus, in addition to using GVL, we have studied γ-hexa- GVL, GHL, or THF with 10 wt% water using AlCl and HCl as
lactone (GHL), γ-octalactone (GOL), and γ-undecalactone catalysts. As shown in Table 2, the results obtained in these
GUL). Similar to GVL, THF can be derived from biomass from monophasic systems are similar to those shown in Table 1.
2
4
3
(
the decarbonylation and hydrogenation of furfural, a product
of xylose dehydration.
A potential advantage of using the above monophasic
systems is that the addition of salt is not necessary (as it is to
2
5,26
To begin our studies of γ-lactones and THF as biomass- achieve a biphasic system with these solvents), allowing the
derived solvents for conversion of hexoses to HMF, we homogeneous catalysts used for glucose isomerization and
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Table 2 Conversion of glucose to HMF in a monophasic system with THF or
Table 3 Conversion of glucose or fructose to HMF in a monophasic system
a
a
γ-lactones and 10 wt% water
using γ-lactones, THF or THF : MTHF with water in a ratio (9 : 1)
Organic
solvent
Time/
min
Conversion/
%
Selectivity/
%
Lewis
acid
Time/ Conv./ Selec./
Feed
Feed
Solvent
min
%
%
b
Glucose
Glucose
Glucose
GVL
GHL
THF
20
20
20
89
90
90
66
65
56
Fructosec
Glucose
GVL
—
—
9
30
20
89
92
92
90
91
85
93
90
91
90
90
90
85
91
80
32
64
51
81
30
59
50
85
25
70
40
26
66
GVL
d
Glucose
GVL
Sn-β
Sn-SBA-15 15
—
—
Sn-β
Sn-SBA-15 15
—
—
Sn-β
Sn-SBA-15 20
—
Sn-β
e
Glucose
GVL
a
b
Reaction conditions: 1.5 g of organic solvent : water (9 : 1); feed Fructosec
GHL
10
30
20
2 wt% glucose, 5.0 mmol L−1 AlCl
temperature 170 °C.
, and 3.17 mmol L HCl); Glucose
−1
(
3
GHL
d
e
Glucose
Glucose
GHL
GHL
b
Fructosec
THF
10
50
30
Glucose
Glucose
THF
fructose dehydration to be replaced by solid acid catalysts.
d
THF
e
Accordingly, conversion of glucose to HMF would need two Glucosec
THF
f
f
Glucose
Glucose
MTHF : THF
MTHF : THF
60
40
kinds of catalysts: a solid Lewis acid or Lewis base to substitute
aluminium chloride and a solid Brønsted acid to substitute
HCl.
Recent studies have shown that hydrotalcites and tin con-
d
a
Reaction conditions: 1.5 g of feed (2 wt% glucose or fructose,
b
2
7
organic : water weight ratio (9 : 1)); temperature 130 °C. Catalysts:
c
d
0
.05 g Amb-70. Catalysts: 0.1 g Amb-70. Catalysts: 0.05 g of Sn-β
2
8
e
taining zeolites and silicas are active for glucose isomeriza-
tion to fructose. Using a combination of Sn-β and HCl in a Amb-70. THF : MTHF weight ratio (1 : 1).
and 0.05 g Amb-70. Catalysts: 0.05 g of Sn-SBA-15 and 0.05 g
f
2
9
biphasic system, Nikolla et al. obtained HMF yields of 57%
at 79% conversion of glucose. No tin leaching was observed.
Takagaki et al. reported HMF yields of 42% at 73% conver-
2
9
2
7
sion in a two-step process by combining the solid Brønsted with mass ratio GVL : H
acid catalyst, Amberlyst-70 (Amb-70), and a solid base catalyst, ity than those with a GVL : H
hydrotalcite, in N,N-dimethylformamide. The bifunctional cat-
O (9 : 1) showed higher HMF selectiv-
O ratio of 4 : 1 or pure GVL.
Table 3 shows the results for conversion of fructose and
alyst Sulfated ZrO –Al O led to 47.9% yield at total conversion glucose to HMF using Amb-70 or a combination of Amb-70
2
2
2
2 3
3
0
in DMSO.
and Sn-based catalysts (Sn-β or Sn-SBA-15) in GVL, GHL or
To establish the most appropriate isomerization catalyst for THF containing 10 wt% water. These experiments were carried
glucose isomerization, a leaching test was performed for Sn-β out using different catalysts and solvents at similar conver-
(
Si : Sn = 400), Sn-SBA-15 (Si : Sn = 40) and hydrotalcite. For sions (∼90%). It can be seen that HMF was obtained from fruc-
this test, 0.1 g of catalyst was stirred in a mixture GVL–H
tose using Amb-70 with selectivities between 80 and 85%. On
9 : 1) for 30 min at 130 °C. The catalyst was removed by filter- the other hand, direct dehydration of glucose using Amb-70
2
O
(
ing (while the solution was still hot), and glucose was added to led to selectivities lower than 35%, in agreement with early
the solvent to make a 2 wt% sugar solution. The mixture was reports showing that direct dehydration of glucose with
6
,29
stirred for 30 min at 130 °C. Conversion of glucose was only mineral acids leads to low selectivity to HMF.
observed in the solution contacted with hydrotalcite, indicat- nation of a Sn-based catalyst and Amb-70 leads to significant
ing leaching.
improvement in the selectivity to HMF from glucose. Systems
The combi-
The solid Brønsted acid catalyst used for our studies in using Sn-β show at least 9% higher selectivity than those using
monophasic reactor systems was Amb-70, a sulfonic acid func- Sn-SBA-15. In this respect, Taarning and co-workers have
tionalized catalyst that was shown in a previous study to be shown that Sn-β displays higher Lewis acid strength than Sn-
3
2
more selective for HMF production from fructose than other SBA-15 which gives it significantly higher catalytic activity.
solid acid catalysts, such as zeolites (mordenite, ZSM-5, Z-Y, Using Sn-β/Amb-70 for the conversion of glucose, selectivities
USY, and Z-β), cubic and amorphous zirconium phosphate, of 64, 59 and 70% were obtained, respectively, using GVL, GHL
titanium oxide, niobium oxide, and phosphated niobic and THF as the solvent.
10,31
acid.
The same study also showed low deactivation of
Because methyltetrahydrofuran (MTHF) can be produced
Amb-70 in the dehydration of fructose at 130 °C in a flow directly from biomass-derived furfural or GVL, we also
1
0,31
reactor system using THF : H O (4 : 1) as solvent.
explored the use of this solvent for conversion of glucose to
2
Because water is produced during glucose conversion to HMF. MTHF is not miscible with water; therefore, to obtain a
HMF and the presence of water increases the solubility of monophasic solvent system, MTHF was mixed with 50% THF.
glucose, we studied the effect of water concentration for the The solvent system consisting of THF : MTHF in a weight ratio
conversion of glucose to HMF using GVL as the solvent and of 1 : 1 and 10 wt% water produced a selectivity of 66% for
Amb-70 and Sn-SBA-15 as catalysts. Although water is known HMF formation from glucose (Table 3), which is comparable
1
4
to promote side reactions in the dehydration of sugars, it can to that obtained in GVL.
be seen in the results from Fig. S1† that water can be beneficial
Fig. 3 shows the conversion of glucose to fructose and HMF
in low concentration. At similar conversion (∼70%), the system as a function of time in the presence of Amb-70 and Sn-β for
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respectively) and can be easily separated from HMF. In the
reaction solvent consisting of THF : MTHF (1 : 1) or THF with
10% water, organic solvents can be evaporated to yield an
aqueous solution of HMF, or alternatively, water can be
removed using a drying agent such as magnesium sulfate or
calcium chloride, followed by distillation to obtain pure HMF.
Another route to separate HMF from GVL or GHL is to convert
HMF to a lower boiling point compound. For example, the
1
4
high value chemical 2,5-dimethylfuran (DMF) has a boiling
point significantly lower than GVL or GHL. Also, it is more
stable than HMF, such that DMF can be removed by distilla-
tion. To achieve this separation route, we have shown that
DMF can be produced with 46% yield by hydrogenolysis of
HMF in the presence of lactones using a RuSn/C catalyst at
200 °C. Importantly, this catalyst produced DMF from HMF
without conversion of the solvent (GVL or GHL), in accordance
3
4
with previous literature.
One of the most attractive compounds that can be produced
from HMF is 2,5-furandicarboxylic acid (FDCA). FDCA can be
produced by oxidation of HMF with molecular oxygen in an
aqueous alkaline solution using supported gold, platinum or
Fig. 3 Glucose dehydration in (A) GVL, (B) GHL, (C) THF, and (D) THF : MTHF
(1 : 1). Solvents contain 10 wt% water. Reaction conditions: 2 wt% glucose;
0
.05 g Sn-β; 0.05 g Amb-70; temperature 130 °C.
3
5–37
palladium catalysts.
GVL (Fig. 3A), GHL (Fig. 3B), THF (Fig. 3C), and THF : MTHF to produce polymers similar to polyethylene terephthalate
Fig. 3D).
(PET). PET has a growing market, with more than 49 million
In glucose conversion (Fig. 3), the product observed initially tons produced in 2009. For this reason, FDCA has been rated
is fructose, and formation of HMF begins at approximately as a top twelve value added chemical by the U.S. Department
FDCA is a monomer that can be used
(
3
8
3
9
5
min of reaction time. Comparing the extent of fructose for- of Energy. For the production of FDCA, HMF has to be separ-
mation in the different solvents, it can be concluded that the ated to avoid oxidation of the organic solvent. As mentioned
effectiveness of glucose isomerization controls the HMF selec- above, HMF can be removed from THF and MTHF by distilla-
tivity (Table 3), i.e., THF > THF : MTHF = GVL > GHL. Dimin- tion, and it can thus be used directly in the oxidation reaction.
ishing the mass ratio Amb-70/Sn-β in an attempt to increase Removal of HMF from the less volatile γ-lactones can be
the relative rate of glucose isomerization in GVL did not lead achieved by contacting these solutions containing HMF with
to any improvement in HMF selectivity (Fig. S2†). Thus, in water and cyclopentane (CP) in different proportions, as
addition to functioning as a catalyst for glucose isomerization, shown in Table S1.†
Sn-β also appears to catalyze fructose degradation to unidenti-
Contacting 1 part of a solution containing HMF in GHL
fied products. After HMF has been formed, it can undergo with 1 part of water and 16 parts of CP, leads to an aqueous
further reaction to form equimolar amounts of levulinic (LA) layer containing 80 wt% of the initial HMF and 5 wt% of the
and formic acid (FA) generated from HMF hydrolysis (HMF = initial GHL. Contacting the resultant aqueous layer twice with
LA + FA). The carbon balances in the reactions carried out 6 parts of CP decreases the GHL concentration to 0.35 wt% of
using GVL, GHL, THF : MTHF (1 : 1) and THF were, respect- the initial value, while retaining all of the HMF in the aqueous
ively, 80, 65, 70 and 85%. Common degradation products, as layer. The HMF : GHL molar ratio in the final aqueous layer is
solid humins and soluble polymers, formed by the cross- equal to 2.51. GVL is more soluble in water than GHL; there-
3
3
polymerization of glucose and HMF were not quantified. fore, extraction of HMF from GVL requires 4 consecutive
However, it was shown before that GVL, for example, can solu- extractions with 20 parts of CP to yield an aqueous solution
3
4
bilize humins, thereby facilitating the separation of the with 80 wt% of the initial HMF amount and 0.5 wt% of the
product and minimizing deposition of carbon on the solid initial amount of GVL. The HMF : GVL molar ratio in the final
catalyst surface.
aqueous layer is equal to 1.52. The boiling point of CP (50 °C)
Because HMF is a platform chemical and not a final is much lower than GVL (207 °C) and GHL (219 °C), hence it
product, it is important to find methods to separate HMF from can be separated easily from the lactone by distillation.
the reaction medium or to integrate the production of HMF
Aqueous solutions of HMF and γ-lactones (that could be
with subsequent upgrading reactions, thereby decreasing the produced by the method outlined above using CP) were used
cost of the final product. GVL and GHL have high boiling as feed solutions for studies of HMF oxidation under the reac-
3
6
points that are similar to HMF; therefore, the separation of tion conditions proposed by Davis et al., i.e., aqueous solu-
HMF from these solvents by distillation would require the use tion containing 0.1 mol L− HMF, 2 mol L NaOH, 2000 kPA
1
−1
of low pressures and could lead to degradation of HMF. In con- oxygen, 1 wt% Au/TiO (HMF : Au = 100) at 22 °C. Using an
2
trast, MTHF and THF have a low boiling point (80 and 66 °C, aqueous solution of HMF with up to 0.5% of GVL or GHL,
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yield, and this low boiling point product can then be separated
from the solvent by distillation. Alternatively, we show that
HMF can be extracted to water assisted by cyclopentane. The
oxidation of HMF to FDCA can then be carried out in the pres-
ence of small amounts of lactones, and yields of 80% were
obtained. Thus, the catalytic systems proposed in this work
not only replace the use of homogeneous catalysts and salts,
but they also allow the integration of HMF production with
processes for HMF upgrading to valuable products.
Acknowledgements
The authors thank Haldor Topsøe A/S, Denmark for the Sn-β
and Fabiola Lárraga and Nestor Hernandez Lozada for their
help with the experiments. This work was supported by the
U.S. Department of Energy; the Center Enabling New Technol-
ogies through Catalysis (CENTC); and the Defense Advanced
Research Projects Agency (DARPA). The views, opinions, and/
or findings contained in this article are those of the author
and should not be interpreted as representing the official
views or policies, either expressed or implied, of the DARPA or
the Department of Defense.
Fig. 4 Overall yields for DMF and FDCA production from glucose starting with
THF, GVL or GHL as solvent.
yields of 80% for FDCA and 20% for 2-hydroxymethylfurancar-
boxylic acid (HFCA) were observed, in accordance with pre-
3
6
vious literature in the absence of lactones. If the reaction
is carried out in the presence of larger amounts of lactones
(
i.e. 5%), yields of 56% for FDCA and 44% for HFCA are
observed, and 35% of the γ-lactone is converted to levulinic
acid (from GVL) or 4-oxohexanoic acid (from GHL). Separation
of FDCA was achieved by decreasing the pH of the reaction
mixture to a value of one, leading to precipitation of FDCA,
while HFCA and salt remained in solution. The precipitate was
filtered and washed with ethanol.
The overall yields we have achieved for production of DMF
and FDCA on a glucose basis for each of the solvent systems
considered in this paper are shown in Fig. 4. Starting with
THF as solvent, an overall yield of 50% is obtained for FDCA,
while 38 and 35% are the yields when the process uses GVL
and GHL as the solvents, respectively. If the target product is
DMF, then yields of 27 and 25% can be obtained in the
systems using GVL and GHL as solvents, respectively.
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1
1
1
1
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