Enhanced conversion of α-cellulose to 5-HMF in aqueous biphasic system catalyzed by FeCl3-CuCl2

Article abstract of DOI:10.1016/j.cclet.2020.12.030

This study was to investigate the optimal additions of the cellulose decomposition reaction to obtain the most yield of 5-HMF and other furan derivatives in various biphasic systems with FeCl₃-CuCl₂ mixed catalysts, and explore its depolymerization kinetics. A series of controllable reactions have been performed under mild environmentally friendly atmosphere. The experiment results showed that 49.13 wt% of 5-HMF was the maximum production along with 2.98 wt% other furan derivatives catalyzed by mixed Lewis acid FeCl₃-CuCl₂ under the two phases which included high concentration NaCl aqueous phase and n-butanol organic phase at 190 °C for 45 min. The conclusion suggested that two-phase systems benefited the yield of 5-HMF, furan derivatives via extracting the target products from reaction phase to organic phase to avoid rehydration of 5-HMF. The kinetic calculation revealed the conversion with mixed catalysts had lower reaction apparent activation energy (21.65 kJ/mol, 190-230 °C) and the reaction rate was faster than that with acid-based catalysts. Based on experiment exploration, the probable mechanism of cellulose decomposition with FeCl₃-CuCl₂ was proposed.

Full text of DOI:10.1016/j.cclet.2020.12.030

G Model
CCLET-6044; No. of Pages 6
Chinese Chemical Letters xxx (xxxx) xxx–xxx
Contents lists available at ScienceDirect
Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
Communication
Enhanced conversion of α-cellulose to 5-HMF in aqueous biphasic
system catalyzed by FeCl -CuCl
3
2
Lilin Zhang, Yinbing Tian, Yuanyuan Wang*, Liyi Dai*
Shanghai Key Laboratory of Green Chemistry and Green Process, College of Chemistry and Molecular Engineering, East China Normal University, Shanghai
2
00241, China
A R T I C L E I N F O
A B S T R A C T
Article history:
This study was to investigate the optimal additions of the cellulose decomposition reaction to obtain the
Received 6 November 2020
Received in revised form 14 December 2020
Accepted 18 December 2020
Available online xxx
3 2
most yield of 5-HMF and other furan derivatives in various biphasic systems with FeCl -CuCl mixed
catalysts, and explore its depolymerization kinetics. A series of controllable reactions have been
performed under mild environmentally friendly atmosphere. The experiment results showed that
49.13 wt% of 5-HMF was the maximum production along with 2.98 wt% other furan derivatives catalyzed
by mixed Lewis acid FeCl
3
-CuCl
2
under the two phases which included high concentration NaCl aqueous
Keywords:
Cellulose
Two phase
Mixed catalysts
Depolymerization
ꢀ
phase and n-butanol organic phase at 190 C for 45 min. The conclusion suggested that two-phase
systems benefited the yield of 5-HMF, furan derivatives via extracting the target products from reaction
phase to organic phase to avoid rehydration of 5-HMF. The kinetic calculation revealed the conversion
ꢀ
with mixed catalysts had lower reaction apparent activation energy (21.65 kJ/mol, 190-230 C) and the
5
-HMF
reaction rate was faster than that with acid-based catalysts. Based on experiment exploration, the
probable mechanism of cellulose decomposition with FeCl
2021 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.
Published by Elsevier B.V. All rights reserved.
3 2
-CuCl was proposed.
©
5-HMF is a significant platform compound from cellulose
4
chromium phosphate (CrPO ) with Lewis and Brønsted acidity as a
degradation and an essential raw material for industry. 5-HMF and
its derivatives are widely used in fine chemical industry, medicine,
degradable plastics, energy and other scopes [1]. Thus, developing
various catalysts for cellulose hydrolysis [2–6] has always been a
broad research subject. Lai et al. reported that one-pot production
catalyst, the production of furfural from xylose and wheat straw in
the water/tetrahydrofuran (THF) biphasic system gained excellent
yield. Meanwhile, 67% yield of furfural and 32% yield of 5-HMF
ꢀ
were achieved from wheat straw at 180 C for 90 min [8].
Halogenated compounds [9–12] who possessed mild reaction
conditions, environmental pollution-free, low toxicity, controlla-
bility and inexpensive price were discovered to solve above
from cellulose was achieved with an excellent yield of 5-HMF over
ꢀ
stable heteropoly acid catalysis ChH
4
CeW12
O
40 at 140 C for 6 h,
and other carbohydrates were converted efficiently, including
fructose, glucose, sucrose, cellobiose and starch in the H O/DMSO/
3
weaknesses of other catalysts. RuCl was found to be the most
effcient on pursuing high output of 5-HMF in NaCl-aqueous/
2
MIBK biphasic system [5]. But the reaction time was too long to
gain ideal production. Besides, N. Sweygers et al. discovered that a
maximum HMF yield of 33.65 Æ 0.46 wt% (or 43.27 mol%) and a
maximal furfural yield of 33.30 Æ 1.30 wt% (or 45.79 mol%) could
be achieved in aqueous phase and methyl isobutyl ketone (MIBK)
phase catalyzed by hydrochloric acid [7]. However, the use of
hydrochloric acid as the main catalyst would corrode equipment
and the entire reaction needed to be carried out under microwave
heating conditions. In addition, S. Xu et al. reported that using the
butanol biphasic system [10]. Subsequently, B. Saha et al. found
that Zr(O)Cl /CrCl mixed catalysts were much more effective for
2 3
the conversion of sugarcane bagasse to HMF and 5-ethoxymethyl-
2-furfural (EMF) than single metal chloride [11].
However, due to the instability of the five-membered hetero-
cyclic ring of 5-HMF, metal chlorides may lead to the further
rehydration reaction to generate levulinic acid and char so that the
yield of 5-HMF is subsided a lot. The emergence of the two-phase
system copes with this problem. It was reported that the most HMF
ꢀ
yield of 39.7% was gained in 2 h at 200 C under the NaCl-H
2
O/THF
3
catalytic system with InCl [12]. Other biphasic systems [7,9,10]
have been selected to achieve high yield of 5-HMF, furan
derivatives and other platform chemicals. In the bi-phase system,
the aqueous phase underwent the process that transformed
*
Corresponding authors.
E-mail addresses: yywang@chem.ecnu.edu.cn (Y. Wang),
ydai@chem.ecnu.edu.cn (L. Dai).
https://doi.org/10.1016/j.cclet.2020.12.030
1001-8417/© 2021 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.
Please cite this article as: L. Zhang, Y. Tian, Y. Wang et al., Enhanced conversion of α-cellulose to 5-HMF in aqueous biphasic system catalyzed by
FeCl -CuCl , Chin. Chem. Lett., https://doi.org/10.1016/j.cclet.2020.12.030
3
2

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L. Zhang, Y. Tian, Y. Wang et al.
Chinese Chemical Letters xxx (xxxx) xxx–xxx
cellulose or lignocellulose into high value-added products such as
monosaccharide, 5-HMF and furan derivatives [13–16]. The organic
phase is used to complete the fractional extraction of value-added
products, preventing the aqueous phase reaction from continuing,
which avoids the extent of generating of byproducts. With regard
of the selecting of the organic phase and the reaction phase, the
basic regulations are mentioned as follows: (1) using an aprotic
solvent with similar polarity to the product as organic phase,
for example DMSO; (2) providing a suitable solvent that dissolves
cellulose completely, for instance, high concentration NaCl
solution.
From Table 1, we found the reaction with combined FeCl
3
and
CuCl (mg/mg = 1:3, c =0.02 mol/L) gained the maximum yield of 5-
2
HMF (49.13 wt%). Compared with single transition metal chloride
salt, bimetal metal salts devoted to higher yield of target products.
CuCl
output, and FeCl
2
with the same substance and solvent could only obtain trace
with the same substance concentration could
3
only obtain 6.31 wt% yield in their best experiment conditions.
ꢀ
(190 C, 60 min, 2 MPa, NaCl/butanol). Besides, the two-phase
reaction system tended to much higher yield. If using a single
solvent and same catalysts, for instance, n-butanol, THF, DCM, the
yield of 5-HMF was found to be only 4.22 wt%, 4.15 wt%, trace
respectively. The results showed a single solvent had not been
achieved the desired effect yet. Too much char and solvent
coupling occurred in single solvent. However, in bi-phasic system,
high concentration NaCl saturated solution as reaction phase
dissolved more α-cellulose based on principle of salting out. THF,
n-butanol and DCM as extraction phase were aprotic dipolar
solvents to extract target chemicals in time. Therefore, conversion
rate of single solvents was lower than two-phase system.
Our work aimed to find the optimal conditions to gain the
highest concentration of 5-HMF and other furan derivatives in
various biphasic systems with FeCl -CuCl mixed catalysts, and
3 2
explore cellulose depolymerization kinetics. We specifically
carried out the following investigation: (1) exploring the effects
of temperature, time, volume ratio of extraction solvent to reaction
solvent on the target product; (2) calculating the activation energy
and the reaction rate constant of biphasic system with optimal
catalyst; (3) proposing the probable kinetic reaction mechanism.
Above all, 0.1 g α-cellulose and combined catalysts were
dissolved in high concentration NaCl aqueous phase with trace
It could be seen from Fig. 1 that within the selected time range,
when the temperature and time improved, the output of HMF
increased sharply high and then decreased in general. Multiple
two-phase systems had different optimal temperatures and time.
In detail, the NaCl/n-butanol system obtained the highest yield of
12 mol/L hydrochloric acid. Then one of 1-butanol, THF, DCM was
regarded as the extraction phase in each run. Next, the above
materials were introduced into the reaction kettle at a preset
volume ratio (R) of extraction solvent to reaction solution.
Subsequently, the reactor was heated to a specified temperature
range of 443À503 K under stirring conditions at 500 rpm, and then
the temperature was raised to a specified temperature for a certain
period of time. During this process, experiments have been
completed in a high-temperature, high-pressure and corrosion-
resistant batch reactor. Condensate water was always passed
through the reactor to maintain a specific temperature. After the
reaction, the reactor was quenched by circulating cooling water.
For the analyses of products, the conversion rate of reactants
and yield of target product are calculated by the following equation
as shown in Table 1.
ꢀ
49.13 wt% at 190 C for 45 min. Meanwhile, the NaCl/THF, NaCl/
DCM systems achieved the best yield 23.15 wt%, 18.92 wt%
ꢀ
respectively at 210 C for 45 min. In addition, furan derivatives
gradually increased with ascendant temperature, reaching the
ꢀ
highest value of 24 wt% in NaCl/THF system under 250 C lasting
for 45 min. It could be speculated that the higher the temperature
rose, the more favorable it was for the formation of furan
derivatives from Fig. 1d. It could be seen from Fig. 1c that the
prolongation of time also had a certain influence on the selectivity
of furan derivatives. Theoretically speaking, the prolongation of
time and the rising of temperature would continue to increase the
production of furan derivatives. However, further increasing the
experimental temperature found that the content of char mounted
sharply, the conversion rate dropped and the 5-HMF content
reduced a lot, which was not conducive to the overall economic
view of conversion.
X
α-cel (wt%) = 100－w
u
/w
p
 100%
(1)
Moreover, the ratio of the organic phase to the reaction phase
also had a critical influence on the reaction (Fig. 2). R was short for
the ratio of the volume of organic phase and the reaction phase.
Based on the effect of the volume of the reactor and the
distribution coefficient, the R was adjusted to include 1:5, 1:3,
1:1, 3:1 and 5:1 (The volume of the container is 30 mL). when R was
Y
tp (wt%)= w
t
/w
p
 100%
(2)
Among them, Xα-cel refers to the conversion rate of cellulose. Ytp
refers to the yield of target products. w is the mass of unreacted
is the mass of added cellulose. w is the target product
u
cellulose. w
p
t
quality.
Table 1
Catalytic performance under various catalysts and solvents.
Entry
Solvents
Catalysts
Temperature and time
Yield of furan derivatives (wt%)
Xcel (wt%)
5
-HMF
Others
ꢀ
ꢀ
1
2
3
4
5
6
7
8
9
n-butanol
THF
DCM
NaCl/n-butanol
NaCl/n-butanol
NaCl/n-butanol
NaCl/n-butanol
NaCl/THF
NaCl/THF
NaCl/THF
NaCl/THF
NaCl/DCM
NaCl/DCM
NaCl/DCM
NaCl/DCM
FeCl
FeCl
FeCl
None
CuCl
3
3
3
+CuCl a
2
275 C, 4 h
4.22
4.15
0
21.8
a
a
+CuCl
+CuCl
2
275 C, 4 h
2.39
Trace
0
20.16
3.9
22.0
Trace
43.0
76.7
77.0
91.3
45.2
78.3
70.5
80.0
Trace
Trace
50.1
65.6
ꢀ
2
275 C, 4 h
Trace
6.31
Trace
6.31
49.13
4.49
12.31
9.36
12
Trace
Trace
4.49
7.01
ꢀ
210 C, 60 min
ꢀ
2
190 C, 60 min
ꢀ
FeCl
FeCl
3
190 C, 60 min
+CuCl a
190 C, 45 min
ꢀ
2.89
3.9
3
2
ꢀ
None
CuCl
210 C, 60 min
ꢀ
2
190 C, 60 min
3.97
3.47
7.62
Trace
Trace
3.9
ꢀ
1
0
FeCl
FeCl
3
190 C, 60 min
ꢀ
1
1
3
+CuCl a
2
190 C, 45 min
ꢀ
1
2
None
CuCl
210 C, 60 min
ꢀ
1
3
2
190 C, 60 min
ꢀ
1
4
FeCl
FeCl
3
190 C, 60 min
ꢀ
15
3
+CuCl a
2
190 C, 45 min
3.48
a
FeCl
3
:CuCl
2
(mg/mg = 1:3), the concentration of the catalyst in the solution is 0.02 mol/L.
2

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Chinese Chemical Letters xxx (xxxx) xxx–xxx
Fig. 1. Effect of time and temperature of the yield of (a, b) 5-HMF and (c, d) furan derivatives.
presented a trend of sharp growth to the maximum in c(Fe3+)/c
2
+
(
Cu ) = 1:3. However, the output of furan derivatives was on the
3
+
2+
contrary. When no Fe only 0.02 mol/L Cu played a catalytic role
in the aqueous phase, the yield of furan derivatives rose rapidly,
and a very small amount of 5-HMF was detected. The results
confirmed that the selectivity of the products was related to the
ratio of the two ions. Within a certain concentration range, Fe
was added a bit, which might promote the production of 5-HMF
and inhibit the production of other furan derivatives. Cu had
the opposite effect. As shown in Fig. 3, when the procedure
was performed in NaCl/butanol at 190 C for 45 min, mixed
catalysts (c(Fe ) /c(Cu ) = 1:3) could transform cellulose into the
maximum output of 5-HMF (49.13 wt%) with 2.98 wt% furan
derivatives, the maximum output of high value-added chemicals
is 52.11%, compared with the other four kinds of total output
3
+
2
+
ꢀ
3
+
2+
1
0.21 wt%, 28.2 wt%, 19.45 wt%, 20.16 wt%, respectively.
As reported in the literature, the radius of Fe was small and
3
+
Fig. 2. Effect of ratio of the organic phase and the reaction phase on the yield of 5-
HMF.
hydration was strong, which could further improve the
1, the three systems could achieve the best yield except for the
NaCl/THF system. Affected by the partition coefficient, the organic
phase was an aprotic polar solvent with a polarity similar to that of
the product, which had an outstanding extraction effect. As R
improved, the extraction efficiency rose firstly and then decreased.
This phenomenon occurred because the extraction efficiency
increased as the extraction volume ascended. But the ratio of the
reaction phase reduced, the content of dissolved cellulose lowered
as the conversion rate dropped. Ultimately, the output lowered.
When the unit concentration was 0.005 mol/L, the catalyst was
chosen in 5 ratios for comparison which included 4:0, 3:1, 1:1, 1:3,
0
:4. The concentration of combined catalysts in the solvent was
3
+
2+
around 0.02 mol/L. Fe and Cu were hydrolyzed in the solution,
which resulted in the addition of trace amount of hydrochloric
acid. It could be seen that the proportion of Fe3 rose up, 5-HMF
Fig. 3. Effect of various concentration ratio of mixed catalysts on yields of 5-HMF in
NaCl/butanol.
+
3

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Chinese Chemical Letters xxx (xxxx) xxx–xxx
]2 from water phase after reaction (190 C,
À
ꢀ
Fig. 4. (a) The variation of UV–vis between mixed catalysts solution and aqueous phase after reaction. (b) The UV–vis of [CuCl
4
4
3 2
5 min, FeCl -CuCl (mg/mg = 1:3), NaCl/bunatol).
concentration of target products in the aqueous phase, and
increase the concentration difference between the two phases,
which was convenient for extraction of organic phase. However,
reaction temperature increased. And the absorption peak at
1165 cm which was the stretching vibrations of C–O–C (1160 cm-
-1
1
) disappeared [20]. The results showed that oligosaccharides had
3
+
2À
excessive Fe could not improve the selectivity of HMF, which
could explain the optimal catalysts with a small proportion of
mixed catalysts. It had been reported that Cu2 improved the
selectivity of furfural and HMF in specific ionic liquids, which
undergone further reactions catalyzed by [CuCl
Cu-Cl vibration presented under 350 cm to confirm the existence
of the [CuCl
4
]
. Besides, the
-1
+
2À
4
]
in Raman as well (Fig. 5c) [20,22].
Based on the experiments, reaction rate constant of catalyst at
diverse temperatures were calculated according to the first-order
2
À
might be related to the formation of [CuCl
4
]
[17] complex in high
concentration of sodium chloride, and the complex participated in
cellulose. Based on experimental phenomena and literature, we
explored the reaction path of cellulose in the NaCl/butanol system
and verified it by XRD, FTIR, Raman and UV–vis spectra.
0
reaction as shown in Eq. 3. Where C represented initial cellulose
concentration (g/L), C was symbol of content of cellulose (g/L) at
À1
time t, k was short for rate constant (h ). Apparent activation
energy of reaction with specific catalyst was defined through
Arrhenius equation (Eq. 4). In the equation, k was rate constant at
It could be found in the UV-spectra (Fig. 4a) that the
characteristic peaks of CuCl
and 330 nm respectively disappeared after reaction, which
might result from n→ * transition of the complex [18,19]. The
2
and FeCl
3
at approximately 240 nm
specific temperature T, T was reaction temperature (K), E
a
was
apparent activation energy of reaction (J/mol of cellulose), and R
À1
À1
s
was universal gas constant (8.31446 J K mol ). To determine the
value of E , the logarithm of both sides of the Arrhenius equation
was taken in Eq. 5. Then the function image of lnk pair 1/T had been
done. The slope was the value of -E /RT.
peak of the dissolved product in the water phase appeared on the
left side of the characteristic peak. The absence of 280 nm
belonging to 5-HMF indicated the high efficiency extraction of the
a
a
2À
4
two-phase system [11]. Additionally, the complex ion [CuCl ]
0
ln(C /C) = -kt
(3)
(4)
(5)
could be detected by UV–vis and Raman. Appearance of two strong
peaks 287 nm, 400 nm proved the formation of the complex in
UV–vis spectrum (Fig. 4b) [20]. In the XRD spectrum (Fig. 5a), the
k = Ae a⁄RT
ÀE
ꢀ
ꢀ
peak at about 14 –16
2u represented the characteristic plane
(
101), which was original from the sub ordered part of samples.
ꢀ
The characteristic at 22 2u of the crystalline plane (002) could be
a
lnk = lnA-E /RT
attributed to the highly crystalline phase of cellulose. The
crystallinity plane (040) was the characteristic of low crystallinity.
After reaction, the intensity of crystalline plane decreased greatly,
which could be confirmed that the distance between cellulose
chains increased obviously due to the formation of hydrogen bond
The kinetic reaction was used to calculate the degradation of
cellulose with mixed catalysts (Fig. 6). According to the results of
linear fitting, a linear equation of 0À90 min in the range of
ꢀ
1
70À230 C was completed. The value of k was derived from the
2
À
in between cellulose chain and [CuCl
4
]
, which resulted in the
slope of the linear equation. As the temperature rose, the slope
that represented k ranged from 0.0122 min at 170 C to 0.0248
À1
ꢀ
loss of crystallization order [21]. In FT-IR (Fig. 5b), the most intense
-
1
-1
À1
signal between 1030 cm and 1060 cm that corresponded to
min
at 230 C, which indicated that the combined catalysts
ꢀ
stretching of C ÀÀ O glycosidic bond became inconspicuous as the
3 2
FeCl -CuCl were greatly affected by temperature. The linear
]2 from water phase after reaction (190 C, 45 min, FeCl
À
ꢀ
-CuCl
Fig. 5. (a) The difference of XRD between raw cellulose and char. (b) The FTIR of char. (c) The Raman of [CuCl
mg/mg = 1:3), NaCl/bunatol).
4
3
2
(
4

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L. Zhang, Y. Tian, Y. Wang et al.
Chinese Chemical Letters xxx (xxxx) xxx–xxx
Fig. 6. Kinetic analysis and reaction rate constants for the hydrolysis of α-cellulose by combined catalysts. (a) The first order reaction quasi-equation of mixed catalysts; (b) lnk
vs. 1/T of mixed catalysts.
3 2
Fig. 7. The probable process for hydrolysis of cellulose with FeCl -CuCl .
2
ꢀ
equation was y = 0.0145x - 0.0545, R = 0.987 at 190 C for 45 min.
glycoside bond was destroyed to the complex by electron transfer
to form monosaccharide. In the presence of Cu , monosaccharide
À1
2+
The reaction rate constant found was 0.0145 min . Then with the
Arrhenius equation, the apparent activation energy of combined
catalysts under various temperature was conducted. The
was dehydrated to form 5-HMF and furan derivatives. The
conjecture mentioned was consistent with the results of UV–vis,
XRD and FTIR.
linear equation was given, which was y=-2604.09x + 1.42578,
2
R
R
2
= 0.9495. The data gave the result, lnk = -2604.09/T + 1.4258,
In conclusion, the mixed catalysts FeCl
3
-CuCl
2
(mg/mg = 1:3,
2
ꢀ
= 0.9495. The apparent activation energy in the range of 170–
0.02 mol/L, 190 C, 45 min) were found to be high efficiency to
generate maximum yield of 5-HMF (49.13 wt%) along with furan
derivatives (2.98 wt%) from cellulose degradation in NaCl/n-
butanol two-phase medium. During the reaction, char was avoid
generating from the side reaction of 5-HMF in two-phase system
that experienced a controllable selective formation of 5-HMF
process. Metal chloride salts resulted in the fracture of hydrogen
ꢀ
30 C was 21.65 kJ/mol, which was lower than the pyrolysis of
cellulose used diluted acid as catalyst (170À180 kJ/mol) [23]. This
also clarified that the acid catalyst could only break through the
barrier of activation energy at high temperature. As if the reaction
took place at the moderate temperature, high concentrations of
acid would not be able to obtain better returns owing to the high
apparent activation energy.
2
bond through binding ÀOH groups in the structure of cellulose. Cu
+
As shown in Fig. 7, we proposed mechanism of pyrolysis of
gave the decent dehydration ability to generate 5-HMF and furan
cellulose in biphasic system with mixed catalysts FeCl
3
-CuCl
2
.
derivatives. The apparent activation energy is 21.65 kJ/mol in the
Above all, the strong hydration of Fe3 led to the coordination of
+
range of 170À230 C, which is far lower than that of inorganic acid
ꢀ
water molecules in concentrated NaCl solution to generate stable
catalysis. Therefore, the reaction had a faster reaction rate under
moderate temperature.
3
+
2+
complex [Fe(H
2
O)
6
] . In this process, Cu reacted with high
À
concentration Cl to form a two-dimensional planar tetrahedral
deformation structure of [CuCl
2-
4
]
that could be detected by UV–
Declaration of competing interest
vis and Raman. It bound to the ÀOH group of the cellulose chain to
break the previous hydrogen bond. Subsequently, the β-1À4
The authors declared no conflict of interest.
5

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L. Zhang, Y. Tian, Y. Wang et al.
Chinese Chemical Letters xxx (xxxx) xxx–xxx
Acknowledgments
[7] N. Sweygers, J. Harrer, R. Dewil, L. Appels, J. Clean. Prod. 187 (2018) 1014–
1024.
[
[
8] S. Xu, D. Pan, Y. Wu, et al., Fuel Process. Technol. 175 (2018) 90–96.
9] T. Deng, X. Cui, Y. Qi, et al., Chem. Commun. (Camb.) 48 (2012) 5494.
This work was finally supported by the National Natural Science
Foundation of China (No. 22078103), National Key Research and
Development Project (No. SQ2019YFE011926), the Key Project of
Science and Technology Commission of Shanghai Municipality (No.
[10] L. Yan, R. Ma, H. Wei, et al., Bioresour. Technol. Rep. 279 (2019) 84–91.
11] S. Dutta, S. De, M.I. Alam, M.M. Abu-Omar, B. Saha, J. Catal. 288 (2012) 8–15.
12] Y. Shen, J. Sun, Y. Yi, et al., Bioresour. Technol. Rep. 172 (2014) 457–460.
13] Y. Li, X. Cao, S. Sun, et al., Ind. Crop. Prod. 147 (2020)112173.
[14] Z. Chen, S. Liao, L. Ge, et al., Chem. Eng. J. 379 (2020)122284.
[
[
[
18DZ1112700) and Shanghai Natural Science Fund (No. 18ZR1411100).
[
15] B. Xue, Y. Yang, M. Zhu, Y. Sun, X. Li, Bioresour. Technol. Rep. 270 (2018) 55–61.
[
[
16] Q. Zhang, Y. Deng, X. Tan, et al., Ind. Crop. Prod. 145 (2020)112091.
17] H. Zhao, J.E. Holladay, H. Brown, et al., Science 316 (2007) 1597–1600.
References
[18] N. Zhang, D. Zeng, G. Hefter, Q. Chen, J. Mol. Liq. 198 (2014) 200–203.
[
[
[
[
1] R.van Putten, J.C. van derWaal, E.deJong,etal.,Chem. Rev.113 (2013)1499–1597.
2] A.S. Amarasekara, Chem. Rev. 116 (2016) 6133–6183.
3] Y. Chen, G. Li, F. Yang, S. Zhang, Polym. Degrad. Stabil. 96 (2011) 863–869.
4] Y. Zhang, W. Guan, H. Song, et al., Microporous Mesoporous Mater. 305 (2020)
[19] Y. Chen, Y. Zhou, R. Zhang, C. Hu, Mol. Catal. 484 (2020)110729.
[20] I.B.H. Sadok, F. Hajlaoui, K. Karoui, et al., J. Mol. Struct. 1186 (2019) 118–126.
[21] V. Flores-Velázquez, G.E. Córdova-Pérez, A.A. Silahua-Pavón, et al., Fuel 265
(2020)116857.
1
10328.
[22] A. Kaiba, M.H. Geesi, P. Guionneau, et al., J. Mol. Struct. 1204 (2020)127380.
[23] V.V. Bravo, M.P. Paez, M. Aoulad, A. Reyes, Enzyme Microb. Technol. 26 (2000)
614–620.
[
[
5] F. Lai, F. Yan, P. Wang, et al., Chem. Eng. J. 396 (2020)125282.
6] M. Wada, M. Ike, K. Tokuyasu, Polym. Degrad. Stabil. 95 (2010) 543–548.
6