Efficient Hydrolytic Breakage of β-1,4-Glycosidic Bond Catalyzed by a Difunctional Magnetic Nanocatalyst

Article abstract of DOI:10.1071/CH18138

A novel difunctional magnetic nanocatalyst (DMNC) was prepared and used to catalyse the hydrolytic breakage of β-1,4-glycosidic bonds. The functional nanoparticle displayed excellent catalytic activity for hydrolysis of cellobiose to glucose under moderate conditions. The conversion of cellobiose and yield of glucose could reach 95.3 and 91.1 %, respectively, for a reaction time of 6 h at pH 4.0 and 130°C. DMNC was also an efficient catalyst for the hydrolysis of cellulose: 53.9 % microcrystalline cellulose was hydrolyzed, and 45.7 % reducing sugar was obtained at pH 4.0 and 130°C after 10 h. The magnetic catalyst could be recycled and reused five times without significant loss of catalytic activity.

Full text of DOI:10.1071/CH18138

CSIRO PUBLISHING
Aust. J. Chem.
Full Paper
https://doi.org/10.1071/CH18138
Efficient Hydrolytic Breakage of b-1,4-Glycosidic Bond
Catalyzed by a Difunctional Magnetic Nanocatalyst
A
A
,
A B
Ren-Qiang Yang, Ni Zhang, Xiang-Guang Meng,
Xiao-Hong
A
A
A
Liao, Lu Li, and Hong-Jin Song
A
Key Laboratory of Green Chemistry and Technology, Ministry of Education,
College of Chemistry, Sichuan University, Chengdu 610064, China.
Corresponding author. Email: mengxgchem@163.com
B
A novel difunctional magnetic nanocatalyst (DMNC) was prepared and used to catalyse the hydrolytic breakage of
b-1,4-glycosidic bonds. The functional nanoparticle displayed excellent catalytic activity for hydrolysis of cellobiose
to glucose under moderate conditions. The conversion of cellobiose and yield of glucose could reach 95.3 and 91.1 %,
respectively, for a reaction time of 6 h at pH 4.0 and 1308C. DMNC was also an efficient catalyst for the hydrolysis of
cellulose: 53.9 % microcrystalline cellulose was hydrolyzed, and 45.7 % reducing sugar was obtained at pH 4.0 and 1308C
after 10 h. The magnetic catalyst could be recycled and reused five times without significant loss of catalytic activity.
Manuscript received: 5 April 2018.
Manuscript accepted: 5 July 2018.
Published online: 14 August 2018.
Introduction
catalytic groups were grafted. A difunctional magnetic nano-
particle with o-chlorophenol and sodium benzene sulfonate
groups was prepared and used to catalyse the hydrolysis of
cellobiose and cellulose under relatively mild conditions.
Cellobiose is connected by the same b-1,4-glycosidic bonds
as in cellulose, and is considered as the simplest model molecule
of cellulose. The recyclable magnetic nanocatalyst displayed
excellent catalytic activity for the hydrolysis of cellobiose into
glucose, and also good activity for the hydrolysis of microcrys-
talline cellulose and filter paper cellulose under relatively mild
reaction conditions.
Increasing energy demand and environmental problems have
highlighted the importance of using renewable lignocellulosic
biomass to produce chemicals to replace fossil fuels. Cel-
lulose, a linear macromolecule connected by b-1,4-glycosidic
bonds of D-glucose units, is one of the most abundant renewable
biomass on earth. The realisation has been made that the
hydrolysis of cellulose into glucose is crucial for its subsequent
conversion into valuable chemicals. As an important platform
[
1–3]
[
4]
[
5]
compound, glucose can be converted into biofuel, polymer
[
6]
materials, and chemicals such as 5-hydroxymethlfurfural,
[
7–9]
ethanol, and lactic acid.
into glucose is still one of the significant and challenging
problems in the field of biomass utilisation.
In recent years, some non-enzyme studies were reported for
Therefore, hydrolysis of cellulose
Results and Discussion
[
10,11]
Characterization of the DMNC
[
12–14]
the hydrolysis of cellulose through acid catalysts,
[
ionic
[17,18]
The synthetic strategy for the preparation of the difunctional
magnetic nanocatalyst (DMNC) is outlined in Scheme 1. Com-
pounds 1 and 2 represent 1-(3-chloro-4-hydroxyphenyl)-3-(3-
(triethoxysilyl)propyl)urea and sodium 4-(3-(3-(triethoxysilyl)
propyl)ureido)benzenesulfonate, respectively. The detailed
synthesis methods are described in the Experimental. The active
groups o-chlorophenol and benzenesulfonate, were loaded on the
surface of Fe O @SiO . Fe O nanoparticles and the surface
15,16]
liquids,
and subcritical and supercritical water.
Among those, the problems of either low activity and selectivity,
severe reaction conditions, or potential environmental pollution
remain. The separation and recovery of the catalyst is also
significant for industrial applications. Magnetic nanoparticles
with loaded functional groups as a catalyst have attracted
[19,20]
extensive attention.
Magnetic nanocatalysts can be easily
3
4
2
3 4
separated and recycled by applying a simple external magnetic
field. Recently, some magnetic catalysts loaded with sulfonic
acid were reported to catalyse the degradation of cellulose.
However, the lower catalytic activity or selectivity and relative
acidic reaction conditions for the hydrolysis of cellulose need
modified Fe O @SiO particles were prepared as described in
3 4 2
the Supplementary Material. In this work, the DMNC was suc-
cessfully prepared by grafting the two functional groups onto
Fe O @SiO . Transmission electron microscopy (TEM) images
3
4
2
of Fe O and Fe O @SiO are shown in Fig. S1 in the Supple-
3
4
3
4
2
[
21–23]
to be improved.
With the aim of developing sustainable
mentary Material. As seen in Fig. S1b, the dark Fe O core was
3 4
chemistry, it would be much more preferable to use recyclable
catalysts.
surrounded by a light amorphous silica shell ,2–4 nm thick.
TEM images of the DMNC are shown in Fig. 1a. From Fig. 1a,
it can be seen that the nanoparticles are uniform and the size was
,20–30 nm in diameter. The TEM images showed no signifi-
cant difference between Fe O @SiO and DMNC.
To develop an effective recyclable catalyst for the catalytic
hydrolysis of b-1,4-glycosidic bonds, we designed a solid phase
catalyst usingFe O @SiO nanoparticles as supporters to which
3
4
2
3
4
2
Journal compilation � CSIRO 2018
www.publish.csiro.au/journals/ajc

B
R.-Q. Yang et al.
Compound 1
and compound 2
TEOS
Fe O
3
4
Fe O @SiO
2
3
4
DMNC
SO
Cl
O
O
O
O
O
O
H
N
H
ϭ
Si
HN
C
OH
Si
N HN
C
Na
3
ϭ
O
O
Scheme 1. Preparation of DMNC.
(b)
(a)
(A)
(B)
1385
799
692
2932
1599
580
1500
1198
1101
20 nm
3000
2500
2000
1500
1000
500
Wavenumber [cmϪ1
]
(c) 40
(d)
(A)
1
00
3
2
1
0
0
0
0
(B)
0
(B)
9
9
8
5
0
5
Ϫ4.0 ϫ 10Ϫ4
Ϫ10
Ϫ20
Ϫ30
Ϫ40
Ϫ8.0 ϫ 10Ϫ4
Ϫ1.2 ϫ 10Ϫ3
(A)
Ϫ40000 Ϫ20000
0
20000
40000
0
100
200
300
400
500
600
Magnetic field [Oe]
Temperature [ЊC]
3 4 2
Fig. 1. (a) TEM images of DMNC; (b) FT-IR spectra of Fe O @SiO (A) and DMNC (B); (c) magnetic hysteresis loop of DMNC at 300 K (A) and 400 K (B);
(d) TGA (A) and differential thermal gravimetric (DTG) analysis (B) curves of DMNC.
The FT-IR spectra of Fe O @SiO and DMNC are shown
3
that the desired chemical groups chlorophenol and benzene
sulfonate were modified on the surface of the magnetic
nanoparticles.
Magnetization profiles of the DMNC were examined using a
vibrating sample magnetometer (VSM) at 300 and 400 K, as
presented in Fig. 1c. The sample curve showed a non-linear and
4
2
in Fig. 1b. The two particles both showed bands at ,1100
and 800 cm , which can be assigned to the stretching vibration
ꢀ
1
[
24]
ꢀ1
25]
of Si–O bonds.
The band at 580 cm can be assigned to
[
the stretching vibration of Fe–O bonds. The peaks at ,1385
and 1198 cm are ascribed to the stretching vibration of S–O
ꢀ1
bonds in –SO Na groups, which indicates that the DMNC
3
reversible behaviour with negligible coercivity and remanence,
[29]
[
26]
was functionalized with –SO Na.
3
A signal for a C–Cl
ꢀ1
which confirms its superparamagnetism.
The saturation
magnetization (Ms) for the DMNC is 32.10 and 28.43
[
27]
stretching vibration
that o-chlorophenol was successfully introduced. The peaks
appears at ,692 cm , implying
ꢀ1
emu g at 300 and 400 K, respectively. When the temperature
is 400 K, the Ms value of DMNC is slightly lower. The net
magnetism is sufficient for efficient separation from solution
ꢀ
1
at ,1599 and 1500 cm are indicative of C=C stretching in
[
28]
the benzene ring.
The FT-IR spectra allows us to conclude

Hydrolysis of b-1,4-Glycosidic Bond by DMNC
C
A
Table 1. Conversion of cellobiose in various systems
System
Conversion of cellobiose [%]
Yield of glucose [%]
Yield of sucrose [%]
Selectivity of glucose [%]
B
Bulk solution
C
16.0
12.4
12.3
4.4
—
77.3
35.7
Fe
3
O
4
@SiO
2
5.5
OH
39.2
37.9
—
96.7
ClD
SO Na
63.3
54.9
—
—
86.7
3
D
C
DMNC
95.3
91.1
95.5
A
ꢀ1
Reaction conditions: pH 4.0, 1308C, 6 h, 0.02 mol L cellobiose.
B
C
—
represents no product.
ꢀ1
@SiO and DMNC were 3.49 g L .
Fe
3
O
4
2
D
ꢀ1
.
o-chlorophenol and sodium benzene sulfonate were 0.002 mol L
through use of a simple external magnetic force, as seen in
Fig. S2 (Supplementary Material).
led to the easy attack of the O atom of phenol on C of cellobiose
1
(Fig. 2a). For benzene sulfonate, the O atom possesses strong
nucleophilic ability, and could attack the C1 of cellobiose
(Fig. 2b). For DMNC, it is possible that o-chlorophenol and
The thermostability of DMNC was evaluated by thermogra-
vimetric analysis (TGA), as presented in Fig. 1d. From Fig. 1d,
it can be seen that only 7 % weight loss occurred in the range
of 30–4008C. The ,5 % weight loss below 1008C is caused by
benzene sulfonate synergistically induce O1–4 and attack C in
0
1
the b-1,4-glycosidic bonds as illustrated as Fig. 2c, which is
similar to the catalytic mechanism of natural b-glucosidases.
[
30]
[33]
the evaporation of adsorbed water. The trace amount (,2 %)
of weight loss maybe due to the slow loss of combined H O in
the silica shell in the temperature range of 100–4008C. A
significant weight loss of 8 % was observed in the range of
To better understand the catalyst DMNC, some experimental
results and reaction conditions were compared with those of
other reports in Table 2. As seen in Table 2, this work’s catalytic
2
400–5008C, which is attributed to the loss of organics grafted on
the surface of the Fe O @SiO particles. The results showed
that the prepared DMNCs could be stable when it was used
below 3508C.
system is slightly more effective than that of SO H0.3-Ph-SNT
3
and obviously more effective than those other catalytic systems
reported in Table 2. Also seen from Table 2, compared with
other catalytic systems, this work’s catalytic system used a
relatively lower temperature and catalyst concentration. More-
over, different from the other reported reaction conditions of
acidity (generally pH , 2), the pH value of this work was 4.0,
which is a mild condition.
3
4
2
Catalytic Performance
The hydrolysis of cellobiose catalyzed by various catalysts was
carried out at pH 4 and 1308C. The results are listed in Table 1.
As seen in Table 1, only 16.0 % of cellobiose conversion
is observed in the absence of catalyst and some small molecule
by-products appeared, such as hydroxymethylfurfural (HMF)
and organic acids. The selectivity of glucose is 77.3 %. When
the Fe O @SiO nanoparticle was used, only 12.4 % conversion
Effect of pH
In the absence of catalyst, the effect of pH on conversion of
cellobiose at 1308C is shown in Fig. S3 (Supplementary Mate-
rial). From Fig. S3, it can be seen that the hydrolytic breakage of
3
4
2
glucosidic bonds is slow in aqueous solution in the range of pH
þ
of cellobiose occurred. Unexpectedly, 5.5 % of cellobiose
isomerized into sucrose in the Fe O @SiO catalytic system.
3
.0–8.5. However, when pH , 3, the high concentration of H
3
4
2
can clearly promote the hydrolysis of cellobiose. In the presence
of DMNC, the effect of pH on the reaction was investigated. As
shown in Table 3, the pH had an obvious influence on both the
rate of reaction and selectivity of the product. The conversion of
cellobiose decreased with increasing pH, especially under the
condition of pH , 5.0. At pH . 6.0, sucrose appeared. At pH
Both o-chlorophenol and sodium benzene sulfonate showed
good catalytic activity for the hydrolysis of cellobiose. Sodium
benzene sulfonate exhibited better catalytic activity and
o-chlorophenol showed better selectivity for glucose. Interest-
ingly, DMNC displayed the best catalytic activity and selec-
tivity for glucose. The conversion of cellobiose and yield of
glucose reached 95.3 and 91.1 %, respectively. Compared with
o-chlorophenol and sodium benzene sulfonate under the same
condition for the catalytic system of DMNC, the conversion of
cellobiose and yield of monosaccharide are enhanced by 32 and
4
.0, the DMNC displayed excellent catalytic activity (95.3 %
conversion after 6 h) and the best selectivity for glucose
95.5 %).
(
Effect of Temperature
3
hydrolysis of cellobiose is the simultaneous actions of attack on
6 %, respectively. In natural b-glucosidases, the key step of
Cellulose is stable and difficult to hydrolyze under mild
conditions owing to the large activation energy of its hydro-
lysis reaction, and hence the hydrolysis is usually carried
out at high temperature. However, a high temperature could
lead to the degradation of glucose and fructose into small
[
31,32]
C and inducing O
1
0
by two groups of carboxylic acids.
1–4
In
this work, the role of the o-chlorophenol group may be different
from that of benzene sulfonate. The inductive effect between the
ortho Cl atom and the H atom on the hydroxy group of phenol

D
R.-Q. Yang et al.
(
a)
(b)
HO
OH
OH
OH
O
6
3Ј
6
OH
O
4
1Ј
2
Ј
4
3Ј
1Ј
5
O
2Ј
HO
HO
HO
O
OH
5
O
2
5Ј
6Ј
HO
OH
3
1
2
5Ј
6Ј
3
1
O
4
Ј
HO
OH
H
4Ј
O
OH
OH
Ϫ
O
Cl
OH
O
S
O
(c)
OH
Cl
OH
O
6
O
H
4
3Ј
1Ј
5
O
2Ј
HO
HO
HO
OH
2
5Ј
6Ј
3
1
O
4Ј
OH
Ϫ
O
OH
O S
O
Fig. 2. Possible ways of attack of catalyst on cellobiose during hydrolysis: o-chlorophenol (a), sodium benzenesulfo-
nate (b), and DMNC (c).
Table 2. Comparison of various reported catalytic systems for the conversion of cellobiose
System
Conversion of cellobiose [%]
Yield of glucose [%]
Selectivity of glucose [%]
Ref.
A
Fe
Fe
3
O
O
4
4
-RGO-SO
3
H
66
—
61
92
—
[2]
[19]
B
3
@nSiO @mSiO
2
2
-SSFBI
53.9
88
C
SO H0.3-Ph-SNT
3
92
95.7
42
[34]
D
Acidified carbon
E
Hb zeolites
F
DMNC
50
21
[35]
76
69
91
[36]
95.3
91.1
95.5
this work
A
ꢀ1
Reduced graphene oxide functionalised with magnetic Fe
3
O
4
nanoparticles and –PhSO
ꢀ1
3
H groups. The S content of the catalyst was 0.63 mmol g , and the
ꢀ1
total acid density was 1.23 mmol g . Reaction conditions: 30 mg cellobiose, 10 g L Fe O, 1508C, 3 h.
B
Magnetic perfluoroalkylsulfonylimide-functionalised silica. 1208C, 4 h, 0.3 g cellobiose, 3 mL distillation water, catalyst amount 25 mol-%, acid loadings
3
O
4
-RGO-SO
3
H, 3 mL H
2
ꢀ1
were 0.61 mmol g
C
Phenylene-bridged sulfonic organosilica nanotubes with different acid contents were synthesised through the –SH oxidation of sulfhydryl organosilica
.
nanotubes. Reaction conditions: 20 mL deionised water, 0.2 g cellobiose, substrates: acid active sites ¼ 14, 1508C, 2 h, 2.5 MPa nitrogen.
D
ꢀ1
Activated carbon is functionalised by different treatments with sulfuric acid and hot water. 2008C, 25 bar, 100 mg catalyst, 0.5 mL min of 0.03 M cellobiose
solution.
E
ꢀ1
Reaction conditions: 50 mg cellobiose, 10 g L Hb, 5 mL H
2
O, 1508C, 6 h.
ꢀ1
F
ꢀ1
Difunctional magnetic nanocatalyst. pH 4.0, 1308C, 6 h, 0.02 mol L cellobiose, DMNC was 3.49 g L
.
A
Table 3. Conversion of cellobiose and distribution of products at various pH
pH
Conversion of cellobiose [%]
Yield of monosaccharide
Fructose [%]
Yield of sucrose [%]
Glucose [%]
Total [%]
B
3.0
3.5
4.0
4.5
5.0
5.5
6.0
7.0
8.0
100
100
87.5
90.6
91.1
81.6
71.2
24.7
21.6
16.5
11.8
—
87.5
90.6
91.1
84.2
73.5
24.7
21.6
16.5
11.8
—
—
—
—
2.6
2.3
—
—
—
—
95.3
—
92.2
83.6
47.1
33.7
27.8
25.89
—
—
—
3.5
7.7
10.1
A
B
ꢀ1
ꢀ1
Reaction conditions: 1308C, 6 h, 0.02 mol L cellobiose, and 3.49 g L DMNC.
— represents no product.
molecular substances and result in low selectivity of mono-
[
Fig. 3, it can be seen that the conversion of cellobiose
increased with increasing temperature and reached 100 % at
1408C. Above 1308C, glucose degraded and led to lower
selectivity.
37,38]
saccharide.
In this work, we found that the catalytic
reaction showed good selectivity for glucose (. 95 %) when
the temperature was low (1308C), as shown in Fig. 3. From

Hydrolysis of b-1,4-Glycosidic Bond by DMNC
E
100
100
80
60
40
20
0
80
60
40
20
90
100
110
120
130
140
150
0
2
4
6
8
T [ЊC]
Time [h]
Fig. 3. Plots of conversion of cellobiose (|) and yield of glucose (
versus reaction temperature, pH 4.0, 6 h.
ꢁ
)
Fig. 4. Plots of conversion of cellobiose versus reaction time at pH 4.0 and
1308C.
Reaction Kinetics
Conversion of cellobiose
Yield of glucose
100
The varieties of conversion of cellobiose and yield of glucose
with time at pH 4.0 and 1308C are shown in Fig. 4 and Fig. S4
(Supplementary Material). From Fig. 4, it can be seen that the
80
conversion of cellobiose could reach 95.3 % after a 6 h reaction
time at 1308C, and it can also be found that the catalytic
conversion of cellobiose showed an apparent first-order kinetic
process. The solid curve fitted according to first-order kinetics
was in agreement with experimental data, as shown in Fig. 4.
Glucose will be generated and subsequently degrade slowly
with time, which leads to the decrease of yield of glucose after
6
0
0
4
20
0
6 h (Fig. S4). Based on the reaction kinetic characteristics,
the apparent first-order kinetic constant (kobs) can be calculated.
Hence, the activation energy (E ) for conversion of cellobiose
a
1
2
3
4
5
ꢀ
1
was evaluated as 88.3 kJ mol according to the Arrhenius plot
of ln kobs versus 1/T, as shown in Fig. S5 (Supplementary
Material). It was reported that the activation energy (Ea)
of the hydrolysis of cellulose was in the range of
Number of repeats
Fig. 5. DMNC cycle for cellobiose hydrolysis.
ꢀ
1 [39–41]
1
10–260 kJ mol
.
The E value of the catalytic reaction
a
was less than those reported, which indicated that the DMNC
particles were an excellent catalyst for the breakage of the
b-1,4-glycosidic bonds under relatively mild conditions.
and 53.9 % (m/m), respectively, after 10 h of reaction at pH 4.0
and 1308C. The yields of total reducing sugar for the hydrolysis
of filter paper and MCC were detected as 49.2 and 45.7 %. The
selectivity of total reducing sugar was 81.5 and 84.8 %.
The results displayed that the DMNC can efficiently catalyse
the hydrolysis of cellulose by hydrolytic breakage of the b-1,4-
glycosidic bond under mild conditions. Comparably, the
hydrolysis of cellulose usually needs a high temperature because
of the high activation energy of the reaction and thus results in
further degradation of reducing sugars under high temperature
Reusability of DMNC
The reusability of the DMNC was investigated in the hydrolysis
of cellobiose for a reaction time of 6 h at pH 4.0 and 1308C. After
each reaction, the DMNC catalyst was separated from the
reaction mixture using an external magnet. The used catalyst
was washed with water and dried in a vacuum oven at 608C for
[42,43]
1
2 h. The recovered DMNC was then used for the next reaction
conditions. In this study, we suggest a green technology to
achieve a satisfactory reducing sugar yield under relatively mild
run under the same conditions. As depicted in Fig. 5, no obvious
decrease in catalytic activity was observed after five successive
reaction runs. The yield of glucose was still more than 85 %,
suggesting that DMNC exhibited excellent catalytic stability
and recyclability.
conditions by using
nanocatalyst.
a recyclable functional magnetic
Conclusions
A novel difunctional magnetic nanocatalyst with o-chlor-
ophenol and benzene sulfonate active groups was prepared and
used to catalyse the hydrolysis of cellobiose and cellulose under
relatively mild conditions. The DMNC displayed excellent
catalytic activity for the hydrolysis of cellobiose to glucose. The
conversions of cellobiose and yield of glucose were 95.3 and
91.1 %, respectively, for a reaction time of 6 h at pH 4.0 and
1308C. MCC can also be efficiently hydrolyzed. MCC was
Hydrolysis of Cellulose
The good catalytic ability of the nanocatalyst for the hydrolytic
breakage of b-1,4-glycosidic bonds encouraged us to further
investigate the catalytic hydrolysis of cellulose. We employed
DMNC to catalyse the hydrolysis of pretreated cellulose filter
paper and microcrystalline cellulose (MCC). The experimental
results showed that filter paper and MCC were dissolved at 60.4

F
R.-Q. Yang et al.
degraded by 53.9 % and 45.7 % reducing sugar was achieved at
pH 4.0 and 1308C for 10 h. Compared with previously reported
studies, the prepared nanocatalyst displayed several advantages
for the hydrolysis of cellobiose, such as a higher conversion of
cellobiose, yield of glucose, and less by-products achieved
at low temperature (1308C) and high pH (4.0). The nanocatalyst
is effective for the hydrolytic cleavage of b-1,4-glycosidic
bonds in both cellobiose and cellulose. The activation energy
stirring in a water bath at 508C and quenched by cooling in ice-
water. Subsequently, the mixture was poured into 150 mL of
deionized water with vigorous stirring. The formed precipitate
was collected by filtration. The solid sample was washed with
deionized water and acetone. Finally, the solid sample was
vacuum dried at 508C for 12 h. The Whatman 42 filter paper
was pretreated using the procedures above.
For the hydrolysis of cellulose, the initial reaction solution
containing 0.2 g of pretreated cellulose, 43.6 mg of catalyst, and
12.5 mL of deionized water was sealed and heated at pH 4.0.
ꢀ
1
for hydrolysis of cellobiose was evaluated as 88.3 kJ mol
.
The magnetic catalyst could be easily separated and reused
without significant loss of catalytic activity five times. This
work provided an environmentally friendly method for the
efficient hydrolysis of cellulose.
Before sealing, N gas was passed into the solution for 30 min.
2
The pH of the solution was adjusted with H SO or NaOH. After
2
4
10 h of reaction, the magnetic catalyst was recovered by
magnetic separation. The reaction mixture was centrifuged
and the solid was vacuum dried and weighed. The centrifuged
solution was analysed, and the concentration of total reducing
Experimental
Materials and Instruments
sugar (CTRS) in the solution was quantified by the dinitrosa-
[45,46]
b-D-(þ)-Cellobiose was of biological grade and purchased
licylic acid (DNS) method with a spectrophotometer.
carbon basis, the dissolution of cellulose D was calculated as
On a
from the J&K Corp. Co. 3-Isocyanatopropyl triethoxysilane,
-chloro-4-hydroxyaniline, sodium sulfanilate, fructose, glu-
3
0
D ¼ (m – m )/m . The yield of total reducing sugar (TRS) was
0
0
cose, sucrose, maltose, ferric chloride hexahydrate, ferrous
sulfate heptahydrate, trisodium citrate dihydrate, ammonium
hydroxide, and tetraethyl orthosilicate were purchased from the
Kelong Reagent Co., and all of the reagents were of analytical
grade and used after relevant purification. Acetonitrile was of
chromatographically pure grade and purchased from the
AdamasCo. Whatman 42 filterpaperwaspurchased from theGE
Healthcare Companies. MCC and phosphoric acid (85 %) were
purchased from the Aladdin Biochemical Technology Co., Ltd
The methods used for characterization and reaction/product
analysis include: NMR spectroscopy (AM-400, Bruker,
Switzerland), TEM (JEM-2010, Japan Electron Optics
Laboratory), VSM (MPMS3, Quantum Design, America),
FT-IR spectroscopy (670FT-IR, Nicolet, America), UV-vis
spectroscopy (UV-5300 spectrophotometer, Yuanxi Co.,
China), elemental analysis (Euro-EA-3000, America), and
high-performance liquid chromatography (HPLC, LC-10T,
Shodex, Japan, with an RI detector (RI-201R, Shodex, Japan)
and a sugar-D chromatographic column).
calculated as TRS ¼ C V M/m . The selectivity of total
TRS
0
0
0
reducing sugar S was calculated as S ¼ TRS/D, where m , m
0
are the quality of cellulose at reaction time t ¼ 0 and 10 h,
respectively, M is the relative molecular mass of glucose units in
cellulose (M ¼ 162), and V is the initial volume of the reaction
0
solution.
Preparation of the Magnetic Nanocatalyst
Syntheses of 1-(3-Chloro-4-hydroxyphenyl)-3-(3-
(
(
triethoxysilyl)propyl)urea (1) and Sodium 4-(3-(3-
Triethoxysilyl) propyl)ureido)benzenesulfonate (2)
The synthesis of 1 is as follows: 3-isocyanatopropyl triethox-
ysilane (12 mmol) was added dropwise to 75 mL of CHCl3
containing 3-chloro-4-hydroxyaniline (10 mmol) with stirring at
room temperature. The mixture was then heated and refluxed for
1
0 h at 808C and then cooled to room temperature. The product
was separated by silica gel column chromatography, and a
lavender crystalline product was obtained. Its identity was
1
confirmed by H NMR spectroscopy. dH (400 MHz, DMSO)
9
(
.60 (s, 1H), 8.22 (s, 1H), 7.51 (s, 1H), 6.97 (d, J 8.8, 1H), 6.82
d, J 8.7, 1H), 6.08 (s, 1H), 3.74 (q, J 7.0, 6H), 3.02 (dd, J 12.9,
Methods
The initial reaction solution, containing 0.1746 g cellobiose,
8
6
2
.7, 2H), 1.51–1.40 (m, 2H), 1.15 (t, J 7.0, 9H), 0.54 (t, J 8.4,
H).
[47]
Compound 2 was prepared according to the literature.
7.3 mg catalyst, and 25 mL of deionized water, was sealed and
heated and kept at the desired temperature. Before sealing, N2
gas was passed into the solution for 30 min. The magnetic
catalyst was recovered by magnetic separation, washed, and
vacuum dried. Concentrations of cellobiose, glucose, fructose,
and other products in the reaction solution were determined
quantitatively by HPLC with an external standard method by
comparing to a standard sample. The pH was adjusted with
H SO or NaOH. On a carbon basis, the conversion of cellobiose
1
Its identity was confirmed by H NMR spectroscopy. dH
(400 MHz, DMSO) 8.48 (s, 1H), 7.44 (d, J 8.6, 2H), 7.31
(d, J 8.6, 2H), 6.22 (t, J 5.6, 1H), 3.75 (q, J 7.0, 6H), 3.04
(dd, J 12.9, 6.7, 2H), 1.53–1.42 (m, 2H), 1.15 (t, J 7.0, 9H), 0.57
(dd, J 16.6, 8.0, 2H).
2
4
Preparation of DMNC
X was calculated as X ¼ (C – C )/C . The yield of the mono-
0
t
0
saccharide Y was calculated as Y ¼ C /2C . The yield of
Fe O @SiO nanoparticles (0.5 g) were ultrasonically dispersed
3
1
1
1t
0
4
2
sucrose Y was calculated as Y ¼ C /C . The selectivity
in methanol (30 mL). A methanol solution containing 1 (0.22 g
in 20 mL) and 20 mL of a methanol solution containing 2
(0.25 g) were added dropwise into the nanoparticle containing
solution with stirring at room temperature. The mixture was
heated and refluxed for 8 h at 808C. It was then cooled to room
temperature. The solid catalyst was separated from the methanol
solution by magnetic adsorption with a magnet. The functional
magnetic nanocatalyst was washed with methanol and dried in a
vacuum dryer for 12 h at 608C. The preparation DMNC is
illustrated in Scheme 1.
2
2
2t
0
of glucose S was calculated as S ¼ Y /X, where C , C are the
1
0
t
concentrations of cellobiose at reaction times t ¼ 0 and t,
respectively, and C , C are the concentrations of the mono-
1
t
2t
saccharide and sucrose at time t, respectively.
The cellulose was pretreated with a modified method from
the literature as follows: 1 mL of deionized water and 3 g of
MCC were added into a 50 mL round-bottomed flask. Phospho-
ric acid (30 mL of 85 %) was then slowly added to the flask with
stirring. The decrystallization was carried out for 10 h with
[44]

Hydrolysis of b-1,4-Glycosidic Bond by DMNC
G
To investigate the content of grafted functional groups on the
magnetic nanocatalyst, the contents of N and S (1.41 % N,
[19] M. Chen, L. You, H. J. Zhang, Z. H. Ma, Catal. Lett. 2016, 146, 2165.
doi:10.1007/S10562-016-1842-2
20] T.-D. Nguyen, H.-D. Nguyen, P.-T. Nguyen, H.-D. Nguyen, Mater.
[
0
amount of benzene sulfonate grafted on the magnetic nanoca-
.83 % S) were quantified by elemental analysis. Thus, the
Trans. 2015, 56, 1434. doi:10.2320/MATERTRANS.MA201539
[21] C. Zhang, H. Wang, F. Liu, L. Wang, H. He, Cellulose 2013, 20, 127.
ꢀ1
talyst was calculated as 0.26 mmol g and that of o-chlorophe-
ꢀ
1
.
doi:10.1007/S10570-012-9839-5
22] Y. Xiong, Z. Zhang, X. Wang, B. Liu, J. Lin, Chem. Eng. J. 2014, 235,
nol was 0.24 mmol g
[
3
49. doi:10.1016/J.CEJ.2013.09.031
Supplementary Material
[23] X. Liu, Q. Xu, J. Liu, D. Yin, S. Su, H. Ding, Fuel 2016, 164, 46.
doi:10.1016/J.FUEL.2015.09.086
24] H. S. Chae, S. D. Kim, S. H. Piao, H. J. Choi, Colloid Polym. Sci. 2016,
Other experimental procedures, experimental results, and
characterization data are available on the Journal’s website.
[
[
[
[
[
[
[
2
94, 647. doi:10.1007/S00396-015-3818-Y
25] L. Chen, Z. Xu, H. Dai, S. Zhang, J. Alloys Compd. 2010, 497, 221.
doi:10.1016/J.JALLCOM.2010.03.016
26] L. Hu, Z. Li, Z. Wu, L. Lin, S. Y. Zhou, Ind. Crops Prod. 2016, 84, 408.
doi:10.1016/J.INDCROP.2016.02.039
27] S. Shen, B. Cai, C. Wang, H. Li, G. Dai, H. Qin, Appl. Catal. A Gen.
Conflicts of Interest
The authors declare no conflicts of interest.
Acknowledgements
2014, 473, 70. doi:10.1016/J.APCATA.2013.12.037
28] T.-C. Su, Z. Fang, F. Zhang, J. Luo, X.-K. Li, Sci. Rep. 2015, 5, 17538.
doi:10.1038/SREP17538
29] H. Guo, Y. Lian, L. Yan, X. Qi, R. L. Smith, Green Chem. 2013,
The authors gratefully acknowledge financial support from the National
Natural Science Foundation of China (No. 21273156).
1
5, 2167. doi:10.1039/C3GC40433A
References
30] S. Liu, Y.-J. Liu, F. Deng, M.-G. Ma, J. Bian, RSC Adv. 2015, 5, 74198.
[
[
[
[
[
[
[
[
[
1] E. J. Cho, S. J. Lee, K. Lee, D.-S. Lee, Y. J. Lee, H.-J. Bae, BioEnergy
doi:10.1039/C5RA12440A
[31] L.-C. Tsai, L.-F. Shyur, Y.-S. Cheng, S.-H. Lee, J. Mol. Biol. 2005,
Res. 2015, 8, 788. doi:10.1007/S12155-014-9559-9
2] Z. Yang, R. Huang, W. Qi, L. Tong, R. Su, Z. He, Chem. Eng. J.
354, 642. doi:10.1016/J.JMB.2005.09.041
(
Amsterdam, Neth.) 2015, 280, 90.
3] Y. Zhu, C. Romain, C. K. Williams, Nature 2016, 540, 354. doi:10.
038/NATURE21001
[32] T. M. Gloster, J. M. Macdonald, C. A. Tarling, R. V. Stick, S. G.
Withers, G. J. Davies, J. Biol. Chem. 2004, 279, 49236. doi:10.1074/
JBC.M407195200
[33] J. R. K. Cairns, A. Esen, Cell. Mol. Life Sci. 2010, 67, 3389.
doi:10.1007/S00018-010-0399-2
[34] J. Sun, X. Liu, X. L. Zhu, H. Wang, S. Rostamnia, J. Y. Han, Catalysts
1
4] L. Vanoye, M. Fanselow, J. D. Holbrey, M. P. Atkins, K. R. Seddon,
Green Chem. 2009, 11, 390. doi:10.1039/B817882H
5] J. Baeyens, Q. Kang, L. Appels, R. Dewil, Y. Lv, T. Tan, Pror. Energy
Combust. Sci. 2015, 47, 60. doi:10.1016/J.PECS.2014.10.003
6] R. Vinu, L. J. Broadbelt, Energy Environ. Sci. 2012, 5, 9808.
doi:10.1039/C2EE22784C
7] O. L. Li, R. Ikura, T. Ishizaki, Green Chem. 2017, 19, 4774.
doi:10.1039/C7GC02143G
8] N. A. S. Ramli, N. A. S. Amin, J. Mol. Catal. Chem. 2015, 407, 113.
doi:10.1016/J.MOLCATA.2015.06.030
2017, 7, 127. doi:10.3390/CATAL7050127
[35] G. S. Foo, A. H. Van Pelt, D. Krotschel, B. F. Sauk, A. K. Rogers,
C. R. Jolly, M. M. Yung, C. Sievers, ACS Sustain. Chem. & Eng. 2015,
3, 1934. doi:10.1021/ACSSUSCHEMENG.5B00530
[36] L. P. Zhou, Z. Liu, Y. Q. Bai, T. L. Lu, X. M. Yang, J. Xu, J Energy
Chem. 2016, 25, 141. doi:10.1016/J.JECHEM.2015.11.010
[37] D.-m. Lai, L. Deng, Q.-x. Guo, Y. Fu, Energy Environ. Sci. 2011, 4,
3552. doi:10.1039/C1EE01526E
9] D. L. Ollis, J.-W. Liu, B. J. Stevenson, Aust. J. Chem. 2012, 65, 652.
doi:10.1071/CH11452
[38] H. Kobayashi, T. Komanoya, K. Hara, A. Fukuoka, ChemSusChem
[
10] L. R. Lynd, M. S. Laser, D. Bransby, B. E. Dale, B. Davison, R.
Hamilton, M. Himmel, M. Keller, J. D. McMillan, J. Sheehan, Nat.
Biotechnol. 2008, 26, 169. doi:10.1038/NBT0208-169
2010, 3, 440. doi:10.1002/CSSC.200900296
[39] S. Suganuma, K. Nakajima, M. Kitano, D. Yamaguchi, H. Kato, S.
Hayashi, M. Hara, J. Am. Chem. Soc. 2008, 130, 12787. doi:10.1021/
JA803983H
[
[
[
[
[
11] X.-H. Liao, Y. Liu, X. Peng, C. Mi, X.-G. Meng, Catal. Lett. 2016, 146,
1
249. doi:10.1007/S10562-016-1745-2
12] L. Hu, Z. Wu, J. Xu, S. Zhou, G. Tang, Korean J. Chem. Eng. 2016, 33,
232. doi:10.1007/S11814-015-0267-8
13] B. Cinlar, T. F. Wang, B. H. Shanks, Appl. Catal. A Gen. 2013, 450,
37. doi:10.1016/J.APCATA.2012.10.013
14] S. L. Hu, T. J. Smith, W. Y. Lou, M. H. Zong, J. Agric. Food Chem.
014, 62, 1905. doi:10.1021/JF405712B
[40] S. M. Shaik, C. Y. Koh, P. N. Sharratt, R. B. H. Tan, Thermochim. Acta
2013, 566, 1. doi:10.1016/J.TCA.2013.05.003
[41] L. Shuai, X. Pan, Energy Environ. Sci. 2012, 5, 6889. doi:10.1039/
C2EE03373A
[42] M. J. Antal, G. Varhegyi, Ind. Eng. Chem. Res. 1995, 34, 703.
doi:10.1021/IE00042A001
[43] L. J. J o¨ nsson, C. Mart ´ı n, Bioresour. Technol. 2016, 199, 103.
doi:10.1016/J.BIORTECH.2015.10.009
1
2
2
15] K. L. Zhuo, Q. Z. Du, G. Y. Bai, C. Y. Wang, Y. J. Chen, J. J. Wang,
Carbohydr. Polym. 2015, 115, 49. doi:10.1016/J.CARBPOL.2014.
[44] J. Zhang, B. Zhang, J. Zhang, L. Lin, S. Liu, P. Ouyang, Biotechnol.
Adv. 2010, 28, 613. doi:10.1016/J.BIOTECHADV.2010.05.010
[45] R. Hu, L. Lin, T. Liu, P. Ouyang, B. He, S. Liu, J. Biobased Mater.
Bioenergy 2008, 2, 156. doi:10.1166/JBMB.2008.306
08.078
[
[
[
16] M. Mizuno, S. Kachi, E. Togawa, N. Hayashi, K. Nozaki, T. Itoh,
Y. Amano, Aust. J. Chem. 2012, 65, 1491. doi:10.1071/CH12342
17] L. K. Tolonen, P. A. Penttila, R. Serimaa, H. Sixta, Cellulose 2015, 22,
¨
[46] K. S. Ba s- kan, E. T u¨ tem, E. Aky u¨ z, S. Ozen, R. Apak, Talanta 2016,
1
715. doi:10.1007/S10570-015-0628-9
18] D. A. Cantero, M. D. Bermejo, M. J. Cocero, ChemSusChem 2015, 8,
026. doi:10.1002/CSSC.201403385
147, 162. doi:10.1016/J.TALANTA.2015.09.049
[47] M. Michau, M. Barboiu, J. Mater. Chem. 2009, 19, 6124. doi:10.1039/
B908680C
1