Controllable synthesis of chainlike hierarchical ZSM-5 templated by sucrose and its catalytic performance

Article abstract of DOI:10.1016/j.catcom.2015.12.002

Hierarchical ZSM-5 with controllable chainlike structure was hydrothermally synthesized with sucrose as template, characterized by XRD, FT-IR, N₂ adsorption, SEM and TEM, and used for methylation of 2-methylnaphthalene. Hierarchical ZSM-5 can be rapidly synthesized, and chainlike morphology is stacked with several submicron crystals. With increasing sucrose amount in the precursor, the chain structure became more obvious, and the surface area and pore volume of mesopores increased. Narrow mesoporous distribution was centered at about 7 nm. It is thought that the formation of mesopores is related to the template role of sucrose. Chainlike hierarchical ZSM-5 exhibited high 2-methylnaphthalene conversion and 2,6-dimethylnaphthalene yield.

Full text of DOI:10.1016/j.catcom.2015.12.002

Controllable synthesis of chainlike hierarchical ZSM-5 templated by sucrose
and its catalytic performance
Lijun Jin, Tong Xie, Sibao Liu, Yexin Li, Haoquan Hu
PII:
DOI:
Reference:
S1566-7367(15)30156-4
doi: 10.1016/j.catcom.2015.12.002
CATCOM 4519
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
14 August 2015
13 October 2015
1 December 2015
Please cite this article as: Lijun Jin, Tong Xie, Sibao Liu, Yexin Li, Haoquan Hu, Con-
trollable synthesis of chainlike hierarchical ZSM-5 templated by sucrose and its catalytic
performance, Catalysis Communications (2015), doi: 10.1016/j.catcom.2015.12.002
This is a PDF file of an unedited manuscript that has been accepted for publication.
As a service to our customers we are providing this early version of the manuscript.
The manuscript will undergo copyediting, typesetting, and review of the resulting proof
before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that
apply to the journal pertain.

ACCEPTED MANUSCRIPT
Controllable synthesis of chainlike hierarchical ZSM-5 templated by sucrose and its
catalytic performance
Lijun Jin, Tong Xie, Sibao Liu, Yexin Li, Haoquan Hu*
State Key Laboratory of Fine Chemicals, Institute of Coal Chemical Engineering, School of Chemical
Engineering, Dalian University of Technology, Dalian 116024, China.
Abstract
Hierarchical ZSM-5 with controllable chainlike structure was hydrothermally synthesized with sucrose as
template, characterized by XRD, FT-IR, N2 adsorption, SEM and TEM, and used for methylation of
2-methylnaphthalene. Hierarchical ZSM-5 can be rapidly synthesized, and chainlike morphology is stacked
with several submicron crystals. With increasing sucrose amount in the precursor, the chain structure became
more obvious, and the surface area and pore volume of mesopores increased. Narrow mesoporous distribution
was centered at about 7 nm. It is thought that the formation of mesopores is related to the template role of
sucrose. Chainlike hierarchical ZSM-5 exhibited high 2-methylnaphthalene conversion and
2,6-dimethylnaphthalene yield.
Keywords: hierarchical ZSM-5; sucrose; chainlike; 2-methylnaphthalene; 2,6-dimethylnaphthalene
1.Introduction
Zeolite has been widely used in industry as catalysts for its unique properties, such as high surface area,
acidity, and shape selectivity, especially in the fields of oil refining and petrochemistry [1]. However, the
* Corresponding author. Tel. & Fax: +86-411-84986157
E-mail: hhu@dlut.edu.cn (Haoquan Hu)

ACCEPTED MANUSCRIPT
micropores in zeolites often impose diffusion limitations that restrict accessibility to the internal surface of
zeolites, especially when bulky molecules are involved [2]. To overcome these problems, one of the most
promising ways is to prepare composites containing mesopores as well as micropores. These hierarchical
materials, which combine the advantages of both zeolites and mesoporous materials, exhibit fast diffusion
rates and many exposed active acidic sites [3-7]. For example, in synthesis of 2,6-dimethylnaphthalene
(2,6-DMN) by methylation of 2-methylnaphthalene (2-MN), it was found that catalytic activity and stability
could be significantly improved when some mesopores were introduced into ZSM-5 [6]. Templating methods
are widely used to synthesize mesoporous materials [8-10]. Therefore, the cost of template and synthesis
process should be considered in industrial application.
Sucrose is often chosen as a template for the synthesis of hierarchical zeolite owing to its low cost. Kustova
et al. [11] reported that mesopore ZSM-5 and ZSM-11 could be synthesized by mixing silica gel with
different concentration solutions of sucrose, carbonization, and crystallization through impregnating a
structure-directing agent. Tong et al. [12] reported that monolithic zeolite BEA could be synthesized using the
same method as that of Kustova et al. Zhu et al. [13] prepared the mesopore Silicate-1 by using porous carbon
from sucrose as the template. Wang et al. [14,15] synthesized hierarchical TS-1 directly using sucrose as the
meso/macroporous template by dry gel conversion. However, these processes generally need a long reaction
time and several steps to prepare mesoporous zeolite. Here we report a rapid, convenient method to fabricate
hierarchical ZSM-5 with a chainlike morphology by using sucrose as the template, and the effect of the
sucrose amount on the structure of hierarchical ZSM-5 and catalytic performance in synthesis of 2,6-DMN by
methylation of 2-MN with methanol was examined.
2. Experimental
2.1 Synthesis of chainlike hierarchical ZSM-5 zeolites

ACCEPTED MANUSCRIPT
Chainlike hierarchical ZSM-5 was synthesized by hydrothermal crystallization. The detailed synthesis
procedure is as follows: tetrapropylammonium hydroxide (TPAOH, 25 wt%, aq; YueyangYutai Chemical
Technology Development Co., Ltd., China), sodium aluminate (NaAlO2, Sinopharm Chemical Reagent Co.,
Ltd.) and distilled water were first mixed and stirred for 30 min until a clear solution is obtained. Then
tetraethyl orthosilicate (TEOS, Sinopharm Chemical Reagent Co., Ltd.) was dropwise added to the solution
under stirring and agitated for 2 h until a clear gel was obtained. The composition of the resultant precursor is
1SiO2/0.011Al2O3/0.25TPAOH/30H2O. Finally, different amounts of sucrose were added to the mixture, and
o
agitated for another 2 h. The precursor was charged into a stainless-steel autoclave and crystallized at 170 C
o
for 72 h. The products were filtered, washed with deionized water, dried at 120 C and calcined at 550 oC for
10 h. Zeolites synthesized with different amounts of sucrose were denoted as MZSM-5(x) (x=0-2.0), where x
represents the mass ratio of sucrose to SiO2.
To investigate the effect of crystallization time on the structure, the precursor with a ratio of sucrose to
o
SiO2 of 2.0 was crystallized at 170 C for 4 h or 8 h. The products were expressed as MZSM-5(2.0)-4h and
MZSM-5(2.0)-8h, respectively.
2.2 Characterizations
X-ray diffraction (XRD) patterns of the samples were obtained on a D/Max2400 diffractor (Rigaku) with
CuKα radiation at 40 kV and 40 mA. FT-IR spectra of the structure band region (1400-400 cm-1) were
investigated on an EQUINOX55 spectrometer. The framework SiO2/Al2O3 molar ratio was determined by
XRF spectroscopy on a SRS3400X instrument after the sample was washed with 1 M HCl at 80 oC for 4 h to
remove extra-framework aluminum. BET specific surface area of the samples was determined by nitrogen
o
o
adsorption using ASAP 2020 apparatus at -196 C. The samples were outgassed at 300 C for 2 h prior to
adsorption. Scanning electron microscopy (SEM) studies were performed on a FEI NOVA NanoSEM 450

ACCEPTED MANUSCRIPT
instrument. Transmission electron microscope (TEM) images were recorded with a Philips Tecnai G2 20
operated at 200 kV.
2.3 Catalytic reaction
Methylation of 2-MN with methanol on ZSM-5 was used as the probe reaction and carried out in a
fixed-bed micro-reactor of 10 mm-i-d under atmospheric pressure. About 0.67 g catalyst was first activated at
o
o
500 C for 2 h under N2 flow, and then cooled down to 400 C. The liquid reactants including 2-MN,
methanol and mesitylene (as the solvent) in molar ratio of 1:5:3 were introduced into the reactor by a metering
pump and preheated before passing to the reactor in 10 ml/min N2 flow. The weight hourly space velocity of
2-MN was 0.5 h-1. The products were analysed by a FID-type gas chromatogram with a 30 m TCIcaps DMN
capillary column. 2-MN conversion, 2,6-DMN selectivity and 2,6-DMN yield were calculated by the method
of ref. [16].
3. Results and discussion
3.1 Structure of hierarchical ZSM-5 zeolites
Fig.1 shows the XRD patterns of the samples synthesized with different amounts of sucrose. All the
samples showed the typical peaks of MFI structure, and no amorphous aluminosilicate was detected. Almost
the same relative intensities were obtained on the MZSM-5(x) shown in Fig.1a, indicative of high crystallinity,
which can be further confirmed by FT-IR spectra in Fig.1c. The FT-IR spectra of MZSM-5(x) samples clearly
showed the presence of a band at 550 cm-1 assigned to the asymmetric stretching mode of double
five-membered rings of MFI-type zeolites, and the optical density ratio (ODR) of the 550 and 450 cm-1 bands
was above 0.7 in all samples, suggesting high crystallinity of the MFI structure of MZM-5(x) [17].
Additionally, Fig.1b also shows that ZSM-5 with high crystallinity could be obtained for a crystallization time
of only 4 h, suggesting the time-saving of this method.

ACCEPTED MANUSCRIPT
3.2 N2 adsorption/desorption
Fig.2a illustrates nitrogen adsorption/desorption isotherms of the MZSM-5(x) samples. All the samples
showed a combined types I and IV isotherms. At low relative pressure, the adsorbed amount has an obvious
increase, indicative of the existence of the micropores. The hysteresis loop at P/P0=0.6-1.0 is mainly
attributed to the capillary condensation in the open mesopores, indicating the hierarchical structure. Moreover,
the hysteresis loop becomes more obviously with the amount of sucrose in the precursor. The BJH pore
diameter distribution shown in Fig. 2c indicates that the samples prepared without or with lower ratio of
sucrose to SiO2 have broader and larger pore size distribution. With increasing the amount of sucrose, the pore
size becomes narrow and is centered at about 7 nm. As listed in Table 1, the surface area and pore volume of
the micropores decreased, whereas the mesoporous surface area and pore volume increased with increasing
sucrose-SiO2 ratio, implying that the formation of mesopores is mainly related to the sucrose.
Fig. 2b and 2d showed that the ZSM-5 sample crystallized only for 4 h was also hierarchical, with the pore
diameter distribution still centered at about 7 nm. Short crystallization time had no obvious effect on
mesoporous dimensions.
3.3 SEM and TEM images
The SEM images of hierarchical ZSM-5 are shown in Fig. 3. In the absence of sucrose, randomly dispersed
crystals of ZSM-5 were observed (Fig. 3a). When sucrose was added to the precursor, the chainlike
morphology of individual particles appeared (Fig. 3b), and the length of chain became more obvious and
longer as more sucrose was added (Fig. 3c to 3e). The SEM images of MZSM-5(2.0) (Fig. 3d and 3e) show
that the chainlike morphology is stacked with several submicron zeolite crystals. This stacking into chains
was sufficiently robust that it was not destroyed by sonication for 4 h (Fig.3f), indicating that this morphology
is not formed by simple aggregation but strong force between the crystals.

ACCEPTED MANUSCRIPT
TEM image (Fig. 3g) of MZSM-5(2.0) further revealed the chainlike structure and the stacking of the
building units of ZSM-5 submicron zeolite crystals. Fig. 3h shows that the chainlike morphology was formed
by stacking the crystals along the [010] direction. The zeolitic phase alternated with the mesoporous phase
(Fig. 3i and 3j), indicating the presence of hierarchical zeolite.
Based on the above results, it can be obviously obtained that the presence of sucrose in the precursor of the
zeolite is critical for the formation of the chainlike and mesoporous structure. As known, the sucrose contains
polar C-OH groups, which will interact with polar species. Therefore, it is thought that the sucrose template
can be present in forms of aggregations or assemblies of aggregations, which can interact with the
aluminosilicate species through hydrogen bonding. Such interactions may play a significant role in directing
the formation of chainlike and hierarchical structure. Moreover, the hydrothermal condition is not only
preferable to the crystallization of aluminosilicate species, but also to the carbonization of the sucrose in some
extent[15-16]. That is, the sucrose may play the roles of both soft and solid templates in the formation of
hierarchical ZSM-5.
3.4 Methylation of 2-MN
2,6-DMN, a precursor of 2,6-naphthalenedicarboxylic acid in the synthesis of polyethylenenaphthalate,
can be synthesized by methylation of 2-MN with methanol over ZSM-5 for its moderate acid, suitable pore
sizes and high selectivity [18,19]. Therefore, catalytic performances of MZSM-5(x) samples in synthesis of
2,6-DMN were investigated. MZSM-5(0) exhibited the lowest catalytic activity than other MZSM-5(x)
samples (Fig.4a) despite the most acidic amount (Fig.4b). The results in NH3-TPD profiles show that the total
acidic amount of MZSM-5(x) decreased with increasing sucrose amount, suggesting that the addition of
sucrose to the precursor is unprofitable to the incorporation of Al into the framework of ZSM-5, which can be
further confirmed by the increasing framework SiO2/Al2O3 ratio of MZSM-5(x) samples shown in Table 1.

ACCEPTED MANUSCRIPT
Less incorporation of Al and the formation of non-framework Al resulted in a decrease in total acidity.
Therefore, higher 2-MN conversion on chainlike ZSM-5 is mainly related to the existence of mesopores. The
mespores can decrease the diffusion resistances of reactants and products into and out the pore channels, and
provide many exposed active sites. Especially, 2-MN conversion remains above 20% after 10 h when
sucrose/SiO2 ratio is 0.5. MZSM-5(1.0) exhibited better catalytic stability. However, less acidic amount on
MZSM-5(2.0) contributes to low 2-MN conversion despite its more mesopores.
Fig.4c shows that MZSM-5(0) has the highest selectivity to 2,6-DMN, and chainlike ZSM-5 synthesized
with sucrose have lower 2,6-DMN selectivity. Since 2,6-DMN synthesis by the methylation of 2-MN with
methanol is a shape-selective reaction, the existence of mesopores is not beneficial to improve the selectivity
[6]. Moreover, 2,6-DMN selectivity on chainlike ZSM-5 samples gradually decreased with increasing the
sucrose/SiO2 ratio. However, the highest 2,6-DMN yield was obtained on chainlike MZSM-5(1.0) for its high
conversion of 2-MN (Fig.4d). Higher catalytic activities and better stability provide an opportunity for further
modification by Zr or Fe to improve the selectivity and yield of 2,6-DMN [20-22].
4. Conclusion
Chainlike hierarchical ZSM-5 was synthesized in a short time by using sucrose as template, and the chain
length and mesoporous structure of ZSM-5 can be controlled by the amount of sucrose in the precursor. This
method of adding the sucrose to the precursor of ZSM-5 is facile and effective. It is thought that the sucrose
plays an important function in driving the submicron zeolite crystals to form a chainlike structure. Chainlike
hierarchical ZSM-5 samples exhibited high catalytic activities and 2,6-DMN yield, which is related to more
mesopores.
Acknowledgements

ACCEPTED MANUSCRIPT
This work was financially supported by the National Natural Science Foundation of China (No.20276011
and 20376012).
References
[1] C.S. Cundy, P.A. Cox, Chem. Rev., 103(2003) 663-702
[2] A. Corma, Chem. Rev., 97(1997) 2373-2419
[3] C.R. Patil, P.S. Niphadkar, V.V. Bokade, P.N. Joshi, Catal. Communi., 43(2014) 188-191
[4] H.S. Cho, R. Ryoo, Micropor. Mesopor. Mater., 151(2012) 107-112
[5] K. Mlekodaj, K. Tarach, J. Datka, K. Góra-Marek, W. Makowski, Micropor. Mesopor. Mater., 183(2014)
54-61
[6] L.J. Jin, X.J. Zhou, H.Q. Hu, B. Ma, Catal. Communi., 10(2008) 336-340
[7] M. Fujiwara, A. Sakamoto, K. Shiokawa, et al. Micropor. Mesopor. Mater., 142(2011) 381-388
[8] Y.M. Fang, H.Q. Hu. J. Am. Chem. Soc., 128(2006) 10636-10637
[9] Y. Tao, H. Kanoh, L. Abrams, K. Kaneko, Chem. Rev., 106(2006) 896-910
[10] D.Y. Ok, N.Z. Jiang, E.A. Prasetyanto, S.E. Park, Micropor. Mesopor. Mater., 141(2011) 2-7
[11] M. Kustova, K. Egeblad, K. Zhu, C.H. Christensen, Chem. Mater., 19(2007) 2915-2917
[12] Y.C. Tong, T.B. Zhao, F.Y. Li, Y. Wang, Chem. Mater., 18(2006) 4218-4220
[13] K. Zhu, K. Egeblad, C.H. Christensen, Eur. J. Inorg. Chem., 25(2007) 3955-3960
[14] W.H. Wang, G. Li, L.P. Liu, Y.Y. Chen, Chin. J. Catal., 33(2012) 1236-1241
[15] W.H. Wang, G. Li, L.P. Liu, Y.Y. Chen, Micropor. Mesopor. Mater., 179(2013) 165-171
[16] L.J. Jin, S.B. Liu, T. Xie, Y.T. Ya, X.H. Guo, H.Q. Hu. Reac. Kinet. Mech. Cat., 113(2014) 575-584
[17] G. Coudurier, C. Naccache, J.C. Vedrine, J. Chem. Soc., Chem. Communi., 24(1982) 1413-1415
[18] L.J. Jin, Y.M. Fang, H.Q. Hu, Catal. Communi., 7(2006) 255-259

ACCEPTED MANUSCRIPT
[19] G. Wu, W. Wu, X. Wang, W. Zan, W.J. Wang, C. Li, Micro. Meso. Mater., 180(2013) 187-195
[20] L.J. Jin, Y.M. Fang, H.Q. Hu, Catal. Communi., 7(2006) 255-259
[21] L.J. Jin, H.Q. Hu, X.Y. Wang, C. Liu, Ind. Eng. Chem. Res., 45(2006) 3531-3536
[22] L.D. Lillwita, C. Song, WO Patent 02 060 581 (2002).

ACCEPTED MANUSCRIPT
Table 1 SiO2/Al2O3 molar ratio and textural properties of MZSM-5(x) samples
SiO2/Al2O3
molar ratio*
102
SBET
(m2/g)
405
Smic
(m2/g)
226
Sext
(m2/g)
179
Vtotal
(cm3/g)
0.32
Vmic
(cm3/g)
0.10
Vmeso
(cm3/g)
0.22
Sample
MZSM-5(0)
MZSM-5(0.5)
MZSM-5(1.0)
MZSM-5(1.5)
MZSM-5(2.0)
108
406
217
189
0.33
0.10
0.23
136
397
202
195
0.36
0.10
0.26
138
397
179
218
0.36
0.08
0.28
141
399
159
240
0.39
0.08
0.31
*: by XRF

ACCEPTED MANUSCRIPT
Figure captions
Fig.1 XRD patterns (a,b) and FT-IR spectra of MZSM-5 (x) samples
Fig.2 Nitrogen adsorption-desorption isotherms (a,b) and pore distribution (c,d) of the samples.
Fig.3 SEM images of MZSM-5(0) (a), MZSM-5(1.0) (b), MZSM-5(1.5) (c), MZSM-5(2.0) (d,e) and
MZSM-5(2.0) by sonication for 4 h (f) and TEM images (g, h, i, j) of MZSM-5(2.0) sample
Fig.4 2-MN conversion (a), NH3-TPD profiles (b), selectivity of 2,6-DMN (c) and 2,6-DMN yield (d) on
MZSM-5(x) samples

ACCEPTED MANUSCRIPT
MZSM-5(2.0)
a
c
b
MZSM-5(2.0)
MZSM-5(1.5)
MZSM-5(1.0)
MZSM-5(2.0)-8h
MZSM-5(1.0)
MZSM-5(0.5)
MZSM-5(0)
MZSM-5(0.5)
MZSM-5(2.0)-4h
MZSM-5(0)
10
20
30
40
1400
40
1200
1000
Wavenumber (cm-1)
800
600
400
10
20
30
2 (degree)
2(degree)
Fig. 1 XRD patterns (a,b) and FT-IR spectra(c) of MZSM-5 (x) samples

ACCEPTED MANUSCRIPT
300
250
200
150
100
50
a
300
b
MZSM-5(0)
MZSM-5(2)-4h
MZSM-5(2)-8h
MZSM-5(0.5)
MZSM-5(1.0)
MZSM-5(1.5)
MZSM-5(2.0)
250
200
150
100
50
0.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0
Relative pressure (P/P0)
Relative pressure (P/P )
0
0.5
0.4
0.3
0.2
0.1
0.0
c
0.5
MZSM-5(0)
d
MZSM-5(0.5)
MZSM-5(1.0)
MZSM-5(1.5)
MZSM-5(2.0)
MZSM-5(2)-4h
MZSM-5(2)-8h
0.4
0.3
0.2
0.1
0.0
1
10
Pore size (W, nm)
100
1
10
100
Pore size (W, nm)
Fig. 2 Nitrogen adsorption-desorption isotherms (a,b) and pore distribution (c,d) of the samples.

ACCEPTED MANUSCRIPT
b)
a)
d)
c)
f)
e)
g)
h)
i)
j)
Fig. 3 SEM images of MZSM-5(0) (a), MZSM-5(1.0) (b), MZSM-5(1.5) (c), MZSM-5(2.0) (d,e) and
MZSM-5(2.0) by sonication for 4 h (f) and TEM images (g, h, i, j) of MZSM-5(2.0) sample

ACCEPTED MANUSCRIPT
50
40
30
20
10
0
(a)
MZSM-5(0)
(b)
MZSM-5(0.5)
MZSM-5(1.0)
MZSM-5(2.0)
0
2
4
6
8
10
100
200
300
400
500
Time (h)
Temperature (oC)
50
40
30
20
10
0
8
(c)
(d)
6
4
2
0
0
2
4
6
8
10
2
4
6
8
10
Time (h)
Time (h)
Fig.4 2-MN conversion (a), NH3-TPD profiles (b), selectivity of 2,6-DMN (c) and 2,6-DMN yield (d) on
MZSM-5(x) samples

ACCEPTED MANUSCRIPT
Graphical abstract

ACCEPTED MANUSCRIPT
Highlights




Chainlike hierarchical ZSM-5 were synthesized by using sucrose as the template.
Chainlike morphology is stacked with several submicron zeolite crystals.
Chain length and pore structures of ZSM-5 can be tuned by added amount of sucrose.
Chainlike ZSM-5 exhibited higher conversion and 2,6-dimethylnaphthalene yield.