Dual-mesoporous ZSM-5 zeolite with highly b-axis-oriented large mesopore channels for the production of benzoin ethyl ether

Article abstract of DOI:10.1002/chem.201300245

Dual-mesoporous ZSM-5 zeolite with highly b axis oriented large mesopores was synthesized by using nonionic copolymer F127 and cationic surfactant CTAB as co-templates. The product contains two types of mesopores - smaller wormlike ones of 3.3 nm in size

Full text of DOI:10.1002/chem.201300245

FULL PAPER
DOI: 10.1002/chem.201300245
Dual-Mesoporous ZSM-5 Zeolite with Highly b-Axis-Oriented Large
Mesopore Channels for the Production of Benzoin Ethyl Ether
Xiaoxia Zhou,[a] Hangrong Chen,*[a] Yan Zhu,[a] Yudian Song,[a] Yu Chen,[a]
Yongxia Wang,[a] Yun Gong,[a] Guobin Zhang,[a] Zhu Shu,[a] Xiangzhi Cui,[a]
Jinjin Zhao,[b] and Jianlin Shi*[a]
Abstract: Dual-mesoporous ZSM-5
zeolite with highly b axis oriented large
mesopores was synthesized by using
nonionic copolymer F127 and cationic
surfactant CTAB as co-templates. The
product contains two types of meso-
pores—smaller wormlike ones of
3.3 nm in size and highly oriented
larger ones of 30–50 nm in diameter
along the b axis—and both of them in-
terpenetrate throughout the zeolite
crystals and interconnect with zeolite
microporosity. The dual-mesoporous
zeolite exhibits excellent catalytic per-
formance in the condensation of benz-
AHCTUNGTRENNaGUN ldehyde with ethanol and greater than
99% selectivity for benzoin ethyl ether
at room temperature, which can be as-
cribed to the zeolite lattice structure
offering catalytically active sites and
the hierarchical and oriented mesopo-
rous structure providing fast access of
reactants to these sites in the catalytic
reaction. The excellent recyclability
and high catalytic stability of the cata-
lyst suggest prospective applications of
such unique mesoporous zeolites in the
chemical industry.
Keywords: heterogeneous catalysis ·
hydrothermal synthesis · mesopo-
rous materials · template synthesis ·
zeolites
Introduction
limited owing to their inherent problems. For example, the
difficulty of separating nanosized zeolite particles from a re-
action mixture and the facile formation of aggregates of
nanosized zeolites during synthesis and catalytic reactions
would hinder practical applications of nanosized zeolites.
The relatively low thermal stability of ordered mesoporous
materials is also unfavorable for practical catalytic processes.
Alternatively, the concept of hierarchically porous zeolites
was proposed in recent years, and opens up a new mode of
heterogeneous catalysts.[6] The successful fabrication of hier-
archically porous zeolite can efficiently solve the problems
associated with nanosized zeolites, large-pore zeolites, and
mesoporous materials.[7] Hierarchically porous zeolites inte-
grate at least two levels of porosity, that is, micro/mesopores
and/or micro/meso/macropores.[8] However, the macropores
(>50 nm) in zeolites contribute little to the surface area and
will easily collapse during heat treatment. Therefore, hier-
archically porous zeolites containing an interpenetrating
micro/mesoporous system are more practical and favorable
for efficient solid acid catalysts.
Zeolite ZSM-5, a heterogeneous solid acid catalyst with
MFI cages connected by 10-ring micropores, has been
widely used in the fields of oil refining and petrochemistry.[1]
However, the limited dimensions of the micropores not only
strongly hinder the diffusion of large molecules, but can sig-
nificantly slow down mass transport to and from active sites
located within the micropores. This major drawback can
strongly restrict its catalytic performance in various industri-
al reactions, for example, cracking, oxidation, alkylation, es-
terification, and isomerization.[2] Great efforts to overcome
these problems have been made over the past years, such as
the synthesis of nanosized zeolites,[3] large-pore zeolites,[4]
and ordered mesoporous materials (e.g., MCM-41 and SBA-
15).[5] However, up to now, the use of these materials is still
[a] Dr. X. Zhou, Prof. H. Chen, Dr. Y. Zhu, Y. Song, Dr. Y. Chen,
Dr. Y. Wang, Dr. Y. Gong, Dr. G. Zhang, Dr. Z. Shu, Dr. X. Cui,
Prof. J. Shi
State Key Laboratory of High Performance Ceramics and
Superfine Microstructures, Shanghai Institute of Ceramics
Chinese Academy of Sciences, 1295 Ding-xi Road
Shanghai 200050 (P. R. China)
Fax: (+86)21-5241-3122
E-mail: hrchen@mail.sic.ac.cn
Many surfactants have been used as templates for creating
inter/intracrystalline mesoporosity in zeolites. For example,
Schuth et al. synthesized mesoporous silicalite-1 zeolite by
using an organic aerogel as a “soft” template.[9] Xiao et al.
prepared hierarchically structured zeolites templated by cat-
ionic polymers.[6b,10] Notably, these mesopores are randomly
oriented in zeolite crystals, and the synthesis of hierarchical-
ly porous zeolite containing dual mesoporosity has not been
reported yet. Therefore, the synthesis of dual-mesoporous
zeolite ZSM-5 and control of mesopore orientation in zeo-
lites continue to be a great challenge. It is believed that the
jishi@mail.sic.ac.cn
[b] Dr. J. Zhao
School of Material Science and Engineering
Shijiazhuang Tiedao University
17 Northeast, Second Inner Ring, Shijiazhuang, Hebei (P. R. China)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201300245.
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interconnected bimodal and/or oriented mesopore system
can further facilitate the diffusion and transport of reactant/
product molecules in catalytic reactions. In addition, it is
still difficult to prepare mesoporous zeolite by using conven-
tional amphiphilic copolymers as templates because of the
weak interaction between the copolymers and silica species
in basic media. Therefore, the real difficulty in the synthesis
of oriented dual-mesoporous zeolites is to understand the
assembly mechanism among different template molecules
and silicon/aluminum sources, and how to achieve an elabo-
rate balance between zeolite crystallization and mesoporous
phase formation, so that crystallization/growth of zeolite
particles can be controlled to a certain degree to match the
assembly of the mesoporous phase.[11]
types of mesopores are present throughout the whole zeolite
crystals and form a highly interpenetrating and uniform
porous network. Interestingly, the larger mesopores grow
with a preferred orientation in the zeolite crystals. Zeolite
ZSM-5-ODM not only provides free diffusion pathways for
large molecules and thus fast access to active zeolite sites,
but also shows high thermal stability owing to the well-crys-
tallized framework. As a heterogeneous solid acid catalyst,
ZSM-5-ODM exhibits excellent catalytic properties in the
conversion of benzaldehyde with high selectivity for benzoin
ethyl ether at room temperature. Moreover, the results of
cycle tests on the catalyst demonstrate that the catalytically
active sites can be regenerated by a simple calcination proc-
ess.
Benzoin ethyl ether has been widely applied as a photo-
sensitizer in the printing and coating industries. In the tradi-
tional industrial production, benzoin ethyl ether is usually
synthesized in a two-step process. First, benzoin is prepared
by condensation of benzaldehyde under harsh reaction con-
ditions. Second, benzoin ethyl ether is obtained by conden-
sation of benzoin with ethanol, in which cyanide and vitamin
B1 are usually employed as catalysts; the former is toxic
and the later is not effective enough. Therefore, the rapid
synthesis of large amount of benzoin ethyl ether is still a
great challenge. Recently, it was reported that the benzoin
ethyl ether could be obtained by a one-step process over an
NiAl-LDHs/SiO2 catalyst (LDH=layered double hydrox-
ide),[12] but it needs an elevated reaction temperature
(343 K) and complicated catalyst composition.
Results and Discussion
Synthesis of dual-mesoporous zeolite ZSM-5 with highly b
axis oriented large mesopores (ZSM-5-ODM): Zeolite
ZSM-5-ODM was obtained by a progressive aggregation–as-
sembly process (Scheme 1). Firstly, silicate and aluminate
oligomers, generated by hydrolysis and condensation of tet-
raethoxysilane and aluminum isopropoxide, further con-
densed into primary aluminosilicate units (zeolite seeds) in
alkaline solution (tetrapropylammonium hydroxide). Dy-
namic light scattering (DLS) was employed to roughly
measure the sizes of the zeolite seeds in the precursor liquid
(see Figure S1 in the Supporting Information). Zeolite seeds
around 400 nm in size were found. Then, a solution of
CTAB and F127 in ethanol/water was added in the alumino-
silicate precursor solution. The hydrophilic ends of the posi-
tively charged CTAB micelles could bind to the hydrophilic
and negatively charged zeolite seeds by both electrostatic in-
Herein, we report a facile route for the controlled synthe-
sis of dual-mesoporous zeolite ZSM-5 with highly b axis ori-
ented large mesopores (ZSM-5-ODM) by using convention-
al cationic cetyltrimethylammonium chloride (CTAB) and
nonionic amphiphilic copolymer F127 as co-templates. Two
Scheme 1. Schematic of the formation mechanism of ZSM-5-ODM. Step I: Condensation between the primary aluminosilicates units (zeolite seeds) and
CTAB micelles forming mesoporous zeolite aggregates. Step II: The zeolite aggregates stack along the b axis, and assembly between the aggregates and
the F127 micelles leads to the synchronous formation of F127 micelles that are themselves b-axis-oriented in between the stacked aggregates. Step III:
Further assembly, crystallization, and growth of the aggregates during hydrothermal treatment leading to the formation of dual-mesoporous ZSM-5 with
b-axis-oriented large mesopores.
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Dual-Mesoporous ZSM-5 Zeolite
FULL PAPER
teraction and hydrophilic affinity on the surface of the
seeds, and the seeds further condensed into mesoporous
zeolite aggregates in the presence of attached CTAB mi-
celles. Meanwhile, the concentration of the copolymer F127
significantly increases during the evaporation of ethanol,
and these aggregates could assemble with the hydrophilic
poly(ethylene oxide) (PEO) segments of triblock copolymer
F127 by hydrogen bonding. Therefore, organic/inorganic
composites with hydrophobic poly(propylene oxide) (PPO)
cores and PEO/aluminosilicate aggregate shells assembled
by a progressive aggregation–assembly process, and the hy-
drophilic PEO shell played an important role in stabilizing
the large PPO/PEO/aluminosilicate aggregate micelles. Ac-
cording to ab initio DFT calculations, the (010) plane is the
most favorable orientation among the (001), (010), and
(101) planes of the zeolite ZSM-5 crystals for growth owing
to the orientation and coordination of the exposed Si/O
atoms on this particular plane.[13] Recently, Zhao et al. re-
ported that additives can greatly impact the growth behavior
of zeolite crystals to form aggregates of ZSM-5 nanorods.[14]
We conjectured that the CTAB molecules, as organic addi-
tives with strong binding force to zeolite seeds, will first be
adsorbed on the (010) plane and suppress the growth of
ZSM-5 crystals along the b direction.[13] These additives can
also act as linkers to form ZSM-5 aggregates which are crys-
tallized to a certain extent and stack along the b axis, where-
as the F127 micelles with weak binding activity can interact/
bind with the b-axis-oriented stacked zeolite aggregates and
themselves become b-axis-oriented. During the following
hydrothermal treatment, these stacked zeolite aggregates
and F127 micelles, both b-axis-aligned, further assemble
with each other, crystallize, and simultaneously grow into
large zeolite crystals with incorporated CTAB micelles and
oriented F127 micelles. Finally, the templates were removed
in a calcination process, leaving dual mesoporosity in the
zeolite crystals. Thus, F127 and CTAB micelles are proposed
to be templates for the large, oriented and small, wormlike
mesoporosity, respectively. Moreover, the larger mesopores
in ZSM-ODM aligned along the b axis are believed to result
from aggregation–assembly of F127 micelles with large
ZSM-5 aggregates.[8a]
Figure 1. a) Small-angle and wide-angle XRD patterns of ZSM-5 and
ZSM-5-ODM. b) N2 adsorption/desorption isotherms and corresponding
BJH pore diameter distribution curves of ZSM-5-ODM.
those of the larger mesopores are about 30–50 nm and
0.10 cm3 gÀ1, respectively. The BET surface area and total
pore volume of ZSM-5-ODM are 487 m2 gÀ1 and
0.37 cm3 gÀ1, respectively. For comparison, the references
ZSM-5-SM (single-mesoporous zeolite ZSM-5) with one
type of mesoporous structure and a typical amorphous
mesoACTHNUTRGENUpGN orous material, namely, Al-MCM-41, were also syn-
thesized (see Figure S2a,b in the Supporting Information).
The BET surface area and total pore volume of ZSM-5-SM
and Al-MCM-41 were calculated to be 597 m2 gÀ1,
0.57 cm3 gÀ1 and 859 m2 gÀ1, 0.82 cm3 gÀ1, respectively.
A low-magnification field-emission (FE) SEM image of
ZSM-5-ODM (Figure 2a) reveals the presence of uniformly
sized particles with similar interpenetrated morphology. The
high-magnification FE-SEM images (Figure 2b and c)
reveal the typical character of hierarchically porous zeolites,
as was similarly observed in our previous reports.[11] The
walls of the interpenetrated ZSM-5-ODM crystals have a
porous structure. The larger mesopores (Figure 2c-d) of 30–
50 nm in diameter are highly oriented in the direction of the
b axis (as shown by arrows) and open only on the (010)
plane, which is ascribed to the prior aggregation–assembly
between amphiphilic F127 polymers and ZSM-5 aggregates
along the b axis. The numerous wormlike smaller mesopores
(ca. 3.3 nm in diameter, inset of Figure 2e) are distributed
randomly in the whole zeolite crystals (Figure 2b and c).
Compared with the single-mesoporous zeolite ZSM-SM, the
dual-mesoporous zeolite ZSM-5-ODM with highly b axis
oriented large mesopores more effectively favors the diffu-
The XRD pattern of ZSM-5-ODM (Figure 1a) shows
well-resolved diffraction peaks of a typical MFI-type phase
of zeolite ZSM-5. In addition, the small-angle XRD pattern
of ZSM-5-ODM shows a clear signal at about 1.98, which
can be ascribed to the short-range ordered mesoporous
structure. Figure 1b shows the N2 adsorption/desorption iso-
therm and the corresponding pore size distribution curve of
ZSM-5-ODM. The type IV adsorption/desorption isotherm
with H1 hysteresis is indicative of the presence of a well-de-
fined mesoporous structure. In particular, the sharp uptakes
of nitrogen at relative pressures of P/P0 =0.4–0.5 and P/P0 =
0.90–0.95 owing to capillary condensation inside the meso-
pores indicate the coexistence of two sets of mesopores in
zeolite ZSM-5-ODM. The average pore size and pore
volume of the smaller mesopores, calculated by means of
the BJH adsorption model, are 3.3 nm and 0.12 cm3 gÀ1, and
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H. Chen, J. Shi et al.
lected-area electron diffraction (SAED) pattern in Figure 2 f
(inset), indicative of the coexistence of interpenetrating in-
trinsic microporosity and mesoporosity within zeolite parti-
cles. Compared with conventional mesoporous zeolites (see
Figure S3b in the Supporting Information), the presence of
the larger mesopores in the ZSM-5-ODM sample is believed
to greatly favor mass transport of bulky molecules.
The Si/Al ratios of the synthesized samples ZSM-5, ZSM-
5-SM, ZSM-5-ODM, and Al-MCM-41 of 50, 51, 46, and 48,
respectively (Table 1), are similar to those of the precursor
Table 1. Texture properties, conversion of benzaldehyde, and selectivity
for benzoin ethyl ether over various catalysts.[a]
Catalyst
Si/Al[b] SBET
[m2 gÀ1
Vtotal
[cm3 gÀ1
Vmeso
[cm3 gÀ1
Conv. Select.
[c]
G
]
E
]
G
]
[%]
[%]
ZSM-5
ZSM-5-SM
Al-MCM-41
50
51
46
341
597
859
487
0.12
0.57
0.82
0.37
0.11
0.49
0.80
0.28
28.6
47.4
62.0
75.6
>99
>99
76.4
>99
ZSM-5-ODM 48
[a] Catalytic properties were compared on the basis of the same weight
of catalyst. All catalytic reactions were performed at room temperature.
[b] Determined by ICP-AES analysis. [c] Vmeso is given by the difference
between Vtotal and the micropore volume.
Figure 3. NH3-TPD profiles of ZSM-5, ZSM-5-ODM, and Al-MCM-41.
solutions. The acidity of synthesized catalysts was studied by
temperature-programmed desorption of ammonia (NH3-
TPD, Figure 3). Compared with ZSM-5 and ZSM-5-ODM,
two distinct desorption peaks are present at about 180 and
4008C, which can be attributed to the weak and strong
acidic sites, respectively. The weak acidic sites are associated
with the nonframework Al atoms and zeolite defects, while
the strong acidic sites are related to the lattice Al atoms of
the crystalline zeolite skeleton. Moreover, ZSM-5-ODM has
a lower total acid content than the reference ZSM-5, owing
to the introduction of mesoporous structure. Nevertheless,
ZSM-5-ODM still retains the strong acidic sites of zeolite
ZSM-5. Clearly, the mesoporous Al-MCM-41 sample has
only weak acidic sites according to the NH3-TPD profile
around 2008C, which can be due to the lack of lattice Al
sites.
Figure 2. Low-magnification (a) and high-magnification (b, c) FE-SEM
images of ZSM-5-ODM. d, e) FE-SEM images taken along the (010) and
(100) planes of ZSM-5-ODM. The inset in e) is the a high-resolution
image. f) Typical HRTEM image of ZSM-5-ODM and the corresponding
SAED pattern (inset).
sion and transport of bulky reactant/product molecules. For
comparison, the FE-SEM image of ZSM-5-SM (see Fig-
ure S3a in the Supporting Information) shows only one set
of disordered wormlike small mesopores (ca. 3.2 nm).
A typical TEM image of ZSM-5-ODM confirms the pres-
ence of mesoporous and microporous structures (Figure 2 f).
The random smaller mesopores can be seen in the figure,
but larger mesopores are too large to be observed in the
TEM image. In addition, ZSM-5-ODM shows clearly single-
crystalline character, as indicated by the corresponding se-
The structural configuration and the local environment of
the Al and Si atoms were quantitatively analyzed by 27Al
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Dual-Mesoporous ZSM-5 Zeolite
FULL PAPER
Figure 5. Condensation of benzaldehyde with ethanol and the effect of
reaction time on the conversion of benzaldehyde over various catalysts.
single-mesoporous zeolite ZSM-5-SM, and mesoporous ma-
terial Al-MCM-41 references in the condensation of benzal-
dehyde with ethanol at room temperature. The conversions
of benzaldehyde increase steadily during the first 4 h over
these catalysts, which can be ascribed to the presence of
active acidic sites. However, beyond about 4 h, the conver-
sions of benzaldehyde reach plateau values over ZSM-5,
ZSM-5-SM, and Al-MCM-41 catalysts, which can most
probably be attributed to blockage of pores by the produced
bulky product molecules (e.g., benzoin ethyl ether) and
coke formation in the smaller mesoporous channels of these
catalysts during the prolonged reaction. In comparison,
dual-mesoporous zeolite ZSM-5-ODM has significantly en-
hanced anti-coke-deposition performance due to the pres-
ence of larger oriented mesopores, which provide free diffu-
sional access for the reactants/products, and the b-axis-
aligned mesopores of the zeolite crystals are open to the sur-
face and are accessible to bulky molecules.[8a] Hence, the
conversion of benzaldehyde over ZSM-5-ODM continues to
increase after 4 h.
Figure 4. a) 27Al and b) 29Si MAS NMR spectra of ZSM-5-ODM and Al-
MCM-41.
and 29Si MAS NMR spectroscopy (Figure 4). The 27Al MAS
NMR spectra of ZSM-5-ODM and Al-MCM-41 show char-
acteristic peaks at about d=53 ppm and d=54 ppm, respec-
tively, owing to tetrahedrally coordinated aluminum species.
In addition, Al-MCM-41 exhibits a second peak at d=
1 ppm, which can be ascribed to octahedrally coordinated
aluminum species. Interestingly, the ZSM-5-ODM only
shows a weak peak at d=0 ppm, which demonstrates that
the Al atoms have been incorporated into the zeolite frame-
work. The MAS 29Si NMR spectra of ZSM-5-ODM and Al-
MCM-41 clearly show two peaks with chemical shifts of d=
À103 and À113 ppm, which are attributed to the (HO)Si-
A
N
Moreover, ZSM-5-ODM has the highest catalytic activity
and selectivity to benzoin ethyl ether among the four cata-
lysts (Table 1), giving benzaldehyde conversions of up to
75.6% and greater than 99% selectivity to benzoin ethyl
ether after 8 h of reaction at room temperature. In contrast,
the reference catalysts ZSM-5 and ZSM-5-SM show only
28.6 and 47.4% conversion, respectively, in the same reac-
tion time. Although Al-MCM-41 shows a higher conversion
of benzaldehyde (62.0%) than the other references, it has
much lower selectivity to benzoin ethyl ether (76.4%) and a
large amount of byproducts, such as benzyl ethyl ether, can
be found in this reaction system. Thus, the large BET sur-
face area and mesopore pore volume of Al-MCM-41 can ac-
celerate the conversion of benzaldehyde, while the amor-
phous skeleton of Al-MCM-41 and the lack of strong acidic
sites lead to the considerably lowered selectivity to benzoin
ethyl ether. The above results suggest that both the acidic
sites and mesoporous channels play an important role in the
ZSM-5-ODM at d=À113 ppm is stronger than that of Al-
MCM-41, and the decrease in Q3/Q4 ratio indicates that the
amorphous aluminosilicate walls were transformed into crys-
tallized zeolite frameworks.[11b]
Catalytic properties of the dual-mesoporous zeolite ZSM-5-
ODM, conventional zeolite ZSM-5, single-mesoporous zeo-
lite ZSM-5-SM, and mesoporous material Al-MCM-41:
Dual-mesoporous zeolite ZSM-5-ODM with highly b axis
oriented large mesopores is expected to be applicable in
many catalytic reactions. As a preliminary test, the conden-
sation of benzaldehyde with ethanol was chosen as a model
catalytic reaction. A series of differently synthesized cata-
lysts were used in the conversion of benzaldehyde, and the
results are summarized in Figure 5 and Table 1. Dual-meso-
porous zeolite ZSM-5-ODM exhibits excellent catalytic
properties compared with the conventional zeolite ZSM-5,
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H. Chen, J. Shi et al.
conversion of benzaldehyde, and the strong acidity provided
by crystalline zeolites makes a great contribution to high se-
lectivity for benzoic ethyl ether. The large pore volume will
lead to increased probability of reactants accessing active
sites owing to the introduction of mesoporosity, which fur-
ther enhances the conversion of benzaldehyde. Furthermore,
the free access/diffusion of the reactants/products facilitated
by dual mesoporosity, especially the oriented large meso-
pore channels, will effectively prevent catalyst deactivation
due to greatly suppressed coke formation in the porous net-
work, which frequently happens in microporous zeolites, es-
pecially when bulky molecules are involved. Therefore, the
dual-mesoporous catalyst ZSM-5-ODM with highly b axis
oriented large mesopores and crystalline zeolite framework
exhibits much superior catalytic activity in the conversion of
benzaldehyde compared to ZSM-5, ZSM-5-SM and Al-
MCM-41.
co-mesoporogens. Two types of interpenetrating mesoporos-
ity are present throughout the whole zeolite crystals: small-
er, wormlike mesopores of 3.3 nm in size and larger meso-
pores of 30–50 nm in diameter, which are highly oriented
along the b axis of the zeolite crystals. The obtained catalyst
shows excellent catalytic performance in the condensation
of benzaldehyde with ethanol at room temperature, which
can be ascribed to the free access of bulky reactants provid-
ed by the unique dual-mesoporous structure, especially the
b-axis-oriented large mesopores, the large number of active
sites, and the strong acidity offered by the crystalline struc-
ture of the zeolite framework. The catalyst can be reused
and the catalytically active sites can be well regenerated by
a simple calcination process. The oriented and dual-mesopo-
rous zeolite is expected to be a highly efficient heterogene-
ous acid catalyst that can be applied in various chemical re-
actions involving bulky molecules.
More importantly, these catalysts could be well separated
from the reaction solution by a filtration process. Unlike
ZSM-SM and Al-MCM-41, the ZSM-ODM catalyst can be
reused for four cycles with only slight loss of catalytic activi-
ty (Figure 6), which can be ascribed to the presence of
Experimental Section
Dual-mesoporous zeolite ZSM-5 with highly b axis oriented large meso-
pores (ZSM-5-ODM): First, an emulsion containing of AlACHTUNGTRENNUNG(OiPr)3
(0.204 g) and of tetraethoxysilane (TEOS, 10.4 g) was stirred at 313 K for
30 min. Second, of tetrapropylammonium hydroxide (TPAOH, 4.06 g,
25 wt% solution) was added to the emulsion at 313 K, and the mixture
was stirred at 313 K for a further 2 h. Subsequently, cetyltrimethylammo-
nium chloride (CTAB, 1.53 g) and triblock copolymer PEO106PPO70-
AHCTNUGTRENPGUNN EO106 (F127, 1.26 g) were dissolved in 20 mL of ethanol/water (1/9) to
obtain a homogeneous solution, which was added to the reaction mixture
at 313 K. Dual-mesoporous zeolite ZSM-5 was then obtained by hydro-
thermal treatment at 423 K for 16 h, after which the products were
washed with distilled water and dried at 373 K. The final products were
obtained after calcination at 823 K for 8 h to remove any organic sub-
stances (ZSM-5-ODM).
Zeolite ZSM-5: First, AlACTHNUTRGNEUNG(OiPr)3 (0.204 g) and TEOS (10.4 g) were dis-
solved in water (20 mL) to obtain a homogeneous solution at 313 K.
Second, of TPAOH (4.06 g, 25 wt% solution) was added to the resultant
solution at 313 K, and the mixture was stirred at 313 K for a further 6 h.
Zeolite ZSM-5 was then obtained by hydrothermal treatment at 423 K
for 16 h, after which the products were washed with distilled water and
dried at 373 K. The final products were obtained after calcination at
823 K for 8 h to remove any organic substances.
Figure 6. Recyclability of ZSM-5-ODM, Al-MCM-41, and ZSM-5-SM
catalysts in the condensation of benzaldehyde with ethanol (1–4: the
sample was recycled after separation by centrifugation from the product
solution and reused in the conversion of benzaldehyde; 5: the sample
was recycled after being calcined at 823 K for 8 h and reused in the con-
version of benzaldehyde).
Single-mesoporous zeolite ZSM-5 (ZSM-5-SM): First, an emulsion con-
taining AlACHTUNGRTENNG(U OiPr)3 (0.204 g) and TEOS (10.4 g) was added to distilled
water (20 mL) and the mixture stirred at 313 K for 3 h. Second, TPAOH
(4.06 g, 25 wt% solution) was added to the resultant solution, and the
mixture was stirred and aged at 313 K for 6 h. Finally, the emulsion was
added to solution of CTAB (1.53 g) in water (10 mL), and the reaction
medium was stirred and aged at ambient temperature. ZSM-5-SM was
then synthesized by hydrothermal treatment at 423 K for 16 h, after
which the products were washed with distilled water and dried at 373 K.
The final products were obtained after calcination at 823 K for 8 h to
remove any organic substances.
larger oriented mesopores. Interestingly, the catalytic activi-
ty of both ZSM-5-ODM and ZSM-SM can be almost fully
recovered in the fifth cycle after a simple calcination treat-
ment, while Al-MCM-41 shows much lower recyclability.
This indicates that ZSM-5-ODM and ZSM-SM with crystal-
line frameworks have higher thermal stability than amor-
phous Al-MCM-41.
Al-MCM-41: The synthesis of MCM-41 was carried out in a conventional
hydrothermal system with a molar composition of 12NH4OH:50SiO2:
0.5Al2O3:8.5CTAB:1200H20. First, AlACHTNUGTRENUNG(OiPr)3 was dissolved in deionized
water, and then ammonia hydroxide and CTAB were added to the solu-
tion. Second, TEOS was added to the mixture with strongly stirring. Mes-
oporous MCM-41 was then synthesized by hydrothermal treatment at
393 K and dried at 333 K. The final product were obtained after calcina-
tion at 823 K for 8 h.
Conclusion
A novel aggregation–assembly process has been developed
for the synthesis of the dual-mesoporous zeolite ZSM-5 with
b-axis-aligned larger mesopore channels by using the non-
ionic copolymer F127 and the cationic surfactant CTAB as
Characterization: Powder XRD patterns were recorded on a Rigaku D/
Max 2200PC diffractometer with CuKa radiation (40 kV and 40 mA) at a
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Chem. Eur. J. 2013, 19, 10017 – 10023

Dual-Mesoporous ZSM-5 Zeolite
FULL PAPER
scanning rate of 48minÀ1 for high-angle measurements, and 0.48minÀ1 for
small-angle measurements. The nitrogen sorption measurements were
performed with Micromeritics Tristar 3000 and Micromeritics ASAP
2020 porosimeters at 77 K; the mesoporous specific surface area and the
pore size distribution were calculated by using the BET and BJH meth-
ods, respectively, while the micropore volume was calculated by the t-
plot method. TEM imaging and SAED were performed on a JEOL-
2010F electron microscope operated at 200 kV, and FE-SEM images
were obtained on Hitachi S-4800. The acidic property of the zeolites
were determined by temperature-programmed desorption of ammonia
(NH3-TPD). The Si/Al ratios were measured by inductively coupled
plasma atomic emission spectroscopy (ICP-AES) on a Vista AX instru-
ment. The particle size distribution of the mesoporous zeolite precursor
was characterized by dynamic light scattering (DLS). 27Al and 29Si MAS
NMR measurements were performed on Bruker DMX500 and Bruker
DSX300 spectrometers, respectively.
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Acknowledgements
This research was sponsored by National Key Basic Research Program of
China (2013CB933200), China National Funds for Distinguished Young
Scientists (51225202), National Natural Science Foundation of China
(51202278, 51102172), Key Program for Science and Technology Com-
mission of Shanghai Municipality (11JC1413400), State Key Laboratory
of Heavy Oil Processing (2012-1-04), and Natural Science Foundation of
Shanghai (12ZR1435).
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Received: January 23, 2013
Published online: June 17, 2013
Chem. Eur. J. 2013, 19, 10017 – 10023
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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10023