An efficient, rapid, and non-centrifugation synthesis of nanosized zeolites by accelerating the nucleation rate

Article abstract of DOI:10.1039/C8TA07171C

Access to nanosized zeolites is a topical subject due to the advantageous mass transfer in zeolite catalyzed reactions. Herein we report a low-cost and generalized methodology to decrease zeolite crystal sizes by accelerating the nucleation rate when reducing the solvent amount in the synthesis. As anticipated, nanosized zeolites like MFI (100-200 nm, Si/Al ratios from 100 to ∞ in the starting gels) and BEA (50-200 nm, Si/Al ratio of 13) have been successfully synthesized with a H₂O/SiO₂ ratio of 2.0-3.0. The lower consumption of water as the solvent in the synthesis leads to non-centrifugation for nanosized zeolites, giving higher yields of the zeolite product. Experimental data confirm lower apparent activation energy for nucleation at higher gel concentrations in the synthesis of ZSM-5 zeolites. Catalytic examination of the conversion of methanol to olefins (MTO) demonstrates that the thus-obtained nanosized ZSM-5 zeolite (NS-ZSM-5) exhibits a much longer catalyst lifetime than conventional ZSM-5 (C-ZSM-5) and even nanosized ZSM-5 crystals (NC-ZSM-5) obtained from a hydrothermal route.

Full text of DOI:10.1039/C8TA07171C

Journal of
Materials Chemistry A
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PAPER
An efficient, rapid, and non-centrifugation
synthesis of nanosized zeolites by accelerating the
nucleation rate†
Cite this: J. Mater. Chem. A, 2018, 6,
21156
Changsheng Zhang,a Qinming Wu,a Chi Lei,a Shichao Han,a Qiuyan Zhu,a
Stefan Maurer,b Daniel Dai,b Andrei-Nicolae Parvulescu,c Ulrich Muller,c
¨
a
a
*
*
Xiangju Meng and Feng-Shou Xiao
Access to nanosized zeolites is a topical subject due to the advantageous mass transfer in zeolite catalyzed
reactions. Herein we report a low-cost and generalized methodology to decrease zeolite crystal sizes by
accelerating the nucleation rate when reducing the solvent amount in the synthesis. As anticipated,
nanosized zeolites like MFI (100–200 nm, Si/Al ratios from 100 to N in the starting gels) and BEA
(50–200 nm, Si/Al ratio of 13) have been successfully synthesized with a H2O/SiO2 ratio of 2.0–3.0. The
lower consumption of water as the solvent in the synthesis leads to non-centrifugation for nanosized
zeolites, giving higher yields of the zeolite product. Experimental data confirm lower apparent activation
energy for nucleation at higher gel concentrations in the synthesis of ZSM-5 zeolites. Catalytic
examination of the conversion of methanol to olefins (MTO) demonstrates that the thus-obtained
nanosized ZSM-5 zeolite (NS-ZSM-5) exhibits a much longer catalyst lifetime than conventional ZSM-5
(C-ZSM-5) and even nanosized ZSM-5 crystals (NC-ZSM-5) obtained from a hydrothermal route.
Received 25th July 2018
Accepted 1st October 2018
DOI: 10.1039/c8ta07171c
rsc.li/materials-a
processes. Therefore, it is of great signicance to develop an
efficient, low-cost, and easy-separation methodology for the
Introduction
synthesis of nanosized zeolites for industrial applications.
In general, the zeolite crystal size distribution is related to
the number of nuclei in a synthetic system. Increasing the
concentration of zeolite nuclei results in a signicant reduction
of zeolite crystal sizes. Therefore, it is possible to reduce the
overall zeolite crystal size by enhancing the nucleation rate in
the synthesis of zeolites. Xu et al. proposed that the crystalli-
zation rate is strongly related to the concentration of nutrients
in the starting gels as follows:
Zeolites have been widely applied as catalysts in the industrial
processes of oil rening and chemical production due to their
high surface area, large pore volume, uniform microporous
channels, and excellent thermal and hydrothermal stabilities.1–4
Owing to their advantages such as fast mass transfer, high
catalytic selectivity, and long catalyst lifetime, much attention
has been paid to nanosized zeolites as well as to hierarchical
zeolites, the latter however with less industrial relevance due to
prohibitive costs due to cumbersome preparation methods most
of the time.5–11 For instance, nanosized ZSM-5 zeolites exhibit
a much longer catalyst lifetime in methanol-to-olen (MTO)
reactions than conventional bulky ZSM-5 crystals.12–16 However,
synthesis of such nanosized zeolites usually requires a large
amount of water as the solvent and organic additives.1,3,17 Addi-
tionally, nanosized zeolite separation from the synthesis gel is
generally challenging. These shortcomings strongly inuence the
practical applications of nanosized zeolites in industrial
dz/dt ¼ ktag
(1)
where z is the number of nuclei, t is the crystallization time, k
and a are constants, and g is the concentration of nutrients for
crystallization of zeolites in the starting gels.18 At a certain
crystallization time t, the nucleation rate could be simplied to
the following:
dz/dt ¼ kg(t)
(2)
aKey Laboratory of Applied Chemistry of Zhejiang Province, Zhejiang University,
Hangzhou 310028, China. E-mail: mengxj@zju.edu.cn; fsxiao@zju.edu.cn
bBASF Catalysts (Shanghai) Co., Ltd., Jinqiao Export Process Zone, 239 Luqiao Road,
Pudong New District, Shanghai, 201206, China
According to this formula, an increase of nutrient concentration
in the starting gels should lead to a signicant acceleration of
the nucleation rate in the synthesis, achieving nanosized zeolite
crystals. In recent efforts studying solvent-free synthesis of
zeolites, a powerful lever to adjust the nutrient concentration in
the starting gels has been identied.19–22
cBASF SE, GCC/PZ – M311, 67056 Ludwigshafen, Germany
† Electronic supplementary information (ESI) available: Extended synthesis and
characterization details as well as additional XRD patterns and SEM images. See
DOI: 10.1039/c8ta07171c
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Journal of Materials Chemistry A
Herein, we show a simple route for synthesis of nanosized conditions according to a previous literature report.15 In
zeolites by accelerating the nucleation rate, which is achieved by a typical run, 14.0 g of TEOS and 22.0 g of TPAOH (20 wt%,
increasing the nutrient concentration in the starting gels. diluted from TPAOH of 40 wt%) were added into 22.0 g of
Interestingly, when the H2O/SiO2 ratio is adjusted to as low as distilled water. Aer they had fully dissolved, 0.093 g of
2.0, ZSM-5 zeolite nanocrystals with sizes between 100 and aluminum isopropoxide was added. Aer stirring for 24–48 h,
ꢀ
200 nm (NS-ZSM-5) are formed. Furthermore, this concept can the gel was transferred into an autoclave and heated at 180 C
be extended to synthesize nanosized Beta zeolites (50–200 nm). for 48 h. The organic templates were removed aer calcination
ꢀ
Compared with conventional routes, this approach comes with at 550 C for 5 h.
obvious advantages such as non-centrifugation work-up, rela-
Synthesis of conventional bulky ZSM-5 zeolite. Conventional
tively low consumption of organic additives, and signicant bulky ZSM-5 zeolite (C-ZSM-5) was synthesized under hydro-
reduction of water as the solvent, paving the way towards thermal conditions. In a typical run, 0.011 g of NaAlO2 and 4.0
a sustainable nanosized zeolite synthesis. More importantly, ml of TPAOH (40 wt%) were added into 9.2 g of distilled water.
this nanosized ZSM-5 exhibits excellent selectivity for light Aer they had fully dissolved, 1.2 g of solid silica gel was added.
olens and good stability in the MTO reaction. The combina- Aer stirring for 4 h, the gel was transferred into an autoclave
tion of simple and sustainable synthesis procedures along with and heated at 180 ꢀC for 24 h.ꢀThe organic templates were
superior catalytic performance might enable wider industrial removed aer calcination at 550 C for 5 h. The H-form of the
application of nanosized zeolites in the future.
samples was prepared by ion-exchange with NH4NO3 solution
ꢀ
(1 M) at 80 C for 2 h, and this procedure was repeated twice,
ꢀ
followed by calcination at 550 C for 5 h.
Experimental
Materials
Characterization
Fumed silica was purchased from Shanghai Tengmin Industrial
Co, boehmite (Al2O3 of 70 wt%) was supplied by Liaoning
Hydratight Co, tetrapropylammonium hydroxide (TPAOH of 40
wt%), tetraethyl orthosilicate (TEOS), aluminum isopropoxide,
NaOH, NaAlO2, and methanol were received from Sinopharm
Chemical Reagent Co, and tetraethylammonium hydroxide
(TEAOH of 35 wt%) was received from Tokyo Chemical Indus-
trial Co. All the materials were used as-received without any
further treatment.
X-ray powder diffraction (XRD) patterns were measured with
a Rigaku Ultima VI X-ray diffractometer (40 kV, 40 mA) using
˚
CuKa (l ¼ 1.5406 A) radiation. The morphology of the samples
was observed on a Bruker Multimode 8 and a Hitachi SU 1510
scanning electron microscope (SEM). High-resolution trans-
mission electron microscopy (HR-TEM) images of the samples
were obtained on a JEM-2100F transmission electron micro-
scope. 29Si and 27Al MAS NMR spectra were recorded on
a Bruker AVANCEIII500WB spectrometer. The nitrogen sorption
isotherms at the temperature of liquid nitrogen were measured
using a Micromeritics ASAP 2020M. The sample compositions
were determined by inductively coupled plasma (ICP) analysis
with a Perkin-Elmer 3300DV emission spectrometer.
Synthesis process
Synthesis of ZSM-5-x zeolite. ZSM-5-x zeolite was synthesized
from the starting materials with a molar ratio of Al2O3/
35TPAOH/300SiO2/x300H2O (x stands for the H2O/SiO2 ratio in
the starting gels), followed by stirring and heating at a certain
temperature. In a typical run, 0.008 g of boehmite was added
into 1.0 g of TPAOH (40 wt%), followed by addition of 1.0 g of
fumed silica and a certain amount of water. Aer stirring, the
gel was transferred into an autoclave for crystallization. Aer
full crystallization, the zeolite product was denoted as ZSM-5-x.
The inuence of alkalinity was evaluated by adding a certain
amount of NaOH. ZSM-5 zeolite crystals with different Si/Al
ratios were synthesized by adjusting the amount of boehmite.
Synthesis of Beta-x zeolite. Beta-x (x means the H2O/SiO2
ratio) was synthesized from the starting materials with a molar
ratio of Al2O3/4TEAOH/26SiO2/x26H2O (x stands for the H2O/
SiO2 ratio in the starting gels), followed by stirring and heating
at 150 ꢀC. In a typical run, 1.14 g of fumed silica, 0.12 g of
NaAlO2, and 1.30 g of TEAOH (35 wt%) were mixed, followed by
grinding and adding a certain amount of water. Aer stirring,
the gel was transferred into an autoclave and sealed for crys-
tallization. Aer heating at 150 ꢀC for 72–120 h, the samples
were fully crystallized, denoted as Beta-x.
Catalytic methanol-to-olen (MTO) reaction
The MTO reaction was carried out with a xed-bed tubular steel
reactor with an inner diameter of 8 mm and a length of 30 cm at
atmospheric pressure. Aer 0.50 g of catalyst (20–40 mesh) was
loaded in the middle of tubular steel between two layers of
quartz wool, it was pretreated in owing nitrogen at 500 ꢀC for 2
ꢀ
h and cooled down to a reaction temperature of 480 C. Meth-
anol was injected into the catalyst bed using a pump with
a weight hourly space velocity (WHSV) of 1.0 hꢁ1. The products
from the reactor were analyzed on-line using an Agilent 6890N
gas chromatograph equipped with an FID detector and a PLOT-
Al2O3 capillary column (50 m ꢂ 0.53 mm ꢂ 25 mm). Selectivity
towards the products was expressed as the mass percentage of
each product among all the detectable products except dimethyl
ether.
Results and discussion
Fig. 1 shows the SEM images of ZSM-5-x zeolites synthesized at
Synthesis of CN-ZSM-5 zeolite. Conventional nanosized 180 ꢀC with a molar ratio of Al2O3/35TPAOH/300SiO2/x300H2O,
ZSM-5 (CN-ZSM-5) was synthesized under hydrothermal where x stands for the H2O/SiO2 ratio in the starting gels
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results demonstrate that the zeolite nucleation rates could be
signicantly enhanced by increasing the nutrient concentration
in the starting gels. It is well established that a lower activation
energy is very favourable for faster nucleation during the zeolite
synthesis.18,25,26 According to the Arrhenius equation, the
apparent activation energy of zeolite nucleation (En) can be
calculated from the plot of ln k vs. 1/T, where the k values could
be estimated at a crystallinity of 15% (Fig. S5 and S6†).23,24 For
example, ZSM-5-2 displays an activation energy for zeolite
nucleation of 25.2 kJ molꢁ1 while the corresponding value for
ZSM-5-10 is 48.9 kJ molꢁ1 (Fig. 2A). These values conrm that
increasing the nutrient concentration in the starting gels is
positively linked with the zeolite nucleation rate. Fig. 2B shows
the dependence of the as-synthesized ZSM-5 crystal size on the
H2O/SiO2 ratio. Interestingly, a linear relationship between the
crystal size distribution and the H2O/SiO2 ratio could be
established for the range between 2 and 18, following the trend
given below:
D ¼ 373R ꢁ 647
(3)
Fig. 1 SEM images of ZSM-5 zeolites synthesized at 180 ꢀC with H2O/
SiO2 ratios of (a) 18, (b) 10, (c) 6, and (d) 2, and (e and f) HRTEM images
of ZSM-5 zeolite with a H2O/SiO2 ratio of 2. Inset in Fig. 1f: SAED
pattern taken from an entire particle.
where D represents the crystal size (nm) of the as-synthesized
ZSM-5 zeolite and R stands for the ratio of H2O/SiO2. Based on
this linear correlation, the ZSM-5 crystal sizes can be easily
tuned from 100 nm to around 5–6 mm by varying the H2O/SiO2
ratio from 2–18.
In addition, as a typical example, the inuence of alkalinity
was also investigated with additional NaOH in the synthesis of
ZSM-5-6 (Fig. S7†). The results show that higher alkalinity
doesn't strongly inuence the size of ZSM-5-6 crystals, sup-
porting the importance of the H2O/SiO2 ratio rather than the
alkalinity for the control of ZSM-5 crystal size.
Fig. 3 displays the X-ray diffraction (XRD) pattern, N2 sorp-
tion isotherms, and 29Si and 27Al magic-angle spinning (MAS)
NMR spectra of ZSM-5-2. The XRD pattern exhibits the charac-
teristic peaks associated with the MFI structure (Fig. 3a).27 The
N2 sorption curves of the calcined ZSM-5-2 (Fig. 3b) exhibit
a steep increase at a relative pressure of 10ꢁ6 < P/P0 < 0.01,
which is due to the lling of micropores.28 In the range of P/P0
from 0.01 to 0.85, the N2 uptake gradually increases, indicating
the presence of mesopores in the nanocrystals, which is in good
agreement with the HR TEM results (Fig. 1e and f). Additionally,
at a relative pressure higher than 0.85, another steep increase
(Fig. S1†). The crystallization curves and XRD patterns of these
zeolites are shown in Fig. S2 and S3.† Clearly, with a decreasing
amount of water in the gels, the average size of the ZSM-5
crystals is signicantly reduced. When the H2O/SiO2 ratio is
18.0, the crystal size of ZSM-5 zeolite is 5–6 mm (ZSM-5-18,
Fig. 1a). When the H2O/SiO2 ratio reaches 2.0, ZSM-5 crystals
with a size of 100–200 nm (ZSM-5-2, Fig. 1d) are obtained. These
results support the hypothesis that nanosized zeolite crystals
can be obtained by controlling the amount of water as the
solvent in the synthesis. Interestingly, the TEM images of ZSM-
5-2 (Fig. 1e and S4†) show the presence of mesopores inside the
crystals. The high-resolution TEM image (Fig. 1f) and SAED
pattern (inset in Fig. 1f) reveal the single crystal nature of the
nanosized particles of ZSM-5.
Table 1 presents the nucleation rates of ZSM-5-x calculated
from eqn (2).18,23,24 Notably, by varying the water content in the
starting gels, the nucleation rates are quite different. For ZSM-5-
2, the nucleation rate is 2.7 ꢂ 10ꢁ1 mol (l h)ꢁ1, while ZSM-5-18
exhibits a much lower rate of 2.9 ꢂ 10ꢁ2 mol (l h)ꢁ1. These
Table 1 Kinetic parameters for nucleation rates of ZSM-5-x synthe-
sized at 180 ꢀC with various H2O/SiO2 ratios
Sample
H2O/SiO2 CSiO /(mol lꢁ1
)
ka, hꢁ1
dz/dtb, mol lꢁ1 hꢁ1
2
ZSM-5-2
ZSM-5-6
ZSM-5-10 10
ZSM-5-18 18
2
6
27.8
9.3
5.6
3.1
9.9 ꢂ 10ꢁ3 2.7 ꢂ 10ꢁ1
8.5 ꢂ 10ꢁ3 7.9 ꢂ 10ꢁ2
7.7 ꢂ 10ꢁ3 4.3 ꢂ 10ꢁ2
6.7 ꢂ 10ꢁ3 2.9 ꢂ 10ꢁ2
a
Fig. 2 (A) Arrhenius plots for (a) ZSM-5-10 and (b) ZSM-5-2; (B)
dependence of the obtained zeolite crystal size on the H2O/SiO2 ratio
(within the experimental range).
The nucleation rate constant (k) is regarded as the reciprocal of the
b
crystallization time at a crystallinity of 15%. Nutrient concentration
[g(t)] is denoted as SiO2 concentration in the starting gels.
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Fig. 4 Dependence of catalytic conversion on time in MTO over the
(a) C-ZSM-5, (b) CN-ZSM-5, and (c) ZSM-5-2 catalysts.
the production of light olens. Remarkably, ZSM-5-2 exhibits
high propylene selectivity (54.0% at a reaction time of 1.0 h,
Fig. S12†) and an extended catalytic lifetime (140 h, Fig. 4c). In
contrast, although C-ZSM-5 with larger crystal sizes (ꢃ3–4 mm)
exhibits high propylene selectivity (52.4%, Fig. S10†), its cata-
lytic life is much shorter (12 h, Fig. 4a). If CN-ZSM-5 is
Fig. 3 (a) XRD pattern, (b) N2-sorption isotherms, and (c) 29Si and (d)
27Al MAS NMR spectra of ZSM-5-2.
can be observed, which is most likely related to agglomerated employed, its catalyst lifetime (40 h, Fig. 4b) is still lower than
nanosized crystals. Correspondingly, the sample has a BET that of ZSM-5-2 (140 h, Fig. 4c). The difference in catalyst
surface area of 434 m2 gꢁ1 and micropore volume of 0.182 cm3 lifetime can be reasonably attributed to the different meso-
gꢁ1. ZSM-5-2 exhibits a mesopore volume of 0.155 cm3 gꢁ1
,
porosity features present in the crystals (Fig. 3b and S4†),35–40
which is higher than that (0.124 cm3 gꢁ1) for nanosized ZSM-5 where the extended external surface area of ZSM-5 nanocrystals
obtained by conventional hydrothermal synthesis (100–150 nm, is favourable for high propylene selectivity and coke resis-
CN-ZSM-5, Fig. S8–S11†). The higher mesopore volume of ZSM- tance.41,42 TG-DTA curves of deactivated ZSM-5-2, CN-ZSM-5,
5-2 than that of CN-ZSM-5 is reasonably related to the presence and conventional large crystal ZSM-5 MTO catalysts
of mesoporosity in ZSM-5-2, as observed in Fig. S4.† This feature (Fig. S19–S21†) display a distinct difference in their weight loss
is supposed to be benecial for mass transfer during catalytic in the temperature range from 450 to 650 ꢀC of about 20 versus
reactions.29–31 Fig. 3c and d display the 29Si and 27Al MAS NMR 11, and 10%, respectively, conrming the difference in lifetime
spectra of ZSM-5-2. The 29Si MAS NMR spectrum mainly and the related resistance against coke formation.
contains two peaks at ꢁ113 and ꢁ104 ppm, which represents
Furthermore, this method can be extended to synthesize
the Si (4Si) and Si (3Si) in the zeolite framework. In the 27Al MAS nanosized Beta zeolites. As anticipated, nanosized Beta crystals
NMR spectrum, only one sharp peak at about 58 ppm can be (50–200 nm) can be obtained using a H2O/SiO2 ratio of 2.5.
observed, which is assigned to tetrahedral 4-coordinated Al Fig. 5 shows the XRD pattern, SEM and TEM images, and N2
species in the zeolite framework. These observations are well in sorption isotherms of the thus-obtained Beta zeolites (Fig. S22–
line with those reported for nanosized zeolites in the litera- S25†). The XRD pattern exhibits the characteristic peaks
ture.25,26,32–34 In addition, the Si/Al ratio in the zeolite product associated with the BEA structure (Fig. 5a).27 It is worth noting
derived from inductively coupled plasma (ICP) analysis for that in the range of P/P0 from 0.01 to 0.85 (Fig. 5b), the N2
ZSM-5-2 is 131.
uptake gradually increases, indicating the presence of meso-
When the Si/Al ratios in the starting gels are changed from porosity in the nanocrystals, which is well consistent with the
100 to N, the zeolite products have similar ZSM-5 particle sizes, TEM images (Fig. 5d). These results demonstrate the general-
as conrmed by the XRD patterns and SEM images of ZSM-5-2 ization of the nanosized zeolite synthesis concept via acceler-
(Fig. S8 and S9†). These results indicate that we can adjust the ating the nucleation rate by increasing the nutrient
ZSM-5 crystal sizes from 100–200 nm to 5–6 mm by changing the concentration in the starting gels. The extension of this strategy
H2O/SiO2 ratio from 2 to 18 in the starting aluminosilicate gels for the synthesis of other zeolite nanocrystals is also under
with Si/Al ratios from 100 to N. The research on the starting gels investigation.
with other Si/Al ratios is under investigation.
Compared with conventional nanosized zeolite crystals re-
Fig. 4 and S10–S12† show the dependence of methanol ported in the literature, the synthesis of nanosized MFI and BEA
conversion and product selectivity on the reaction time over the reported in this work has obvious advantages as such: (1) easy
conventional nanosized ZSM-5 (CN-ZSM-5, Fig. S13–S16†), separation work-up of the products:3,43–45 in this work, for
traditional bulky ZSM-5 (C-ZSM-5, Figs. S17 and S18†) and ZSM- H2O/SiO2 ratios in the starting gels adjusted between 2 and 3,
5-2 in the MTO reaction, which is a typical industrial process for both the starting and nal gels aer crystallization are solid-like
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Compared with these advantages, a major drawback is the
difficulty in dispersion. However, aer grinding and ultrasonic
treatment, these zeolite nanocrystals could be still dispersed in
the aqueous media. In addition, the industrial application of
such dense gel systems is not easy. However, aer changing the
stirrer in industrial vessels, this issue could be solved.
Conclusions
In summary, we have developed both a simple and a sustainable
route for the synthesis of zeolite nanocrystals via accelerating
nucleation rates by increasing the nutrient concentration in the
starting gels. Such zeolite nanocrystals exhibit high crystallinity,
large surface area, and mesoporosity features. More impor-
tantly, the MFI nanocrystals in this work display a signicantly
longer catalyst lifetime in the MTO reaction than conventional
MFI nanocrystals. Ease of preparation plus excellent catalytic
performance should pave the way for zeolite nanocrystals for
a wider application in industry in the future.
Fig. 5 (a) XRD pattern, (b) N2-sorption isotherms, and (c) SEM, and (d)
TEM images of Beta-2.5. Inset in Fig. 1d: SAED pattern taken from an
entire particle.
Author contributions
and the raw materials are directly transformed into nanosized
zeolite crystals. Fig. S26† shows fully crystallized MFI and BEA C. Zhang and Q. Wu obtained the zeolite catalysts, C. Lei and S.
nanocrystals from the solid-like gels. Therefore, it is not Han performed catalytic tests, Q. Zhu recorded nitrogen sorp-
¨
necessary to apply any centrifugation step or other ltration tion isotherms, S. Maurer, D. Dai, A. Parvulescu, and U. Muller
concepts that might require particle agglomeration. (2) Rela- partially discussed and analyzed the results for synthesis and
tively low consumption of organic additives: the conventional catalysis, and X. Meng and F.-S. Xiao designed this study,
synthesis of zeolite nanocrystals generally needs a relatively analyzed the data, and wrote the paper.
large amount of organic templates in the starting gels.1–3,17 For
example, nanosized MFI crystals (100 nm) are typically synthe-
Conflicts of interest
sized from gels with the molar ratio of TPA+ to silica higher than
0.30. If this ratio is not high enough, it is difficult to obtain There are no conicts to declare.
nanosized MFI crystals due to relatively slow nucleation
rates.15,35,36 Accelerating the nucleation rate by increasing the
nutrient concentration in the starting gels renders any excessive
Acknowledgements
amount of templates unnecessary. As a result, the consumption This work is supported by the National Key Research and
of organic templates can be signicantly reduced in this work. Development Program of China (2017YFB0702803) and
(3) High zeolite yields: the conventional synthesis of nanosized National Natural Science Foundation of China (21720102001,
zeolite crystals generally uses a large amount of water as the 91634201, and 21333009).
solvent under strongly alkaline conditions, where the water
together with the base is anticipated to partially dissolve the
nutrients such as silicates and aluminates. When reducing the
References
amount of water as the solvent in the starting gels to
a minimum, at the same time the efficiency of nutrient utili-
zation increases along with the zeolite yields. For example, in
the synthesis of ZSM-5-2 more than 98% utilization of the silica
source can be observed, which is higher than that reported in
the literature.12–16 (4) Introduction of mesoporosity: normally, it
is difficult to introduce mesoporosity in the zeolite nanocrystals
under conventional hydrothermal conditions. However, with
a H2O/SiO2 ratio at 2.0, both HR-TEM and N2-isotherm support
the fact that ZSM-5-2 nanocrystals exhibit mesopores to
a certain extent, which in turn are benecial to mass transfer.
(5) Rational tuning of zeolite crystal size: as highlighted in
Fig. 2B, a linear relationship between the crystal size and
H2O/SiO2 in turn allows the rational control of the crystal sizes
by adjusting the water content in the starting gels.
1 J. Shin, M. A. Camblor, H. C. Woo, S. R. Miller, P. A. Wright
and S. B. Hong, Angew. Chem., Int. Ed., 2009, 48, 6647.
2 C. S. Cundy and P. A. Cox, Chem. Rev., 2003, 103, 663.
3 X. J. Meng and F.-S. Xiao, Chem. Rev., 2014, 114, 1521.
4 V. Valtchev and L. Tosheva, Chem. Rev., 2013, 113, 6734.
5 Y. Liu, C. M. Lew, M. W. Sun, R. Cai, J. L. Wang, G. Kloster,
B. Boyanov and Y. S. Yan, Angew. Chem., Int. Ed., 2009, 48,
4777.
6 S. Mintova, N. H. Olson, V. Valtchev and T. Bein, Science,
1999, 283, 958.
7 H. Chen, J. Wydra, X. Zhang, P. S. Lee, Z. Wang, W. Fan and
M. Tsapatsis, J. Am. Chem. Soc., 2011, 133, 12390.
8 D. Jo, G. T. Park, J. Shin and S. B. Hong, Angew. Chem., Int.
Ed., 2018, 57, 2199.
9 L. Tosheva and V. P. Valtchev, Chem. Mater., 2005, 17, 2494.
21160 | J. Mater. Chem. A, 2018, 6, 21156–21161
This journal is © The Royal Society of Chemistry 2018

View Article Online
Paper
Journal of Materials Chemistry A
10 S. M. T. Almutairi, B. Mezari, E. A. Pidko, 30 F.-S. Xiao, L. Wang, C. Yin, K. Lin, Y. Di, J. Li, R. Xu, D. Su,
P. C. M. M. Magusin and E. J. M. Hensen, J. Catal., 2013,
307, 194.
R. Schlogl, T. Yokoi and T. Tatsumi, Angew. Chem., Int. Ed.,
2006, 45, 3090.
11 Y. S. Tao, H. Kanoh, L. Abrams and K. Kaneko, Chem. Rev., 31 F. J. Liu, T. Willhammar, L. Wang, L. F. Zhu, Q. Sun,
2006, 106, 896.
X. J. Meng, W. Carrillo-Cabrera, X. D. Zou and F.-S. Xiao, J.
Am. Chem. Soc., 2012, 134, 4557.
32 M. Shete, M. Kumar, D. Kim, N. Rangnekar, D. Xu, B. Topuz,
K. V. Agrawal, E. Karapetrova, B. Stottrup, S. Al-Thabaiti,
S. Basahel, K. Narasimharao, J. D. Rimer and M. Tsapatsis,
Angew. Chem., Int. Ed., 2017, 56, 535.
33 R. M. Barrer, Hydrothermal Chemistry of Zeolites, Academic
Press, London, 1982.
34 D. W. Breck, Zeolite Molecular Sieves, Krieger, Malabar,
Florida, 1984.
12 P. Tian, Y. Wei, M. Ye and Z. M. Liu, ACS Catal., 2015, 5,
1922.
13 Z. M. Cui, Q. Liu, W. G. Song and L. J. Wan, Angew. Chem.,
Int. Ed., 2006, 45, 6512.
14 R. Cai, Y. Liu, S. Gu and Y. S. Yan, J. Am. Chem. Soc., 2010,
132, 12776.
15 R. W. Wang, W. T. Liu, S. Ding, Z. T. Zhang, J. X. Li and
S. L. Qiu, Chem. Commun., 2010, 46, 7418.
16 Z. J. Berkson, R. J. Messinger, K. Na, Y. Seo, R. Ryoo and
B. F. Chmelka, Angew. Chem., Int. Ed., 2017, 56, 5164.
17 Introduction to Zeolite Science and Practice, ed. P. A. Jacobs, E.
35 J. H. Lee, M. B. Park, J. K. Lee, H.-K. Min, M. K. Song and
S. B. Hong, J. Am. Chem. Soc., 2010, 132, 12971.
M. Flanigen, J. C. Jansen and H. van. Bekkum, Elsevier, 36 C. M. Wang, Y. D. Wang, H. X. Liu, Z. K. Xie and Z. P. Liu, J.
Amsterdam, 2001. Catal., 2010, 271, 386.
18 R. R. Xu, W. Q. Pang, J. H. Yu, Q. S. Huo and J. S. Chen, 37 L. Lakiss, F. Ngoye, C. Canaff, S. Laforge, Y. Pouilloux,
Chemistry of Zeolites and Related Porous Materials, Wiley,
Singapore, 2007.
19 L. M. Ren, Q. M. Wu, C. G. Yang, L. F. Zhu, C. J. Li,
Z. X. Qin, M. Tarighi, K. Thomas, V. Valtchev, A. Vicente,
L. Pinard, J.-P. Gilson and C. Fernandez, J. Catal., 2015,
328, 165.
P. L. Zhang, H. Y. Zhang, X. J. Meng and F.-S. Xiao, J. Am. 38 J. Zhu, Y. H. Zhu, L. K. Zhu, M. Rigutto, A. V. D. Made,
Chem. Soc., 2012, 134, 15173.
C. G. Yang, S. X. Pan, L. Wang, L. F. Zhu, Y. Y. Jin, Q. Sun,
Q. M. Wu, X. J. Meng, D. L. Zhang, Y. Han, J. X. Li,
Y. Y. Chu, A. M. Zheng, S. L. Qiu, X. M. Zheng and
F.-S. Xiao, J. Am. Chem. Soc., 2014, 136, 2503.
20 Y. Y. Jin, Q. Sun, G. D. Qi, C. G. Yang, J. Xu, F. Chen,
X. J. Meng, F. Deng and F.-S. Xiao, Angew. Chem., Int. Ed.,
2013, 52, 9172.
21 Q. M. Wu, X. Wang, G. D. Qi, Q. Guo, S. X. Pan, X. J. Meng, 39 Q. W. Tian, Z. H. Liu, Y. H. Zhu, X. L. Dong, Y. Saih,
J. Xu, F. Deng, F. T. Fan, Z. C. Feng, C. Li, S. Maurer,
J.-M. Basset, M. Sun, W. Xu, L. K. Zhu, D. L. Zhang,
J. F. Huang, X. J. Meng, F.-S. Xiao and Y. Han, Adv. Funct.
Mater., 2016, 26, 1881.
¨
U. Muller and F.-S. Xiao, J. Am. Chem. Soc., 2014, 136, 4019.
22 R. E. Morris and S. L. James, Angew. Chem., Int. Ed., 2013, 52,
2163.
23 C. T. H. Andrew, AIChE J., 1971, 17, 1311.
24 A. Culfaz and L. B. Sand, Adv. Chem. Ser., 1973, 121, 140.
25 C. Madsen and C. J. H. Jacobsen, Chem. Commun., 1999, 0,
673.
40 Z. H. Liu, X. L. Dong, Y. H. Zhu, A.-H. Emwas, D. L. Zhang,
Q. W. Tian and Y. Han, ACS Catal., 2015, 5, 5837.
41 M. Bjørgen, S. Svelle, F. Joensen, J. Nerlov, S. Kolboe,
F. Bonino, L. Palumbo, S. Bordiga and U. Olsbye, J. Catal.,
2007, 249, 195.
ˇ ´
26 G. Majano, A. Darwiche, S. Mintova and V. Valtchev, Ind. Eng. 42 A. Palcic, V. V. Ordomsky, Z. X. Qin, V. Georgieva and
Chem. Res., 2009, 48, 7084. V. Valtchev, Chem. - Eur. J., 2018, 24, 13136.
27 C. Baerlocher, L. B. McCusker and D. H. Olson, Atlas of 43 S. Mintova, J.-P. Gilson and V. Valtchev, Nanoscale, 2013, 5,
Zeolite Framework Types, 6th rev. edn, Elsevier, Amsterdam,
6693.
2007.
44 W. Fan, M. Ogura, G. Sankar and T. Okubo, Chem. Mater.,
2007, 19, 1906.
28 O. Sel, D. Kuang, M. Thommes and B. Smarsly, Langmuir,
´
2006, 22, 2311.
45 V. J. Margarit, M. R. D. Rey, M. T. Navarro, C. MartInez and
29 A. Vantomme, Z. Yuan and B. Su, New J. Chem., 2004, 28,
A. Corma, Angew. Chem., Int. Ed., 2018, 57, 3459.
1083.
This journal is © The Royal Society of Chemistry 2018
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