Synthesis of EU-1/ZSM-48 Co-Crystalline Zeolites from High-Silica EU-1 Seeds: Tailoring Phase Proportions and Promoting Long Crystalline-Phase Stability

Article abstract of DOI:10.1002/chem.201705805

A facile, specific, seed-assisted strategy for the synthesis of EU-1/ZSM-48 co-crystalline zeolites in the presence of hexamethonium ions (HM²⁺) has been developed. EU-1/ZSM-48 co-crystalline zeolites with various phase proportions, with EU-1 in the range of 25 wt %–86 wt %, were obtained by adding high-silica EU-1 seeds (SiO₂/Al₂O₃ ratio of 300) and adjusting the synthesis parameters. Not only can the phase proportions of EU-1/ZSM-48 co-crystalline zeolites be controlled, but also the stability period for co-crystallization of the two phases can be extended through varying the amount of EU-1 seeds and the HM²⁺ template. Moreover, with the increase of the EU-1 proportion in the EU-1/ZSM-48 co-crystalline, the framework SiO₂/Al₂O₃ ratios of EU-1 phase promotes steadily. Major differences in acidity and textural properties of the EU-1/ZSM-48 co-crystalline zeolites (Coz) were found with varying phase proportions, due to their distinct topological structures, crystal morphology and asymmetry between the EU-1 and ZSM-48 phases. For instance, the EU-1/ZSM-48 zeolite containing 75 wt % of EU-1 (Coz-75) possesses specific acidity and mesoporous characteristics, showing an excellent catalytic activity and stability in n-hexane cracking reaction. Compared to EU-1, ZSM-48, and a mechanical mix of the two zeolites (Mix-75), Coz-75 resulted in the highest hexane conversion and yields of light olefins, with a propylene yield, in particular, up to 38.3 wt %, which is 6.3 % more than that of the Mix-75 sample.

Full text of DOI:10.1002/chem.201705805

A Journal of
Accepted Article
Title: Synthesis of EU-1/ZSM-48 Co-crystalline Zeolite by High Silica
EU-1 Seeds: Tailoring Phase Proportions and Promoting Long
Crystalline Phase Stability
Authors: Yafei Zhang, Yasheng Liu, Liyuan Sun, Luoming Zhang, Jun
Xu, Feng Deng, and Yanjun Gong
This manuscript has been accepted after peer review and appears as an
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of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
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To be cited as: Chem. Eur. J. 10.1002/chem.201705805
Link to VoR: http://dx.doi.org/10.1002/chem.201705805
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Synthesis of EU-1/ZSM-48 Co-crystalline Zeolite by High Silica
EU-1 Seeds: Tailoring Phase Proportions and Promoting Long
Crystalline Phase Stability
Yafei Zhang, [a] Yasheng Liu, [a] Liyuan Sun, [a] Luoming Zhang, [a] Jun Xu, [b] Feng Deng [b] and Yanjun
Gong * [a]
Abstract: A facile, specific seeds-assisted strategy for the synthesis
Zeolites are metastable materials and in most cases, a
perfect crystalline phase could be obtained only when the
synthesis parameters are precisely tuned. It is a common
phenomenon that the majority of zeolite crystallization
conditions often result in the formation of materials with
several different topological phases, which can be treated as
of EU-1/ZSM-48 co-crystalline zeolite in the presence of
2
+
hexamethonium ions (HM ) has been developed. EU-1/ZSM-48 co-
crystalline zeolites with various phase proportions, with EU-1 in the
range of 25 wt%-86 wt%, were obtained by adding high silica EU-1
2
seeds (SiO /Al
2
O
3
ratio of 300) and adjusting the synthesis
[
2]
parameters. Not only the phase proportions of EU-1/ZSM-48 co-
crystalline zeolite can be controlled but also the stability period for co-
crystallization of the two phases can be extended through varying the
zeolite-zeolite composite.
Zeolite-zeolite composite is
usually constructed by two-phase intergrowth (epitaxial and
polytypism) and/or co-crystalline (or co-growth) during the
crystallization process.[3] Hence, the composite with different
zeolitic phases not only possesses advantages of the
individual zeolite structure, but also displays specific pore
structure and acid property, which leads to unique synergistic
performance in various catalytic reactions.[2a,2b] Accordingly,
enormous efforts have been devoted to the synthesis of new
intergrowth or co-crystalline zeolites and to the further
2+
amount of EU-1 seeds and the HM template. Moreover, with the
increase of EU-1 proportion in the EU-1/ZSM-48 co-crystalline, the
2 2 3
framework SiO /Al O ratios of EU-1 phase promotes steadily,
pointing to an ever-changing synthesis phase area during the
competitive growth of the two phases. Major differences in acidity and
textural properties of the EU-1/ZSM-48 co-crystalline zeolites were
found with varying phase proportions, due to their distinct topological
structures and crystal morphology and asymmetry between the EU-1
and ZSM-48 phases. For instance, EU-1/ZSM-48 zeolite containing
[
4]
development of their potential applications.
The two zeolites that can form an intergrowth zeolite
should be structurally related or have similar planar building
units and elemental composition. These similar composition
units could induce stacking in different sequences or oriented
overgrowth upon different phases.[5] MFI/MEL zeolite, for
example, is one of the typical intergrowth zeolites and has
drawn great attention both for academic research and
75 wt% of EU-1(Coz-75) possesses specific acidity and mesoporous
characteristics, showing an excellent catalytic activity and stability in
n-hexane cracking reaction. Compared to EU-1, ZSM-48 and a mixed
one (Mix-75), Coz-75 resulted in the highest hexane conversion and
yields of light olefins, with a propylene yield, in particular, up to
3
8.3 wt%, which is 6.3 percentage point higher than that of Mix-75
[
6]
sample.
industrial application.
Some intergrowth zeolites may
provide the opportunity for the construction of
multidimensional nanospacial network, such as zeolite
beta,[7]
STF/SFF,
[8]
CHA/AEI,
[9]
NON/EUO/NES,[10]
Introduction
[11]
[12]
MTT/TON, and ETS-10/ETS-4.
In contrast, the co-crystalline zeolites are formed without
necessarily requiring a structural similarity between the two
crystal units. Co-crystalline zeolites can be structurally
fabricated by diversified crystal forms according to the actual
design arrangement.[13] The synthesis of co-crystalline
zeolites can usually adopt a simple one-pot synthetic
Zeolites are widely used in oil refining, fine chemicals
production, and adsorption/separation fields due to their
diverse topological structures and adjustable acidities.
[1]
[
[
a]
b]
Dr. Y. Zhang, Y. Liu, L. Sun, L. Zhang, Prof. Y. Gong*
State Key Laboratory of Heavy Oil Processing and the Key
Laboratory of Catalysis of CNPC,
China University of Petroleum-Beijing, 102249, Beijing, China
E-mail: gongyj@cup.edu.cn
strategy mainly by employing dual templates or a single
[4,13d]
template with seed-assisted system.
For instance,
MCM-49/ZSM-35 co-crystalline zeolite was synthesized in
the mixed amines system composed of hexamethyleneimine
(HMI) and cyclohexylamine (CHA), with HMI acting as the
Prof. J. Xu, Prof. F. Deng
template for the formation MCM-49 phase, and CHA
directing the structure of ZSM-35 phase in MCM-49/ZSM-35
composites was adjusted by the molar ratio of HMI/CHA.[
A noteworthy aspect of the seeded approach is that one of
the crystal phases in the co-crystalline zeolite could be
induced by organic template, while the other phase could be
State Key Laboratory of Magnetic Resonance and Atomic and
Molecular Physics, Wuhan Centre for Magnetic Resonance,
Wuhan Institute of Physics and Mathematics, Chinese Academy of
Sciences, 430071, Wuhan,
4]
Supporting information for this article is given via a link at the end
of the document
[
13d]
generated with the assist of seeds.
1
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Chemistry - A European Journal
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The excellent results on co-crystalline zeolites were obtained
in many catalytic reactions, including light paraffin cracking,
oil catalytic cracking, and aryl alkylation and so on, due to
their structurally synergic effect.[14] The SAPO-11/Hβ co-
crystalline zeolite gave rise to higher selectivity both for
propylene and ethylene in the cracking reaction of 2-butene
when compared to the system utilizing a mechanically mixed
zeolite sample. This was mainly attributed to the increased
density of Brönsted acid sites and higher ratio of
Brönsted/Lewis acid sites due to the presence of strong
chemical interaction between SAPO-11 and Hβ phases in
the co-crystalline zeolites.[13d] ZSM-5/Y co-crystalline zeolites
exhibited an increase in the production of gasoline and the
decrease in the yield of light cycle oil (LCO) and coke in the
heavy oil cracking reaction, due to the unique structural
complement within the ZSM-5 and Y phase.[15] Most recently,
EU-1/ZSM-48 composite exhibited high yield of i-
hexadecane compared to mechanical mixtures of zeolites in
the hexadecane hydroisomerization reaction.[24]
ZSM-48 (*MRE) is a high-silica zeolite with a one-
dimensional 10-ring pore system and crystal face (100). Due
to the highly-disordered framework, the catalytic
performance of ZSM-48 zeolite can be readily adjusted by
controlling the disorder degree from different synthesis
processes. It was found that ZSM-48 has higher propylene
selectivity than the conventional ZSM-5 in the catalytic
cracking reaction of C4-olefins.[16]
of highly effective catalysts. Recently, EU-1 zeolites with
SiO
systemically in the n-hexane cracking reaction. We have
observed that high silica EU-1 (SiO /Al ratio of ca. 300,
2 2 3
/Al O ratios ranging from 55 to 300 were evaluated
[
22]
2
2 3
O
EU-1-300) exhibited a high propylene selectivity of up to
~35%, an increase of 9.6 percentage points compared to
ZSM-5-300. Moreover, EU-1 zeolites would produce the low
aromatic hydrocarbons, which could be attributed to the
more confined channel system (0.41 × 0.58 nm). Meanwhile,
ZSM-48-300 was also shown to exhibit high propylene
selectivity and low aromatics compared to the best
alternative ZSM-5.[22] In addition, EU-1 zeolites have
tremendous potential for applications in the isomerization of
aromatics and the conversion of methanol to
[23]
hydrocarbons.
Therefore, new approaches to zeolitic composite with
EU-1 and ZSM-48 structures, ideally in a one-pot synthesis,
have become highly desirable and attracted great academic
and industrial interests. Due to the possibility to induce
distortion of zeolitic microstructure, the composite zeolite
properties, including its acidity and texture property, can be
finely tuned during the competitive co-growth process and
may eventually exert excellent catalytic activity. Still, there
exist many challenges in the specific design of the co-
crystalline structure and in the control of phase proportion,
particularly it applies to a specific reaction. On the one hand,
a slight change in the synthesis conditions would result in the
transformation between the two zeolites, leading to the
uncertainty of phase proportion of the co-crystalline. Thus,
the co-crystalline zeolites cannot be tuned and the
physicochemical properties are hardly predictable. On the
other hand, it is quite difficult to retain a long period of
EU-1 zeolite (EUO) has a one-dimensional 10-ring pore
system with crystal face (100), but is periodically interrupted
by alternating “side-pockets” circumscribed by 12-ring along
with crystal face (001).[17] Since the original report of EU-1
zeolite in 1985 by Casci et al.,[18] much effort has been
devoted to the optimization of its primary structural properties, crystallization stability for the co-crystalline zeolite, due to the
by a variety of methods, such as variation of the crystal
morphology/size, widening of the range of framework Si/Al
ratio, and the introduction of mesopores into the crystals. In
the early report, the synthesis of pure EU-1 phase in
hexamethonium ions (HM) medium was strongly confined to
the gel compositions and crystallization conditions. Pure
synthetic phase area and phase composition for the
individual zeolites are dynamically changing during the co-
growing process.
Herein we wish to report a facile strategy for controllable
synthesis of EU-1/ZSM-48 co-crystalline zeolite by
employing specific EU-1 seeds in the presence of a HM
single-template. As a result, EU-1/ZSM-48 co-crystalline
zeolites with series of phase proportions were obtained with
a wide range of EU-1 phase proportions (25 wt%-86 wt%).
The specific high silica EU-1 seeds played a pivotal role in
controlling the phase proportion, also providing a long period
of stability of the resulting EU-1/ZSM-48 co-crystalline zeolite.
Research firstly provides the new insight into the way of EU-1
EU-1 was only obtained when the SiO
initial gel was less than 120. An increased SiO
2
/Al
2
O
3
ratio in the
/Al ratio
2
2 3
O
would lead to the formation of mixed phases of EU-1 and
ZSM-48 or even pure ZSM-48.[18] Meanwhile, alumina rich
EU-1 could be readily prepared in an HM rich system,
whereas ZSM-48 zeolite was favored with low ratios of
-
-
[19]
2
OH /SiO and OH /HM (between 2.5 and 5). It was later
reported that all-silica EU-1 zeolite was synthesized by
employing the strategy of dry-gel conversion,[20] indicating
2 2 3
framework SiO /Al O ratios behave as varying the phase
proportion in the EU-1/ZSM-48. The crystallization process
regulating the phase proportion of the EU-1/ZSM-48 are
proposed. Its catalytic performance was also evaluated in
catalytic n-hexane cracking reaction.
that the extremely high HM concentration, due to a small
amount of water in the gel, was conducive to inhibiting the
ZSM-48 phase. In our previous work, by using Al-rich EU-1
2 2 3
seeds, pure EU-1 zeolites with a wide range of SiO /Al O
ratios (55-1500) has been successfully prepared in the
optimized HM system. The result indicates that Al-rich EU-1
2 2 3
seeds (SiO /Al O ratio of ca.55) can reduce the activation
Results and Discussion
energy for EU-1 nucleation, and hence inhibits the crystal
transformation from EU-1 into ZSM-48 during the long
crystallization process, and finally leads to the formation of
high-silica EU-1 zeolite. [21]
There has been a growing interest in replacing the
current steam cracking process of naphtha to produce light
olefins by catalytic ones. A major challenge is the exploration
Effect of seeds on the crystallization process of EU-1/ZSM-
4
(
8 co-crystalline zeolite: As our reported, Al-rich EU-1 seeds
i.e. SiO /Al ratio of 55) was required for the synthesis of high
silica EU-1 zeolite (SiO /Al ratio > 120), because it could
facilitate the nucleation/growth of EU-1 and inhibit the formation
2
2 3
O
2
2 3
O
2
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Chemistry - A European Journal
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FULL PAPER
of ZSM-48 phase.[21] Instead, an attempt to choose high silica
seeds to examine the influence on the co-growth behavior of EU-1
and ZSM-48 phases is very meaningful. Figure 1 shows the
relationship between crystalline phase content and crystallization
time at 453 K, where 2.5 wt% of EU-1-300, ZSM-48-300 and Mix-
crystallized structures. The EU-1/ZSM-48 co-crystalline and their
mechanical mixture samples exhibit the characteristic diffraction
peaks of both EU-1 and ZSM-48 phases, and almost similar to
each other.
5
2 2 3
5 were used as seeds, respectively (300 refers to the SiO /Al O
ratio of the initial prepared gels for EU-1 and ZSM-48 and 55 is
the EU-1 proportion in the mechanical mixture of EU-1-300 and
ZSM-48-300. The sum of crystalline phase content of EU-1 and
ZSM-48 approximates the content of EU-1/ZSM-48).
(a)
(
b)
1
00
100
50
(A)
(
c)
5
0
0
0
(
d)
1
00
(B)
100
5
10
15
20
25
30
35
40
45
50
EU-1
ZSM-48
EU-1/ZSM-48
50
50
2Theta (degree)
0
0
Figure 2. XRD patterns of (a) EU-1 (b) ZSM-48 (c) EU-1/ZSM-48 (d) Mechanical
100
100
(C)
mixture.
5
0
50
0
SEM images (Figure 3) reveal that EU-1 zeolite presents
petal-like crystal (Figure 3a) while ZSM-48 possesses strips
morphology with thin fibres binding together (Figure 3b).
However, ZSM-48 phase in EU-1/ZSM-48 co-crystalline
zeolite changes into stacks of small crystals and embeds into
the petal-like EU-1 crystals while the mechanical mixture
sample shows only the discrete mixture of the two kinds of
crystals. These results well demonstrate the formation of EU-
0
0
10
20
30
40
50
60
Crystallization time (h)
Figure 1. The variation of crystalline phase content with crystallization time at
53 K with the different seeds (A) EU-1-300 (B) ZSM-48-300 and (C) Mix-55.
4
1
/ZSM-48 co-crystalline zeolites during the crystallization
The EU-1/ZSM-48 co-crystalline zeolites are obtained only in the
presence of EU-1-300 (Figure 1A) or the Mix-55 seeds (Figure
process.
1
C), while ZSM-48-300 as seeds leads to the formation of well-
crystallized pure ZSM-48 zeolite (Figure 1B). Note that if the Mix-
5 is used as seeds, both EU-1 and ZSM-48 phases appear
5
simultaneously and increase with crystallization time, but the rate
of increase upon ZSM-48 is much more remarkable at the initial
stage. In this case, the variation trend of ZSM-48 content has a
perfect parabola, while the content of EU-1 rises gradually, which
suggests the EU-1/ZSM-48 co-crystalline zeolite with large
proportion of ZSM-48 is formed and the phase proportions are
ever-changing with time. As can be observed in the EU-1-300
seed system, the EU-1 crystals firstly appear and the ZSM-48
phase begins to emerge after 10 h, then both phases co-grow in
a nearly consistent rate. These results indicate that EU-1-300
seeds not only facilitate the growth of EU-1/ZSM-48 co-crystalline
zeolite, but also provide a relatively long period of crystallization
stability (keeping invariable phase proportion from 20 h to 36 h)
during the crystallization process. XRD patterns of the samples
obtained at different crystallization time with EU-1-300 seeds
were displayed in Figure S2. The co-crystalline zeolite with
expected phase proportion would have more competitive
advantage over others because the long period of crystallization
stability is necessary for controllable and large-scale preparation
under an industrial condition.
Figure 3. SEM images of (a) EU-1 (b) ZSM-48 (c) EU-1/ZSM-48 (d) Mechanical
mixture.
Tuning the crystal phase proportions of EU-1/ZSM-48 co-
crystalline zeolites: Using EU-1-300 as seeds in the gel
Figure 2 shows XRD patterns of EU-1, ZSM-48, EU-1/ZSM-
composition of SiO
2 2 3 2 2 2
-1/300Al O -0.12Na O-0.08HMBr -12H O,
48 co-crystalline and the mixed one. All samples have well-
the effect by adding seed on crystal phase proportion was
3
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Chemistry - A European Journal
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FULL PAPER
investigated systematically. Figure 4 illustrates the seed content
as a function of EU-1 phase proportion in EU-1/ZSM-48 co-
crystalline zeolites. In the absence of EU-1 seed in the initial gel,
only ZSM-48 phase was detected in the resulting sample due to
the high silica mixture gel, which is consistent with previous
work. [21] After addition of EU-1-300 seeds, with the seeds
50%-55% (Sample 7, 3, 8). Therefore, HM ions mainly direct the
structure of EU-1 phase, while the suitable alkalinity (Na O/SiO
2 2
ratio) could improve the crystallinity, and it hardly impacts the
EU-1 phase proportion. Interestingly, when using high-silica
EU-1-300 as seeds in the high-silica gel with SiO
2 2 3
/Al O ratio of
300 and Na O/SiO ratio of 0.12, EU-1/ZSM-48 co-crystalline
2
2
accounting for 1.5 wt% to 6.0 wt% of SiO
2
in the initial gel, the
zeolite was steadily produced. Instead, adding the Al-rich seeds
(EU-1-55), only EU-1 phase was produced without formation of
ZSM-48.[ This suggest Al content in EU-1 seeds could play a
crucial role in the balance of formation of EU-1 and ZSM-48
crystalline phase during the crystallization process.
mass fraction of EU-1 phase in co-crystalline zeolite increases
from 40% to 80%. When the seed content reaches to 10.0 wt%,
the proportion of EU-1 phase in EU-1/ZSM-48 co-crystalline
zeolite goes up to 86%, and it cannot increase further with the
seeds content. It is deduced that the proportion of EU-1 phase in
the resulting co-crystalline zeolites may also related to other
factors.
21]
Table 1. Typical products with various EU-1 phase proportions obtained with
[
a]
different concentrations of HM and alkalinity.
Initial gel composition
Sample
Products
100
Crystalline
phases
HM/SiO
2
Na
2
O/SiO
2
Proportion of EU-1
80
60
40
20
0
1
2
3
4
5
0.04
0.06
0.08
0.12
0.12
0.12
0.12
0.12
0.12
EU-1/ZSM-48
EU-1/ZSM-48
EU-1/ZSM-48
EU-1/ZSM-48
EU-1/ZSM-48
25
43
54
75
86
0.15
Amorphous +
EU-1/ZSM-48
6
0.08
0.06
—
7
8
0.08
0.08
0.08
0.16
EU-1/ZSM-48
EU-1/ZSM-48
50
55
[
2 2 3 2 2 2
a] Initial gel composition: SiO - 1/300 Al O - x HMBr - y Na O - 12H O with 2.5
0
2
4
6
8
10
wt% EU-1-300 seeds at 453 K for 36 h, where x varies from 0.04-0.15 and y is
from 0.06 to 0.16.
Content of EU-1 seeds (wt%)
Figure 4. The influence of EU-1 seed content on the proportions of EU-1 phase
in the co-crystalline samples.
With the same gel composition SiO
HMBr -12 H O and 2.5 wt% of EU-1-300 seeds, the relationship
between crystalline phase content and crystallization time at
33 K and 453 K are shown in Figure 5. An elevated temperature
pronouncedly improves the nucleation, growth and the content of
EU-1/ZSM-48 zeolite. At temperature of 433 K, it takes nearly 60 h
for completing nucleation and growth of zeolites while it is only
2 2 3 2
-1/300 Al O -0.12 Na O-0.08
2
2
4
As known, the template concentration and alkalinity in the initial
gel are key factors for the nucleation and crystallization of each
zeolite, which also present strong influence on the formation of
[
25]
co-crystalline zeolite. Table 1 shows the synthesis parameters
and corresponding proportion of EU-1 phase in the co-crystalline
2
4 h at 453 K. Note that the crystallization period when the well-
crystallized products exhibit a stable phase state is called the
crystallization stability period. At low temperature (433 K), the
resulting co-crystalline has a longer stable period of 50 h and it
has ca. 18 h at high temperature of 453 K. Based on the
normalized crystallinity of EU-1/ZSM-48 co-crystalline during the
stability period, the individual crystallinity of EU-1 and ZSM-48
zeolites at 433 K are about 40% and 35%, respectively, while
those are about 51% and 48%, respectively at 453 K. It is notable
that the proportion of EU-1 phase in EU-1/ZSM-48 co-crystalline
maintains at constant value (about 52-54%) under the two
crystallization temperatures. Meticulously examining the curves at
zeolite. At the same Na
the proportion of EU-1 phase remarkably increases with the
HM/SiO ratio, which is in perfect accordance with the result that
2
HM rich system favors the synthesis of EU-1 phase.[21] The length
of HM ion is around 14.5 Å, so it can be accommodated in a
perpendicular position to the a-axis between the channel and a
side-pocket in the framework of EU-1 zeolite, but only can be filled
in the channel of ZSM-48 zeolite.[19] As
accommodation is about 4 per unit cell for EU-1 zeolite and only
2 2
O/SiO ratio and 2.5 wt% EU-1-300 seeds,
a
result, HM
1
per unit cell for ZSM-48. Thus, there are more HM ions required
-
to stabilize the EU-1 zeolite negative [Si-O-Al] framework
compared with ZSM-48 zeolite. Herein, EU-1 proportion varies
433 K and 453 K, EU-1 is preferential nucleation and growth,
while ZSM-48 phase appears after 20 h and 10 h, respectively.
The result implies that the both phases have the similar co-growth
mechanisms under the two crystallization temperatures, but their
growth rate are different.
from 25% to 86% with the HM/SiO
The influence of alkalinity is also exhibited in Table 1. When
O/SiO ratio is 0.06, EU-1/ZSM-48 mixing with amorphous
materials is obtained, showing a very low relative crystallinity
Sample 6). Increasing Na O/SiO ratio from 0.06 to 0.16, the
2
ratio ranges from 0.04 to 0.15.
Na
2
2
(
2
2
crystallinity of EU-1/ZSM-48 co-crystalline zeolite increases
gradually, while EU-1 proportion in co-crystalline zeolites retains
4
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FULL PAPER
1
00
100
50
220
00
180
60
433K
2
5
0
1
0
0
140
120
1
00
100
453K
100
5
0
50
0
8
0
0
EU-1
ZSM-48
EU-1/ZSM-48
EU-1
Coz-54
ZSM-48
Coz-75
Mix-75
Coz-86
6
0
0
10
20
30
40
50
60
0.0
0.2
0.4
0.6
0.8
1.0
Crystallization Time (h)
Partial pressure (P/ Po)
Figure 5. The relationship between crystalline phase content and crystallization
2
Figure 6. N adsorption/desorption isotherms of the samples. Putting in 20
3
-1
time at 433 K and 453 K.
cm g offset for the adjacent isotherms up on Y-axis.
The structural properties of EU-1/ZSM-48 co-crystalline
The differences in the topological structure, morphology (Figure
3), and the growth rates between the two zeolites are responsible
for the formation of porosities in EU-1/ZSM-48 co-crystalline
zeolites. Table 2 shows the textural properties of EU-1/ZSM-48
zeolites with different phase proportions. Compared with single
zeolite, all of the co-crystalline samples display lower BET surface
area, but the first two Coz samples denote larger mesopore
volume. Typically, Coz-75 has larger external surface area and
pore volume than those of Mix-75, and particularly the mesopore
volume is almost three times as high as those of other samples.
Coz-86 and single EU-1 has a slight difference in texture property,
which suggests that the uneven co-growth of EU-1 and ZSM-48
is weakened as further increasing EU-1 proportion in the co-
crystalline zeolite. Thus, the micro/mesoporosity distribution of
co-crystalline zeolites could be finely tuned by adjusting the phase
proportion in the co-crystalline zeolites.
zeolites: Figure
6
presents the
N
2
adsorption/desorption
isotherms of the samples. For single EU-1, ZSM-48 and Mix-75,
the isotherms exhibit typical type-I curve, indicating their
microporous characteristics. Among the samples, Coz-54 and
Coz-75 (the co-crystalline zeolites with EU-1 proportions of 54
and 75) exhibit the similar type-IV isotherms with type H3
hysteresis loop, while Coz-86 presents the typical type-I isotherm
similar to that of pure EU-1 zeolite. Moreover, there is difference
in the H3 hysteresis loops between Coz-54 and Coz-75,
particularly the desorption branch at relative pressure P/P
0
of
0.45-0.50. Such isotherms without levelling off at relative pressure
close to the saturation vapor pressure indicate the material has
slit-like pores from the aggregates of plate-like particles.[26] For
Coz-75, very different from Mix-75, presents a representative
modified type-IV isotherms, with
corresponding to capillary condensation at P/P
a
big hysteresis loop
=0.45-0.99. It
0
suggests that the irregular mesoporosity may arise from the voids
or defects between co-crystals, and increase the pore volume of
the co-crystalline zeolite.[27] The uneven pore distribution of EU-
1/ZSM-48 co-crystalline zeolite changes gradually as increasing
the proportion of EU-1 phase as can be observed in Figure S3.
Table 2. Texture properties of different zeolite samples.
[
a]
[b]
[b]
[c]
[b]
-1
S
BET
S
micro.
S
ext
V
total
V
micro
V
meso
Sample
2
-1
2
-1
2
-1
3
-1
3
3
-1
(
m g )
（m g ）
（m g ）
（cm g ）
（cm g ）
（cm g ）
EU-1
356.1
355.3
360.1
257.2
329.5
332.1
301.5
297.1
301.5
170.0
255.5
281.0
54.6
58.2
58.6
87.2
74.0
51.1
0.20
0.20
0.21
0.26
0.30
0.18
0.15
0.14
0.15
0.08
0.12
0.14
0.05
0.06
0.06
0.18
0.18
0.04
ZSM-48
Mix-75
Coz-54
Coz-75
Coz-86
[
a] SBET (BET surface area) obtained from the adsorption isotherm. [b] Smicro (micorpore area), Sext (external surface area) and Vmicro (micropore volume) calculated
using t-plot method. [c] Vtotal (total pore volume) obtained at P/P =0.99.
0
5
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Figure 7 shows the acidities of the samples measured by NH
TPD. All of the profiles denote two desorption peaks in the
temperature region of 350-550 (Peak l) and 550-850 K (Peak h),
3
-
ppm is found, indicating all the aluminum species are incorporated
into the zeolite framework.[29]
Coz-54
3
which are attributed to the NH desorbed from weak and strong
Coz-75
Coz-86
EU-1
(A)
acidic sites, respectively. The acid amount and acid strength by
the integrated areas and peak temperatures are listed in Table
[
22]
S7. Compared to EU-1, ZSM-48 and Mix-75, Coz-75 exhibits
remarkably more acid amount, while the acid strength, especially
the strong acid is also higher than others. The enhanced acid
property of the co-crystalline zeolite mainly ascribes to the crystal
defect arising from the symbiotic process and the synergetic effect
of acid sites from the two zeolitic phases. The co-crystalline
zeolites with different EU-1 proportion, as seen in Fig 7B, display
similar acid strength. It suggests that the as-prepared Coz
samples by one-pot method may have the close framework Al
Mix-54
Mix-75
Mix-86
ZSM-48
120 100
80
60
40
20
0
-20
2 2 3
content due to the same SiO /Al O ratio in synthesis gel. The
acid amount of Coz-75 is slightly larger than other two Coz
samples.
Chemical shift (ppm)
-
114
Coz-54
Coz-75
Coz-86
(B)
(A)
Coz-75
Mix-75
EU-1
ZSM-48
-104
-80
-90
-100 -110 -120 -130 -140
Chemical shift (ppm)
300
400
500
600
700
800
900
Figure 8. (A) 27Al MAS NMR of the correlative samples and (B)29Si MAS NMR
Temperature (K)
spectra of Coz-54, Coz-75 and Coz-86 samples.
(B)
Coz-54
Coz-75
Coz-86
Figure 8B shows 29Si MAS NMR spectra of Coz-54, Coz-75 and
Coz-86 zeolites. The two resonances at -104 and -114 ppm are
attributed to the Q species of Si (3Si, 1Al) and Q Si (4Si, 0Al),
respectively.[30] The relative intensity of signal at -104 ppm
markedly decreases with EU-1 phase proportion increases from
4
4
54% to 86%, while there is almost invariable for the peak at -114
ppm. It could be deduced that number of aluminum atoms
incorporated into the framework of EU-1/ZSM-48 co-crystalline
zeolites decrease as increasing the EU-1 proportion. In sharp
contrast, for pure EU-1, ZSM-48 and their mechanical mixture,
both signals at -104 and -114 ppm exhibit an irregular change in
intensity, due to the different mixing proportions of the two phases
300
400
500
600
700
800
900
Temperature (K)
2 2 3
Figure S4). For zeolites with relatively high SiO /Al O
ratio, 29Si
(
MAS NMR has not been used to calculate the framework
2 2 3
SiO /Al O
ratio precisely. [
31]
3
Figure 7. NH -TPD profiles of correlative samples.
FT-IR spectra, as our previous report, could provide the
2 2 3
information for the variation of SiO /Al O
ratio in EU-1 zeolite. [
21]
To identify the content of framework aluminum that incorporated
into each crystal phase in the co-crystalline zeolite, FT-IR spectra
of the correlative samples are presented in Figure S5. The
vibration peaks at 450-470, 540-650, 770-800 and 970-1220 cm-1
are assigned to the characteristic bands of EU-1 zeolite.[32] For all
Since the acidity of zeolite is strongly dependent on the aluminum
[
28]
site and its coordination environment with framework silica, The
2
7
Al MAS NMR and 29Si MAS NMR spectra of the relevant
samples were determined as shown in Figure 8. The 27Al MAS
NMR (Figure 8A) spectra demonstrate only a sharp signal at 52
ppm on each sample, which is assigned to tetrahedral
coordinated framework aluminum species. No signal around 0
-
1
the samples, except the vibrations in the region of 540-650 cm ,
the other three bands have neither nor change in wavenumber
6
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Chemistry - A European Journal
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[
32]
and the vibration intensity, which are assigned to the Si-O band,
external link symmetric stretch and internal tetrahedral
asymmetric stretch, respectively. The band of 540-650 cm-1
related to external linkages between the tetrahedral unit is
sensitive to the framework structure and the presence of some
secondary building unit and building block polyhedra, such as the
double rings and large pore openings.
Therefore, the
-
1
corresponding region of 500-900 cm is amplified (Figure 9). In
order to investigate the variation in sample structures of EU-1,
ZSM-48 and their co-crystalline and mechanical mixture zeolites
with different EU-1 contents.
(C)
(A)
(B)
6
13
6
13
6
13
579
5
63
5
79
555
5
78
6
13
5
50
6
11
5
48
5
77
79
5
57
5
46
Coz-54
Coz-75
Coz-86
611
Mix-54
Mix-75
Mix-86
EU-1-300
ZSM-48-300
EU-1-60
ZSM-48-100
5
561
5
44
500
900
800
700
600
900
800
700
600
500
900
800
700
600
500
-
1
-1
-1
Wavenumber (cm )
Wavenumber (cm )
Wavenumber (cm )
Figure 9. FT-IR spectra of the correlative samples.
As in Figure 9A, two vibrations at 548 and 613 cm-1 are observed
for EU-1-60, whereas for EU-1-300, an extra strong vibration at
proportion, and the cell volumes gradually close to that of pure
EU-1-300.
-
1
-1
-1
5
79 cm occurs and the band at 548 cm shifts to 563 cm . Rao
-
1
reported that there was a strong band at 572 cm in high-silica
EU-1 zeolite wherein the SiO /Al ratio higher than 120, using
O
2 3
Table 3. The SiO
correlative samples.
2
/Al
2
O
3
ratio and unit cell parameters of EU-1 phase in the
Unit cell parameters (Å) [b]
2
a mixture of benzyldimethylamine (BDMA) and benzyl chloride as
the templating agents, and IR absorption bands in this region
should be assigned to the vibration of the double rings in high-
silica zeolite frameworks.[32] ZSM-48 presents only one vibration
SiO /Al O [a]
3
Samples
2
2
3
V(Å )
a
b
c
at about 548 cm-1 regardless of SiO
2 2 3
/Al O ratios. The co-
EU-1-60
Coz-54
Coz-75
Coz-86
Mix-54
―
13.757
13.729
13.721
13.716
13.715
13.715
13.713
13.716
22.345
22.249
22.241
22.224
22.224
22.225
22.225
22.226
20.402
20.317
20.307
20.297
20.294
20.294
20.294
20.294
6271.650
6205.840
6197.062
6187.177
6185.655
6185.933
6185.031
6186.802
crystalline zeolites and mechanical mixture samples display three
vibrations, but the peaks have significant distinctions with the
increase of EU-1 contents. For mixture samples (Figure 9C),
when the EU-1 proportion increases from 54% to 86%, three
vibration bands in the region of 540-650 cm-1 remain unchanged
129.86
129.39
131.17
―
(neither the wavenumber nor the intensity). Interestingly, the co-
Mix-75
―
crystalline zeolites, Coz-54, Coz-75 and Coz-86 has the band shift
Mix-86
―
-
1
from 550, 557 to 561 cm , respectively (Figure 9B) due to the
increase of the EU-1 content. Meanwhile, the intensity of shoulder
band at 577 cm-1 increases gradually with the increase of EU-1
content in co-crystalline zeolites. Moreover, the intensity ratio of
the maximum peak at 579 cm-1 to 561 cm-1 increases largely in
Coz-86, which is close to that of EU-1-300. Because of no
vibrational peak around 577-579 cm-1 for ZSM-48 zeolite, the
intensity change in the co-crystalline samples affirmatively is
EU-1-300
156.99
[a] Determined by XRF method.
[b] The date of unit cell parameters are calculated by XRD date using the Miller
indices of (1,1,4), (2,4,0), (1,3,4),(0,2,5), (0,6,0), and (4,0,0) and the d values
they are relevant to.
caused by the framework SiO
result qualitatively demonstrates that SiO
2
/Al
2
O
3
ratio of EU-1 phase. This
/Al ratio of EU-1
The significant decrease in the unit cell volume suggests that
the SiO /Al O ratio of EU-1 crystal phase in co-crystalline
2 2 3
2
2
O
3
crystal increase with the increase of EU-1 phase proportion in the
co-crystalline zeolites.
zeolites increases with the EU-1 proportion, which is good
agreement with the results from FT-IR experiments.
Obviously, the values of unit cell parameters of EU-1 crystals
for the mechanical mixtures are irrelevant to the content of
The unit cell parameters of zeolites could provide a powerful
2 2 3
evidence for the variation of framework SiO /Al O ratio due to the
[
21]
shorter length of Si-O band than that of Al-O band. Thus, the
unit cell parameters of the correlative samples were specifically
determined from XRD data and shown in Table 3. It is obvious
that the unit cell for pure EU-1-60 is larger than that of EU-1-300,
and the unit cell volumes are 6271.650 Å3 and 6186.802 Å3,
respectively. For the co-crystalline zeolites, the unit cell values of
a, b, and c for EU-1 phase decrease with the increase of EU-1
2 2 3
EU-1 phase. The SiO /Al O ratios determined from XRF
present similar values of about 130 for Coz-54, Coz-75 and
Coz-86 samples. These changes in co-crystalline framework
should be ascribed to the two phases competitive co-growth
in the synthesis of EU-1/ZSM-48 co-crystalline zeolites. It
has been confirmed that ZSM-48 was favourably formed with
2 2 3
high SiO /Al O ratio mixing gel, thus as the co-growth
7
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process of EU-1/ZSM-48, higher EU-1 content would make
In this work, no phase transformation of the two phases was
found when synthesized at temperature either 433 K or 453 K.
The big difference in framework structures and morphologies
between EU-1 and ZSM-48 zeolites could result in the
microstructure distortion of the EU-1/ZSM-48 co-crystalline
zeolite during their competitive growth, giving rise to the
special physical-chemical properties, which would exert
excellent catalytic performance.
the decrease of SiO
to the decrease of proportion of ZSM-48 in the resulting EU-
/ZSM-48 zeolite. As a result, no crystal transformation from
2 2 3
/Al O ratio in the reaction gel, leading
1
EU-1 to ZSM-48 is detected during the co-growth process,
which leads to the long period of two phase co-crystallization
stability.
Primary crystallization process of EU-1/ZSM-48 co-
crystalline zeolites: The insights into the EU-1/ZSM-48 co-
crystallization is primarily described in Scheme 1. XRD
patterns in Figure S2 show the solid products with
crystallization time. Firstly, the synthesis gel is prepared with
large silica particles and EU-1-300 seeds with initial molar
Catalytic performance of EU-1/ZSM-48 co-crystalline
zeolites: The Coz-75, Mix-75, EU-1-300 and ZSM-48-300
are comparatively evaluated in n-hexane catalytic cracking
reaction. The catalytic performance of the samples as a
function of time on stream displays in Figure 10. The initial n-
hexane conversion (TOS=15 min) is in the order of
Coz-75>EU-1>Mix-75>ZSM-48, which is extremely in
accordance with the order of strong acid amount. Among the
four samples, Coz-75 exhibits the highest activity and
catalytic stability with time on stream, and the n-hexane
conversion over Coz-75 decreases from 93.9 wt% to 80.9 wt%
within 600 min. The performance of Mix-75 sample
unaffectedly displays in middle of pure EU-1-300 and ZSM-
48-300 zeolites.
composition of SiO
2 2 3 2 2
-1/300 Al O -0.12 Na O-0.08 HMBr -12
H
2
O. At the early crystallization stage (0-6 h), the solid silica
species and EU-1-300 seeds dissolved gradually under
alkaline aqueous medium and the solution gains the high
concentrated nutrition, such as HM and the dissolved EU-1
crystallite precursors. After 6-14 h, XRD patterns are notable
for the EU-1 characteristics peaks, this can be explained that
the prepared gel composition, especially for high HM content
and the addition of EU-1-300 seeds, both benefits for the
formation of EU-1 phase.[19,21] Thereafter, along with an
increasing amount of EU-1 phase, and the compositions in
both solid and liquid phase are varying simultaneously. More
and more nutrition, such as HM ions, EU-1 seeds, especially
Al species are consumed and transferred to the solid phase
as structure directing agent and/or framework atoms for the
formation of EU-1 phase. As decreasing the Al nutrition in the
prepared gel, the higher silica mixture gel is suitable for the
nucleation of ZSM-48, due to high silica medium and the
mixture composition could promote the growth of the ZSM-
100
9
0
0
8
70
60
50
48
structure phase.[19] Under this circumstance,
thermodynamic stability phase area of the crystallization
system tends to adjust the growth balance of each crystal
phase in its favour. Due to presence of more high silica EU-1
seeds, EU-1 crystals still can work as effective seeds for
subsequent EU-1 growth. As a result, EU-1 and ZSM-48
phases grow competitively (14-20 h), which brings about the
co-crystallization of EU-1/ZSM-48 zeolite and a steady
crystallization period. More importantly, supported by XRD
Coz-75
EU-1
Mix-75
ZSM-48
40
0
0
100
200
300
400
500
600
700
Time on stream (min)
(Figure S2), a phase proportion in the EU-1/ZSM-48 zeolite
Figure 10. n-Hexane conversion with time on stream over different zeolites
remains invariable during proceeding 20-36 h crystallization,
suggesting the crystallization stability period is as the same
with synthesis for an individual zeolite. Thus, this co-growth
process is significantly different from the Al-rich EU-1-55
seeds system, where the severe crystal transform from
purely high-silica EU-1 zeolite into ZSM-48 phase continued
after 24 h.[21]
Figure11 illustrates the initial product yields (TOS=15 min)
over different zeolites. Coz-75 displays the highest yields of
ethylene (14.7 wt%) and propylene (38.3 wt%), which are
respectively higher than Mix-75 by 3.7 and 6.3 percentage
points. Noteworthy, the propylene yield over Coz-75 is higher
than the single EU-1 zeolite. While previous research
reported EU-1 had higher propylene yield than the
conventional catalytic cracking catalyst of ZSM-5 by 9.0
percentage points under the same reaction conditions.[
During the whole catalytic process, Coz-75 also exhibits the
highest yield of the ethylene and propylene than other
samples. The yield of ethylene ranges from 14.7 to 11.8 wt%
and propylene decreases from 38.3 to 31.9 wt% within 600
min (Figure S6). According to the mechanism of alkane
cracking, the alkane molecules initially adsorb on a strong
22]
Scheme 1. Primary crystallization process of EU-1/ZSM-48 co-crystalline
acid sites, especially the strong BrÖnsted acid sites and form
8
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Chemistry - A European Journal
10.1002/chem.201705805
FULL PAPER
a “carbonium ion type” activated complex, which further
(Al
2
O
3
, 45 wt%; Na
2
O, 27 wt%, A.R.) and sodium hydroxide
accelerates the reaction, leading to a higher initial conversion. (NaOH, 99 wt%, A.R.) were purchased from Sinopharm
[
33]
Therefore, Coz-75 with more acid amount and specific
Chemical Reagent Co. All of the reagents were used without
further purification.
texture properties could enhance the control over the
cracking products.
Synthesis of seed materials
5
4
3
2
1
0
0
0
0
0
0
The pure EU-1-300 and ZSM-48-300 were respectively
prepared according to the procedure reported in our previous
work. For comparative research, EU-1-300 and ZSM-48-
300 as seeds were used in the synthesis of co-crystalline EU-
=
C1
C2
=
C3
C2
C3
=
C4
[
21]
C4
+
C5
BTX
1
/ZSM-48. Meanwhile, the mechanical mixture of EU-1-300
and ZSM-48-300 was also investigated as seeds, and was
prepared according to the description below.
Synthesis of EU-1/ZSM-48 co-crystalline zeolites
EU-1/ZSM-48 co-crystalline zeolites were hydrothermally
synthesized in a seeded system. A series of hydrogels with
varying molar compositions SiO
2 2 3 2
-1/300Al O -xNa O-
yHMBr -12H O were prepared (x ranged from 0.06 to 0.16,
2
2
Coz-75
Mix-75
EU-1
ZSM-48
and y ranged from 0.04 to 0.15) by mixing the starting
reactants with seeds. The amount of seeds with respect to
silica content in the initial gel ranged from 0 to 10 wt%. The
final mixture was further stirred and then heated in a Teflon-
coated stainless steel autoclave at 433 K or 453 K. After
thermal treatment, the reactor was quenched by cooling
down the mixture to room temperature. The solid was
obtained after filtration, thoroughly wash and then dried at
Figure 11. Initial product yield over different zeolites (C +
hydrocarbons with the carbon number is 5 and higher than 5 except BTX, and
BTX stands for benzene, toluene, and xylenes, the same below)
stands for the aliphatic
5
Conclusions
EU-1/ZSM-48 co-crystalline zeolites with various phase
proportions were synthesized by seed-assisted approach in the
presence of HM. In addition to the HM content and alkalinity, high
3
93 K overnight. The protonated samples were obtained by
repeated ion exchange with 1 M NH Cl solution for 2 h at 363
K and then calcined at 823 K for 5 h.
4
2 2 3
silica EU-1 seeds (such as SiO /Al O ratio of 300) is the most
A mechanical mixture was prepared by physical mixing
of pure EU-1-300 and ZSM-48-300 zeolites in a water bath
at 303 K for 2 h with the same weight proportion of EU-1
phase to the EU-1/ZSM-48 co-crystalline zeolites. After
filtration, the obtained solid was washed thoroughly with
deionized water and then dried at 393 K overnight. The
protonated samples of mechanical mixtures were obtained
by simply mixing of protonated EU-1 and ZSM-48 zeolites
according to the aforesaid method.
The weight proportion of EU-1 phase in EU-1/ZSM-48
co-crystalline zeolites can be deduced from a working curve
of the relative diffraction intensities to the EU-1 proportion
and the detailed process was described in support
information S1.[5b,13d]
crucial factor that generates EU-1 and then ZSM-48 in sequence
and controls the crystal proportions of EU-1/ZSM-48 co-
crystalline zeolite. With the proportions of EU-1 phase in EU-
1/ZSM-48 composite increase from 25 wt% to 86 wt%, the
framework SiO /Al ratio of EU-1 also increases accordingly.
2
2 3
O
The co-crystallization process of EU-1/ZSM-48 co-crystalline
possess a long stability period and no phase transformation
occurs at 433 K and 453 K. EU-1/ZSM-48 co-crystalline zeolites
with various EU-1 proportions present different texture properties,
resulting from the competitive crystallization of the two zeolitic
phases, which is ascribed to the notable difference in framework
structure and morphology of both phases. The primary
crystallization process of EU-1/ZSM-48 co-crystalline zeolites
was proposed. In n-hexane catalytic cracking reaction, Coz-75
displays the highest yield of ethylene (14.7 wt%) and propylene
(
6
38.3 wt%), which is respectively higher than Mix-75 by 3.7 and
.3 percentage points. Especially, Coz-75 provides higher
Characterization
propylene yield than the single EU-1 zeolite, while the latter being
higher than ZSM-5 by 9.0 percentage points.
Powder X-ray diffraction (XRD) patterns for crystal phase,
crystallinity and proportion identification were carried out on
a Bruker D8 Advance diffractometer (40 kV, 4 mA) using Cu
Kα radiation (α=1.5406 Å) at a scanning rate of 4 °/min from
5° to 50° (2θ). The unit cell parameters of EU-1 crystal phase
in as-synthesized zeolitic samples were recorded exactly on
a Rigaku D/Max 2000 diffractometer (120 kV, 40 mA) with
Cu Kα radiation (α=1.5418 Å) at a scanning rate of 0.5 °/min
from 18° to 28° (2θ).
Experimental Section
Materials
Hexamethonium bromide (HMBr
template was purchased from Aldrich. Reagent-grade colloid
silica (SiO , 40 wt%, Qingdao Haiyang Chemical Co.) was
used as silica source. Reagent-grade sodium aluminates
2
, >98 wt%, A.R.) used as
Fourier transform infrared (FT-IR) spectra were
collected by a Nicolet Magna-IR 560 E.S.P instrument using
2
9
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Chemistry - A European Journal
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FULL PAPER
-
1
KBr discs in the range of 400-1600 cm . The morphologies
and the bulk chemical compositions of the obtained samples
were derived by Field-emission Environmental Scanning
Electron Microscope (SEM, FEI Quanta 200F) and X-ray
Fluorescence Analyzer (XRF, PANalytical AxiosMAX),
respectively.
All of the percent values used in this paper are taken in
weight proportions.
Acknowledgements
Nitrogen adsorption-desorption experiments were
measured on a Micromeritics ASAP 2020M instrument at 77
K, and the powder zeolites were evacuated at 823 K for 6 h
and degassed at 573 K under vacuum for 5 h. The specific
surface area was calculated by Brunauer-Emmett-Teller
The authors acknowledge the State Key Development Program
for Basic Research of China (2012CB215002), the National
Natural Science Foundation of China (21276278, U1662116) and
CNPC Key Research Projuct (2014A-2111) for the financial
support of this work.
(BET) equation with the adsorption data obtained at P/P
0
between 0.05 and 0.25. The total pore volume was derived
from the nitrogen amount adsorbed at a relative pressure of
Keywords: composite zeolite •ZSM-48 • EU-1• n-hexane•
0
.99. The micropore surface area and volume were
catalytic cracking
calculated by t-plot method. The pore size distribution was
determined from the desorption branch of the isotherm
according to BJH model.
[
[
1]
2]
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1
Temperature-programmed desorption of ammonia
a) T. Okubo, T. Wakihara, J. Plévert, S. Nair, M. Tsapatsis, Y. Ogawa, H.
3
(NH -TPD) was carried out to evaluate the acidity of the
Komiyama, M. Yoshimura, M. E. Davis, Angew. Chem. Int. Ed. 2001, 40,
samples on an adsorption instrument (TP-5076, Tianjin
Xianquan Industry and Trade Development Co., LTD). Prior
to the measurement, the sample (100 mg) was degassed at
1
069-1071; b) Y. Bouizi, L. Rouleau, V. P. Valtchev, Chem. Mater. 2006,
18, 4959-4966; c) K. Itabashi, Y. Kamimura, K. Iyoki, A. Shimojima, T.
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[
[
3]
4]
C. N. R. Rao, J. M. Thomas, Acc. Chem. Res. 1985, 18, 113-119.
S. Xie, S. Liu, Y. Liu, X. Li, W. Zhang, L. Xu, Microporous Mesoporous
Mater. 2009, 121, 166-172.
8
73 K for 2 h and then cooled down to 373 K in N
that, the sample was saturated in NH -N (mole ratio 1:1)
stream for 30 mins, followed by purging with nitrogen for 1 h
to remove the physisorbed ammonia. The chemisorbed NH
2
flow. After
3
2
[
[
5]
6]
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This article is protected by copyright. All rights reserved.

Chemistry - A European Journal
10.1002/chem.201705805
FULL PAPER
FULL PAPER
Yafei Zhang, [ Yasheng Liu,
a]
[a]
Liyuan
Sun, [ Luoming Zhang,
Feng Deng [ and Yanjun Gong,* [a]
a]
[a]
Jun Xu, [b]
b]
Page No. – Page No.
Synthesis
of
EU-1/ZSM-48
Co-
A series of EU-1/ZSM-48 co-crystalline zeolites with long crystallization stability can
be obtained with a high silica seeded method. This article discusses the influences
of the different synthesized factors and the synthesis process.The EU-1/ZSM-48 co-
crystalline zeolite also displays great performance in n-hexane catalytic cracking
reaction.
crystalline Zeolite by High Silica EU-1
Seeds: Tailoring Phase Proportions
and Promoting Long Crystalline
Phase Stability
1
2
This article is protected by copyright. All rights reserved.