Synthesis of ZSM-22 and Testing Its Catalytic Properties in the Ethylene Oxide Isomerization Reaction

Article abstract of DOI:10.1134/S0965544119080103

Abstract: The influence of the key parameters of the synthesis of a TON-type zeolite (ZSM-22) with or without an organic structure-directing agent on its phase composition has been established. The optimal composition of the reaction mixture and the crystallization time of ZSM-22 in the presence of 1,6-diaminohexane under static conditions have been determined. The dynamics of the formation of an impurity ZSM-5 by cocrystallization during the synthesis with stirring has been revealed. For zeolite ZSM-22 synthesized using the template-free procedure, the most important factors affecting the crystallinity and the crystallization time are the synthesis temperature, the amount of seed, and agitation of the reaction mixture. The zeolites synthesized according to the both procedures have been examined in the reaction of isomerization of ethylene oxide to acetaldehyde. Zeolite ZSM-22 obtained without adding the template is not inferior in activity to the zeolite of the same structure prepared in the presence of 1,6-diaminohexane. Moreover, it exhibits higher selectivity of ethylene oxide conversion to acetaldehyde. The complete conversion of ethylene oxide has been observed on ZSM-22 zeolites of both types at a reaction temperature of 400°C, the selectivity of its conversion to acetaldehyde being at least 93%.

Full text of DOI:10.1134/S0965544119080103

ISSN 0965-5441, Petroleum Chemistry, 2019, Vol. 59, No. 8, pp. 910–917. © Pleiades Publishing, Ltd., 2019.
Russian Text © The Author(s), 2019, published in Sovremennye Molekulyarnye Sita, 2019.
Synthesis of ZSM-22 and Testing Its Catalytic Properties
in the Ethylene Oxide Isomerization Reaction
S. V. Lazarevaa, L. V. Piryutkoa, *, V. S. Chernyavskiia, and A. S. Kharitonova
aBoreskov Institute Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
*e-mail: pirutko@catalysis.ru
Received February 27, 2019
Abstract—The influence of the key parameters of the synthesis of a TON-type zeolite (ZSM-22) with or with-
out an organic structure-directing agent on its phase composition has been established. The optimal compo-
sition of the reaction mixture and the crystallization time of ZSM-22 in the presence of 1,6-diaminohexane
under static conditions have been determined. The dynamics of the formation of an impurity ZSM-5 by
cocrystallization during the synthesis with stirring has been revealed. For zeolite ZSM-22 synthesized using
the template-free procedure, the most important factors affecting the crystallinity and the crystallization time
are the synthesis temperature, the amount of seed, and agitation of the reaction mixture. The zeolites synthe-
sized according to the both procedures have been examined in the reaction of isomerization of ethylene oxide
to acetaldehyde. Zeolite ZSM-22 obtained without adding the template is not inferior in activity to the zeolite
of the same structure prepared in the presence of 1,6-diaminohexane. Moreover, it exhibits higher selectivity
of ethylene oxide conversion to acetaldehyde. The complete conversion of ethylene oxide has been observed
on ZSM-22 zeolites of both types at a reaction temperature of 400°C, the selectivity of its conversion to acet-
aldehyde being at least 93%.
DOI: 10.1134/S0965544119080103
Zeolites that have the porous space formed by 10- thesis (speed, horizontal or vertical stirring, periodic-
membered rings and possess a one-dimensional chan- ity) [13]. All of these options lead in varying degrees to
nel system are of great interest for catalysis, since they a reduction in the number of foreign phases and amor-
exhibit high configurational selectivity for products in phous impurities.
a number of the most important petrochemical and
petroleum refining reactions [1, 2]. This class of zeo-
lites includes materials with the TON framework
structure: ZSM-22, Theta-1, Nu-10, etc. It is known
that they exhibit sufficient catalytic activity and high
selectivity for the desired products in important reac-
tions, such as hydroisomerization [3, 4], isomerization
of butenes [5] and xylenes [6], alkylation and dispro-
portionation of toluene [7], and methanol reforming
to hydrocarbons [8].
At the same time, synthesis methods for any zeo-
lite, including ZSM-22, using organic structure-
directing agents have common drawbacks: the forma-
tion of impurity phases, the presence of defects in the
zeolite structure due to the removal of the template
during high-temperature calcination, the high cost
and toxicity of the templates, and the formation of
harmful emissions and effluents during the synthesis
process. Therefore, studies devoted to the develop-
ment of template-free synthesis methods based on the
use of seed or seed solutions [14, 15] are of particular
interest.
This paper is devoted to a comparative study of the
features of two different procedures for the synthesis of
zeolite ZSM-22: with the use of 1,6-diaminohexane
and without a template. The main objective of the
study was to identify the key synthesis parameters that
affect the phase composition, morphology, texture,
and acidity of zeolites and their catalytic properties in
a test reaction.
As other high-silica zeolites, ZSM-22 is synthe-
sized by hydrothermal synthesis in the presence of a
number of organic structure-directing agents (tem-
plates), such as 1,6-diaminohexane, 1,8-diaminooc-
tane, and 1-ethylpyridinium bromide [9–11]. In the
literature on the synthesis of these zeolites, it is noted
that the use of the most available templates 1,6-diami-
nohexane and 1,8-diaminooctane usually leads to the
formation of impurities ZSM-5 and cristobalite in the
resulting zeolite material along with the main phase
ZSM-22 [12]. Researchers propose various
As a test, the reaction of ethylene oxide isomeriza-
approaches to the synthesis of ZSM-22 zeolites, but tion to acetaldehyde was chosen [16]. It has
basically they boil down to the optimal organization of already been shown that ZSM-23 zeolites, which, like
the agitation of the reaction mixture during the syn- ZSM-22, have a one-dimensional system of channels
910

SYNTHESIS OF ZSM-22 AND TESTING ITS CATALYTIC PROPERTIES
Characterization of Synthesized Zeolites
911
of similar diameter, exhibit high selectivity for the
desired product in this reaction [17]. This gives
grounds to hope that ZSM-22 will also be of interest as
an isomerization catalyst.
The concentration of aluminum, iron, and
potassium in all samples was determined by induc-
tively-coupled-plasma atomic emission spectroscopy
(AES-ICP) using a PerkinElmer OPTIMA 4300 DV
ICP spectrometer.
X-ray phase analysis (XRD) was performed using a
HZG-4C high-resolution diffractometer in the angu-
lar range of 2θ = 4°–40° (CuKα radiation).
The textural characteristics of zeolites were deter-
mined by low-temperature nitrogen adsorption at
77 K on a Micromeritics ASAP 2010 instrument.
Before nitrogen adsorption, the samples were out-
gassed by vacuum pumping at 250°C for 10 h.
EXPERIMENTAL
Zeolite Synthesis
The following chemicals were used to synthesize
ZSM-22
zeolites:
1,6-diaminohexane
(NH2(CH2)6NH2, 98%), aluminum sulfate (Al2(SO4)3 ⋅
18H2O, ≥97%), and ammonium nitrate (NH4NO3,
≥99%) from Sigma-Aldrich; silica sol (30% SiO2,
Ludox AS30, DuPont); and potassium hydroxide
(KOH, 85%) and tetraethoxysilane (C2H5O)4Si,
99+%) of Alfa Aesar.
The morphology of zeolites was studied using a
Jeol JSM 6460LV scanning electron microscope at an
accelerating voltage of 20 kV.
In the presence of 1,6-diaminohexane (DAH), the
zeolite was synthesized according to the procedure
described in [9] with minor changes. The reaction
mixture with a molar ratio of components 27.5DAH :
xKOH : Al2O3 : 90SiO2 : 3650Н2О (x = 20.1, 22.8, or
24.7) was held under hydrothermal conditions at a
temperature of 160°C for 48 h in the static mode
(autoclave volume, V = 100 mL) and up to 26 h in an
autoclave with stirring (Vautoclave = 600 mL, the stirrer
rotation speed of 100 rpm). After that, the solid phase
was separated from the mother liquor by filtration,
washed with distilled water, and dried for 18 h at room
temperature and 8 h at 110°C. To be converted into the
H+ form, zeolites were calcined at 650°C for 3 h to
remove the template. Next, the zeolite was subjected
to ion exchange in a 1 M NH4NO3 solution, followed
by filtration, washing with water, and drying at room
temperature for 18 h and at 110°C for 8 h. Samples in
Examination by high-resolution transmission elec-
tron microscopy (HR-TEM) was performed on a Jeol
JEM-2010 electron microscope (accelerating voltage
200 kV, resolution 1.4 Å (lattice)). The samples to be
studied were applied using an ultrasonic disperser on
standard carbon-coated copper grids, which were
placed in special holders.
The acidic properties of the TON and MTT zeo-
lites were characterized using the technique of ther-
mally programmed desorption of ammonia (TPD
NH3) in an adsorption unit, equipped with a mass
spectrometer, in a semiautomatic mode. A 1-g portion
of zeolite was poured into the reactor zone with con-
trolled temperature. The sample was preliminarily cal-
cined in a helium stream at a flow rate of 1 cm3/s in the
temperature-programmed mode from room tempera-
ture to 550°C. After calcination, the sample was
cooled to 100°C in a helium stream and ammonia was
adsorbed for 5 min. The TPD of ammonia was mea-
sured upon linear heating (10°C/min) of the sample
layer at a constant helium flow rate of 1 cm3/s.
+
the NH4 form were calcined at 480°C for 2 h. Zeolite
samples synthesized by this method are designated by
symbol “T”: ZSM-22-T.
The synthesis of ZSM-22 without the use of an
organic template was based on the procedure
described in [18]. The reaction mixture with the com-
ponent ratio of хKOH : Al2O3 : 100SiO2 : 4450Н2О
Catalytic Tests
Catalytic experiments were performed in an auto-
mated flow-through unit with on-line chromato-
graphic analysis of the gas phase. A gaseous mixture of
ethylene oxide and helium (10% ethylene oxide by vol-
ume, the rest is helium) was passed at a flow rate of
50 cm3/min through a stainless steel reactor of a
0.5 cm diameter, into which 0.2 g of the test zeolite in
the form of granules of 0.25−0.5 mm in diameter was
preloaded. . Before feeding the reaction mixture, the
zeolites were calcined in a stream of dry air at 500°C
for 2 h; then, the reactor was cooled in a stream of He
to the required temperature of the experiment and
held under these conditions for 10 min. The tempera-
(х = 19 or 21) and a seed (ZSM-22 in Н+-form) con-
tent or 2.3 to 10% was held under hydrothermal condi-
tions at temperatures of 140 and 150°С within 92 h in
the static mode (autoclave V = 100 mL) and at a tem-
perature of 160°C for up to 24 h in an autoclave with
agitation (Vautoclave = 600 mL, 100 rpm). After hydro-
thermal treatment, the synthesized samples were sep-
arated from the mother liquor by filtration and further
treated similar to the ZSM-22-T samples. Zeolites
synthesized by this method are denoted by symbol
“TF”: ZSM-22-TF.
A sample of zeolite ZSM-23 (MTT structure) used ture in the reactor was varied from 300 to 400°C. The
in this work for comparison was synthesized and char- contact time was about 0.5 s. Chromatographic analy-
acterized previously [17].
sis was performed in a temperature-programming
PETROLEUM CHEMISTRY Vol. 59 No. 8 2019

912
LAZAREVA et al.
Table 1. Synthesis conditions of zeolites ZSM-22
Sample
Agitation
Molar ratio of reaction mixture components
Crystallization conditions
Synthesis in the presence of 1,6-diaminohexane
27.5DAH : 24.3КОН : Al2O3 : 90SiO2 : 3650Н2О
27.5DAH : 22.5КОН : Al2O3 : 90SiO2 : 3650Н2О
27.5DAH : 19.8КОН : Al2O3 : 90SiO2 : 3650Н2О
27.5DAH : х19.8КОН : Al2O3 : 90SiO2 : 3650Н2О
27.5DAH : 22.5КОН : Al2O3 : 90SiO2 : 3650Н2О
27.5DAH : 19.8КОН : Al2O3 : 90SiO2 : 3650Н2О
27.5DAH : 19.8КОН : Al2O3 : 90SiO2 : 3650Н2О
27.5DAH : 19.8КОН : Al2O3 : 90SiO2 : 3650Н2О
27.5DAH : 19.8КОН : Al2O3 : 90SiO2 : 3650Н2О
ZSM-22-Т-1
ZSM-22-Т-2
ZSM-22-Т-3
ZSM-22-Т-4
ZSM-22-Т-5
ZSM-22-Т-6
ZSM-22-Т-7
ZSM-22-Т-8
ZSM-22-Т-9
No
No
No
No
Yes
Yes
Yes
Yes
Yes
160°С, 48 hours
160°С, 48 hours
160°С, 48 hours
160°С, 26 hours
160°С, 20 hours
160°С, 6 hours
160°С, 12 hours
160°С, 20 hours
160°С, 26 hours
Template-free synthesis
19KOH : Al2O3 : 100SiO2 : 4450Н2О
2.3% seed
19KOH : Al2O3 : 100SiO2 : 4450Н2О
2.3% seed
19KOH : Al2O3 : 100SiO2 : 4450Н2О
2.3% seed
19KOH : Al2O3 : 100SiO2 : 4450Н2О
5% seed
19KOH : Al2O3 : 100SiO2 : 4450Н2О
10% seed
21KOH : Al2O3 : 100SiO2 : 4450Н2О
5% seed
21KOH : Al2O3 : 100SiO2 : 4450Н2О
10% seed
21KOH : Al2O3 : 100SiO2 : 4450Н2О
10% seed
ZSM-22-TF-1
ZSM-22-TF-2
ZSM-22-TF-3
ZSM-22-TF-4
ZSM-22-TF-5
ZSM-22-TF-6
ZSM-22-TF-7
ZSM-22-TF-8
No
No
No
No
No
Yes
Yes
Yes
140°С, 92 hours
150°С, 48 hours
150°С, 92 hours
150°С, 92 hours
150°С, 92 hours
140°С, 48 hours
160°С, 16 hours
160°С, 24 hours
mode from 50 to 170°C on a DB-1701 capillary col-
Figures 1a and 1b show powder diffraction patterns
of zeolite samples of the ZSM-22-T series synthesized
under static conditions with different OH−/SiO2 ratios
and in an autoclave with agitation at a constant
OH−/SiO2 value, but over different crystallization
times, respectively. As OH−/SiO2 decreases (Fig. 1a,
diffractograms 2–4), the intensity of the peaks due to
the ZSM-5 phase decreases. All samples synthesized
within 48 h are characterized by the presence of a cris-
tobalite impurity. By reducing the crystallization time
to 26 h, a sample had been obtained in which the
ZSM-5 phase was present in trace amounts and the
cristobalite phase was absent altogether (Fig. 1a, dif-
fractogram 5). From the reaction mixture with a com-
position similar to that of the sample having diffrac-
umn (J&W Scientific) using FID.
The conversion was calculated from the data on
ethylene oxide (EO) concentration at the reactor out-
let. The selectivity for a particular product was deter-
mined as the ratio of the analyte concentration to the
total concentration of all the products.
RESULTS AND DISCUSSION
In the zeolite syntheses in the presence of 1,6-
diaminohexane, three parameters affecting the forma-
tion of ZSM-5 and cristobalite impurity phases were
varied: the OH−/SiO2 ratio in the reaction mixture,
the agitation of the reaction mixture, and the crystal-
lization time (Table 1). Under static conditions, the tion pattern 3, but in an autoclave with stirring, a sam-
zeolites were synthesized from the reaction mixture
ple with a higher ZSM-5 content was obtained after
20 h (Fig. 1a, diffractogram 1). Thus, agitation of the
with OH−/SiO2 ratios of 0.22, 0.25, and 0.27.
PETROLEUM CHEMISTRY
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SYNTHESIS OF ZSM-22 AND TESTING ITS CATALYTIC PROPERTIES
(a) (b)
913
5
4
∗
∗
4
3
∗
∗
∗
3
∗
∗
∗
∗
∗
∗
∗
2
1
2
1
10 15 20 25 30 35 40 45 50
10 15 20 25 30 35 40 45 50
5
5
2Θ, deg
2Θ, deg
Fig. 1. Powder X-ray diffraction patterns of zeolites of the ZSM-22-T series synthesized (a) under static conditions: (1) ZSM-22-
T-5 (for reference), (2) ZSM-22-T-1, (3) ZSM-22-T-2, (4) ZSM-22-T-3, and (5) ZSM-22-T-4 or (b) in an autoclave with stir-
ring: (1) ZSM-22-T-6, (2) ZSM-22-T-7, (3) ZSM-22-T-8, and (4) ZSM-22-T-9.
synthesis gel during the crystallization process acceler- process both under static conditions (Fig 2a, diffracto-
ates the formation of the impurity phase.
gram 1) and in the stirring-assisted synthesis (Fig. 2b,
diffractogram 1). The above diffraction patterns show
the presence of a large amount of the amorphous
phase (halo in the region of 19°–25°). An increase in
the process temperature to 150°C for the process car-
ried out for 92 h with the same amount of seed (2.3%)
led to an increase in the intensity of the peaks charac-
teristic of ZSM-22 (Fig. 2a, diffractogram 3). From
the results of the further experiments with increasing
the amount of seed in the reactant mixture to 10%, it
was concluded at with the given gel composition
(OH−/SiO2 = 0.19), the process temperature of 150°C,
and the amount of seed of 5–10% in the static mode,
the resulting ZSM-22 had an admixture of amorphous
material. Synthesis in the autoclave with stirring was
carried out using a reaction mixture of the same com-
position, but with a ratio of OH−/SiO2 = 0.21, at a
temperature of 160°C. The conditions found made it
possible to reduce the ZSM-22 synthesis time to 16 h
(Fig. 2b, diffractogram 2).
To clarify the ZSM-5 formation route, the synthe-
sis was carried out in an autoclave with stirring at the
optimum composition of the reaction mixture, as
determined by synthesis under static conditions (see
Fig. 1a, the sample with diffraction pattern 5 and
Table 1). In Fig. 1b, it can be seen that the peaks char-
acteristic of the ZSM-5 phase begin to appear on the
diffraction pattern of the sample synthesized for 6 h
and their intensity increases with increasing crystalli-
zation time. This means that ZSM-5 is formed almost
simultaneously with the desired ZSM-22 phase as a
result of cocrystallization. It should be noted that
during the synthesis with stirring, a decrease in the
OH−/SiO2 ratio leads to a decrease in the amount of
ZSM-5 in the sample (Fig. 1a, diffractogram 1 and
Fig. 1b, diffractograms 3, 4). The samples synthesized
with stirring contained a small amount of the cristob-
alite phase.
In the case of template-free synthesis of zeolites,
the key parameters are agitation, synthesis tempera-
ture (T, °С), and seeding. The data on the template-
free synthesis conditions of zeolite samples are also
presented in Table 1. In contrast to the published
data [18], we have shown that the crystallization tem-
perature of 140°C is insufficient for the synthesis of
ZSM-22 over a time appropriate for the fabrication
According to the SEM and TEM data (Fig. 3), the
ZSM-22 samples synthesized with 1,6-diaminohex-
ane are bundled needle crystals of a 30–50 nm width.
The size of the bundles is 2 to 3 μm. There was no
noticeable impurity of amorphous material. The
ZSM-22 samples prepared by the template-free syn-
thesis also represent a mixture of bundled needle-
shaped crystals of about 100–200 nm in width and 4–
6 μm in length and a certain amount of amorphous
material. The morphology of the samples of both types
complies with the morphology of TON zeolites
described in the literature [9, 18].
Table 2. Textural characteristics of synthesized zeolites
SBET
,
Vmicro
,
Vmeso
,
Vtot, Smicro,
Sample
m2/g cm3/g cm3/g cm3/g m2/g
Table 2 presents the textural characteristics of the
zeolites synthesized with 1,6-diaminohexane and
according to the template-free procedure. The volume
of micropores of the zeolite synthesized using the tem-
ZSM-22-Т-4
ZSM-22-TF-7 151
239
0.08
0.034 0.18
0.17
0.25
0.22
186.4
92
PETROLEUM CHEMISTRY Vol. 59 No. 8 2019

914
LAZAREVA et al.
(a)
(b)
5
4
3
2
1
3
2
1
10 15 20 25 30 35 40 45 50
10 15 20 25 30 35 40 45 50
5
5
2Θ, deg
2Θ, deg
Fig. 2. Powder X-ray diffraction patterns of zeolites of the ZSM-22-TF series synthesized (a) under static conditions: (1) ZSM-
22-TF-1, (2) ZSM-22-TF-2, (3) ZSM-22-TF-3, (4) ZSM-22-TF-4, and (5) ZSM-22-TF-5 or (b) in an autoclave with stirring:
(1) ZSM-22-Tf-6, (2) ZSM-22-TF-7, and (3) ZSM-22-TF-8.
1 μm
500 nm
Fig. 3. SEM image of ZSM-22-T-4 synthesized with the template (left) and TEM image of ZSM-22-TF-7 prepared by template-
free synthesis (right).
0.0018
0.0016
0.0014
0.0012
0.0010
0.0008
0.0006
0.0004
0.0002
0.0000
0.0002
plate agrees with the data available in the literature for
the pure phase [19], thereby indirectly confirming the
absence of impurities of cristobalite and amorphous
material. The zeolite synthesized without a template
has a smaller micropore volume, which is natural for
an insufficiently crystallized sample containing a
noticeable amount of amorphous material.
1
Figure 4 depicts ammonia TPD spectra on the
ZSM-22-T-4 and ZSM-22-TF-7 samples, and Table 3
shows the temperatures of ammonia desorption max-
ima, determined by the Gaussian deconvolution of the
curves, and the concentrations of NH3 desorption
sites. As can be seen from Fig. 4 and Table 3, zeolites
have two types of acid sites which are close in strength
(although the temperature of the maximum due to
desorption from strong acid sites in ZSM-22-T-4 is
2
200
300
400
500
600
100
Temperature, °C
Fig. 4. TPD NH spectra for zeolites (1) ZSM-22-T-4 and
(2) ZSM-22-TF-7.
3
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SYNTHESIS OF ZSM-22 AND TESTING ITS CATALYTIC PROPERTIES
Table 3. TPD NH3 data for zeolites ZSM-22-T-4 and ZSM-22-TF-7
Peak 1 Peak 2
915
Peak 3
ΣC,
Zeolite
μmol/g
Tmax, °С
Tmax, °С*
Tmax, °С
C, μmol/g
C, μmol/g
C, μmol/g
ZSM-22-T-4
ZSM-22-TF-7
–
158
–
42
220
221
190
123
452
441
178
112
368
235
*Accuracy of determination 2°С.
higher by 11°C than that in ZSM-22-TF-7), but sig- about 15% at 400°C. On ZSM-23 zeolites, in addition
nificantly differ in concentration.
to the main product, acetaldehyde, crotonaldehyde,
1,4-dioxane, 2-methyl-1,3-dioxolane, and degrada-
tion products (light hydrocarbons and carbon oxides)
are formed during the reaction [21]. Figure 5 illus-
trates the change in the EO conversion and the AA
selectivity during the isomerization of ethylene oxide
at temperatures of (a) 300 and (b) 400°C. The selectiv-
ity values for the other products in the initial period of
the process and for catalyst on-stream times of 10 and
16 h are presented in Table 4. At 300°C, the EO con-
version on ZSM-22-TF-7 is 100% within the first
6 hours of the reaction and then decreases to 90% for
the on-stream time of 10 h. The EO conversion on
ZSM-22-T-7 decreases much faster: within the cata-
lyst on-steam time of 12 h, the value decreases from 97
to 72%. Since zeolite deactivation is due to the forma-
tion of coke precursors on acid sites of the zeolite and
coke deposition on the catalyst surface, these differ-
ences can be explained in terms of different levels of
acidity in the samples. In the sample ZSM-22-T-4, the
concentration of both strong and medium-strength
acid sites exceeds that in ZSM-22-TF-7 by more than
a factor of 1.5. At 400°С, the EO conversion on both
types of zeolites is maintained at 100% for 16 h on
stream. The selectivity for AA at the beginning of the
reaction does not exceed 93% due to side reactions, as
can be seen from the selectivity for light hydrocarbons
(Table 4), which are the products of degradation of
larger molecules. However, contribution of side reac-
tions decreases with the progress of the reaction and
the AA selectivity reaches a stationary value of more
than 97%.
The catalytic properties of the ZSM-22 samples
obtained in this work were investigated in the gas-
phase isomerization reaction of ethylene oxide (EO)
to acetaldehyde (AA). This reaction proceeds at 250–
400°C on various acid catalysts; thermodynamic equi-
librium at these temperatures is shifted toward the for-
mation of AA [20, 17].
Earlier, we showed that the reaction of EO isomer-
ization to AA barely proceeds in this temperature
range in the absence of a catalyst. The EO conversion
does not exceed 1% at a temperature of 300°C and is
Table 4. Catalytic properties in the reaction of ethylene
oxide isomerization to acetaldehyde (10 vol % EO, the rest
is He, contact time 0.5 s). MD stands for 2-methyl-1,3-
dioxolane; DO, for 1,4 dioxane; CA, for crotonaldehyde;
and LHC, for light hydrocarbons
Selectivity, %
EO
Time, h
conversion, %
АA MD DO CA LHC + СО
ZSM-22-Т-4, 300°С
0.3
1.1
10
95
95
75
66
90 6.2 1.8 1.4
88 6.6 2.0 1.0
90 7.2 2.2 0.6
90 6.3 2.5 0.5
ZSM-22-TF-7, 300°С
91 3.3 3.6 1.4
92 3.3 3.7 0.3
95 1.9 3.3 0.15
95 1.3 2.9 0.1
ZSM-22-Т-4, 400°С
90 0.2 1.1 2.7
94 0.3 0.3 2.6
97 0.2 0.3 1.8
99 0.3 0.2 0.4
ZSM-22-TF-7, 400°С
93 0.1 0.4 4.8
94 0.05 0.5 4.2
97 0.2 0.3 2.3
97 0.3 0.4 1.7
0.08
0.07
0.04
0.05
16
0.4
1.1
10
100
100
96
0.4
0.3
0.15
0.1
Figure 5 also presents the results of testing zeolite
ZSM-23 with the MTT structure having a one-
dimensional channel system with similar pore sizes. It
can be seen that the catalytic properties of the ZSM-22
zeolites prepared by both methods are close to those of
the MTT-type ZSM-23 zeolite tested under the same
conditions.
16
90
0.4
1.1
10
100
100
100
100
6.2
3.1
0.8
0.6
Thus, the study of the influence of the key param-
eters of the synthesis of TON-type zeolites (ZSM-22)
using the organic template 1,6-diaminohexane or the
template-free procedure on the phase composition of
the synthesized samples has led the following conclu-
sions. The alkalinity (OH−/SiO2 molar ratio) of the
initial reaction mixture and the time of the hydrother-
mal process are the main factors that allow fine con-
16
0.4
1.1
10
100
100
100
100
2.3
1.6
0.6
0.4
16
PETROLEUM CHEMISTRY Vol. 59 No. 8 2019

916
LAZAREVA et al.
(a) 300°C
(b) 400°C
100
95
90
85
80
75
70
65
60
100
95
90
85
80
75
70
65
60
1
2
3
1
2
3
2
4
6
8
10 12 14 16 18
2
4
6
8
10 12 14 16
0
0
Time, h
Time, h
100
90
80
70
60
50
40
100
90
80
70
60
50
40
1
2
3
1
2
3
2
4
6
8
10
12
0
2
4
6
8
10 12 14 16
0
Time, h
Time, h
Fig. 5. Dependence of the ethylene oxide conversion and the selectivity for acetaldehyde on the on-stream time of zeolite samples
(1) ZSM-22-T-4 and (2) ZSM-22-TF-7 and (3) reference zeolite ZSM-23 at (a) 300 and (b) 400°C. 10 vol % OE in He, contact
time, 0.5 s.
trol of the amount of the ZSM-5 phase in the zeolite
product, both under static crystallization conditions
and in an autoclave with stirring. For example, a
decrease in the OH−/SiO2 ratio in the reaction mix-
ture from 0.27 to 0.19 and the process time to 12 h in
the case of crystallization in the static mode makes it
possible to obtain ZSM-22 zeolite that does not con-
tain ZSM-5. Dynamic synthesis conditions (stirring
the reaction mixture during crystallization) facilitate
the formation of ZSM-5. Nonetheless, by reducing
the OH−/SiO2 ratio, it is possible to obtain the desired
ZSM-22 phase and minimize the amount of the
byproduct ZSM-5 phase. However, it should be noted
that the formation of ZSM-5 cannot be completely
avoided under these conditions; thus, it can be con-
cluded that the ZSM-22 and ZSM-5 phases are
formed simultaneously, not consecutively. As regards
the condensed cristobalite phase, its formation is
accelerated by stirring under the same synthesis
parameters, although the presence of this impurity in
the case of synthesis in the static mode is determined
by the process time.
As in the template-free synthesis of other zeolites,
the most important factor in the synthesis of TON
zeolites in the absence of an organic template is the use
of seeding. The optimal amount of seed is about
5 wt % ZSM-22 relative to the amount of SiO2 con-
tained in the starting reaction gel. Increasing the tem-
perature to 160°C and stirring the reaction gel during
the crystallization process significantly increase the
rate of formation of the target phase, thereby reducing
the synthesis time from 92 to 16 h.
The catalytic experiments have shown that
ZSM-22 zeolites with a ratio of Si/Al = 40–50,
obtained by both methods, exhibit a high activity in
the gas-phase reaction of isomerization ethylene oxide
to acetaldehyde. At a process temperature of 400°C,
the complete EO conversion is observed. The selectiv-
ity for AA is 93–94% within the first hours of the reac-
tion, and it gradually increases to reach a value of 97–
99%, remaining unchanged within 16 hours of
the process. Using the example of EO isomerization
reaction to give AA, we have shown that the zeolite
ZSM-22 synthesized in the absence of a template
PETROLEUM CHEMISTRY
Vol. 59
No. 8
2019

SYNTHESIS OF ZSM-22 AND TESTING ITS CATALYTIC PROPERTIES
917
9. S. Ernst, J. Weitkamp, J. A. Martens, and P. A. Jacobs,
can serve as a cheaper and more environmentally
friendly alternative to the classical “template-
directed” ZSM-22. In particular, it exhibits catalytic
properties close to those of a zeolite synthesized in the
presence of an organic template. Undoubtedly, syn-
theses in the absence of a template are distinguished by
high adaptability, environmental friendliness, and low
cost. Subject to further optimization or the develop-
ment of new methods for template-free synthesis of
ZSM-22 zeolites, these zeolites can be key compo-
nents of a variety of catalysts for various processes.
Appl. Catal. 48, 137 (1989).
10. G. Kuhl, Verified Syntheses of Zeolitic Materials, Ed. by
H. Robson (Elsevier, Amsterdam, 2001), 2nd Ed.,
p. 258.
11. Y. Luo, Z. Wang, S. Jin, Bet al., Cryst. Eng. Commun.
18, 5611 (2016).
12. D. Verboekend, A. M. Chabaneix, K. Thomas, et al.,
Cryst. Eng. Commun. 13, 3408 (2011).
13. D. Malish, T. Kobayashi, and T. Baba, Chem. Com-
mun., 3303 (2007).
14. Y. Wang, Q. Wu, X. Meng, and F. S. Xiao, Engineering
3, 567 (2017).
FUNDING
15. M. D. Oleksiak and J. D. Rimer, Rev. Chem. Eng. 30,
This work was performed as part of the state assignment
of the Boreskov Institute of Catalysis of the Siberian Branch
of the Russian Academy of Sciences.
1 (2014).
16. A. S. Kharitonov, V. S. Chernyavskii, L. V. Piryutko,
et al., RU Patent No. 2600452 (2016).
17. L. V. Piryutko, V. S. Chernyavskii, A. I. Lysikov, et al.,
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Translated by S. Zatonsky
(2016).
PETROLEUM CHEMISTRY Vol. 59 No. 8 2019