Nonoxidative Conversion of Methane to Aromatic Hydrocarbons in the Presence of ZSM-5 Zeolites Modified with Molybdenum and Rhenium

Article abstract of DOI:10.1134/S0965544119010146

Abstract: The nonoxidative conversion of methane to aromatic hydrocarbons in the presence of a high-silica ZSM-5 zeolite modified with molybdenum and rhenium nanopowders has been studied. Data on the acid characteristics of the catalysts have been derived by temperature-programmed desorption of ammonia. The microstructure and composition of the Re/ZSM-5 and Re–Mo/ZSM-5 catalyst systems have been studied by transmission electron microscopy. It has been shown that modification of a Mo-containing zeolite with rhenium leads to an increase in the activity and stability of the catalyst in the methane dehydroaromatization reaction.

Full text of DOI:10.1134/S0965544119010146

ISSN 0965-5441, Petroleum Chemistry, 2019, Vol. 59, No. 1, pp. 91–98. © Pleiades Publishing, Ltd., 2019.
Russian Text © A.A. Stepanov, V.I. Zaikovskii, L.L. Korobitsyna, A.V. Vosmerikov, 2019, published in Neftekhimiya, 2019, Vol. 59, No. 1, pp. 83–90.
Nonoxidative Conversion of Methane to Aromatic Hydrocarbons
in the Presence of ZSM-5 Zeolites Modified
with Molybdenum and Rhenium
A. A. Stepanova, V. I. Zaikovskiib, c, L. L. Korobitsynaa, and A. V. Vosmerikova, *
aInstitute of Petroleum Chemistry, Siberian Branch, Russian Academy of Sciences, Tomsk, Russia
bBoreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
cNovosibirsk National Research State University, Novosibirsk, Russia
*e-mail: pika@ipc.tsc.ru
Received April 17, 2018; Revised May 21, 2018; Accepted July 26, 2018
Abstract—The nonoxidative conversion of methane to aromatic hydrocarbons in the presence of a high-silica
ZSM-5 zeolite modified with molybdenum and rhenium nanopowders has been studied. Data on the acid
characteristics of the catalysts have been derived by temperature-programmed desorption of ammonia. The
microstructure and composition of the Re/ZSM-5 and Re–Mo/ZSM-5 catalyst systems have been studied
by transmission electron microscopy. It has been shown that modification of a Mo-containing zeolite with
rhenium leads to an increase in the activity and stability of the catalyst in the methane dehydroaromatization
reaction.
Keywords: methane, aromatic hydrocarbons, natural gas, zeolite, molybdenum and rhenium nanopowders
DOI: 10.1134/S0965544119010146
The development of processes for converting natu- the nonoxidative conversion of methane is their rapid
ral and associated petroleum gases to valuable chemi- deactivation in the process. To increase the activity
cal products, instead of gas flaring at fields, will pro- and stable on-stream time, the catalysts are modified
with various metals, such as La, Pt, V, Fe, Zn, Co, and
Ni [3–6].
This paper describes results of studying the nonox-
idative conversion of methane to aromatic hydrocar-
bons in the presence of Re/ZSM-5 and Re–
Mo/ZSM-5 catalysts prepared by solid-phase synthe-
sis using Mo and Re nanopowders (NPs).
vide not only a decrease in the negative environmental
impact, but also the prevention of a loss of valuable
hydrocarbon feedstocks in which the main component
is methane. Of greatest interest is the nonoxidative
conversion of methane to aromatic hydrocarbons in
the presence of zeolite catalysts modified with transi-
tion metal ions; with respect to activity in this process,
the metals can be arranged in the following order:
Mo > W > Fe > V > Cr [1]. Wang et al. [2] studied the
methane conversion process in the presence of
Re/ZSM-5 catalysts synthesized by impregnating the
zeolite with an (NH4)2ReO4 · 4H2O aqueous solution
and subsequently calcining the samples at 500°C. It
was reported that the activity of Re-containing zeolites
in the methane dehydroaromatization reaction is
comparable with the activity of Mo/ZSM-5 catalysts.
With respect to a number of physical properties, rhe-
nium approaches group VI refractory metals (molyb-
denum, tungsten) and platinum group metals. With
respect to the melting point, rhenium ranks second
among metals, being inferior only to tungsten. It is the
basic component in the production of catalysts for
EXPERIMENTAL
The Re/ZSM-5 and Mo/ZSM-5 catalysts were
prepared by solid-phase synthesis by dry mechanical
mixing of the ZSM-5 zeolite in the H-form
(SiO2/Al2O3 molar ratio of 40) and Mo and Re NPs in
a KM-1 vibratory ball mill (German Democratic
Republic) for 2 h. The Mo and Re NPs were prepared
by an electric explosion of respective wires in an argon
atmosphere. The average particle size of Mo and Re
was 70 and 150 nm, respectively. The resulting mixture
was calcined at a temperature of 540°C for 4 h. The
Mo and Re content in the zeolite was 4.0 and 5.0 wt %,
respectively. The Re–Mo/ZSM-5 catalysts were syn-
petroleum refining processes, for example, rhenium– thesized by adding the Re NP to the 4.0%Mo/ZSM-5
platinum catalysts used to produce a high-octane gas- sample and subsequently stirring the resulting mixture
oline component. The main problem of catalysts for in a vibratory mill for 2 h. The rhenium content in the
91

92
STEPANOV et al.
4
3
2
1
15
25
35
45
2θ, deg
55
65
75
85
5
Fig. 1. Powder diffraction patterns of : (1) ZSM-5, (2) the Re NP, and (3) 5.0%Re/ZSM-5 samples before the reaction, and
(4) 5.0%Re/ZSM-5 after the reaction.
of the catalyst loaded in the reactor was 1 cm3. Before
reaction, the catalyst was heated in a helium stream to
750°C and held at this temperature for 10 min; after
that, the supply of helium was ceased; instead, meth-
ane (purity of 99.99 vol %) was fed at a space velocity
of 1000 h–1. Every 40 min of the process, the reaction
products were analyzed by gas–liquid chromatogra-
phy on a Chromatec Kristall-5000.2 chromatograph.
To determine the catalytic activity of the samples, the
methane conversion and the product yield were deter-
mined.
Re–Mo/ZSM-5 catalyst was varied in a range of 0.1–
5.0 wt %.
X-ray diffraction analysis was conducted on a
Bruker DISCOVER D8 diffractometer using mono-
chromatic CuKα radiation and a Lynx-Eye detector.
Scanning was conducted in an angular range of 2θ =
5°–88° in increments of 0.02 deg at an acquisition
time of 3 s per point.
The specific surface area of the catalysts was mea-
sured by low-temperature nitrogen adsorption on a
Micromeritics ASAP 2020 instrument (the United
States). The calculation of the specific surface area of
the test sample was conducted by a multipoint BET
method.
The acid characteristics of the samples were stud-
ied by temperature-programmed desorption of
ammonia; this method makes it possible to determine
the strength distribution of acid sites and their concen-
tration. The acid site concentration in the catalysts was
determined from the amount of ammonia desorbed at
the time of recording of the desorption peaks and
expressed in terms of micromoles per gram of catalyst.
RESULTS AND DISCUSSION
Figure 1 shows powder diffraction patterns of the
ZSM-5 zeolite, the Re NP, and the 5.0%Re/ZSM-5
catalyst samples before and after the nonoxidative
conversion of methane. It is evident that the patterns
of the two 5.0%Re/ZSM-5 catalyst samples exhibit
peaks at 37.613°, 40.454°, 42.895°, 56.394°, 67.819°,
75.259°, 81.997°, and 83.659°, which are characteristic
of metallic Re (PDF 01-089-2935); the presence of
rhenium oxide phases in the catalyst is not observed.
The structure of the Re/ZSM-5 and Re–
Mo/ZSM-5 catalysts was studied by high-resolution
transmission electron microscopy (HR-TEM) in a
scanning mode using the Z-contrast imaging (high-
angle annular dark-field scanning transmission elec-
tron microscopy (HAADF-STEM)) [7]. The studies
were conducted on a JEM-2200FS atomic-resolution
electron microscope.
Results of studying the activity of the
4.0%Mo/ZSM-5 and 5.0%Re/ZSM-5 catalysts and
Re–4.0%Mo/ZSM-5 samples containing different
amounts of rhenium in the methane dehydroaromati-
zation reaction are shown in Fig. 2. It is evident that
the activity of the 5.0%Re/ZSM-5 catalyst is signifi-
cantly lower than that of the 4.0%Mo/ZSM-5 sample.
In a 20-min reaction in the presence of the
The nonoxidative conversion of methane was run 5.0%Re/ZSM-5 and 4.0%Mo/ZSM-5 catalysts, the
on a laboratory flow system at atmospheric pressure maximum methane conversion is 3.6 and 13.5%,
and a temperature of 750°C. A catalyst sample with a respectively. With an increase in the process time, the
particle size of 0.5–1.0 mm was placed into a tubular methane conversion decreases in the presence of
quartz reactor with a diameter of 12 mm; the volume either of the catalysts.
PETROLEUM CHEMISTRY
Vol. 59
No. 1
2019

NONOXIDATIVE CONVERSION OF METHANE
93
(а)
2
1
2
3
4
5
6
7
1
3
4
14
12
10
8
1.2
1.0
0.8
0.6
0.4
0.2
0
6
4
2
100 140 180 220 260 300 340 380
20 60
0
Reaction time, min
(b)
100 140 180 220 260 300 340 380
Reaction time, min
20 60
1
2
3
4
Fig. 2. Variation in methane conversion in the presence of
Re–4.0%Mo/ZSM-5 catalysts containing different
amounts of rhenium: (1) 0, (2) 0.1, (3) 0.5, (4) 0.7, (5) 1.0,
and (6) 2.0 wt % and (7) the 5.0%Re/ZSM-5 catalyst as a
function of on-stream time.
7
6
5
4
3
2
1
0
An increase in the Re NP content in the
4.0%Mo/ZSM-5 catalyst leads to an increase in the
catalyst activity in the methane conversion process.
Thus, within 20 min of reaction in the presence of the
0.5%Re–4.0%МоZSM-5 catalyst, the methane con-
version achieves 14.8% versus 13.5% provided by the
4.0%МоZSM-5 sample. A further increase in the Re
concentration in the 4.0%Mo/ZSM-5 catalyst leads to
a decrease in the catalyst activity in methane conver-
sion. Within the first 20 min of reaction in the pres-
ence of the 2.0%Re–4.0%Мо/ZSM-5 catalyst, the
methane conversion achieves 11.9%. For all the stud-
ied Re–Мо/ZSM catalysts, the methane conversion
decreases with increasing process time.
20 60 100 140 180 220 260 300 340 380
Reaction time, min
(c)
1
2
3
4
4
3
2
1
0
Analysis of the composition of the gaseous meth-
ane conversion products formed in the presence of
zeolites containing Re and Mo showed that the total
yield of ethane and ethylene gradually increases during
the reaction; after 180–260 min the process, it
decreases because of the coking of the active sites of
the catalysts (Fig. 3a). The highest amount of ethane
and ethylene—1.2%—is formed in the presence of the
2.0%Re–4.0%Mo/ZSM-5 catalyst. However, after
220 min of reaction, the total yield of ethane and eth-
ylene abruptly decreases; after 300 min on stream, the
yield provided by this catalyst is lower than the yield
observed for the other samples. The lowest amount of
ethane and ethylene is formed in the presence of the
5.0%Re/ZSM-5 catalyst; it does not exceed 0.6%.
20 60 100 140 180 220 260 300 340 380
Reaction time, min
Fig. 3. Total yield of (a) ethane and ethylene, (b) benzene,
and (c) naphthalene in the presence of the Re–
4.0%Mo/ZSM-5 samples containing different amounts
of Re: (1) 0, (2) 0.5, and (3) 2.0% and (4) the
5.0%Re/ZSM-5 catalyst as a function of on-stream time
the 4.0%Mo/ZSM-5 catalyst. The lowest amount of
benzene (1.8%) within 20 min of reaction is formed
over the 5.0%Re/ZSM-5 catalyst. During methane
dehydroaromatization, the benzene yield decreases in
the presence of all the catalysts.
Analysis of the liquid products of methane conver-
sion showed that they mostly contain benzene and
naphthalene (Figs. 3b, 3c). The highest amount of
benzene (7.5%) is formed in the presence of the
Mo/ZSM-5 catalyst containing 0.5% Re within the
first 20 min of reaction (Fig. 3b). In the presence of
the 1.0%Re–4.0%Mo/ZSM-5 sample, the benzene
The addition of 0.5% rhenium to the
4.0%Mo/ZSM-5 catalyst leads to a 0.4% increase in
the naphthalene yield; after 100 min of reaction, the
naphthalene yield abruptly decreases in the presence
of either of the catalysts (Fig. 3c). The other samples
yield decreases compared with the yield provided by provide the formation of a significantly lower amount
PETROLEUM CHEMISTRY Vol. 59 No. 1 2019

94
STEPANOV et al.
Table 1. Acid characteristics and specific surface area of the catalysts
Temperature, °С
Concentration, μmol/g
Ssp, m2/g
Catalyst
ТI
ТII
СI
СII
СΣ
ZSM-5
201
200
190
190
185
180
435
415
420
395
390
385
710
694
602
671
658
637
286
234
287
214
193
170
996
928
889
885
851
807
377
315
395
330
337
358
4.0%Mo/ZSM-5
5.0%Re/ZSM-5
0.5%Re–4.0%Mo/ZSM-5
1.0%Re–4.0%Mo/ZSM-5
2.0%Re–4.0%Mo/ZSM-5
T and T are the temperatures of the low- and high-temperature peak maxima in the thermal desorption curves; C , C , and C are the con-
I
II
I
II
Σ
centrations of weak and strong acid sites and their sum, respectively.
of naphthalene both at the beginning of the process tion of the catalyst in air at 540°C, molybdenum com-
and during the reaction.
pounds are partially localized on the outer zeolite sur-
face and some of the compounds migrate to the zeolite
channels, where they interact with the acid sites [13].
At high calcination temperatures, the zeolite matrix
can undergo dealumination to form aluminum molyb-
date Al2(MoO4)3, which leads to the degradation of the
crystal lattice of the zeolite [14]. Thus, during the cat-
alyst synthesis, the state of both the molybdenum and
the zeolite matrix undergoes changes. In addition, the
patterns of change in the acid properties of the zeolite
upon the introduction of rhenium and molybdenum
are different.
For the 5.0%Re/ZSM-5 catalyst, the concentra-
tion of low-temperature acid sites located mostly on
the outer zeolite surface decreases, while the content
of high-temperature acid sites located in the zeolite
channels does not change. This finding is attributed to
the fact that, at high calcination temperatures of the
catalyst, rhenium nanoparticles undergo aggregation
into large entities that block the zeolite channels. At
the same time, rhenium does not migrate to the zeolite
channels and does not interact with strong acid sites
Thus, the additional introduction of Re into the
Mo-containing zeolite does not lead to a change in the
qualitative composition of the liquid products of
methane conversion; it provides an increase in the
yield of these products. The highest activity and stabil-
ity in the nonoxidative conversion of methane is
exhibited by the 0.5%Re–4.0%Mo/ZSM-5 catalyst.
The increase in the catalyst activity is attributed to the
unique properties of rhenium, which performs both
the dehydrogenating and hydrogenating functions;
this feature provides a decrease in the coking rate [8].
In addition, rhenium does not undergo recrystalliza-
tion during catalysis because it has a high melting
point [9].
Since catalysts for the nonoxidative conversion of
methane have a bifunctional nature of action [10–12],
which is associated with the involvement of both the
metal active sites and the Brønsted acid sites of the
zeolite, it was of interest to study the acid properties of
the ZSM-5 zeolite and the zeolite samples modified
with molybdenum and rhenium.
Results of studying the acid properties of the [15]. The addition of rhenium to the 4.0%Mo/ZSM-5
catalysts are shown in Table 1. It is evident that the catalyst leads to a decrease in the acid site concentra-
ZSM-5 zeolite is characterized by the highest concen- tion in the sample. With an increase in the Re content
tration of strong acid sites. The addition of the Mo NP in the catalyst from 0.5 to 2.0%, the concentration of
to the zeolite leads to a decrease in the strength and strong acid sites decreases from 214 to 170 μmol/g;
concentration of the acid sites of the catalyst: the total the concentration of weak acid sites also
number of acid sites decreases from 996 to significantly decreases. It should be noted that the
928 μmol/g, while the concentration of strong acid Re–Mo/ZSM-5 catalysts, after adding Re NP to
sites decreases from 286 to 234 μmol/g. The observed Mo/ZSM-5 and mixing in a vibratory mill, were not
changes in the acid properties of the Mo/ZSM-5 cat- calcined prior to studies by temperature-programmed
alyst are attributed to the fact that, during the calcina- desorption of ammonia. The observed decrease in the
PETROLEUM CHEMISTRY
Vol. 59
No. 1
2019

NONOXIDATIVE CONVERSION OF METHANE
95
4
1
5
3
2
10 nm
10 nm
Fig. 4. High-angle annular dark-field STEM image of the 5.0%Re/ZSM-5 catalyst before reaction.
catalyst acidity is apparently associated with the block- face and undergoes agglomeration into large surface
ing of the active sites by rhenium both in the zeolite particles.
channels and on the zeolite surface during the catalyst
Figure 5a shows Re particles with a size of 15–
synthesis. In the case of calcination of the Re/ZSM-5
20 nm. A carbon layer with a graphite structure and a
catalyst, large rhenium oxide particles are formed;
thickness of ≈2 nm is present on the zeolite surface
they do not penetrate into the zeolite channels, and
(Fig. 5b). The HRTEM image of an individual large
the concentration of strong acid sites does not change
Re particle (size of ≈20 nm) on zeolite shows that the
[15].
Re surface is covered with a carbon layer with a graph-
Results of studying the specific surface area of the
ite structure (d002 = 0.35 nm) and a thickness of ≈2 nm
Re/ZSM-5 and Re–Mo/ZSM-5 catalysts showed
(Fig. 5c). The interplanar distance for the Re particles
that all the samples have a high specific surface area,
after fast Fourier transform filtering is d101 = 0.21 nm.
which increases with an increase in the Re content in
Rhenium clusters with a size of ≈1 nm are present in
the catalyst (Table 1). Thus, an increase in the Re con-
the zeolite channels (Fig. 5d).
centration from 0.5 to 2.0% in the Re–Mo/ZSM-5
catalyst leads to an increase in the specific surface area
The studies showed that, after the methane dehy-
droaromatization reaction, the 5.0%Re/ZSM-5 cata-
lyst does not contain a rhenium carbide phase,
whereas a molybdenum carbide phase is always pres-
ent in Mo/ZSM-5 catalysts after exposure to methane.
The absence of a rhenium carbide phase in a
Re/ZSM-5 catalyst after reaction was also shown in
[8]. Apparently, the absence of a rhenium carbide
phase in the 5.0%Re/ZSM-5 catalyst is responsible for
the low activity of this catalyst compared with the
activity of the Mo/ZSM-5 sample.
from 330 to 358 m2/g.
Electron microscopic studies showed that the
5.0%Re/ZSM-5 catalyst contains a small amount of
Re particles with a size of up to 10 nm; the dominant
state of rhenium is aggregated clusters of particles with
a particle size of about 2 nm and a cluster size of 10–
30 nm. Along with aggregates, individual Re clusters
with a size of about 2 nm are present (Fig. 4, marked
with arrow 1). Some of the clusters have the form of
sticks (2) with shape anisotropy: I × d = (2–3) × (5–
100) nm. An ordered arrangement of clusters with a
periodicity of 2.5 nm is observed (3); sometimes, the
periodicity is ≈4.5 nm (4). In some cases, branched
sticks are observed (5). It can be assumed that individ-
ual clusters and sticks are localized in the zeolite chan-
nels; their spreading takes place; however, they spread
no farther than to two adjacent zeolite channels.
Large molybdenum particles are observed on the
zeolite surface in the 0.5%Re–4.0%Mo/ZSM-5 cata-
lyst after 380 min on stream in methane conversion;
the nature of these particles was studied in detail by
HRTEM and electron paramagnetic resonance in [16]
(Fig. 6a). The catalyst contains the highest amount of
Mo–Re clusters with a size of less than 1 nm, which
After 380 min on stream in the nonoxidative con- are localized in the channels and cavities of the zeolite
version of methane, the 5.0%Re/ZSM-5 catalyst con- (Fig. 6b). These clusters are aggregated to form larger
tains Re particles differing in size and morphology particles (2–5 nm), which are localized in the large
(Fig. 5). It is evident that rhenium emerges to the sur- inner cavities and on the outer surface of the zeolite.
PETROLEUM CHEMISTRY Vol. 59 No. 1 2019

96
STEPANOV et al.
0.2 μm
20 nm
(а)
(b)
Re:
5 nm
5 nm
(c)
(d)
Fig. 5. High-angle annular dark-field STEM image of the 5.0%Re/ZSM-5 catalyst exposed to methane for 380 min: (a) Re par-
ticles, (b) carbon deposits on the zeolite surface, (c) a Re particle with carbon deposits, and (d) Re particles in the zeolite chan-
nels.
Unlike the catalyst containing 0.5% Re, the zeolite size of <1 to 2–5 nm, which are localized both in the
surface in the 1.0%Re–4.0%Mo/ZSM-5 sample, after
reaction, contains, in addition to Mo particles, small
and large elongated Re particles: I × d = (20 –30) ×
(1–2) nm (Fig. 7a). In addition, Mo–Re clusters and
nanoparticles localized in the channels and cavities of
the zeolite are observed (Fig. 7b).
zeolite channels and on the outer surface. An increase
in the Re concentration to 1.0% leads to the formation
of small and large elongated Re particles. The forma-
tion of rhenium particles and Mo–Re clusters in the
catalyst leads to an increase in the catalyst activity and
stability in the nonoxidative conversion of methane
[8]. The fact that the activity of the 5.0%Re/ZSM-5
catalyst is lower than the activity of the
Thus, electron microscopic studies have shown
that Re–Mo/ZSM-5 catalysts are characterized by the
presence of a large number of Mo–Re clusters with a 4.0%Mo/ZSM-5 sample is attributed to the absence
PETROLEUM CHEMISTRY
Vol. 59
No. 1
2019

NONOXIDATIVE CONVERSION OF METHANE
97
0.2 μm
50 nm
(а)
(b)
Fig. 6. High-angle annular dark-field STEM image of the 0.5%Re–4.0%Mo/ZSM-5 catalyst exposed to methane for 380 min:
(a) large Mo particles and (b) Mo–Re clusters.
0.5 μm
50 nm
(а)
(b)
Fig. 7. High-angle annular dark-field STEM image of the 1.0%Re–4.0%Mo/ZSM-5 catalyst exposed to methane for 340 min:
(a) Re particles and (b) Mo–Re clusters.
of a rhenium carbide phase in it under methane dehy- formation of Re particles and Mo–Re clusters that are
droaromatization reaction conditions.
active in this process.
Thus, rhenium modification of a Mo/ZSM-5 cat-
alyst leads to an increase in the catalyst activity and
stable on-stream time in methane conversion to aro-
matic compounds. The highest activity and stability is
ACKNOWLEDGMENTS
This work was performed under the Basic Research
exhibited by the 0.5%Re–4.0%Mo/ZSM-5 catalyst. Program of State Academies of Sciences, project
The increase in the catalyst activity is attributed to the no. V.46.2.1.
PETROLEUM CHEMISTRY Vol. 59 No. 1 2019

98
STEPANOV et al.
9. M. A. Ryashentseva and Kh. M. Minachev, Usp.
REFERENCES
1. Y. Xu and L. Lin, Appl. Catal., A 188, 53 (1999).
2. L. Wang, R. Ohnishi, and M. Ichikawa, J. Catal. 190,
Khim. 38, 2050 (1969).
10. F. Solymosi, J. Cserenyi, A. Szoke, et al., J. Catal. 165,
150 (1997).
276 (2000).
11. D. Wang, J. H. Lunsford, and M. P. Rosynek, J. Catal.
3. A. Szoke and F. Solymosi, Appl. Catal., A 142, 361
169, 347 (1997).
(1996).
12. S. Liu, L. Wang, R. Ohnishi, and M. Ichikawa, J. Catal.
4. R. Kojima, S. Kikuchi, H. T. Ma, et al., Catal. Lett.
181, 175 (1999).
110, 15 (2006).
13. R. W. Borry, Y. H. Kim, A. Huffsmith, et al., J. Phys.
Chem. B 103, 5787 (1999).
5. V. Abdelsayed, D. Shekhawat, and M. W. Smith, Fuel
139, 401 (2015).
14. Y. Xu, Y. Shu, S. Liu, et al., Catal. Lett. 35, 233 (1995).
6. S. Maihi, P. Mohanty, H. Wang, and K. K. Pant, J.
15. L. Wang, R. Ohnishi, and M. Ichikawa, J. Catal. 190,
Energy Chem. 22, 543 (2013).
276 (2000).
7. V. I. Bukhtiyarov, V. I. Zaikovskii, A. S. Kashin, and
16. V. I. Zaikovskii, A. V. Vosmerikov, V. F. Anufrienko,
V. P. Ananikov, Usp. Khim. 85, 1198 (2016).
et al., Kinet. Catal. 47, 389 (2006).
8. R. Ohnishi and M. Ichikawa, Catal. Surv. Jpn. 5, 103
Translated by M. Timoshinina
(2002).
PETROLEUM CHEMISTRY
Vol. 59
No. 1
2019